Finite Element Analysis Simulating Indentation Testing of Human Vaginal Tissue

Abstract

Finite element analysis has often been used in conjunction with experimental testing to provide in-depth understanding of material properties. The aim of this study was to develop a finite element model to be utilized for the interpretation of indentation testing on human, in vivo vaginal tissue. Two distinct models were explored to understand the mechanical material properties and the dynamic influences. First, a single layer, flat tissue model was evaluated. Small indentation simulation was performed to validate the model according to Hertz theory of elasticity. Once validated for multiple elastic moduli, large deformation was applied. Stress and strain along with force were investigated in relation to the displacement of the indenter into the tissue and the Young’s modulus. Next, the findings of the single layer simulation were compared against preliminary, experimental, indentation, test results. Force-displacement results were assessed. Although fundamental differences including geometric and process variances lead to non-congruent results, highly valuable information was attained including understanding of extreme limits that may be found during in vivo experimentation. Finally, a second model was developed based on the findings of the first single-layer model. This new model incorporated multiple tissue layers for the investigation of influence of adjacent tissue properties on vaginal tissue properties during compression testing. Interpretations of each model were then discussed and conclusions drawn regarding how changes in the properties provide further understanding of tissue dynamics. Further discussion was also provided on possible changes to enhance the model.