Backgrou nd Dense titanium(Ti)fusion cages have been commonly used in transforaminal lumbar interbody fusion.However,the stiffness mismatch between cages and adjacent bone endplates increases the risk of stress shield...Backgrou nd Dense titanium(Ti)fusion cages have been commonly used in transforaminal lumbar interbody fusion.However,the stiffness mismatch between cages and adjacent bone endplates increases the risk of stress shielding and cage subsidence.Methods The current study presents a multiscale optimization approach for porous Ti fusion cage development,including microscale topology optimization based on homogenization theory that obtains a unit cell with prescribed mechanical properties,and macroscale topology optimization that determines the layout of framework structure over the porous cage while maintaining the desired stiffness.The biomechanical performance of the designed porous cage is assessed using numerical simulations of fusion surgery.Selective laser melting is employed to assists with fabricating the designed porous structure and porous cage.Results The simulations demonstrate that the designed porous cage increases the strain energy density of bone grafts and decreases the peak stress on bone endplates.The mechanical and morphological discrepancies between the as-designed and fabricated porous structures are also described.Conclusion From the perspective of biomechanics,it is demonstrated that the designed porous cage contributes to reducing the risk of stress shielding and cage subsidence.The optimization of processing parameters and post-treatments are required to fabricate the designed porous cage.The present multiscale optimization approach can be extended to the development of cages with other shapes or materials and further types of orthopedic implants.展开更多
A mesoporous UiO-66-NH_(2) aerogel is prepared via a straightforward sol-gel method without using any binders or mechanical pressures, in which the amine groups are directly introduced into the matrix by using 2-amino...A mesoporous UiO-66-NH_(2) aerogel is prepared via a straightforward sol-gel method without using any binders or mechanical pressures, in which the amine groups are directly introduced into the matrix by using 2-aminoterephthalic acid. The novel UiO-66-NH_(2) aerogel also exhibits high specific surface area and mesopore-dominated structure, implying its highly potential use in CO_(2) adsorption. For ulteriorly investigating the effect of amine loading on the CO_(2) adsorption ability, a series of UiO-66-NH_(2) aerogel with different amino content is fabricated by changing the ligand/metal molar ratio. When the molar ratio is 1.45, the CO_(2) adsorption capacity reaches the optimum value of 2.13 mmol·g^(-1) at 25 ℃ and 0.1 MPa, which is 12.2% higher than that of pure UiO-66 aerogel. Additionally, UiO-66-NH_(2)-1.45 aerogel also has noticeable CO_(2) selectivity against N_(2) and CH_(4) as well as good regeneration stability. Such results imply that it has good application prospect in the field of CO_(2) adsorption, and also contains the potential to be applied in catalysis, separation and other fields.展开更多
During molten salt cleaning of remanufactured 27SiMn hydraulic support column,oxidation occurs on the surface of metal substrate.This results in a change of the surface roughness of metal substrate after cleaning,whic...During molten salt cleaning of remanufactured 27SiMn hydraulic support column,oxidation occurs on the surface of metal substrate.This results in a change of the surface roughness of metal substrate after cleaning,which affects subsequent remanufacturing process.To decrease the effect is very important.This paper analyzed the oxidation mechanism of molten salt cleaning,explored the oxidation reaction that occurred during cleaning,and determined the key process parameters of cleaning that affecting oxidation reaction.By using central composite experimental design method and taking surface roughness variation of 27SiMn steel samples before and after molten salt cleaning as response variable to optimize the key process parameters,the optimal parameters of molten salt for cleaning remanufactured 27SiMn hydraulic support column could be obtained.The results show that the oxidation reaction of cleaning paint dirt can protect metal substrate from oxidation to a certain extent,and cleaning temperature and placement depth of metal substrate have a direct impact on the degree of oxidation reaction.When the cleaning temperature is 300℃and the distance between paint dirt and free surface of molten salt is 0.5 times the height of the parts,the surface roughness variation is minimal.Therefore,the cleaning quality will be improved under such parameters.展开更多
In order to reduce the temperature difference caused by condensed water in vulcanized tire capsules,the flow field and temperature field inside vulcanized tire capsules were numerically simulated by setting three diff...In order to reduce the temperature difference caused by condensed water in vulcanized tire capsules,the flow field and temperature field inside vulcanized tire capsules were numerically simulated by setting three different intake angles based onvolume of fluid(VOF)multiphase flow model.When the intake air is blown to the upper and lower tire sides of the vulcanized capsule at 18°from the horizontal direction,the distribution of condensed water at the bottom of the capsule changes obviously due to the effect of vorticity flow,and the distribution along the wall is more uniform.When the inlet air is blown down the tire side,the condensate is most evenly distributed along the wall,and the maximum temperature difference drops to 9.5℃.The results show that changing the distribution of condensed water by adjusting the proper intake angle can effectively reduce the temperature difference of condensed water in vulcanized capsules.展开更多
Bioactive coating of ceramic scaffolds is an effective way to ameliorate osseointegration and attenuate implant-induced inflammatory responses,which should be biocompatible and possess suitable mechani-cal properties ...Bioactive coating of ceramic scaffolds is an effective way to ameliorate osseointegration and attenuate implant-induced inflammatory responses,which should be biocompatible and possess suitable mechani-cal properties to regulate cell adhesion and migration.In this study,a poly(ethylene glycol)diacry-late/tricalcium phosphate(PEGDA/TCP)ceramic scaffold was prepared using SLA-3D printing,and its com-pressive strength was 8.9±1.0 MPa.Chitosan(Chi)and chondroitin sulfate(CS)were assembled on the sur-face of the PEGDA/TCP scaffolds and crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide(EDC/NHS).Scanning electron microscope(SEM),Fourier transform infrared(FTIR),and laser scanning microscope were used to evaluate the surface modification of the PEGDA/TCP scaffolds.Cellu-lar tests showed that polyelectrolyte multilayers(PEMs)promoted cell adhesion and proliferation of osteoblasts relative to unmodified scaffolds.Furthermore,it can be demonstrated that the SLA-3D printed TCP scaffolds could meet the compressive requirements of trabecular bones,and the bioactivity of the bone scaffolds could be effectively improved by combining them with Chi/CS PEM.展开更多
Laser cladding is a new surface modification technology, and is widely used for fabricating wear and corrosion resistant composites coatings. Self-fluxing alloys have many advantages, such as excellent properties of d...Laser cladding is a new surface modification technology, and is widely used for fabricating wear and corrosion resistant composites coatings. Self-fluxing alloys have many advantages, such as excellent properties of deoxidizing and slagging, high wear resistance, low melting point and easy cladding, and are often used in laser cladding to improve wear and corrosion resistance of titanium and its alloys. In this paper, the recent development of Ni-based and Co-based self-fluxing alloy coatings which includes the influenee of rare earth and ceramic particles in coatings are summarized. Besides, the effects of processing parameters, such as laser power and scanning speed, on coatings are reviewed. Finally, the trend of development in the future is forecasted.展开更多
