Numerical Estimates of the Compressive Strength of Impact-damaged Sandwich Composites

Abstract

Improved numerical models have been developed for predicting the compressive strength of impact-damaged sandwich composites comprised of woven-fabric graphite-epoxy facesheets and Nomex honeycomb cores. The proposed methodology contains three key elements: (1) the use of nondestructive inspection estimates of damage, (2) the incorporation of nonlinear through-the-thickness core-crush constitutive response to account for core failure, and importantly (3) the simulation of progressive loss of facesheet structural integrity based upon userspecified ply failure criteria. The finite element predictions of residual strength for panels impacted with relatively blunt objects correlate well with the experimental observations; this is in contrast to a number of estimates from literature that tend to overestimate the strength. The proposed approach may potentially facilitate sandwich design by providing insight into the relationships between material configuration and damage that lead to improved damage tolerance characteristics.

Compression After Impact on Honeycomb Core Sandwich Panels with Thin Facesheets, Part 2: Analysis

“…Hwang and Lacy [8] also considered the analytic work of Minguet and others and created a FEM approach for predicting the CAI strength of similar honeycomb core panels. Non-destructive techniques were used to estimate material property degradation due to the initial impact damage and honeycomb core crush tests were used to obtain a non-linear transverse core behavior for implementation.…”

Compression After Impact Analysis on Thin Face Sheet Honeycomb Core Sandwich Panels

“…Hwang and Lacy [8] also considered the analytic work of Minguet [3] and others and created a FEM approach for predicting the CAI strength of similar honeycomb core panels. Nondestructive techniques were used to estimate material property degradation due to the initial impact damage, and honeycomb core crush tests were used to obtain a nonlinear transverse core behavior for implementation.…”

Experimental and numerical investigation of the effect of asymmetry on the residual strength of a composite sandwich panel

“…This uncertainty results in a degree of inefficiency in structural design as higher factors of safety are required to provide confidence using composites over traditional metallic samples. Accurate prediction of damage and failure in composite materials is an area of considerable interest (5,6), and there remains no standard approach for evaluating the CAI strength of composite sandwich panels (7).…”