Development Of Rolling Device And Articular Cartilage Numerical Analysis Of Mechanical Behavior

The knee joint is the hub of various motions of the human body.The force bore by articular cartilage is complex and strong,that make it as a prevalent site for clinical disease.Excessive exercise or an inappropriate mechanical environment can cause changes in the structure and function of chondrocytes,which can be expected to result in cartilage degradation.The growth and maintenance of articular cartilage are greatly affected by the load,so it is important to study the mechanical state of articular cartilage.At present,the effect of mechanical stimulation on arthritis is explored at the cellular level by establishing a two-phase model of cartilage and numerically simulating the strain of the solid matrix under cyclic compression loading.However,there are little research on the load and the angle of motion of cartilage in actual exercise.Therefore,on the one hand,this study designed a bioreactor for the functionalization of cartilage in vitro based on the characteristics of physiological cartilage.On the other hand,considering the kinematics of flexion and extension,internal/valgus and internal/external rotation,a three-dimensional finite element model of the knee joint can be realized when walking,revealing the compression,rolling,sliding or rotating of the knee cartilage and the composite load.The mechanical state underneath.On the one hand,this paper combines materials science,biomechanics,cell biology and tissue engineering.The literature research summarizes the knee kinematics,the composite load of the knee joint and the actual movement stage and the mechanical environment.The impact.Founded on the characteristics of cartilage under normal physiological conditions,a rolling loading device designed to achieve cartilage function in vitro is designed.The device consists of a swing adjusting mechanism and a compression adjusting mechanism.The bottom plate swings left and right in combination with the rolling load to enable it closer to the actual motion state of the cartilage,and the composite load condition is more in line with the physical environment in which the tissue grows and develops.Moreover,the roller is pressed by its own gravity,and no external mechanical parts are required to supply power,and the culture and the roller are in a closed space,which can reduce pollution and avoid evaporation of the culture liquid during the cultivation.On the other hand,through the finite element software Abaqus,an articular cartilage model considering the action of calcification layer and subchondral bone was established to make the model closer to the physiological structure of intact native cartilage.Knee joint motion is the relative motion of the tibial plateau and the distal femur,which are simplified as a geometric model of a rigidized sphere acting on the plane cartilage.Considering the kinematics of flexion and extension,internal/valgus and internal/external rotation,a three-dimensional finite element model of the composite load of the knee joint during walkingis established.Numerical analysis of knee cartilage under compression,rolling,sliding or rotating and combined loads.The main points of the cartilage are analyzed.The principal conclusions are as follows: During the simulated gait,the stress of the articular cartilage is quickly concentrated,while the elastic modulus of the subchondral bone is 3200 MPa higher than that of calcified cartilage(320 MPa).The cartilage layer(0.5-0.9 MPa),the greater the elastic modulus,the smaller the deformation amount,the less easily the cartilage is deformed,and it may be more protective.The result is also pointed out that the maximum Mises stress is distributed in the cartilage.Lower bone;as the compression process progresses,the Mises stress,strain and pore pressure increase with the increase of the compression amount,and the increase rate decreases nonlinearly;respectively,sliding,rolling,flipping,rotating and any two The preliminary statistical comparison of Mises stress,strain and void ratio in 15 different mechanical loads and three kinds of composite loads and comprehensive loads can be roughly divided into three kinds of mechanical states: rolling,sliding and rolling,and flipping,The effect of rotation on cartilage is almost negligible,and the rolling load is closest to the total composite load.