For improving the theory of gradient microstructure of cartilage/bone interface, human distal femurs were studied. Scanning Electron Microscope （SEM）, histological sections and MicroCT were used to observe, measure ...For improving the theory of gradient microstructure of cartilage/bone interface, human distal femurs were studied. Scanning Electron Microscope （SEM）, histological sections and MicroCT were used to observe, measure and model the micro- structure of cartilage/bone interface. The results showed that the cartilage/bone interface is in a hierarchical structure which is composed of four different tissue layers. The interlocking of hyaline cartilage and calcified cartilage and that of calcified car- tilage and subchondral bone are in the manner of＂protrusion-pore＂ with average diameter of 17.0 gm and 34.1 lam respectively. In addition, the cancellous bone under the cartilage is also formed by four layer hierarchical structure, and the adjacent layers are connected by bone trabecula in the shape of H, I and Y, forming a complex interwoven network structure. Finally, the simplified structure model of the cartilage/bone interface was proposed according to the natural articular cartilage/bone interface. The simplified model is a 4-layer gradient biomimetic structure, which corresponds to four different tissues of natural cartilage/bone interface. The results of this work would be beneficial to the design of bionic scaffold for the tissue engineering of articular cartilage/bone.展开更多
Complicated tribological behavior occurs when human fingers touch and perceive the surfaces of objects.In this process,people use their exploration style with different conditions,such as contact load,sliding speed,sl...Complicated tribological behavior occurs when human fingers touch and perceive the surfaces of objects.In this process,people use their exploration style with different conditions,such as contact load,sliding speed,sliding direction,and angle of orientation between fingers and object surface consciously or unconsciously.This work addressed interlaboratory experimental devices for finger active and passive tactile friction analysis,showing two types of finger movement.In active sliding experiment,the participant slid their finger freely against the object surface,requiring the subject to control the motion conditions themselves.For passive sliding experiments,these motion conditions were adjusted by the device.Several analysis parameters,such as contact force,vibration acceleration signals,vibration magnitude,and fingerprint deformation were recorded simultaneously.Noticeable friction differences were observed when comparing active sliding and passive sliding.For passive sliding,stick-slip behavior occurred when sliding in the distal direction,evidenced by observing the friction force and the related deformation of the fingerprint ridges.The employed devices showed good repeatability and high reliability,which enriched the design of the experimental platform and provided guidance to the standardization research in the field of tactile friction.展开更多
Ti6Al4V alloy‒CoCrMo alloy pair is commonly applied for modular head‒neck interfaces for artificial hip joint.Unfortunately,the fretting corrosion damage at this interface seriously restricts its lifespan.This work st...Ti6Al4V alloy‒CoCrMo alloy pair is commonly applied for modular head‒neck interfaces for artificial hip joint.Unfortunately,the fretting corrosion damage at this interface seriously restricts its lifespan.This work studied the fretting corrosion of Ti6Al4V‒CoCrMo pair in calf serum solution.We established this material pair’s running condition fretting map(RCFM)regarding load and displacement,and revealed the damage mechanism of this material pair in various fretting regimes,namely partial slip regime(PSR),mixed fretting regime(MFR),and gross slip regime(GSR).The damage mechanism of Ti6Al4V alloy was mainly abrasive wear induced by CoCrMo alloy and tribocorrosion.Adhesive wear(material transfer)also existed in MFR.The damage mechanism of CoCrMo alloy was mainly abrasive wear induced by metal oxides and tribocorrosion in GSR and MFR,while no apparent damage in PSR.Furthermore,a dense composite material layer with high hardness was formed in the middle contacting area in GSR,which reduced the corrosion and wear of Ti alloys and exacerbated damage to Co alloys.Finally,the ion concentration maps for Ti and Co ions were constructed,which displayed the transition in the amount of released Ti and Co ions under different displacements and loads.展开更多
The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade.This review takes stock of the recent advances in research pertaining to ...The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade.This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years.Different aspects of tribology that have been reviewed including lubrication,wear and surface engineering,biotribology,high tem perature tribology,and computational tribology.This review attempts to highlight recent research and also presents future outlook pertaining to these aspects.It may however be noted that there are limitations of this review.One of the most important of these is that tribology being a highly multidisciplinary field,the research results are widely spread across various disciplines and there can be omissions because of this.Secondly,the topics dealt with in the field of tribology include only some of the salient topics(such as lubrication,wear,surface engineering,biotribology,high tem perature tribology,and computational tribology)but there are many more aspects of tribology that have not been covered in this review.Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.展开更多
Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021,and reviewed as the representative advances in tribology research worldwide.The survey highlights the development in lubr...Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021,and reviewed as the representative advances in tribology research worldwide.The survey highlights the development in lubrication,wear and surface engineering,biotribology,high temperature tribology,and computational tribology,providing a show window of the achievements of recent fundamental and application researches in the field of tribology.展开更多
Numerous medical devices have been applied for the treatment or alleviation of various diseases.Tribological issues widely exist in those medical devices and play vital roles in determining their performance and servi...Numerous medical devices have been applied for the treatment or alleviation of various diseases.Tribological issues widely exist in those medical devices and play vital roles in determining their performance and service life.In this review,the bio-tribological issues involved in commonly used medical devices are identified,including artificial joints,fracture fixation devices,skin-related devices,dental restoration devices,cardiovascular devices,and surgical instruments.The current understanding of the bio-tribological behavior and mechanism involved in those devices is summarized.Recent advances in the improvement of tribological properties are examined.Challenges and future developments for the prospective of bio-tribological performance are highlighted.展开更多
Long-term loosening is the major cause of failure of arthroplasty. One of the major causes is stress shielding, initiated by the large stiffness difference between prosthesis and bone tissue. Therefore, prosthesis wit...Long-term loosening is the major cause of failure of arthroplasty. One of the major causes is stress shielding, initiated by the large stiffness difference between prosthesis and bone tissue. Therefore, prosthesis with reduced stiffness properties to match those of the bone tissue may be able to minimize such a problem. Design with porous structure is believed to reduce the stiffness of the prosthesis, however at the cost of decreased strength. In this study, a patient-specific bone-implant finite element model was developed for contact mechanics study of hip joint, and algorithms were developed to adjust the elastic modulus of elements in certain regions of the femoral stem, until optimal properties were achieved according to the pre-defined criterions of the strength and stability of the system. The global safety factor of the optimized femoral stem was 11.3, and 26.4% of elements were designed as solid. The bone volume with density loss was reduced by 40% compared to the solid stem. The methodology developed in this study provides a universal method to design a patient-specific prosthesis with a gradient modulus distribution for the purposes of minimizing the stress shielding effect and extending the lifespan of the implant.展开更多
Friction studies in biological systems are reviewed,including synovial joints(cartilage,meniscus),eye,pleurae,fat pad,skin,and oral cavity as well as daily activities associated with shaving,brushing,slip,etc.Both nat...Friction studies in biological systems are reviewed,including synovial joints(cartilage,meniscus),eye,pleurae,fat pad,skin,and oral cavity as well as daily activities associated with shaving,brushing,slip,etc.Both natural systems and medical interventions in terms of diagnoses and artificial replacements are considered.Important relevant biomechanical,physiological,and anatomical factors are reviewed in conjunction with friction studies in terms of both methodologies and friction coefficients.Important underlying tribological mechanisms related to friction are briefly discussed.A unified view on the lubrication mechanism responsible for the low friction in most soft biological tissues is presented.展开更多
While total knee replacement is successful, hemiarthroplasty is necessary for some young, obese and active patients who are especially not suitable for unicompartmental or total knee prostheses. Hemiarthroplasty also ...While total knee replacement is successful, hemiarthroplasty is necessary for some young, obese and active patients who are especially not suitable for unicompartmental or total knee prostheses. Hemiarthroplasty also provides an opportunity for children with bone tumors. The design ofhemiarthroplasty should be patient-specific to reduce contact stress and friction as well as instability, compared to conventional hemi-knee prosthesis. A novel bipolar hemi-knee prosthesis with two flexion stages was developed according to a healthy male＇s knee morphological profile. The motion mode of the bipolar hemi-knee prosthesis was observed through roentgenoscopy in vitro experiment. The biomechanical properties in one gait cycle were evaluated though finite element simulation. The bipolar hemi-knee prosthesis was found to produce knee flexion at two stages through X-ray images. The first stage is the motion from upright posture to a specified 60~ flexion, followed by the second stage of motion subsequently to deep flexion. The finite element simulation results also show that the designed hemi-knee prosthesis has the ability to reduce stresses on the joint contact surfaces. Therefore, it is possible for the bipolar hemi-knee prosthesis to provide better biotribological performances because it can reduce stresses and potentially wear on the opposing contacting surface during a gait cycle, orovidin~ a t^romisin~ treatment strate^v in future Joint renair znd renlneement展开更多