Material removal in the cutting process is regarded as a friction system with multiple input and output variables.The complexity of the cutting friction system is caused by the extreme conditions existing on the tool...Material removal in the cutting process is regarded as a friction system with multiple input and output variables.The complexity of the cutting friction system is caused by the extreme conditions existing on the tool–chip and tool–workpiece interfaces.The critical issue is significant to use knowledge of cutting friction behaviors to guide researchers and industrial manufacturing engineers in designing rational cutting processes to reduce tool wear and improve surface quality.This review focuses on the state of the art of research on friction behaviors in cutting procedures as well as future perspectives.First,the cutting friction phenomena under extreme conditions,such as high temperature,large strain/strain rates,sticking–sliding contact states,and diverse cutting conditions are analyzed.Second,the theoretical models of cutting friction behaviors and the application of simulation technology are discussed.Third,the factors that affect friction behaviors are analyzed,including material matching,cutting parameters,lubrication/cooling conditions,micro/nano surface textures,and tool coatings.Then,the consequences of the cutting friction phenomena,including tool wear patterns,tool life,chip formation,and the machined surface are analyzed.Finally,the research limitations and future work for cutting friction behaviors are discussed.This review contributes to the understanding of cutting friction behaviors and the development of high-quality cutting technology.展开更多
The application of cutting fluid is significantly increased in the machining sector to improve productivity.However,the inherent characteristics of cutting fluids on ecology,environment,and society shift the interest ...The application of cutting fluid is significantly increased in the machining sector to improve productivity.However,the inherent characteristics of cutting fluids on ecology,environment,and society shift the interest of researchers to work on environmentally friendly cooling conditions such as cryogenic cooling.Here,the effect of cutting speed and feed rate on the machining performance of the AISI‑L6 tool steel is investigated under cryogenic cooling conditions.Then,the L9 Taguchi based grey relational analysis(GRA)is conducted to investigate the essential machining indices such as cutting energy,surface roughness,tool wear,and material removal rate(MRR).The results indicate that the cutting speed of 160 m/min and feed rate of 0.16 mm/r are the optimum parameters that significantly improves the machining performance of AISI‑L6 tool steel.展开更多
To address the problem of conventional approaches for mechanical property determination requiring destructive sampling, which may be unsuitable for in-service structures, the authors proposed a method for determining ...To address the problem of conventional approaches for mechanical property determination requiring destructive sampling, which may be unsuitable for in-service structures, the authors proposed a method for determining the quasi-static fracture toughness and impact absorbed energy of ductile metals from spherical indentation tests (SITs). The stress status and damage mechanism of SIT, mode I fracture, Charpy impact tests, and related tests were frst investigated through fnite element (FE) calculations and scanning electron microscopy (SEM) observations, respectively. It was found that the damage mechanism of SITs is diferent from that of mode I fractures, while mode I fractures and Charpy impact tests share the same damage mechanism. Considering the diference between SIT and mode I fractures, uniaxial tension and pure shear were introduced to correlate SIT with mode I fractures. Based on this, the widely used critical indentation energy (CIE) model for fracture toughness determination using SITs was modifed. The quasi-static fracture toughness determined from the modifed CIE model was used to evaluate the impact absorbed energy using the dynamic fracture toughness and energy for crack initiation. The efectiveness of the newly proposed method was verifed through experiments on four types of steels: Q345R, SA508-3, 18MnMoNbR, and S30408.展开更多
Needle biopsy is an essential part of modern clinical medicine.The puncture accuracy and sampling success rate of puncture surgery can be effectively improved through virtual surgery.There are few three-dimensional pu...Needle biopsy is an essential part of modern clinical medicine.The puncture accuracy and sampling success rate of puncture surgery can be effectively improved through virtual surgery.There are few three-dimensional puncture(3D)models,which have little significance for surgical guidance under complicated conditions and restrict the development of virtual surgery.In this paper,a 3D simulation of the muscle tissue puncture process is studied.Firstly,the mechanical properties of muscle tissue are measured.The Mooney-Rivlin(M-R)model is selected by considering the fitting accuracy and calculation speed.Subsequently,an accurate 3D dynamic puncture model is established.The failure criterion is used to define the breaking characteristics of the muscle,and the bilinear cohesion model defines the breaking process.Experiments with different puncture speeds are carried out through the built in vitro puncture platform.The experimental results are compared with the simulation results.The experimental and simulated reaction force curves are highly consistent,which verifies the accuracy of the model.Finally,the model under different parameters is studied.The simulation results of varying puncture depths and puncture speeds are analyzed.The 3D puncture model can provide more accurate model support for virtual surgery and help improve the success rate of puncture surgery.展开更多
Fused deposition modeling(FDM)has unique advantages in the rapid prototyping of thermoplastics which have been developed in diverse fields.However,although great efforts have been made to optimize FDM process,the mech...Fused deposition modeling(FDM)has unique advantages in the rapid prototyping of thermoplastics which have been developed in diverse fields.However,although great efforts have been made to optimize FDM process,the mechanical properties of printed parts are limited by the weak interlamination bonding as well as the poor performance of raw filaments used,such as acrylonitrile butadiene styrene(ABS),polylactic acid(PLA).Adding fibers into thermoplastic matrix and preparing high-performance filaments have been indicated to enhance the properties of fabricated parts.Recently,heat-resistant polyetheretherketone(PEEK)and its fiber reinforced composites were proposed for FDM process due to overcoming the limitation of equipment and process.However,few researches have been reported on the effects of FDM-3 D printing parameters on the mechanical properties of fiber reinforced PEEK composites.Therefore,5 wt%carbon fiber(CF)and glass fiber(GF)reinforced PEEK composite filaments were prepared respectively in this study.The effects of various printing parameters including nozzle temperature,platform temperature,printing speed and layer thickness on the mechanical properties(including tensile strength,flexural strength and impact strength)were surveyed.To analyze the microstructure and failure reasons of printed CF/PEEK and GF/PEEK samples,the tensile fractured surfaces were investigated via scanning electron microscope(SEM).展开更多
