Abstract

This study underscores the remarkable strength-to-weight advantage offered by curved composite laminates in comparison to conventional materials like metal, preserving or even surpassing strength levels. To comprehensively assess the strength characteristics of such laminates, the research delves into the primary failure modes governing their out-of-plane strength, predominantly matrix failure and delamination. It is essential to consider the impact of manufacturing processes, which introduce residual stresses and spring-in phenomena.

To address these complexities, a finite element simulation is employed, integrating manufacturing effects and adopting a semi-discrete damage model. Within this model, matrix failure within the plies is delineated using a smeared crack approach, whereby crack directionality aligns passively with fiber orientation within each ply. Furthermore, the smeared crack approach is extended to model damage occurring at ply interfaces.

This comprehensive investigation is done for the layup sequence: [45°/0°/−45°/90°]3S - symmetric and balanced laminate. Experimental validation is achieved through a 4-point bending test by adhering close to ASTM D6415 standards, gauging the curved beam strength/inter-laminar strength of fiber-reinforced polymer matrix composites. The utilization of DIC images aids in the systematic observation and comprehension of failure modes across various scenarios.

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