PSI - Issue 17

Andrey V. Babushkin et al. / Procedia Structural Integrity 17 (2019) 658–665 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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to use reference data to identify, at least, the ratios of effective properties and characteristics. Given that the design of critical structures requires a complete set of data. The presence of such problems makes researchers resort to non obvious solutions. For example, Babushkin and Lobanov (2017) introduced the concepts of conditional stresses under collapse and the coefficient of elasticity under collapse in the full understanding that these concepts do not reflect the entire complexity of the stress-strain state in the collapse zone. However, these quantities turned out to be quite suitable for analyzing the loading diagrams and identifying certain effects. In this study using the example of composite materials based on 3D preforms was proposed to refine the basic characteristics obtained during the installation tests and to conduct a comparative analysis (calculated and experimental data) with the characteristics of comparison when tested according to non-trivial methods. The choice was made and the optimal variant of the research direction, the plan for conducting experimental and theoretical work, taking into account the capabilities and features of the newest experimental equipment, was substantiated. Formed a plan of experimental studies to determine the basic composite materials characteristics under tension, compression and shear, as well as promising tests using nontrivial methods of stretching and compressing samples with a hole (ASTM D5766 (ASTM International, 2018) and ASTM D6484 (ASTM International, 2014)), bending a curved beam (ASTM D6415 (ASTM International, 2013)) and compressing plates after impact (ASTM D7136 (ASTM International, 2005) and ASTM D7137 (ASTM International, 2017)). Formed a task for the manufacture of non-trivial samples. For the study, were used samples whose preforms were made using 3D weaving technology using six different ways of weaving shown in Fig. 1 (A - H series). To obtain the samples, six patterns of interlacing 3D-woven preforms were developed: orthogonal (Fig. 1 a); orthogonal combined (Fig. 1 b); with pairwise interlayer reinforcement (Fig. 1 c); with pairwise interlayer reinforcement and longitudinal layer (Fig. 1 d); with pairwise interlayer combined reinforcement (Fig. 1 e) and through interlayer reinforcement (Fig. 1 f). As well as two layered structures (G, H series): the usual carbon-fiber-laminate structure (Fig. 2 a) and the structure reinforced by the Tufting firmware method (Fig. 2 b) is presented in Figure 2. 3. Materials and technology work

Series A Series B Series C Series D Series E Series F

a

b

Fig. 2. Samples with layered structures : “G” series - usual carbon-fiber-laminate structure (a); “H” series – structure reinforced by the Tufting firmware method (b)

a b f Fig. 1. Samples of 3D-woven performs with weave pattern: orthogonal (a), orthogonal combined (b); with pairwise interlayer reinforcement (c); with pairwise interlayer reinforcement and longitudinal layer (d); with pairwise interlayer combined reinforcement (e); with through interlayer reinforcement (f) c d e