Overview of Technology
A polymer model to capture the history effects of a polymer, the damage progression and predication of fracture.
Background on Technology
The elastic-plastic polymer damage model was developed in a glassy, amorphous, thermoplastic, thermomechanical, inelastic, and internal state variable framework. Internal state variable evolution equations are defined through thermodynamics, kinematics, and kinetics for isotropic damage arising from two different inclusion types: pores and particles.
The damage arising from the particles and crazing is accounted for by three processes of damage: nucleation, growth, and coalescence. Nucleation is defined as the number density of voids/crazes with an associated internal state variable rate equation that is a function of stress state, molecular weight, fracture toughness, particle size, particle volume fraction, temperature, and strain rate.
The damage growth is based upon a single void growing as an internal state variable rate equation that is a function of stress state, rate sensitivity, and strain rate. The coalescence internal state variable rate equation is an interactive term between voids and crazes and is a function of the nearest neighbor distance of voids/crazes and size of voids/crazes, temperature and strain rate.
The damage arising from the pre-existing voids employs the Cocks-Ashby void growth rule. The total damage progression is a summation of the damage volume fraction arising from particles and pores and subsequent crazing. The modeling results compare well to experimental findings garnered from the literature. Finally, this formulation is implemented into a finite element analysis and can be used to design any structural component made of a polymer.
Applications
The Polymer model described can capture the history effects of a polymer, the damage progression and predication of fracture, and can also do temperature and strain rate development.