PSI - Issue 28

A.A. Lukyanchuk et al. / Procedia Structural Integrity 28 (2020) 2291–2296 A.A.Lukyanchuk / Structural Integrity Procedia 00 (2019) 000–000

2292

2

2. Investigations An experimental study was conducted on specimens of two types, made of CFRP in the form of a strip of rectangular cross-section with central impact damage (sketch of the specimen in Figure 1). Specimens of the first and second types differ by the impact energy applied to them (62.7 J and 20 J respectively) to the central area, and therefore by the depth and size of impact damage. Impact damage was applied according to standard of the institute, harmonized with ASTM D7136.

Figure 1 – Sketch of the specimen with impact damage

The impact damage parameters for the studied specimens are as follows: - For the first type of specimens: impact damage depth in the range of 0.3 ÷ 0.5 mm, the maximum size L max is in the range of 84 ÷ 100 mm; - For the second type of specimens: impact damage depth in the range of 0.14 ÷ 0.38 mm, the maximum size L max is in the range of 38 ÷ 57 mm. Figure 2 shows the difference in impact damage areas for two types of samples.

Figure 2 - Impact damage areas of the first type and the second type specimens

Despite the fact that cross-size of impact damage of some first type specimens didn`t correspond to recommendations of the standard for the test, the aim was to obtain experimental data for the depth of impact damage which meets the case of BVID in the accordance with reference documentation [2]. Tests for fatigue life were carried out according to two irregular programs. All loading cycles of the programs used had a loading cycle asymmetry factor: