Investigation To The Damage Evolution Process Of Defect Cartilage

The knee is a large and complex joint, which bears large amount of exercise and highstress that make articular cartilage injury more common in clinical practice. Due to poorregeneration of the articular cartilage, repair is very difficult. If damage occurred, it wouldresult in a significant change in the carrying capacity. Therefore, to study the mechanicalproperties of the articular cartilage in-depth can provide reliable reference for clinical repair.The main topic has studied the mechanical behavior of the cartilage from the analysis ofnumerical and experimental research in two ways. The experimental results and numericalsimulation results are compared to verify the numerical simulation results. Study themechanical properties of the articular cartilage from the aspects both numerical simulationand experimental. The results may provide a reference to both of the design for cartilagealternatives and clinical repair of defect cartilage.The thickness of different layers of cartilage was obtained by a kind of experiment, inwhich the displacement in different layers zone cartilage under the compression load wasobtained by the non-contact digital correlation technique. The multi-layer cartilage modelwith fiber and defect was established by the multi-physics analysis software ANSYS, with thedifferent layers of the cartilage refer to the experimental results. According to the strengthcondition, the cartilage damage evolution process was simulated by the method of modifyingthe stiffness of the elements. The influence of the different defect depth to the damageevolution of cartilage was considered in parameter study.The simulation results have shown that the stress distribution in matrix was related to thecartilage defect depth. The minimum stress was distributed in the deep areas and below thedamage area, stress concentration was located in the both sides of the defect area in thecartilage matrix, and the damaged area developed gradually from surface to deep, themaximum stress located at both sides of defect area. The stress distribution of cartilage fibersrelated with their location, the compressive stresses are mainly distributed in the middle anddeep area, which are greater than those of undamaged. Experimental validation of thesimulation results are obtained by the compression experiment.In the process of damage evolution, the damaged area gradually developed from thesurface to the deep. In the case of defect value of60%, the maximum equivalent stresses inmatrix will be increased in the process of damage evolution; in the case of defect value of5%,the maximum axial stresses in fibers will be increased in the process of damage evolution.During the unidirectional compression experiment, the three lines near the gap are consideredand extract the Y strain curves and the experiment results are basically consistent with simulation results.