Low velocity impact on CFRP plates with compressive preload: Test and modelling

Abstract

When laminated composite materials in modern aircraft structures are subject to impact loads, they are typically not unloaded but under a certain state of prestress. Therefore, in this study the effect of a compressive preload on the low velocity impact behaviour of three different carbon fibre-reinforced plastic (CFRP) materials is investigated. An experimental test programme is documented first, including the design of a preload test device, the specimen manufacture and the results description. An increased deflection and energy absorption for composite plates with a preload of 80% of the buckling load could be observed. Non-destructive inspections showed a large extent of delaminations occurring between individual plies, being an important energy absorption mechanism. The development of numerical simulation methods for this impact scenario using the commercial explicit finite element code LS-DYNA is described in detail. The focus is on the composite material, delamination and preload modelling. The final simulation results showed a good correlation to the experimental data in terms of force and energy plots or the evaluated interlaminar and intralaminar damage, although these numerical results proved to be strongly influenced by simulation parameters like mesh size or the number of shell element layers.

Behaviour of uniaxially preloaded aluminium plates subjected to high-velocity impact

“…A relatively small number of studies have analysed the behaviour of preloaded structures subjected to low-velocity impacts (Nettles et al, 1995;Whittingham et al, 2004;Herszberg and Weller, 2006;Heimbs et al, 2009;Minak et al, 2010). Some of these focus on plates undergoing a uniaxially in-plane load, tensile (Nettles et al, 1995) or compressive (Whittingham et al, 2004), subjected to a transversal impacts.…”

Characterization of microscopic damage due to low-velocity and high-velocity impact in CFRP with toughened interlayers

“…They observed that two different tensile damage modes are produced after different impact energies. Heimbs et al (2009) studied impact load coupled with a prestress condition and found that delamination is a major energy absorption mechanism.…”

Experimental Validation of Composite Structures in Explicit Impact Analysis

“…The main advantage of this modeling technique is the revocation of aspect ratio restrictions concerning the in-plane and through thickness element dimensions, presenting obvious advantages in regard to simulation accuracy and computational efficiency, compared to traditional modeling techniques. In the studies [8][9][10][11][12][13][14] of the literature the use of the stacked shell method has been reported for the simulation of composite laminates.…”