Selective laser melting(SLM)has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features.Therefore,this study invest...Selective laser melting(SLM)has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features.Therefore,this study investigated the effects of the process parameters and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V fabricated using SLM.The influences of various process parameters on the relative density,tensile properties,impact toughness,and hardness of Ti-6Al-4V alloy parts were studied.By employing parameter optimization,a high-density high-strength Ti-6Al-4V alloy was fabricated by SLM.A relative density of 99.45%,a tensile strength of 1188 MPa,and an elongation to failure of 9.5%were achieved for the SLM-fabricated Ti-6Al-4V alloy with optimized parameters.The effects of annealing and solution aging heat treatment on the mechanical properties,phase composition,and microstructure of the SLM-fabricated Ti-6Al-4V alloy were also studied.The ductility of the heat-treated Ti-6Al-4V alloy was improved.By applying a heat treatment at 850℃ for 2 h,followed by furnace cooling,the elongation to failure and impact toughness were found to be increased from 9.5%to 12.5%,and from 24.13 J/cm^(2)to 47.51 J/cm^(2),respectively.展开更多
The integration of ultrasonic vibration into sheet forming process can significantly reduce the forming force and bring benefits including the enhancement of surface quality,the enhancement of formability and the redu...The integration of ultrasonic vibration into sheet forming process can significantly reduce the forming force and bring benefits including the enhancement of surface quality,the enhancement of formability and the reduction of spring-back.However,the influencing mechanisms of the high-frequency vibration on parts properties during the incremental sheet forming(ISF)process are not well known,preventing a more efficient forming system.This paper comprehensively investigates the effects of different process parameters(vibration amplitude,step-down size,rotation speed and forming angle)on the micro-hardness,minimum thickness,forming limit and residual stress of the formed parts.First,a series of truncated pyramids were formed with an experimental platform designed for the ultrasonic-assisted incremental sheet forming.Then,microhardness tests,minimum thickness measurements and residual stress tests were performed for the formed parts.The results showed that the surface micro-hardness of the formed part was reduced since the vibration stress induced by the ultrasonic vibration within the material which eliminated the original internal stress.The superimposed University,Beijing 100083,People’s Republic of China ultrasonic vibration can effectively uniform the residual stress and thickness distribution,arid improve the forming limit in the case of the small deformation rate.In addition,through the tensile fracture analysis of the formed part,it is shown that the elongation of material is improved and the elastic modulus and hardening index are decreased.The findings of the present work lay the foundation for a better integration of the ultrasonic vibration system into the incremental sheet forming process.展开更多
Although incremental sheet forming(ISF)is an efficient way to manufacture customized parts,the forming performance and geometric accuracy of formed parts need to be improved to meet industrial application.One feasible...Although incremental sheet forming(ISF)is an efficient way to manufacture customized parts,the forming performance and geometric accuracy of formed parts need to be improved to meet industrial application.One feasible solution for these problems is to adopt proper heat treatment strategies for the sheet material both before and during the forming process.In this paper,the effects of heat treatment before forming and heat-assisted forming on the formability and performance of formed parts were experimentally investigated.First,TA1 sheets were heat-treated at different temperatures before forming,and then the sheets were incrementally formed into the target shape with variable angles at different temperatures.After heat treatment,the strength of sheets was decreased due to the occurrence of recrystallization and the growth of grains.Meanwhile,the surface quality of formed parts was also improved with pre-heat treatment before forming.During the heat-assisted forming process,the sheet was softened and the deformation resistance was reduced with the increase of temperature.Therefore,the axial forming force was decreased obviously and the formability of the sheet was increased obviously.Furthermore,by adopting both heat treatment and heat-assisted forming,it was found that the forming force could be further reduced and the formability of the sheet and surface quality could be further improved.As for geometric accuracy,heat treatment has a good effect on improving it,while heat-assisted forming has adverse effect.These findings provide an effective heat treatment strategy for improving the geometric accuracy and surface quality of the incrementally formed parts with lower forming force.展开更多
During ultrasonic vibration-assisted machining,the large impact force induced by tool-workpiece reengagement(TWR)is an important factor that affects tool chipping.However,mechanical analysis into process factors that ...During ultrasonic vibration-assisted machining,the large impact force induced by tool-workpiece reengagement(TWR)is an important factor that affects tool chipping.However,mechanical analysis into process factors that affect the impact force and their influencing mechanisms are insufficient.Herein,a prediction model for the instantaneous cutting force during both TWR and the stable turning process,which depends on the process parameters and material properties,is firstly proposed based on the kinematic and dynamic analysis of ultrasonic vibration-assisted oblique turning(UVAOT).The results calculated using the developed cutting force model agree well with the experimental results presented in the literature.Next,the linear change law of the instantaneous cutting force with cutting time during the actual TWR is clarified using the proposed model.The effect of the UVAOT process parameters on the average impact force during the periodic TWR process is discussed,and the influence mechanism is analyzed from the perspective of mechanics.A positive linear correlation is discovered between the feed speed and average impact force.The ultrasonic amplitude and cutting speed do not significantly affect the average impact force of the new sharp cutting tools.These findings are consistent with the experimental observations of tool chipping and are applicable to select process parameters for reducing tool chipping during UVAOT.展开更多
Large amounts of microplastics(MPs)have been found in rivers and oceans,bringing great harm to aquatic animals,plants,even human beings.However,the effective removal method of MPs,especially those with small sizes(5-...Large amounts of microplastics(MPs)have been found in rivers and oceans,bringing great harm to aquatic animals,plants,even human beings.However,the effective removal method of MPs,especially those with small sizes(5-20 μm)is still lacking.This work presents mini-hydrocyclones to remove 10 μm(average size)diameter MPs.The removal performance of nine mini-hydrocyclones with different diameters of spigot and vortex finder is examined experimentally and numerically.The performance of the designed cyclones is evaluated in terms of recovery,water split,concentration ratio and pressure drop.The results show that mini-hydrocyclones are applicable to removing small-size MPs with the maximum concentra-tion ratio at 2.16 and the particle recovery at 51%.The flow characteristics inside the mini-hydrocyclones are analyzed in detail.It is shown that the distributions of water axial velocity and radial velocity could collectively affect the behaviors of small-size MPs in mini-hydrocyclones.Specifically,a larger amount of water split could entrain more fine particles to underflow.Meanwhile,a less frequent alternation of radial velocity between the positive and negative directions on the same side of the cyclone should benefit the removal of small-size MPs.展开更多