In the fast growing field of scaffold-based tissue engineering, improvement on the mechanical properties of newly formed tissues, e.g. the repaired cartilage, has always been one of the core issues. Studies on the cor...In the fast growing field of scaffold-based tissue engineering, improvement on the mechanical properties of newly formed tissues, e.g. the repaired cartilage, has always been one of the core issues. Studies on the correlations among scaffold composition, in vivo morphological changes of the construct, and the finite deformation behaviors of new tissues （e.g. creep and stress-relaxation, and equilibrium response）, have attracted increasing interests. In this paper, the correlations between the compressive biphasic mechanical properties （i.e., equilibrium elastic modulus E and permeability coefficient k） of 3D printing scaffold （consisting of collagen and fl-tricalcium phosphate） and the proteoglycans （PGs） concentration of the repaired carti- lages after 24 weeks, 36 weeks and 52 weeks of scaffold implantation were investigated. Results indicated that the repaired cartilage covered the entire cartilage surface of large cylindrical osteochondral defects （10 mm in diameter ~ 15 mm in depth） on the canine trochlea grooves after 24 weeks. The equilibrium elastic modulus of the repaired cartilage reached 22.4% at 24 weeks, 70.3% at 36 weeks, and 93.4% at 52 weeks of the native cartilage, respectively. Meanwhile, the permeability coefficient decreased with time and at 52 weeks was still inferior to that of the native cartilage in one order of magnitude. In addition, the amount of glycosaminoglycans （GAGs） of repaired cartilage increased constantly with time, which at 52 weeks approached to nearly 60% of that of native cartilage. 3D printed scaffolds have potential applications in repairing large-scale cartilage defects.展开更多
Corrosion at the taper/trunnion interface of total hip replacement(THR)often results in severe complications.However,the underlying mechanisms of biotribocorrosion at the taper/trunnion interface during the long-term ...Corrosion at the taper/trunnion interface of total hip replacement(THR)often results in severe complications.However,the underlying mechanisms of biotribocorrosion at the taper/trunnion interface during the long-term walking gait cycles remain to be fully understood.In this study,a hip joint simulator was therefore instrumented with an electrochemical cell for in-situ monitoring of the tribocorrosion evolution in a metal-on-polyethylene(MoP)THR during a typical long-term walking gait.In addition,the biotribocorrosion mechanism was investigated via surface and chemical characterizations.The experimental results confirmed that the taper/trunnion interface dominated the contemporary MoP hip joint corrosion.Three cyclic variations in the open circuit potential(OCP)were observed throughout the long-term electrochemical measurements,attributed to the formation and disruption of the adsorbed protein layer.The corrosion exhibited an initial increase at each period,peaking at approximately 0.125 million cycles,followed by a subsequent gradual reduction.Surface and chemical analyses revealed the formation of a tribochemical reaction layer(tribolayer)on the worn surface of the taper/trunnion interface.The surface/chemical characterizations and the electrochemical measurements indicated that the adhesion force of the adsorbed protein layer was weaker than that of the tribolayer.In contrast,the opposite was true for the corrosion resistance.Based on the observations from this study,the tribocorrosion mechanism of the taper/trunnion interface under the long-term walking gait cycles is deduced.展开更多
This numerical study predicted wear of lubricated total knee replacements with the existing of textured surfaceand the possibility of surface designs to reduce wear.In the first part,a wear model of metal-on-polyethyl...This numerical study predicted wear of lubricated total knee replacements with the existing of textured surfaceand the possibility of surface designs to reduce wear.In the first part,a wear model of metal-on-polyethylene total kneereplacement was developed.The medial and lateral knee compartments was accounted for separately,with the contactforce and motion during walking cycles applied.An adapted Archard wear formula was employed where the wearfactor was an exponential function of the'Lambda ratio'(film thickness to the average roughness).Wear of the softbearing surface(polyethylene insert)was simulated with regularly geometry update until a steady-state wear observed.ln the second part,the effect of surface topography of the knee replacements was investigated.The surface texturingtechniques have shown promising benefit to machine components in many areas of engineering practice.The textureparameters were designed using the Taguchi method for the geometry,size,and distribution of the micro dimples.twas observed that the lateral compartment may benefit from surface texturing if dimples were properly designed,while the texturing showed hardly advantageous effect on the medial surface in terms of lubrication enhancement andwear reduction.Some results were presented in the 6th World Tribology Conference.展开更多
In this study,the effects of in vivo(head flexion-extension,lateral bending,and axial rotation)and in vitro(ISO 18192-1)working conditions on the wear of ultrahigh mo-lecular weight polyethylene(UHWMPE)-based cervical...In this study,the effects of in vivo(head flexion-extension,lateral bending,and axial rotation)and in vitro(ISO 18192-1)working conditions on the wear of ultrahigh mo-lecular weight polyethylene(UHWMPE)-based cervical disc prosthesis were studied via numerical simulation.A finite-element-based wear prediction framework was built by using a sliding distance and contact area dependent Archard wear law.Moreover,a pre-developed cervical spine multi-body dynamics model was incorporated to obtain the in vivo conditions.Contact mechanic analysis stated that in vitro conditions normally led to a higher contact stress and a longer sliding distance,with oval or crossing-path-typed sliding track.In contrast,in vivo conditions led to a curvilinear-typed sliding track.In general,the predicted in vivo wear rate was one order of magnitude smaller than that of in vitro.According to the yearly occurrence of head movement,the estimated total in vivo wear rate was 0.595 mg/annual.While,the wear rate given by the ISO standard test condition was 3.32 mg/annual.There is a significant impact of loading and kinematic condition on the wear of UHMWPE prosthesis.The work conducted in the present study provided a feasible way for quantitatively assessing the wear of joint prosthesis.展开更多
The elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or converge...The elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or convergence problems, thus the evolution of the contact behaviour is obtained in a semi-analytical manner. Numerical results obtained by the proposed approach facilitate the understanding of the contact behaviour in the following aspects: 1) the ratio of contact area to load decreases with an increase in real contact area;2) normal approach-load relationship is approximated by an exponential decay under relatively small loads and a linear decay under relatively large loads;and 3) average gap shows an exponential relationship with load only in moderate load range.展开更多
It is with great regret that we have to inform the readers of our journal Friction that professor Duncan Dowson has passed away.He had not been feeling well in the last few years and his condition was worsened after a...It is with great regret that we have to inform the readers of our journal Friction that professor Duncan Dowson has passed away.He had not been feeling well in the last few years and his condition was worsened after a fall.He died in hospital on 6 January 2020.This is a great loss to all of us in the tribology community and we will remember him as one of the greatest tribologists,an eminent scientist and a visionary engineer of our time.展开更多
It is with great regret that we have to inform the readers of our Journal that Professor Duncan Dowson,the Honorary Editor of our Journal,has passed away at age 91(6 January 2020).He had not been feeling well in the l...It is with great regret that we have to inform the readers of our Journal that Professor Duncan Dowson,the Honorary Editor of our Journal,has passed away at age 91(6 January 2020).He had not been feeling well in the last few years and his condition was worsened after a fall.He died in hospital on 6th January 2020.This is a great loss to all of us,particularly in the biotribology community and we will remember him as one of the greatest biotribologists of our time.展开更多
Low shape matching and high stress shielding rates between bone plate and human bone are not conducive to the primary healing of fracture.In this study,taking the fracture site of the lower one‐third of human tibia a...Low shape matching and high stress shielding rates between bone plate and human bone are not conducive to the primary healing of fracture.In this study,taking the fracture site of the lower one‐third of human tibia as an application case,six types of personalised Ti6Al4V tibial plates with grooved surface were designed and evaluated by reverse en-gineering and finite element analysis.The results showed that the grooved design can reduce the stress shielding rate of bone plate and promote the facture healing.Among the six types of bone plates,the‘OUT-MI’bone plate has the lowest stress shielding rate and the most uniform stress distribution.Meanwhile,with the increasing tibial load during the convalescence,the average stress and maximum axial displacement of the tibial fracture surface increased,which can effectively improve the bone regeneration in the tibial fracture area.Moreover,there was no significant difference in four-point bending performance between the‘OUT-MI’bone plate and the‘STR-BE’bone plate,indicating that the mechanical properties of this bone plate were reliable.The results provide a theoretical basis for the design of fracture fixation plates on clinical treatment.展开更多
Titanium cermet combining metallic toughness with ceramic wear resistance has been proven to be a potential candidate for implanted joint material.In this work,titanium cermet was synthesized by means of the elevated ...Titanium cermet combining metallic toughness with ceramic wear resistance has been proven to be a potential candidate for implanted joint material.In this work,titanium cermet was synthesized by means of the elevated temperature solid carburizing technology.The Ti_(13)Nb_(13)Zr alloy surface was found to be converted into TiC ceramic layer combined with a carbon strengthened diffusion zone underneath.The overall thickness of the carburized region grew to about 100 um after 120 min carburization at 1,500 K.In order to clarify the growth behaviors of TiC ceramic layer,a growth mechanism is proposed.At the beginning of carburizing process,carbonaceous gas decomposed from carburizer due to high temperature and then converted to free atomic carbons through reduction reaction.Then,in-situ generated TiC ceramic layer possessing certain thickness formed on the surface,meanwhile,the inner carbon diffusion zone also grew inwards due to physical diffusion of carbon,and finally forming a gradient carbon distribution.In addition,the tribological behaviors of the new materials were evaluated through reciprocating ball-on-plate sliding wear tests in bovine calf serum.Although there was an increase in friction coefficient,the wear rate decreased by 59.6%due to the formation of the wear-resistant TiC ceramic layer.The wear mechanisms evolved from severe abrasive wear for bare Ti_(13)Nb_(13)Zr alloy to mild adhesive wear for titanium cermet.展开更多
The year 2022 marks the 10th anniversary of the founding of Friction.Friction was launched on 26 March 2013,with an aim to promote the development in tribology by publishing theoretical and experimental research works...The year 2022 marks the 10th anniversary of the founding of Friction.Friction was launched on 26 March 2013,with an aim to promote the development in tribology by publishing theoretical and experimental research works as well as monographic review articles related to surface contact,friction,wear,lubrication,adhesion,and interface science.展开更多
基金This paper was supported by the National Natural Science Foundation of China （Grant No： 50875201） and the National Hi-Tech Program of China （Grant No： 2009AA043801）. The authors thank Professor Yiping Tang from Xi＇an Jiaotong University for improving the manuscript.
