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

Abstract

A research study has been conducted on compression after impact of thin facesheet honeycomb core sandwich panels. This paper is focused on the modeling and analysis used to simulate the tests described in a companion paper. Of interest are composite sandwich panels with aerospace applications, which contain either a 3 or 6 lb∕ft 3 honeycomb core. It was found that compression after impact testing of these coupons resulted in either an indentation propagation failure for the lower density core or a crack propagation failure mode for the higher density core. An analysis model is developed to account for both modes through the inclusion of progressive failure analysis of the facesheets and a homogenized, nonlinear material model for the honeycomb core. In addition, significant impact damage detail is included in the model based on experimental observation. Analysis results are compared with the experimental results for each of the 24 sandwich panel specimens tested. Good agreement of failure mode predictions with test results demonstrates the importance of considering both facesheet and core failure, as well as the initial damage severity. Finally, a parametric study highlights the strength benefits compared with mass penalty for various core densities.Young's modulus G = shear modulus h max = maximum dent depth I = stress invariant i = subscript indicator W = waviness coefficient x = global coordinate or axis, coupon width direction y = global coordinate or axis, coupon load direction z = global coordinate or axis, coupon through the thickness direction ϵ = strain σ = stress υ = Poisson's ratio ϕ f = fiber volume fraction ϕ m = matrix volume fraction

Surface damage evaluation of honeycomb sandwich aircraft panels using 3D scanning technology

“…ACCEPTED MANUSCRIPT 2 and buckled honeycomb core, which may reduce residual strength and compromise structural integrity [1]. Dent limits for aircraft panels are usually defined in the aircraft standard repair manual (SRM), which is provided by the original equipment manufacturer (OEM).…”