Whirling has been adopted for the cost-effective machining of blade-shape components in addition to traditional end milling and flank milling processes.To satisfy the requirements of rotary forming in the blade whirli...Whirling has been adopted for the cost-effective machining of blade-shape components in addition to traditional end milling and flank milling processes.To satisfy the requirements of rotary forming in the blade whirling process,the workpiece must be clamped at both ends in suspension and rotated slowly during machining,which complicates the dynamics.This study aims to identify the dynamic characteristics within the blade whirling operation and present strategies for stability prediction.In this study,the dynamic characteristics of a whirling system are modeled by assuming symmetric and asymmetric parameters.Theoretical prediction frequency response function(FRF)results are compared with experimental results.Moreover,semi-discretization stability lobe diagrams(SLDs)obtained using the dynamic parameters of these models are investigated experimentally.The results show that the asymmetric model is more suitable for describing the whirling system,whereas the symmetric model presents limitations associated with the frequency range and location of measuring points.Finally,a set of airfoil propeller blade whirling operations is conducted to verify the prediction accuracy.展开更多
Flanks of end mills are prone to wear in a long machining process.Regrinding is widely used in workshops to restore the flank to an original-like state.However,the traditional method involves material waste by trial a...Flanks of end mills are prone to wear in a long machining process.Regrinding is widely used in workshops to restore the flank to an original-like state.However,the traditional method involves material waste by trial and error and dramatically decreases the potential regrinding.Moreover,over-cut would happen to the flutes of worn cutters in the regrinding processes because of improper wheel path.This study presented a new approach to planning the wheel path for regrinding worn end mills to minimize material loss and recover the over-cut.In planning,a scaling method was developed to determine the maximum size of the new cutter according to the similarity of cutter shapes before and after regrinding.Then,the wheel path is first generated by envelope theory to regrind the worn area with a four-axis computer numerical control grinder according to the new size of cutters.Moreover,a second regrinding strategy is applied to recover the flute shape over-cut in the first grinding.Finally,the proposed method is verified by an experiment.Results showed that the proposed approach could save 25%of cutter material compared with the traditional method and ensure at least three regrinding times.This work effectively provides a general regrinding solution for the worn flank with maximum material-saving and regrinding period.展开更多
Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,etc.Despite many review papers promoting the understanding and research of this area,chatter su...Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,etc.Despite many review papers promoting the understanding and research of this area,chatter suppression techniques are generally discussed within limited pages in the framework of comprehensive chatter-related problems.In recent years,the developments of smart materials,advanced sensing techniques,and more effective control strategies have led to some new progress in chatter suppression.Meanwhile,the widely used thin-walled parts present more and more severe machining challenges in their milling processes.Considering the above deficiencies,this paper summarizes the current state of the art in milling chatter suppression.New classifications of chatter suppression techniques are proposed according to the working principle and control target.Based on the new classified framework,the mechanism and comparisons of different chatter suppression strategies are reviewed.Besides,the current challenges and potential tendencies of milling chatter suppression techniques are highlighted.Intellectualization,integration,compactness,adaptability to workpiece geometry,and the collaboration of multiple control methods are predicted to be important trends in the future.展开更多
Laser directed energy deposition(LDED)is widely used in the remanufacturing and surface strengthening of high-value thin-walled components.However,the transformation mechanism of mechanical properties for substrates i...Laser directed energy deposition(LDED)is widely used in the remanufacturing and surface strengthening of high-value thin-walled components.However,the transformation mechanism of mechanical properties for substrates induced by laser deposition,especially for thin metal sheets,remains unclear.In this study,the affecting mechanism of Fe_(3)0_(4)coatings fabricated by LDED on the ductility of Q235 thin plates was investigated.Samples of original substrate(OS),deposited plates with one to three layers of coating(D1–D3),the substrate zone of deposited plates with one to three layers of coating(D1-S–D3-S),and deposited coating were prepared to evaluate the effect of coating and laser heat on substrate ductility.The Fe_(3)0_(4)coating deposited by LDED and the accompanying laser heat drastically reduced substrate ductility by about 87%.Specifically,laser heat reduced the ductility by 24%–51%.The Fe_(3)0_(4)coating deposited by LDED led to the ductile-to-brittle transition of the substrate.Compared with ductile dimples in the OS,cleavage fracture was found in the substrate of deposited plates.Meanwhile,the mechanisms of ductile-tobrittle transition of the substrate were analyzed.Laser heat caused the precipitation of cementite and the generation of a decarburization layer in the substrate.Coating resulted in the pileup of dislocations in the substrate,then nonuniform deformation occurred in the substrate.The cracks of the coating fracture extended to the substrate,inducing local cracking of the substrate.This study provides fundamental guidance for the surface manufacturing of ductile thin-walled components through LDED.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51975336)the Key Basic Research Project of Natural Science Foundation of Shandong Province,China(No.ZR2018ZB0106)the Key Research and Development Program of Shandong Province,China(No.2019JZZY010112)。
文摘Backgrou nd Dense titanium(Ti)fusion cages have been commonly used in transforaminal lumbar interbody fusion.However,the stiffness mismatch between cages and adjacent bone endplates increases the risk of stress shielding and cage subsidence.Methods The current study presents a multiscale optimization approach for porous Ti fusion cage development,including microscale topology optimization based on homogenization theory that obtains a unit cell with prescribed mechanical properties,and macroscale topology optimization that determines the layout of framework structure over the porous cage while maintaining the desired stiffness.The biomechanical performance of the designed porous cage is assessed using numerical simulations of fusion surgery.Selective laser melting is employed to assists with fabricating the designed porous structure and porous cage.Results The simulations demonstrate that the designed porous cage increases the strain energy density of bone grafts and decreases the peak stress on bone endplates.The mechanical and morphological discrepancies between the as-designed and fabricated porous structures are also described.Conclusion From the perspective of biomechanics,it is demonstrated that the designed porous cage contributes to reducing the risk of stress shielding and cage subsidence.The optimization of processing parameters and post-treatments are required to fabricate the designed porous cage.The present multiscale optimization approach can be extended to the development of cages with other shapes or materials and further types of orthopedic implants.