文摘For improving the theory of gradient microstructure of cartilage/bone interface, human distal femurs were studied. Scanning Electron Microscope （SEM）, histological sections and MicroCT were used to observe, measure and model the micro- structure of cartilage/bone interface. The results showed that the cartilage/bone interface is in a hierarchical structure which is composed of four different tissue layers. The interlocking of hyaline cartilage and calcified cartilage and that of calcified car- tilage and subchondral bone are in the manner of＂protrusion-pore＂ with average diameter of 17.0 gm and 34.1 lam respectively. In addition, the cancellous bone under the cartilage is also formed by four layer hierarchical structure, and the adjacent layers are connected by bone trabecula in the shape of H, I and Y, forming a complex interwoven network structure. Finally, the simplified structure model of the cartilage/bone interface was proposed according to the natural articular cartilage/bone interface. The simplified model is a 4-layer gradient biomimetic structure, which corresponds to four different tissues of natural cartilage/bone interface. The results of this work would be beneficial to the design of bionic scaffold for the tissue engineering of articular cartilage/bone.
基金Supported by the China Scholarship Council (Grant No.201907000020)the 111 Project (Grant No.B20008)。
文摘Complicated tribological behavior occurs when human fingers touch and perceive the surfaces of objects.In this process,people use their exploration style with different conditions,such as contact load,sliding speed,sliding direction,and angle of orientation between fingers and object surface consciously or unconsciously.This work addressed interlaboratory experimental devices for finger active and passive tactile friction analysis,showing two types of finger movement.In active sliding experiment,the participant slid their finger freely against the object surface,requiring the subject to control the motion conditions themselves.For passive sliding experiments,these motion conditions were adjusted by the device.Several analysis parameters,such as contact force,vibration acceleration signals,vibration magnitude,and fingerprint deformation were recorded simultaneously.Noticeable friction differences were observed when comparing active sliding and passive sliding.For passive sliding,stick-slip behavior occurred when sliding in the distal direction,evidenced by observing the friction force and the related deformation of the fingerprint ridges.The employed devices showed good repeatability and high reliability,which enriched the design of the experimental platform and provided guidance to the standardization research in the field of tactile friction.
基金supported by the National Natural Science Foundation of China(Nos.52035012 and 52275215)the Natural Science Foundation of Sichuan Province(No.2022NSFSC1940).
文摘Ti6Al4V alloy‒CoCrMo alloy pair is commonly applied for modular head‒neck interfaces for artificial hip joint.Unfortunately,the fretting corrosion damage at this interface seriously restricts its lifespan.This work studied the fretting corrosion of Ti6Al4V‒CoCrMo pair in calf serum solution.We established this material pair’s running condition fretting map(RCFM)regarding load and displacement,and revealed the damage mechanism of this material pair in various fretting regimes,namely partial slip regime(PSR),mixed fretting regime(MFR),and gross slip regime(GSR).The damage mechanism of Ti6Al4V alloy was mainly abrasive wear induced by CoCrMo alloy and tribocorrosion.Adhesive wear(material transfer)also existed in MFR.The damage mechanism of CoCrMo alloy was mainly abrasive wear induced by metal oxides and tribocorrosion in GSR and MFR,while no apparent damage in PSR.Furthermore,a dense composite material layer with high hardness was formed in the middle contacting area in GSR,which reduced the corrosion and wear of Ti alloys and exacerbated damage to Co alloys.Finally,the ion concentration maps for Ti and Co ions were constructed,which displayed the transition in the amount of released Ti and Co ions under different displacements and loads.
基金National N atural Science Foundation of China(Grant Nos.51635009 and 51775460)the funding of State Key Laboratory of Tribology,China(SKLT2018C05).
文摘The reach of tribology has expanded in diverse fields and tribology related research activities have seen immense growth during the last decade.This review takes stock of the recent advances in research pertaining to different aspects of tribology within the last 2 to 3 years.Different aspects of tribology that have been reviewed including lubrication,wear and surface engineering,biotribology,high tem perature tribology,and computational tribology.This review attempts to highlight recent research and also presents future outlook pertaining to these aspects.It may however be noted that there are limitations of this review.One of the most important of these is that tribology being a highly multidisciplinary field,the research results are widely spread across various disciplines and there can be omissions because of this.Secondly,the topics dealt with in the field of tribology include only some of the salient topics(such as lubrication,wear,surface engineering,biotribology,high tem perature tribology,and computational tribology)but there are many more aspects of tribology that have not been covered in this review.Despite these limitations it is hoped that such a review will bring the most recent salient research in focus and will be beneficial for the growing community of tribology researchers.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.52225502,51922058,52035012,and U2141243).
