PSI - Issue 25

Angelika Wronkowicz-Katunin et al. / Procedia Structural Integrity 25 (2020) 13–18 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

14

2

metals and their alloys, are increasingly being replaced by composite materials whose properties can be shaped depending on the demand. One of the main recipients of these materials is the aircraft industry, where particularly important parameters are the mass, mechanical strength and their behavior during an impact. One of the weaknesses of these materials is the risk of delamination formation during the impact, so the determination of these parameters is very important for engineers responsible for creating new components. Delamination is often characterized in terms of the energy release rate which defines the resistance of materials against a crack growth (Mouritz, 2012). The process of the determination of the energy release rate is widely described in the literature (see e.g. Shokrieh et al., 2012; Simon et al., 2017; Hufenbach et al., 2013; Bin Mohamed Rehan et al., 2017; Heidari-Rarani et al., 2013; Franklin et al., 2013). The aim of this study is to evaluate the influence of several technological factors during the preparation of the specimens and performing the tests, which may significantly affect the obtained results. These experiments cover the quasi-static tension and compression tests as well as interlaminar fracture toughness tests. The obtained results will be used for a preparation of a numerical model for the prediction of structural residual life of composites with impact damage, which is a next step of on-going research project realized by the authors. The experiments were performed on two types of specimens: CFRP specimens made of double twill 2/2 carbon fabric with the layup of 0/90° impregnated with epoxy resin manufactured and supplied by Dexcraft S.C. (Helenów, Poland), and GFRP specimens made of plain weave fabric with the same orientation of particular layers and also impregnated with epoxy resin manufactured and supplied by IZO-ERG S.A. (Gliwice, Poland) – a symbol EP GC 201. The CFRP specimens were manufactured using the resin infusion technology, while GFRP specimens were manufactured using the impregnation technology. For each material three geometrical configurations were considered: specimens for the tensile tests were prepared according to (Standard, 2000) – see Fig. 1(a), specimens for the compressive tests were prepared according to (Standard, 2016) – see Fig. 1(b), while specimens for the fracture toughness were prepared according to (Standard, 2013) – see Fig. 1(c). In order to fit loading ranges of the testing machine, the dimensions of specimens for same types of tests and for different materials were different. These dimensions are presented in Table 1. 2. Specimens and experiments 2.1. Specimens preparation

(a)

(b)

(c)

Fig. 1. Schemes of tested specimens: (a) tensile tests, (b) compressive tests, (c) DCB specimen for fracture toughness tests.