PSI - Issue 75

Aijia Li et al. / Procedia Structural Integrity 75 (2025) 318–333 Aijia Li, Christian Garnier,, Marie-Laetitia Pastor, Xiaojing Gong, Clément Keller/ Structural Integrity Procedia (2025)

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Fig. 10. Failure location (white arrow) and S11 stress distribution on the 1 st layer and 9 th layer of: (a) cross-ply specimen; (b) quasi-isotropic specimen

The third criterion regarding thermography is considered by analyzing the thermal response of the specimen in another simulation. To realize a similar condition with the real test, a body heat flux is used to represent the heat source caused by fatigue behaviors, and the duration of heating and cooling is defined as 1200 s and 300 s, in terms of the previous self-heating tests (Huang et al. 2019 and Jia et al. 2023). In both the cross-ply specimen and the quasi isotropic specimen, the temperature in Fig. 11 firstly increases at a stable and varying rate, then stabilizes at a constant of 18 degrees Celsius, and finally decreases after stopping the heating load. Hence, the specimen is capable of characterizing the typical thermodynamic phases, named the initial temperature increase phase, temperature stabilization phase, and cooling stage, which were identified and reported by numerous fatigue studies on the self heating effect (Huang et al. 2019, Huang et al. 2020, and Jia et al. 2023). Fig. 12 points out the calculated temperature at each node of the finite element model. The temperature field of the gauge region is uniform and large enough (area of the plane: 153.86 mm 2 ) for an accurate calculation of temperature or different heat dissipation, such as the heat loss by conduction, convection, and radiation, based on thermodynamic laws. For the last criterion related to manufacturing, the 3D-printing machine and silicone material can be adopted for making the mold, and the cutting and curing process of the composite is feasible with the help of the cookie cutter and autoclave in our laboratory, thus the proposed cruciform does not have any trouble in the manufacturing procedure shown in Fig. 2. Overall, the proposed specimen design was validated by a numerical simulation, a thermal simulation, and a pre-assessment of specimen fabrication, and it will be further evaluated in the upcoming biaxial static and fatigue tests.