文摘Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021,and reviewed as the representative advances in tribology research worldwide.The survey highlights the development in lubrication,wear and surface engineering,biotribology,high temperature tribology,and computational tribology,providing a show window of the achievements of recent fundamental and application researches in the field of tribology.
基金We appreciate the financial supports of the National Natural Science Foundation of China(Nos.52035012,52005418,51905456,and 51775460).
文摘Numerous medical devices have been applied for the treatment or alleviation of various diseases.Tribological issues widely exist in those medical devices and play vital roles in determining their performance and service life.In this review,the bio-tribological issues involved in commonly used medical devices are identified,including artificial joints,fracture fixation devices,skin-related devices,dental restoration devices,cardiovascular devices,and surgical instruments.The current understanding of the bio-tribological behavior and mechanism involved in those devices is summarized.Recent advances in the improvement of tribological properties are examined.Challenges and future developments for the prospective of bio-tribological performance are highlighted.
基金The work was supported by the funding from the program of the National Nature Science Foundation of China （Grant Nos. 51205303 and 51323007）, the pro- gram of Scientific and Technological Innovation in Shaanxi Province （Grant No. 2014KTZB01-02）, the Fundamental Research Funds for the Central Universities, and Research Fund for the Doctoral Program （RFDP） of Higher Education of China.
文摘Long-term loosening is the major cause of failure of arthroplasty. One of the major causes is stress shielding, initiated by the large stiffness difference between prosthesis and bone tissue. Therefore, prosthesis with reduced stiffness properties to match those of the bone tissue may be able to minimize such a problem. Design with porous structure is believed to reduce the stiffness of the prosthesis, however at the cost of decreased strength. In this study, a patient-specific bone-implant finite element model was developed for contact mechanics study of hip joint, and algorithms were developed to adjust the elastic modulus of elements in certain regions of the femoral stem, until optimal properties were achieved according to the pre-defined criterions of the strength and stability of the system. The global safety factor of the optimized femoral stem was 11.3, and 26.4% of elements were designed as solid. The bone volume with density loss was reduced by 40% compared to the solid stem. The methodology developed in this study provides a universal method to design a patient-specific prosthesis with a gradient modulus distribution for the purposes of minimizing the stress shielding effect and extending the lifespan of the implant.
文摘Friction studies in biological systems are reviewed,including synovial joints(cartilage,meniscus),eye,pleurae,fat pad,skin,and oral cavity as well as daily activities associated with shaving,brushing,slip,etc.Both natural systems and medical interventions in terms of diagnoses and artificial replacements are considered.Important relevant biomechanical,physiological,and anatomical factors are reviewed in conjunction with friction studies in terms of both methodologies and friction coefficients.Important underlying tribological mechanisms related to friction are briefly discussed.A unified view on the lubrication mechanism responsible for the low friction in most soft biological tissues is presented.
基金Acknowledgments This work was supported by grants from the Natural Science Foundation of China （51075320, 51375371, 51323007）, and the Fundamental Research Funds for the Central Universities. The authors would like to acknowledge the contributions of Peng Liu of Fourth Military Medical University.
文摘While total knee replacement is successful, hemiarthroplasty is necessary for some young, obese and active patients who are especially not suitable for unicompartmental or total knee prostheses. Hemiarthroplasty also provides an opportunity for children with bone tumors. The design ofhemiarthroplasty should be patient-specific to reduce contact stress and friction as well as instability, compared to conventional hemi-knee prosthesis. A novel bipolar hemi-knee prosthesis with two flexion stages was developed according to a healthy male＇s knee morphological profile. The motion mode of the bipolar hemi-knee prosthesis was observed through roentgenoscopy in vitro experiment. The biomechanical properties in one gait cycle were evaluated though finite element simulation. The bipolar hemi-knee prosthesis was found to produce knee flexion at two stages through X-ray images. The first stage is the motion from upright posture to a specified 60~ flexion, followed by the second stage of motion subsequently to deep flexion. The finite element simulation results also show that the designed hemi-knee prosthesis has the ability to reduce stresses on the joint contact surfaces. Therefore, it is possible for the bipolar hemi-knee prosthesis to provide better biotribological performances because it can reduce stresses and potentially wear on the opposing contacting surface during a gait cycle, orovidin~ a t^romisin~ treatment strate^v in future Joint renair znd renlneement
基金This work was supported by grants from the Native Science Foundation of China （Nos. 51323007, 51375371 and 51075320）, the National High Technology Research and Development Program of China （No. 2015AA020303） and the Fundamental Research Funds for the Central Universities. The authors would like to acknowledge the contributions of Dichen Li, Manyi Wang, Yongmei Chen and Yusheng Qiu of Xi＇an Jiaotong University.
