A Review of the Combination of Experimental Measurements and Fibril-Reinforced Modeling for Investigation of Articular Cartilage and Chondrocyte Response to Loading

Figure 6

To demonstrate the role of experimental testing in optimization, we present a stress-relaxation experiment with 10 steps (2%-strain/step). We optimized 2 models (elastic and inhomogeneous fibril reinforced poroelastic, FRPE) to that test. The elastic model was fitted to all steps simultaneously by minimizing the mean squared error while the FRPE was fitted to 2 steps and 10 steps. The elastic model was unable to predict the data from the stress-relaxation curve, while the FRPE model agreed better with the experimental data. However, when the FRPE model parameters were optimized for 2-step data, the predicted data in the following 8 steps did not agree well with the experimental data. Instead, when the model was fitted to all 10 steps, a good agreement was achieved.