Issue 71

M. Abdulla et alii, Fracture and Structural Integrity, 71 (2025) 124-150; DOI: 10.3221/IGF-ESIS.71.10

Thermo-Mechanical Load Condition: The most significant deformation is observed under thermo-mechanical loading, as shown in Fig. 24. In this condition, the adhesive volume is subjected to both high temperature and mechanical load, resulting in a complex and irregular shape change. The deformation is evident in both the x and y directions, indicating a more complex and irregular shape change. The grid lines indicate substantial displacement, highlighting the combined effects of thermal and mechanical stresses. The deformation along the y-axis is primarily due to the external mechanical load, similar to the mechanical load condition. However, the deformation along the x-axis, which is irregular in shape, is attributed to the thermal load. The thermal expansion of the adhesive material, coupled with the mechanical load, causes a more pronounced deformation. In Fig. 24, the empty spaces in the grid lines represents the amount of deformation, whereas the blue volume within the grid shows the new configuration of the adhesive disbond.

Figure 24: Deformation in adhesive volume when the thermo-mechanical load is acting on the model.

Oil Canning Effect The deformation behaviour of the composite patch under both mechanical and thermo-mechanical loading conditions, highlights the profound impact of thermal effects, particularly regarding the oil canning phenomenon. Under pure mechanical loading, the composite patch demonstrates no deformation, maintaining a close resemblance to its original shape (represented by the dashed line) and the deformed contour as depicted in Fig. 25. This outcome suggests that the mechanical load, in isolation, does not exert enough force to induce significant deformation, thereby allowing the patch to distribute the applied stresses effectively across its surface and ensuring the stability of the repair.

(a) (b) Figure 25: Oil canning in the composite patch under mechanical loading (a) side view (b) top view.

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