文摘In the fast growing field of scaffold-based tissue engineering, improvement on the mechanical properties of newly formed tissues, e.g. the repaired cartilage, has always been one of the core issues. Studies on the correlations among scaffold composition, in vivo morphological changes of the construct, and the finite deformation behaviors of new tissues （e.g. creep and stress-relaxation, and equilibrium response）, have attracted increasing interests. In this paper, the correlations between the compressive biphasic mechanical properties （i.e., equilibrium elastic modulus E and permeability coefficient k） of 3D printing scaffold （consisting of collagen and fl-tricalcium phosphate） and the proteoglycans （PGs） concentration of the repaired carti- lages after 24 weeks, 36 weeks and 52 weeks of scaffold implantation were investigated. Results indicated that the repaired cartilage covered the entire cartilage surface of large cylindrical osteochondral defects （10 mm in diameter ~ 15 mm in depth） on the canine trochlea grooves after 24 weeks. The equilibrium elastic modulus of the repaired cartilage reached 22.4% at 24 weeks, 70.3% at 36 weeks, and 93.4% at 52 weeks of the native cartilage, respectively. Meanwhile, the permeability coefficient decreased with time and at 52 weeks was still inferior to that of the native cartilage in one order of magnitude. In addition, the amount of glycosaminoglycans （GAGs） of repaired cartilage increased constantly with time, which at 52 weeks approached to nearly 60% of that of native cartilage. 3D printed scaffolds have potential applications in repairing large-scale cartilage defects.
基金supported by the National Natural Science Foundation of China(52035012)the Science and Technology Planning Project of Sichuan Province(2020YJ0032)the 111 Project(B20008).
文摘Corrosion at the taper/trunnion interface of total hip replacement(THR)often results in severe complications.However,the underlying mechanisms of biotribocorrosion at the taper/trunnion interface during the long-term walking gait cycles remain to be fully understood.In this study,a hip joint simulator was therefore instrumented with an electrochemical cell for in-situ monitoring of the tribocorrosion evolution in a metal-on-polyethylene(MoP)THR during a typical long-term walking gait.In addition,the biotribocorrosion mechanism was investigated via surface and chemical characterizations.The experimental results confirmed that the taper/trunnion interface dominated the contemporary MoP hip joint corrosion.Three cyclic variations in the open circuit potential(OCP)were observed throughout the long-term electrochemical measurements,attributed to the formation and disruption of the adsorbed protein layer.The corrosion exhibited an initial increase at each period,peaking at approximately 0.125 million cycles,followed by a subsequent gradual reduction.Surface and chemical analyses revealed the formation of a tribochemical reaction layer(tribolayer)on the worn surface of the taper/trunnion interface.The surface/chemical characterizations and the electrochemical measurements indicated that the adhesion force of the adsorbed protein layer was weaker than that of the tribolayer.In contrast,the opposite was true for the corrosion resistance.Based on the observations from this study,the tribocorrosion mechanism of the taper/trunnion interface under the long-term walking gait cycles is deduced.
基金the Imperial Junior Research Fellowship(2015-2018)Shanghai Natural Science Foundationof China(16ZR1411800).M.S.Andersen was supported by theSapere Aude program of the Danish Council for IndependentResearch(DFF-4184-00018).
文摘This numerical study predicted wear of lubricated total knee replacements with the existing of textured surfaceand the possibility of surface designs to reduce wear.In the first part,a wear model of metal-on-polyethylene total kneereplacement was developed.The medial and lateral knee compartments was accounted for separately,with the contactforce and motion during walking cycles applied.An adapted Archard wear formula was employed where the wearfactor was an exponential function of the'Lambda ratio'(film thickness to the average roughness).Wear of the softbearing surface(polyethylene insert)was simulated with regularly geometry update until a steady-state wear observed.ln the second part,the effect of surface topography of the knee replacements was investigated.The surface texturingtechniques have shown promising benefit to machine components in many areas of engineering practice.The textureparameters were designed using the Taguchi method for the geometry,size,and distribution of the micro dimples.twas observed that the lateral compartment may benefit from surface texturing if dimples were properly designed,while the texturing showed hardly advantageous effect on the medial surface in terms of lubrication enhancement andwear reduction.Some results were presented in the 6th World Tribology Conference.
基金National Natural Science Foundation of China,Grant/Award Number:51675508Natural Science Foundation of Shaanxi Province,China,Grant/Award Number:2020JQ-728。
文摘In this study,the effects of in vivo(head flexion-extension,lateral bending,and axial rotation)and in vitro(ISO 18192-1)working conditions on the wear of ultrahigh mo-lecular weight polyethylene(UHWMPE)-based cervical disc prosthesis were studied via numerical simulation.A finite-element-based wear prediction framework was built by using a sliding distance and contact area dependent Archard wear law.Moreover,a pre-developed cervical spine multi-body dynamics model was incorporated to obtain the in vivo conditions.Contact mechanic analysis stated that in vitro conditions normally led to a higher contact stress and a longer sliding distance,with oval or crossing-path-typed sliding track.In contrast,in vivo conditions led to a curvilinear-typed sliding track.In general,the predicted in vivo wear rate was one order of magnitude smaller than that of in vitro.According to the yearly occurrence of head movement,the estimated total in vivo wear rate was 0.595 mg/annual.While,the wear rate given by the ISO standard test condition was 3.32 mg/annual.There is a significant impact of loading and kinematic condition on the wear of UHMWPE prosthesis.The work conducted in the present study provided a feasible way for quantitatively assessing the wear of joint prosthesis.
