Monitored indentation for the detection of inclusions in elastomer material

Abstract

The detection of inclusions in soft material is of great interest, especially in the medical field. Traditionally, a biopsy exam is performed after palpation, when necessary. In the present work, a potentially quantitative method, via monitored indentation, is used to mimic palpation. This method consists in investigating the relaxation and stress‐free relaxation responses to an indentation test performed on a silicone block with an inclusion. The aim of the study is to evaluate how a difference in position, size and adhesion of the inclusion can influence the response of the samples to monitored indentation. A finite element model is constructed to conduct comparative studies. The hyper‐viscoelastic parameters of the silicone have been identified experimentally. Results from the simulations showed that the indicators measured during monitored indentation, especially during the stress‐free relaxation phase, are sensitive to adhesive inclusions, while they provide little information regarding their non‐adhesive counterparts. Depths and sizes for which adhesive inclusions are more likely to be detected have been identified. These results are encouraging but are conducted on polymer material and a rigid inclusion; nevertheless, they suggest that the non‐destructive measure of the stress‐free relaxation response of a tissue may help practicians to quantitatively characterize the nature of a nodule.