Numerical Research Of Mechanical Response On Articular Cartilage Microstructure

Knee joints are important organs of human activity.Under abnormal load,articular cartilage can cause changes in its internal components,change the mechanical properties of cartilage can cause secondary damage to cartilage.Therefore,it is very important to study the changes in the mechanical properties of the cartilage’s meso-structure on the mechanical behavior of the cartilage.This research can supplement and improve the mechanical mechanism of the development of articular cartilage damage,and provide reference data for the prevention and treatment of cartilage diseases.This paper starts from the micro-structure of articular cartilage,and uses ABQUS software to establish a mesoscale numerical model of fiber-reinforced porous viscoelastic articular cartilage.The model considers the mechanical parameters of fibers and matrix as a function of cartilage depth.This paper starts with the microstructure of articular cartilage and uses ABQUS software to establish a mesoscale numerical model of fiber-reinforced porous viscoelastic articular cartilage.The model treats the mechanical parameters of fibers and matrix as a function of cartilage depth.First,the effects of the location and manner of collagen fiber breakage on the mechanical behavior of cartilage under abnormal stress or rolling load after softening degradation were studied,and then the mechanical mechanism of fiber "bundling" during cartilage degradation was studied.The numerical analysis results show that the maximum principal strain of the matrix appears at the position above the middle layer of cartilage,which is not affected by the fiber breaking mode and fiber bundle size.Intermediate fiber rupture has a greater impact on the mechanical properties of cartilage.The thickening of the fiber bundle can reduce the maximum principal strain of the matrix.Once the fiber bundle is ruptured,the maximum principal strain value of the cartilage matrix of the thicker fiber bundle is greater,thereby causing greater damage to the cartilage.Thicker cartilage matrix bundles have larger maximum principal strain values,making cartilage more vulnerable to damage.It can be speculated that "bundling" of cartilage under abnormal pressure is a self-protection mechanism.Secondly,on the basis of the fiber-reinforced two-dimensional porous viscoelastic numerical model,measures should be taken and the stiffness evolution method should be used to study the evolution process of damage caused by internalsoftening of the spine.he results showed that starting from the inner middle layer,the range of damage gradually expanded,forming an oval region in the cartilage.In the middle position,the damage spreads fastest in the horizontal direction,and the interstitial fluid velocity in the damage area is the largest.Finally,a three-dimensional model of a fiber-reinforced porous viscoelastic joint with a calcified layer structure was established,and the mechanical effects of the calcified layer under impact,rolling,and torsional loads were studied.The results show that when the impact load is applied,the maximum stress of the cartilage is 1/3of the cartilage depth,and the stress increases with the increase of the impact velocity.Under the same impact load,the strain of the cartilage matrix increases with the hardness of the calcified layer.Under various loads,the stress of the contact portion between the calcified layer and the subchondral bone does not decrease as the hardness of the calcified layer increases,but when the hardness of the calcified layer is moderate,the stress of the calcified layer is the largest.The hardness of the calcified layer is too small to transfer the load to the subchondral bone.The calcification layer is too hard to destroy cartilage,which shows that although the structure of the calcification layer is small,it plays an important role in mechanics.In this paper,a mesoscopic model is established to study the mechanical effects of cartilage mesoscopic structure under load,and some meaningful conclusions are drawn,which can provide references for the construction of tissue engineering cartilage and the prevention and treatment of cartilage diseases.