Multi-Scale Experimental Characterization for LS-DYNA MAT213 Modeling of Composite Structures under High Strain Rate

TL;DR

This paper develops and characterizes a material model for simulating the high strain rate response of a specific composite material in LS-DYNA, using multi-scale experiments and digital image correlation techniques.

Contribution

It introduces a multi-scale experimental approach to accurately characterize material parameters for the MAT213 model of a composite under dynamic loading.

Findings

Successful multi-scale testing method for transverse strains

Reliable stress-strain data obtained via digital image correlation

Enhanced material model parameters for composite under high strain rates

Abstract

Aerospace structures often experience high strain rate events such as ballistic impact, crash, or crush. A material model has been developed that enhances the capability to simulate the dynamic response of composite materials under these loading conditions. The material model has been implemented into the commercially available transient dynamic finite element code LS-DYNA as MAT213. The model can simulate the nonlinear deformation, damage, and failure that takes place in a composite under dynamic loading conditions. The specific goal of this work is to characterize the MAT213 input for the representative material. The specific composite material being examined consists of T700G unidirectional carbon fibers and a low-melt PolyArylEtherKetone (LMPAEK) thermoplastic resin system. It is formally referred to as Toray TC1225 LMPAEK T700G. As the initial part of this work, this paper is focused on characterizing the material parameters for the MAT213 deformation model based on results obtained from multi-scale experimentation. The effort concentrated on characterizing the in-plane material response suitable for use with thin shell elements. For shell elements within MAT213, tabulated stress-strain results from tension and compression tests in the longitudinal and transverse directions and in-plane shear tests are required. Due to the difficulty of measuring small strains in the transverse direction, a multi-scale testing method was developed. Macro-scale testing is performed per the typical ASTM methods while micro-scale testing uses a microscope along with smaller coupon sizes to obtain the smaller strains in the transverse direction of each test. For both testing methods, a VIC-2D camera and software for digital image correlation analysis are used. Using the DIC combined with each test fixture, reliable stress and strain data are collected.