Study On Mechanical Behavior Of Different Layers For Articular Cartilage Under Rolling And Sliding Loads

Articular cartilage is an important part of human body, as a viscoelastic and nonlinearconnective tissue, its internal organizational structure is complex, which determines its ownunique mechanical properties. In the daily activities, articular cartilage bears the sliding androlling load, so it is important to study the mechanical properties of the individual layers ofcartilage under these loading. Researching the mechanical property changes of different layersof femoral articular cartilage under sliding and rolling loading, can provide an important basisfor clinical treatment and promote the research progress of cartilage disease. It is importantfor structure and composition of artificial cartilage, artificial construct and mechanicalfunction evaluation.In this paper, the pig articular cartilage behavior under sliding and rolling load was studiedby experimental apparatus. The images were acquired throughout the mechanical loadingprocess by using the digital correlation technique. Later, the images were processed and themechanical properties of different layers in cartilage under different loading conditions wereresearched. Experiments showed that the normal displacement of superficial layer is thelargest, the normal displacement of deep layer is the smallest and the normal displacement ofmiddle layer is between superficial layer and deep layer. At a constant compression amount,with the sliding and rolling time increasing, the displacements of cartilage different layershave consistent trends. The normal displacement are all increased first and then decreasedslightly; with the increment of the compression, the displacement of cartilage different layersincrease; with the sliding rate increasing, the normal displacements of the cartilage differentlayers are decreased. With the increase of the loading numbers, the normal displacements ofarticular cartilage different layers are affected. The mechanical properties of different layers incartilage are different under sliding and rolling load, which depend on the complexity of itsinternal organization and structure.Basing on the above cartilage experimental data, two finite element models of articularcartilage under sliding and rolling load were established in this paper. This model consideredthe solid and liquid material, and used the spring element to simulate the mechanicalproperties of collagen fibers in the articular cartilage. This model is closer to the real articularcartilage. By simulating the different loading rates and different amount of cartilagecompressions, the different mechanical properties of cartilage layers were obtained.Compared with experimental data, the simulation data was consistent with the experimentaldata, but some differences still exist. This was mainly due to the complicated internalstructure of cartilage, so the cartilage model still need further progressive to make thetheoretical results more reliable. The mechanical properties of different layers of articularcartilage were studied from the experimental and theoretical point of view, and a theoretical basis for the prevention and treatment of articular cartilage clinical disease were provided.