Gradient-Enhanced Modelling of Damage for Rate-Dependent Material Behaviour—A Parameter Identification Framework

Abstract

The simulation of complex engineering components and structures under loads requires the formulation and adequate calibration of appropriate material models. This work introduces an optimisation-based scheme for the calibration of viscoelastic material models that are coupled to gradient-enhanced damage in a finite strain setting. The parameter identification scheme is applied to a self-diagnostic poly(dimethylsiloxane) (PDMS) elastomer, where so-called mechanophore units are incorporated within the polymeric microstructure. The present contribution, however, focuses on the purely mechanical response of the material, combining experiments with homogeneous and inhomogeneous states of deformation. In effect, the results provided lay the groundwork for a future extension of the proposed parameter identification framework, where additional field-data provided by the self-diagnostic capabilities can be incorporated into the optimisation scheme.

Destruction of polymer insulation and threshold amplitudes of current pulses of different temporal shapes for electric wires and cables in the low- and high-current circuits of pulse power engineering, electrical engineering and electronic devices

“…At present, when developing and creating in the world new polymeric insulating materials with various nano-and microstructural structures of electrical engineering and other (including medical and biological) purposes, the issues of behaviour of polymer insulation under conditions of the action of destabilizing (damaging) physical factors are given increased attention [8][9][10][11].…”

“…. (10) Similarly to (9), using (10) to find the calculated value I mpk for a particular wire (cable) with known characteristics S Ci and C l (see Table 2) at given temporal parameters Δ p и T p for the discharge pulse current i p (t) flowing through the CWP will actually be reduced to the calculation according to (7) of the numerical value of the normalizing coefficient k p2 ≥1.…”

“…According to (9), (10), the threshold values I mpk of the amplitudes I mp of aperiodic and damped sinusoidal current pulses i p (t) are directly proportional to the crosssections S Ci of the metal cores (shells) of the electrical wires and cables under study. In addition, the sought values of I mpk are actually inversely proportional to the temporal parameters τ p 1/2 и T p 1/2 for current pulses p (t)flowing through the CWP.…”

Analysis of Damage and Permeability Evolution for Mudstone Material under Coupled Stress-Seepage

“…In the current theoretical analysis of seepage-stress damage coupling [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ], the permeability evolution model cannot describe the characteristics of sudden permeability change after rock capacity expansion. According to the permeability evolution characteristics of mudstone, the sudden change of permeability evolution before and after capacity expansion in the process of total stress-strain is analyzed.…”

A computational framework for gradient‐enhanced damage – implementation and applications

“…The load-displacement-curves in combination with the contour plots of the damage value for both mesh discretisations demonstrate mesh-objective results. For further details, see [Photos of the tensile test with inhomogeneous deformation states of a notched specimen a) at the beginning of the experiment at t = 2.55 s and b) before the sample starts to tear at t = 1139.8 s; cf [6]…”