PSI - Issue 66

Carl H. Wolf et al. / Procedia Structural Integrity 66 (2024) 26–37 Carl H. Wolf, Sebastian Henkel, Christian Düreth, Maik Gude and Horst Biermann / Structural Integrity Procedia 00 (2025) 000–000 3

28

growth direction

crack opening displacement (with a gauge length of 4 mm) in crack growth direction

 T ,  4 , T

µ

coefficient of friction

transverse Poisson contraction

2. Methods and Material 2.1. Material and specimen geometry

The specimens were made of a carbon fiber-reinforced plastic composite. In this study, three different weights of the fabric were investigated: (i) 160 g/m² (#160), (ii) 200 g/m² (#200) and (iii) 245 g/m² (#245). The properties of the matrix and fabric used and of the composite materials are given in Table 1 . The materials were produced in a resin transfer molding process. For this purpose, the matrix and fabric were first machined into 10 mm thick plates, which were then cut to the width of the specimens. The hole and notch were then drilled or milled. The specimen geometry consisting of a hole and a notch was intended to represent the stress state of a bolt-rivet connection employing a hole notch arrangement. Based on the specimen geometry, the path of the crack was determined by the fabric layers. The design of the specimens and their dimensions are shown in Figure 2 .

Table 1: Properties of the (a) thermoset matrix HexFlow RTM6, (b) the Tenax-E® HTMA 3K fabric and (c) - Carbon fiber-plastic composite [1].

(a)

Property density (consolidated) glass transition temperature

1.14 g/cm 3 167-183 °C 2890 MPa

E

75 MPa 3.4 %

tensile strength strain at failure

(b)

Property Roving

Pyrofil® TR30S 447/450/460 plain-weave

ECC-style type of bond

160, 200 and 245 g/m 2 4, 5 or 6 threads/cm

Weight Setting Property E 1 , E 2

(c)

69.4 GPa 11.5 GPa

E 3 ν 12

0.08 0.015

ν 13 , ν 23

2.2. Test Setup The uniaxial tests were performed on a MTS 810 (MTS Systems Corporation, Eden Prairie, USA) servo-hydraulic universal testing system with a 10 kN load cell and the biaxial tests were performed on an Instron 8800 test system with four 250 kN load cells. A camera with a resolution of 11 µm/Px (mvBlueCOUGAR-XD104bG, Matrix Vision GmbH, Oppenweiler, Germany) was attached to both test systems to determine the displacements. To investigate the fatigue crack growth behavior, the following interrupted test procedure was applied: (1) image acquisition in unloaded state,