基金supported by the National Natural Science Foundation of China (21603125)Science-Education-Industry Integration Innovation Pilot Project of Qilu University of Technology (2020KJC-GH13)+2 种基金International Cooperation Project of Shandong Academy of Sciences (2019GHPY09)Natural Science Foundation of Shandong Province (ZR2019BEM025)Young doctor Cooperation Foundation of Qilu University of Technology (Shandong Academy of Sciences) (2019BSHZ0016)。
文摘A mesoporous UiO-66-NH_(2) aerogel is prepared via a straightforward sol-gel method without using any binders or mechanical pressures, in which the amine groups are directly introduced into the matrix by using 2-aminoterephthalic acid. The novel UiO-66-NH_(2) aerogel also exhibits high specific surface area and mesopore-dominated structure, implying its highly potential use in CO_(2) adsorption. For ulteriorly investigating the effect of amine loading on the CO_(2) adsorption ability, a series of UiO-66-NH_(2) aerogel with different amino content is fabricated by changing the ligand/metal molar ratio. When the molar ratio is 1.45, the CO_(2) adsorption capacity reaches the optimum value of 2.13 mmol·g^(-1) at 25 ℃ and 0.1 MPa, which is 12.2% higher than that of pure UiO-66 aerogel. Additionally, UiO-66-NH_(2)-1.45 aerogel also has noticeable CO_(2) selectivity against N_(2) and CH_(4) as well as good regeneration stability. Such results imply that it has good application prospect in the field of CO_(2) adsorption, and also contains the potential to be applied in catalysis, separation and other fields.
基金supported by the National Natural Science Foundation of China(No.51375278)。
文摘During molten salt cleaning of remanufactured 27SiMn hydraulic support column,oxidation occurs on the surface of metal substrate.This results in a change of the surface roughness of metal substrate after cleaning,which affects subsequent remanufacturing process.To decrease the effect is very important.This paper analyzed the oxidation mechanism of molten salt cleaning,explored the oxidation reaction that occurred during cleaning,and determined the key process parameters of cleaning that affecting oxidation reaction.By using central composite experimental design method and taking surface roughness variation of 27SiMn steel samples before and after molten salt cleaning as response variable to optimize the key process parameters,the optimal parameters of molten salt for cleaning remanufactured 27SiMn hydraulic support column could be obtained.The results show that the oxidation reaction of cleaning paint dirt can protect metal substrate from oxidation to a certain extent,and cleaning temperature and placement depth of metal substrate have a direct impact on the degree of oxidation reaction.When the cleaning temperature is 300℃and the distance between paint dirt and free surface of molten salt is 0.5 times the height of the parts,the surface roughness variation is minimal.Therefore,the cleaning quality will be improved under such parameters.
基金supported in part by the National Natural Science Foundation of China(No.52176040)Shandong Natural Science Foundation(No.ZR2021ME161)the Science and Technology SMES Innovation Ability Improvement of Shandong Province(No.2023TSGC0290)。
文摘In order to reduce the temperature difference caused by condensed water in vulcanized tire capsules,the flow field and temperature field inside vulcanized tire capsules were numerically simulated by setting three different intake angles based onvolume of fluid(VOF)multiphase flow model.When the intake air is blown to the upper and lower tire sides of the vulcanized capsule at 18°from the horizontal direction,the distribution of condensed water at the bottom of the capsule changes obviously due to the effect of vorticity flow,and the distribution along the wall is more uniform.When the inlet air is blown down the tire side,the condensate is most evenly distributed along the wall,and the maximum temperature difference drops to 9.5℃.The results show that changing the distribution of condensed water by adjusting the proper intake angle can effectively reduce the temperature difference of condensed water in vulcanized capsules.
基金supported by National Key Research and Development Project of China(Grant.No.2022YFB4601403)National Natural Science Foundation of China(Grant.No.52175336).
文摘Bioactive coating of ceramic scaffolds is an effective way to ameliorate osseointegration and attenuate implant-induced inflammatory responses,which should be biocompatible and possess suitable mechani-cal properties to regulate cell adhesion and migration.In this study,a poly(ethylene glycol)diacry-late/tricalcium phosphate(PEGDA/TCP)ceramic scaffold was prepared using SLA-3D printing,and its com-pressive strength was 8.9±1.0 MPa.Chitosan(Chi)and chondroitin sulfate(CS)were assembled on the sur-face of the PEGDA/TCP scaffolds and crosslinked with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide/N-hydroxysuccinimide(EDC/NHS).Scanning electron microscope(SEM),Fourier transform infrared(FTIR),and laser scanning microscope were used to evaluate the surface modification of the PEGDA/TCP scaffolds.Cellu-lar tests showed that polyelectrolyte multilayers(PEMs)promoted cell adhesion and proliferation of osteoblasts relative to unmodified scaffolds.Furthermore,it can be demonstrated that the SLA-3D printed TCP scaffolds could meet the compressive requirements of trabecular bones,and the bioactivity of the bone scaffolds could be effectively improved by combining them with Chi/CS PEM.
基金supported by the Shandong Provincial Key Research and Development Plan(Project No.2016GGX102018)Shandong Provincial Natural Science Foundation,China(Project No.ZR2017MEE063)
文摘Laser cladding is a new surface modification technology, and is widely used for fabricating wear and corrosion resistant composites coatings. Self-fluxing alloys have many advantages, such as excellent properties of deoxidizing and slagging, high wear resistance, low melting point and easy cladding, and are often used in laser cladding to improve wear and corrosion resistance of titanium and its alloys. In this paper, the recent development of Ni-based and Co-based self-fluxing alloy coatings which includes the influenee of rare earth and ceramic particles in coatings are summarized. Besides, the effects of processing parameters, such as laser power and scanning speed, on coatings are reviewed. Finally, the trend of development in the future is forecasted.
基金financial support from the National Key Research and Development Program of China (2019YFB2005401)National Natural Science Foundation of China (Nos. 91860207 and 52175420)+5 种基金Shandong Provincial Key Research and Development Program (Major Scientific and Technological Innovation Project)(No. 2020CXGC010204)Shandong Provincial Natural Science Foundation of China (2021JMRH0301 and2021JMRH0304)Taishan Scholar FoundationInternational Partnership Scheme of the Bureau of the International Scientific Cooperation of the Chinese Academy of Sciences(No. 181722KYSB20180015)Research and Innovation Office of The Hong Kong Polytechnic University (BBX5and BBX7)funding support to the State Key Laboratories in Hong Kong
文摘Material removal in the cutting process is regarded as a friction system with multiple input and output variables.The complexity of the cutting friction system is caused by the extreme conditions existing on the tool–chip and tool–workpiece interfaces.The critical issue is significant to use knowledge of cutting friction behaviors to guide researchers and industrial manufacturing engineers in designing rational cutting processes to reduce tool wear and improve surface quality.This review focuses on the state of the art of research on friction behaviors in cutting procedures as well as future perspectives.First,the cutting friction phenomena under extreme conditions,such as high temperature,large strain/strain rates,sticking–sliding contact states,and diverse cutting conditions are analyzed.Second,the theoretical models of cutting friction behaviors and the application of simulation technology are discussed.Third,the factors that affect friction behaviors are analyzed,including material matching,cutting parameters,lubrication/cooling conditions,micro/nano surface textures,and tool coatings.Then,the consequences of the cutting friction phenomena,including tool wear patterns,tool life,chip formation,and the machined surface are analyzed.Finally,the research limitations and future work for cutting friction behaviors are discussed.This review contributes to the understanding of cutting friction behaviors and the development of high-quality cutting technology.
基金the National Natural Science Foundation of China(No.51922066)the Natural Science Outstanding Youth Fund of Shandong Province(No.ZR2019JQ19)+1 种基金the National Key Research and Development Program(No.2018YFB2002201)the Key Laboratory of High‑Efficiency and Clean Mechanical Manufacture at Shandong University,Ministry of Education。
文摘The application of cutting fluid is significantly increased in the machining sector to improve productivity.However,the inherent characteristics of cutting fluids on ecology,environment,and society shift the interest of researchers to work on environmentally friendly cooling conditions such as cryogenic cooling.Here,the effect of cutting speed and feed rate on the machining performance of the AISI‑L6 tool steel is investigated under cryogenic cooling conditions.Then,the L9 Taguchi based grey relational analysis(GRA)is conducted to investigate the essential machining indices such as cutting energy,surface roughness,tool wear,and material removal rate(MRR).The results indicate that the cutting speed of 160 m/min and feed rate of 0.16 mm/r are the optimum parameters that significantly improves the machining performance of AISI‑L6 tool steel.
基金Supported by National Natural Science Foundation of China(Grant No.52275154)National Key Research and Development Project of China(Grant No.2016YFF0203005).
文摘To address the problem of conventional approaches for mechanical property determination requiring destructive sampling, which may be unsuitable for in-service structures, the authors proposed a method for determining the quasi-static fracture toughness and impact absorbed energy of ductile metals from spherical indentation tests (SITs). The stress status and damage mechanism of SIT, mode I fracture, Charpy impact tests, and related tests were frst investigated through fnite element (FE) calculations and scanning electron microscopy (SEM) observations, respectively. It was found that the damage mechanism of SITs is diferent from that of mode I fractures, while mode I fractures and Charpy impact tests share the same damage mechanism. Considering the diference between SIT and mode I fractures, uniaxial tension and pure shear were introduced to correlate SIT with mode I fractures. Based on this, the widely used critical indentation energy (CIE) model for fracture toughness determination using SITs was modifed. The quasi-static fracture toughness determined from the modifed CIE model was used to evaluate the impact absorbed energy using the dynamic fracture toughness and energy for crack initiation. The efectiveness of the newly proposed method was verifed through experiments on four types of steels: Q345R, SA508-3, 18MnMoNbR, and S30408.
基金the Natural Science Foundation of Shandong Province(Grant No.ZR2019JQ19)the interdisciplinary research project of Shandong University(Grant No.2017JC027).
文摘Needle biopsy is an essential part of modern clinical medicine.The puncture accuracy and sampling success rate of puncture surgery can be effectively improved through virtual surgery.There are few three-dimensional puncture(3D)models,which have little significance for surgical guidance under complicated conditions and restrict the development of virtual surgery.In this paper,a 3D simulation of the muscle tissue puncture process is studied.Firstly,the mechanical properties of muscle tissue are measured.The Mooney-Rivlin(M-R)model is selected by considering the fitting accuracy and calculation speed.Subsequently,an accurate 3D dynamic puncture model is established.The failure criterion is used to define the breaking characteristics of the muscle,and the bilinear cohesion model defines the breaking process.Experiments with different puncture speeds are carried out through the built in vitro puncture platform.The experimental results are compared with the simulation results.The experimental and simulated reaction force curves are highly consistent,which verifies the accuracy of the model.Finally,the model under different parameters is studied.The simulation results of varying puncture depths and puncture speeds are analyzed.The 3D puncture model can provide more accurate model support for virtual surgery and help improve the success rate of puncture surgery.
基金supported by Shandong Science Fund for Distinguished Young Scholars of China(JQ201715)National Natural Science Foundation of China(No.51575322)+1 种基金Major Program of Shandong Province Natural Science Foundation of China(ZR2018ZA0401 and ZR2018ZB0521)Key Research and Development Program of Shandong Province of China(2019GGX104049)。
文摘Fused deposition modeling(FDM)has unique advantages in the rapid prototyping of thermoplastics which have been developed in diverse fields.However,although great efforts have been made to optimize FDM process,the mechanical properties of printed parts are limited by the weak interlamination bonding as well as the poor performance of raw filaments used,such as acrylonitrile butadiene styrene(ABS),polylactic acid(PLA).Adding fibers into thermoplastic matrix and preparing high-performance filaments have been indicated to enhance the properties of fabricated parts.Recently,heat-resistant polyetheretherketone(PEEK)and its fiber reinforced composites were proposed for FDM process due to overcoming the limitation of equipment and process.However,few researches have been reported on the effects of FDM-3 D printing parameters on the mechanical properties of fiber reinforced PEEK composites.Therefore,5 wt%carbon fiber(CF)and glass fiber(GF)reinforced PEEK composite filaments were prepared respectively in this study.The effects of various printing parameters including nozzle temperature,platform temperature,printing speed and layer thickness on the mechanical properties(including tensile strength,flexural strength and impact strength)were surveyed.To analyze the microstructure and failure reasons of printed CF/PEEK and GF/PEEK samples,the tensile fractured surfaces were investigated via scanning electron microscope(SEM).
