Tensile testing of polymeric materials: a model-based approach to estimate the material strength without position sensor

Tensile testing probably represents the foremost important mechanical test that can performed on materials. This characterization has great relevance on polymeric materials, where the evaluation of the polymer goes beyond the pure chemical composition analysis. On the other hand, chemical labs are not always equipped with complete tensile machines due to space and budget constraints while often rely on much simpler machines usually provided with a dynamometer only. In this contest, the goal of the work is to provide a useful and effective method to estimate the stress–strain curve based only on force (and therefore the specimen stress) data. Of course, to recover the missing information (i.e. the sample elongation, and thus its strain) a suitable model of the tensile machine is needed to complement the dynamometer measures. Throughout the paper the steps to achieve such a model are described, together with an extensive experimental validation: firstly, we validated the method on metals which exhibit a well-defined behaviour. Then, we selected three different polymeric materials (polyvinyl alcohol, polydimethylsiloxane and natural rubber) in order to assess the performances of proposed approach in estimating their stress–strain characteristics. The obtained results confirmed the suitability and effectiveness of the proposed method in real-world applications.