Application of VFM for the simultaneous identification of visco-pseudo-hyper elastic constants of rubbers

In this work, the Virtual Fields Method is employed in order to identify the parameters of constitutive models describing the visco-pseudo-hyper elastic behavior of rubber-like materials; a cruciform specimen is subjected to several biaxial loading/unloading cycles at different strain amplitudes, while load and full-field strain histories are recorded. The material is considered from its virgin state and no conditioning is performed, so not only the hyperelastic and viscoelastic characteristics have to be considered, but also the damage or Mullins effect has to be accounted for. The numerical procedure here developed exploits the large amount of information provided by the experiment (over 18,000 pictures are processed) and put them into equations of virtual work where the models constants are unknown. It is worth to note that here all the material constants are determined simultaneously by solving a unique system of non linear equations, instead of determine them separately from different tests. © The Society for Experimental Mechanics, Inc. 2014.