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
The human knee implant is computationally modelled in the mixed lubrication regime to investigate the tribological performance of the implant.This model includes the complex geometry of the implant components,unlike e...The human knee implant is computationally modelled in the mixed lubrication regime to investigate the tribological performance of the implant.This model includes the complex geometry of the implant components,unlike elliptical contact models that approximate this geometry.Film thickness and pressure results are presented for an ISO gait cycle to determine the lubrication regime present within the implant during its operation.It was found that it was possible for the lubrication regime to span between elastohydrodynamic,mixed and boundary lubrication depending on the operating conditions of the implant.It was observed that the tribological conditions present in one condyle were not necessarily representative of the other.Multiple points of contact were found within the same condyle,which cannot be computed by the elliptical contact solvers.This model can be used to balance forces in all directions,instead of only the normal loads,as often done in elliptical contact models.This work is an initial step towards understanding the role of the complex geometry in the tribological characteristics of the human knee implant when operating in physiological conditions.展开更多
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Imperial College Research FellowshipEngineering and Physical Sciences Research Council,Grant/Award Number:EP/N509486/1。
文摘The human knee implant is computationally modelled in the mixed lubrication regime to investigate the tribological performance of the implant.This model includes the complex geometry of the implant components,unlike elliptical contact models that approximate this geometry.Film thickness and pressure results are presented for an ISO gait cycle to determine the lubrication regime present within the implant during its operation.It was found that it was possible for the lubrication regime to span between elastohydrodynamic,mixed and boundary lubrication depending on the operating conditions of the implant.It was observed that the tribological conditions present in one condyle were not necessarily representative of the other.Multiple points of contact were found within the same condyle,which cannot be computed by the elliptical contact solvers.This model can be used to balance forces in all directions,instead of only the normal loads,as often done in elliptical contact models.This work is an initial step towards understanding the role of the complex geometry in the tribological characteristics of the human knee implant when operating in physiological conditions.
