PSI - Issue 25

Jamaloddin Jamali et al. / Procedia Structural Integrity 25 (2020) 180–185 Author name / Structural Integrity Procedia 00 (2019) 000–000

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used to obtain the fracture toughness results under different in-plane modes. Several researches have been carried out to study fracture behavior of composite parts [6]. In the CTS test, a through-thickness crack proceeds perpendicular to the layers. The crack in a UD composite, used to be studied as a function of loading angle with respect to the macroscopic initial crack direction using the CTS fixture and the position of the holding pin in the fixture (see Fig. 1).

Fig.1 3D model of the CTS fixture with detailed dimension. The left picture shows the grip plate with pin holes to provide different ranges of loading mode. The right picture shows the CTS specimen fit in the fixture and their corresponding dimension. This is done in order to measure the associated crack propagation energy.” [7-9]. This paper introduces both modeling and modification of the CTS fixture to perform mixed mode fracture of woven carbon fiber epoxy that are fabricated. Also, the displacement of different points of the crack is measured using a simplified displacement tracking method. Finally, calculations were done to determine the values of fracture toughness using the measured value of the maximum force. Nomenclature �

mode I stress intensity factor �� mode II stress intensity factor ��� Effective stress intensity factor Angle of loading P maximum load w CTS specimen width t CTS specimen thickness a CTS specimen crack length

2. 3D MODELING AND MANUFACTURING OF CTS FIXTURE SolidWorks [10] was used to model a 3D design of CTS specimen, and to simulate it. 3D modeling was done to check the dimensions of each part and to make sure of the easy assembly of the parts while testing (as shown in Fig. 1). Mild carbon steel sheet (thickness = 10mm) was used to make the circular parts and the washers. Cutting and milling machines were used to fabricate the parts. For the circular piece, the milling machine used to form the specified holes and irregular geometry there.