Parameter estimation of a rate-dependent damage constitutive model for damage-tolerant brittle composites by Self-OPTIM analyses

Abstract

This article demonstrates a novel parameter identification of a rate-dependent damage constitutive model using self-optimizing inverse method. In the self-optimizing inverse method, an implicit-explicit objective function is formulated as a function of two sets of full-field stresses/strains (implicit non-measurable variables) from two nonlinear finite element analyses, that is, force-driven and displacement-driven simulations, respectively, and global boundary displacements and forces (explicit measurable variables) from experimental tests. The self-optimizing inverse method can self-correct the damage parameter set through optimization procedures referring to global responses measured in laboratory tests. A micromechanics and fracture mechanics based damage constitutive law that accounts for the microcrack nucleation and growth is adopted. Synthetic data from impact tension test simulations were used to demonstrate successful performances of the self-optimizing inverse method in identifying the nonlinear constitutive and damage-related parameters. Comparative studies were conducted using two different optimization techniques -the simplex method and the steady-state genetic algorithm. The identified parameters proved to be identical to the reference values. Finally, in order to further verify the inverse identification method, self-optimizing inverse method analyses were conducted to identify the damage parameter set based on real experimental data from impact tension tests at different strain rates.

Inverse problems of damage mechanics for a hub of a friction pair

“…Despite the extremely small sizes of such irregularities, they affect the different service properties of tribo-conjugation (Bhushan, 1998; Carbone and Bottiglione, 2011; Czifra and Horvath, 2011; Thomas, 1982). In the contemporary stage of engineering, optimal design of friction pair details providing increase of efficiency of friction pair elements is a of great value (Gadzhiev and Mirsalimov, 2004; Halouani et al., 2014; Mirsalimov, 2006a, 2006b, 2008, 2009a, 2009b, Mirsalimov et al., 2013; Meng et al., 2014; Sayyad and Kumar, 2012; Shang et al., 2013). The solution of a mechanics problem on definition of such a function of displacements of external contour points of a hub at which the stress field formed by it would decelerate the crack growth in the hub is of considerable interest.…”

Equivalent damage-healing approach to residual fatigue life prediction for copper film by laser repair

“…Fatigue damage is a process in which material properties are continuously deteriorated under cyclic loading and the damage variable is dependent on the stress and strain (Marco and Starvey, 1954). Some nonlinear damage cumulative theories for materials are proposed based on these characteristics of fatigue damage (Murzewski, 2006;Shang, Yun, et al, 2013;Yang et al, 2005). In order to further investigate the damage accumulation behavior for the damaged components, fatigue property after healing the damage has been given more and more attention.…”