基金The authors acknowledge the financial support provided by the Major Scientific and Technological Project of Shandong Province(Grant No.2019GGX104006)the Natural Science Foundation of Shandong Province(Grant No.ZR2020ME159)the Construction Engineering Special Fund of“Taishan Scholars”of Shandong Province(Grant No.ts20190975).
文摘Selective laser melting(SLM)has provided an alternative to the conventional fabrication techniques for Ti-6Al-4V alloy parts because of its flexibility and ease in creating complex features.Therefore,this study investigated the effects of the process parameters and heat treatment on the microstructure and mechanical properties of Ti-6Al-4V fabricated using SLM.The influences of various process parameters on the relative density,tensile properties,impact toughness,and hardness of Ti-6Al-4V alloy parts were studied.By employing parameter optimization,a high-density high-strength Ti-6Al-4V alloy was fabricated by SLM.A relative density of 99.45%,a tensile strength of 1188 MPa,and an elongation to failure of 9.5%were achieved for the SLM-fabricated Ti-6Al-4V alloy with optimized parameters.The effects of annealing and solution aging heat treatment on the mechanical properties,phase composition,and microstructure of the SLM-fabricated Ti-6Al-4V alloy were also studied.The ductility of the heat-treated Ti-6Al-4V alloy was improved.By applying a heat treatment at 850℃ for 2 h,followed by furnace cooling,the elongation to failure and impact toughness were found to be increased from 9.5%to 12.5%,and from 24.13 J/cm^(2)to 47.51 J/cm^(2),respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.51975328,51605258)the Postdoctoral Innovation Project of Shandong Province(Grant No.201701011)Young Scholars Program of Shandong University(Grant No.2018WLJH55).
文摘The integration of ultrasonic vibration into sheet forming process can significantly reduce the forming force and bring benefits including the enhancement of surface quality,the enhancement of formability and the reduction of spring-back.However,the influencing mechanisms of the high-frequency vibration on parts properties during the incremental sheet forming(ISF)process are not well known,preventing a more efficient forming system.This paper comprehensively investigates the effects of different process parameters(vibration amplitude,step-down size,rotation speed and forming angle)on the micro-hardness,minimum thickness,forming limit and residual stress of the formed parts.First,a series of truncated pyramids were formed with an experimental platform designed for the ultrasonic-assisted incremental sheet forming.Then,microhardness tests,minimum thickness measurements and residual stress tests were performed for the formed parts.The results showed that the surface micro-hardness of the formed part was reduced since the vibration stress induced by the ultrasonic vibration within the material which eliminated the original internal stress.The superimposed University,Beijing 100083,People’s Republic of China ultrasonic vibration can effectively uniform the residual stress and thickness distribution,arid improve the forming limit in the case of the small deformation rate.In addition,through the tensile fracture analysis of the formed part,it is shown that the elongation of material is improved and the elastic modulus and hardening index are decreased.The findings of the present work lay the foundation for a better integration of the ultrasonic vibration system into the incremental sheet forming process.
基金supported by the National Natural Science Foundation of China(Grant Nos.51975328,52275348)the Project funded by China Postdoctoral Science Foundation(Grant Nos.2021T140418,202102051)Young Scholars Program of Shandong University(Grant No.2018WLJH55).
文摘Although incremental sheet forming(ISF)is an efficient way to manufacture customized parts,the forming performance and geometric accuracy of formed parts need to be improved to meet industrial application.One feasible solution for these problems is to adopt proper heat treatment strategies for the sheet material both before and during the forming process.In this paper,the effects of heat treatment before forming and heat-assisted forming on the formability and performance of formed parts were experimentally investigated.First,TA1 sheets were heat-treated at different temperatures before forming,and then the sheets were incrementally formed into the target shape with variable angles at different temperatures.After heat treatment,the strength of sheets was decreased due to the occurrence of recrystallization and the growth of grains.Meanwhile,the surface quality of formed parts was also improved with pre-heat treatment before forming.During the heat-assisted forming process,the sheet was softened and the deformation resistance was reduced with the increase of temperature.Therefore,the axial forming force was decreased obviously and the formability of the sheet was increased obviously.Furthermore,by adopting both heat treatment and heat-assisted forming,it was found that the forming force could be further reduced and the formability of the sheet and surface quality could be further improved.As for geometric accuracy,heat treatment has a good effect on improving it,while heat-assisted forming has adverse effect.These findings provide an effective heat treatment strategy for improving the geometric accuracy and surface quality of the incrementally formed parts with lower forming force.
基金financial support from the National Natural Science Foundation of China(Grant No.91860207)supported by the National Key Research and Development Program of China(Grant No.2019YFB2005401)the Shandong Provincial Natural Science Foundation of China(Grant No.2019JMRH0307).
文摘During ultrasonic vibration-assisted machining,the large impact force induced by tool-workpiece reengagement(TWR)is an important factor that affects tool chipping.However,mechanical analysis into process factors that affect the impact force and their influencing mechanisms are insufficient.Herein,a prediction model for the instantaneous cutting force during both TWR and the stable turning process,which depends on the process parameters and material properties,is firstly proposed based on the kinematic and dynamic analysis of ultrasonic vibration-assisted oblique turning(UVAOT).The results calculated using the developed cutting force model agree well with the experimental results presented in the literature.Next,the linear change law of the instantaneous cutting force with cutting time during the actual TWR is clarified using the proposed model.The effect of the UVAOT process parameters on the average impact force during the periodic TWR process is discussed,and the influence mechanism is analyzed from the perspective of mechanics.A positive linear correlation is discovered between the feed speed and average impact force.The ultrasonic amplitude and cutting speed do not significantly affect the average impact force of the new sharp cutting tools.These findings are consistent with the experimental observations of tool chipping and are applicable to select process parameters for reducing tool chipping during UVAOT.
