Development of a test method for evaluating the crushing behaviour of unidirectional laminates

Abstract

More fundamental test methods are needed to assist the development of physically based and truly predictive simulation tools for composite materials under crash conditions. In this paper, a unidirectional flat specimen that can be used to validate the predicted behaviour from a simulation to the physical behaviour in the experiment is developed. A systematic experimental investigation is conducted to evaluate the influence of the trigger geometry on the crushing response by selecting two trigger types and different trigger angles. For longitudinal crushing, the traditional bevel trigger leads to out-of-plane failure by splaying with a limited amount of in-plane fracture, while the proposed trigger achieves a high amount of compressive fragmentation failure. For transverse crushing, the symmetry of the proposed new trigger improves the specimen stability during the crushing process. It is also observed that the weft threads of the unidirectional fabric reinforcement used for the tests have a strong influence on the longitudinal crushing response. The boundary conditions of the test and the information on the specimen failure gleaned from video recordings and microscopic inspections are discussed in order to facilitate a future correlation with modelling results.

An experimental and numerical study on the crush behaviour of hybrid unidirectional/woven carbon-fibre reinforced composite laminates

“…The specimen geometry was based on a similar experimental study in [14]. The lay-up of each specimen was [5HS/-45/+45/90/0/-45/+45/90/+45/-45/90/+45/-45/0/90/+45/-45/5HS], and the two trigger geometries of these specimens are shown in Fig.…”

“…3. In the figure, the red arrow [14] indicates the longitudinal (0°) direction of the specimen, which is aligned with the crushing load direction. and are the sample thickness and sample width, respectively.…”

Improvement and validation of a physically based model for the shear and transverse crushing of orthotropic composites

“…The geometry of the specimen and its supports in Figure 12 were taken from Bru et al. 36,37 The chosen design is not meant to represent real energy absorbing structures which are generally larger, self-supported (tube or corrugated structures) and with a multidirectional lay-up. 2,6–8,28,38 The simplicity of the design aims to simplify the identification of the crush mechanisms.…”

Assessing the current modelling approach for predicting the crashworthiness of Formula One composite structures

“…Different coupon designs and loading fixtures have been tested, including both open section (e.g. flat [3][4][5][6][7], corrugated/sinusoidal [8,9], C-channels [10,11], semi-circular [8,12]) and closed section (e.g. round tube [13][14][15][16], square tube [11,17,18], double hat [19]) geometries, for a variety of unidirectional (UD), 2D, and 3D woven and braided architectures.…”