Novel volumetric Helmholtz free energy function accounting for isotropic cavitation at finite strains

摘要

AbstractCavitation in rubber-like materials is commonly known as sudden void growth under hydrostatic tension till material failure occurs. Experimental investigations of adhesives, e.g. structural silicones accounting for cavitation in combination with the numerical treatment of this phenomenon are rare. Accordingly, this paper presents a micro-mechanically motivated constitutive model accounting for isotropic void growth. It was developed based on numerical homogenization schemes of a cube with an incompressible matrix containing a single, vacuous void in the center. To differentiate whether an initial void is growing, a new developed void growth criterion is presented. The void growth criterion was coupled with the new developed volumetricHelmholtzfree energy function to extend the classical volumetric-deviatoric split to large volume strains. Experiments were performed with a structural silicone under uniaxial tension as well as so-called pancake tests and compared with the new developed volumetric constitutive model accounting for isotropic cavitation. To observe qualitatively cavitation during experiments, a new testing device was developed, which enables one to characterize this damaging effect of the adhesive bonding. The numerical validation shows a good approximation of the experimental results. In order to improve the simulation results, an optimization study on the constitutive parameters was conducted.Graphical AbstractDisplay OmittedHighlights•Experimental Analysis of Nano-Cavitation of Transparent Structural Silicon•Numerical Modeling of Poro-Hyperelastic Material with Finite Void Fraction•Novel Micro-Mechanically Motivated Hyperelastic Constitutive Model Accounting for Cavitation at Finite Void Fraction•New Testing Device to Visualize Cavitation during Macroscopic Experimental Testing•Contradictory Results between Established Critical Load for Cavitation and Experimental Results