Research on residual strain monitoring and failure behavior of thick L-shaped composite laminates

doi:10.19936/j.cnki.2096-8000.20250428.001

Abstract

Abstract: The study involves monitoring residual strains and investigating failure behavior in thick L-shaped composite laminates. It aims to explore how the stacking sequence under high thickness conditions affects the structural load-bearing capacity and failure modes. Utilizing embedded fiber bragg grating (FBG), the study monitors the evolution and distribution characteristics of the temperature field and strain field within the curved region of the L-shaped composite laminate during the curing process. It aims to investigate how thickness and ply orientation angle influence the thermal residual strain and spring-in angle in L-shaped composite laminates. Conducting bending tests, utilizing DIC(digital image correlation) to observe the strain field and failure modes in the lateral cross-section. And comparing the results with empirical formulas, exploring the influence of thermal residual stress under different ply orientations on the load-carrying capacity and failure modes. The results indicate that the large-thickness L-shaped laminates exhibit a certain temperature gradient, but the temperature difference between the upper and lower layers and the middle layer is relatively small. Due to the mold effect, L-shaped laminates with angles are more likely to generate pre-loaded regions on the inner side of the corner compared to pure 0° ply. The results of the bending test indicate that the ultimate load obtained for pure 0° ply is essentially consistent with the theoretical prediction. However, for quasi-isotropic ply, the ultimate load is 25% smaller than the theoretical prediction. The pre-load region has a certain influence on the subsequent load-carrying capacity and failure mode.

Key words: L-shaped composite, curing monitoring, pre-loaded, failure mode, residual stress

CLC Number:

TB332

WANG Weilun, CAO Zihe, YU Xingchen, LU Yixian, CAO Dongfeng, HU Haixiao, JI Yundong, LI Shuxin. Research on residual strain monitoring and failure behavior of thick L-shaped composite laminates[J]. COMPOSITES SCIENCE AND ENGINEERING, 2025, 0(4): 1-10.

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