Continuum mechanical constitutive modeling
Continuum mechanical constitutive models
In partitioned-domain multiscale simulations of polymers, the constitutive model used in the continuum has to coincide at least partly with the mechanical behavior of the particle-based domain. Under small deformations, hyperelastic constitutive models are accurate enough. However, under larger deformations, polymers can exhibit viscous or plastic behavior simultaneously, which requires a more sophisticated constitutive model that has to be derived from multiple MD simulations with different loading cases.
Fig. 1: Material characterization based on numerical pseudo-experiments [1]
In contrast to experiments, the high strain rates make it difficult to decouple the elastic and viscous behavior. In our research, we try to find a way to identify the constitutive model with only few parameters for polymers under high strain rates.
The material characterization of polystyrene in [1] as shown in Fig. 1 identifies viscoelastic behavior with compressibility. Based on this, we propose a constitutive model within the parallel networks framework that can accurately describe the mechanical behavior obtained from MD simulations.
[1] Ries M., Possart G., Steinmann P., Pfaller S., “Extensive CGMD simulations of atactic PS providing pseudo experimental data to calibrate nonlinear inelastic continuum mechanical constitutive laws”, Polymers 11 (2019), 1824.