Viscoelasticity and the Small Punch Creep Recovery Test: Numerical analysis and experimental tests on the applicability for polyvinyl chloride (PVC)

Abstract

Research on the Small Punch Test (SPT) has been mainly focused on metallic alloys, with limited investigations in polymeric materials. The miniature size of the SPT eases and motivates its use in biomedical applications, like the mechanical characterization of surgical implants made of different polymers. It is noted that the aim of these publications was focused on mechanical properties inherent to the tensile test (yield strength, ultimate tensile strength, Young's modulus, etc.), but the applicability of this miniature test for the estimation of singular polymer properties like viscoelasticity or viscoplasticity has not been addressed.

The aim of this paper was the assessment of SPT as a characterization test for the viscoelastic properties of polymers. To analyze this applicability, numerical FEM simulations of hypothetical materials were performed and a novel Small Punch Creep Recovery Test (SPCRT) was designed. These FEM simulations were verified with experimental compressive creep recovery tests and SPCRTs for specimens made of polyvinyl chloride (PVC). The results showed that SPCRTs accurately estimated the viscoelastic properties for materials with non-stress-dependent viscoelastic properties. In the case of materials with stress-dependent viscoelastic properties, the SPCRT would estimate a mean or intermediate value of these stress-dependent viscoelastic properties.