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

作者：Drass M^*; Schneider J; Kolling S

来源：Materials and Design, 2018, 138: 71-89.

DOI：10.1016/j.matdes.2017.10.059

• Nano-cavitation
• Transparent structural silicone adhesive
• Poro-hyperelastic materials
• Finite porosity
• Numerical homogenization
• Void growth criteria

Cavitation 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 volumetric HELMHOLTZ free 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.

• 出版日期2018-1-15