基金supports from the National Natural Science Foundation of China(grant No.52006125)China Postdoctoral Science Foundation(grant No.2020M682180)Young Scholars Program of Shandong University,Fundamental Research Funds of Shandong University(grant No.2019HW041)。
文摘Large amounts of microplastics(MPs)have been found in rivers and oceans,bringing great harm to aquatic animals,plants,even human beings.However,the effective removal method of MPs,especially those with small sizes(5-20 μm)is still lacking.This work presents mini-hydrocyclones to remove 10 μm(average size)diameter MPs.The removal performance of nine mini-hydrocyclones with different diameters of spigot and vortex finder is examined experimentally and numerically.The performance of the designed cyclones is evaluated in terms of recovery,water split,concentration ratio and pressure drop.The results show that mini-hydrocyclones are applicable to removing small-size MPs with the maximum concentra-tion ratio at 2.16 and the particle recovery at 51%.The flow characteristics inside the mini-hydrocyclones are analyzed in detail.It is shown that the distributions of water axial velocity and radial velocity could collectively affect the behaviors of small-size MPs in mini-hydrocyclones.Specifically,a larger amount of water split could entrain more fine particles to underflow.Meanwhile,a less frequent alternation of radial velocity between the positive and negative directions on the same side of the cyclone should benefit the removal of small-size MPs.
基金the Shandong Provincial Natural Science Foundation,China(Grant No.ZR2017MEE021)for the financial support toward this research.
文摘Whirling has been adopted for the cost-effective machining of blade-shape components in addition to traditional end milling and flank milling processes.To satisfy the requirements of rotary forming in the blade whirling process,the workpiece must be clamped at both ends in suspension and rotated slowly during machining,which complicates the dynamics.This study aims to identify the dynamic characteristics within the blade whirling operation and present strategies for stability prediction.In this study,the dynamic characteristics of a whirling system are modeled by assuming symmetric and asymmetric parameters.Theoretical prediction frequency response function(FRF)results are compared with experimental results.Moreover,semi-discretization stability lobe diagrams(SLDs)obtained using the dynamic parameters of these models are investigated experimentally.The results show that the asymmetric model is more suitable for describing the whirling system,whereas the symmetric model presents limitations associated with the frequency range and location of measuring points.Finally,a set of airfoil propeller blade whirling operations is conducted to verify the prediction accuracy.
基金supported by the National Key R&D Program of China(Grant No.2020YFB1711603)the Key Technology R&D Program of Shandong Province,China(Grant No.2020CXGC010304)the National Natural Science Foundation of China(Grant No.52175473).
文摘Flanks of end mills are prone to wear in a long machining process.Regrinding is widely used in workshops to restore the flank to an original-like state.However,the traditional method involves material waste by trial and error and dramatically decreases the potential regrinding.Moreover,over-cut would happen to the flutes of worn cutters in the regrinding processes because of improper wheel path.This study presented a new approach to planning the wheel path for regrinding worn end mills to minimize material loss and recover the over-cut.In planning,a scaling method was developed to determine the maximum size of the new cutter according to the similarity of cutter shapes before and after regrinding.Then,the wheel path is first generated by envelope theory to regrind the worn area with a four-axis computer numerical control grinder according to the new size of cutters.Moreover,a second regrinding strategy is applied to recover the flute shape over-cut in the first grinding.Finally,the proposed method is verified by an experiment.Results showed that the proposed approach could save 25%of cutter material compared with the traditional method and ensure at least three regrinding times.This work effectively provides a general regrinding solution for the worn flank with maximum material-saving and regrinding period.
基金co-supported by the National Natural Science Foundation of China(No.52275445)the Key Research and Development Plan of Shandong Province(Nos.2020CXGC010204,2023CXPT014,and 2021JMRH0301).
文摘Chatter in the machining system can result in a decrease in tool life,poor surface finish,conservative cutting parameters,etc.Despite many review papers promoting the understanding and research of this area,chatter suppression techniques are generally discussed within limited pages in the framework of comprehensive chatter-related problems.In recent years,the developments of smart materials,advanced sensing techniques,and more effective control strategies have led to some new progress in chatter suppression.Meanwhile,the widely used thin-walled parts present more and more severe machining challenges in their milling processes.Considering the above deficiencies,this paper summarizes the current state of the art in milling chatter suppression.New classifications of chatter suppression techniques are proposed according to the working principle and control target.Based on the new classified framework,the mechanism and comparisons of different chatter suppression strategies are reviewed.Besides,the current challenges and potential tendencies of milling chatter suppression techniques are highlighted.Intellectualization,integration,compactness,adaptability to workpiece geometry,and the collaboration of multiple control methods are predicted to be important trends in the future.
基金funded by the National Natural Science Foundation of China(Grant Nos.52275495 and 52305542)the Taishan Scholar Project of Shandong Province,China(Grant No.tsqn202306006)+1 种基金the Youth Innovation Technology Support Program of Shandong Provincial Universities,China(Grant No.2022KJ041)the Youth Fund from the Natural Science Foundation of Shandong Province,China(Grant No.ZR2023QE320).
文摘Laser directed energy deposition(LDED)is widely used in the remanufacturing and surface strengthening of high-value thin-walled components.However,the transformation mechanism of mechanical properties for substrates induced by laser deposition,especially for thin metal sheets,remains unclear.In this study,the affecting mechanism of Fe_(3)0_(4)coatings fabricated by LDED on the ductility of Q235 thin plates was investigated.Samples of original substrate(OS),deposited plates with one to three layers of coating(D1–D3),the substrate zone of deposited plates with one to three layers of coating(D1-S–D3-S),and deposited coating were prepared to evaluate the effect of coating and laser heat on substrate ductility.The Fe_(3)0_(4)coating deposited by LDED and the accompanying laser heat drastically reduced substrate ductility by about 87%.Specifically,laser heat reduced the ductility by 24%–51%.The Fe_(3)0_(4)coating deposited by LDED led to the ductile-to-brittle transition of the substrate.Compared with ductile dimples in the OS,cleavage fracture was found in the substrate of deposited plates.Meanwhile,the mechanisms of ductile-tobrittle transition of the substrate were analyzed.Laser heat caused the precipitation of cementite and the generation of a decarburization layer in the substrate.Coating resulted in the pileup of dislocations in the substrate,then nonuniform deformation occurred in the substrate.The cracks of the coating fracture extended to the substrate,inducing local cracking of the substrate.This study provides fundamental guidance for the surface manufacturing of ductile thin-walled components through LDED.