基金The authors acknowledge the financial supports by the National Key Research and Development Program of China(2016YFF0204305)the National Natural Science Foundation of China(51775460 and 51905456)the China Postdoctoral Science Foundation(2019M653836XB).
文摘The elastic loading behaviour of rough surfaces is derived based on the physical understanding of the contact phenomena, where the pressure distribution is analytically obtained without any negative values or convergence problems, thus the evolution of the contact behaviour is obtained in a semi-analytical manner. Numerical results obtained by the proposed approach facilitate the understanding of the contact behaviour in the following aspects: 1) the ratio of contact area to load decreases with an increase in real contact area;2) normal approach-load relationship is approximated by an exponential decay under relatively small loads and a linear decay under relatively large loads;and 3) average gap shows an exponential relationship with load only in moderate load range.
文摘It is with great regret that we have to inform the readers of our journal Friction that professor Duncan Dowson has passed away.He had not been feeling well in the last few years and his condition was worsened after a fall.He died in hospital on 6 January 2020.This is a great loss to all of us in the tribology community and we will remember him as one of the greatest tribologists,an eminent scientist and a visionary engineer of our time.
文摘It is with great regret that we have to inform the readers of our Journal that Professor Duncan Dowson,the Honorary Editor of our Journal,has passed away at age 91(6 January 2020).He had not been feeling well in the last few years and his condition was worsened after a fall.He died in hospital on 6th January 2020.This is a great loss to all of us,particularly in the biotribology community and we will remember him as one of the greatest biotribologists of our time.
基金This work was supported by the Key R&D project of Sichuan Province(2018JY0552)National Natural Science Foundation of China(No.51,675,447).
文摘Low shape matching and high stress shielding rates between bone plate and human bone are not conducive to the primary healing of fracture.In this study,taking the fracture site of the lower one‐third of human tibia as an application case,six types of personalised Ti6Al4V tibial plates with grooved surface were designed and evaluated by reverse en-gineering and finite element analysis.The results showed that the grooved design can reduce the stress shielding rate of bone plate and promote the facture healing.Among the six types of bone plates,the‘OUT-MI’bone plate has the lowest stress shielding rate and the most uniform stress distribution.Meanwhile,with the increasing tibial load during the convalescence,the average stress and maximum axial displacement of the tibial fracture surface increased,which can effectively improve the bone regeneration in the tibial fracture area.Moreover,there was no significant difference in four-point bending performance between the‘OUT-MI’bone plate and the‘STR-BE’bone plate,indicating that the mechanical properties of this bone plate were reliable.The results provide a theoretical basis for the design of fracture fixation plates on clinical treatment.
基金This work was supported by National Natural Science Foundation of China(Nos.51875563,51575514,and 51911530200)the Tribology Science Fund of State Key Laboratory of Tribology(No.SKLTKF19A03).
文摘Titanium cermet combining metallic toughness with ceramic wear resistance has been proven to be a potential candidate for implanted joint material.In this work,titanium cermet was synthesized by means of the elevated temperature solid carburizing technology.The Ti_(13)Nb_(13)Zr alloy surface was found to be converted into TiC ceramic layer combined with a carbon strengthened diffusion zone underneath.The overall thickness of the carburized region grew to about 100 um after 120 min carburization at 1,500 K.In order to clarify the growth behaviors of TiC ceramic layer,a growth mechanism is proposed.At the beginning of carburizing process,carbonaceous gas decomposed from carburizer due to high temperature and then converted to free atomic carbons through reduction reaction.Then,in-situ generated TiC ceramic layer possessing certain thickness formed on the surface,meanwhile,the inner carbon diffusion zone also grew inwards due to physical diffusion of carbon,and finally forming a gradient carbon distribution.In addition,the tribological behaviors of the new materials were evaluated through reciprocating ball-on-plate sliding wear tests in bovine calf serum.Although there was an increase in friction coefficient,the wear rate decreased by 59.6%due to the formation of the wear-resistant TiC ceramic layer.The wear mechanisms evolved from severe abrasive wear for bare Ti_(13)Nb_(13)Zr alloy to mild adhesive wear for titanium cermet.
文摘The year 2022 marks the 10th anniversary of the founding of Friction.Friction was launched on 26 March 2013,with an aim to promote the development in tribology by publishing theoretical and experimental research works as well as monographic review articles related to surface contact,friction,wear,lubrication,adhesion,and interface science.
