Research on enhancement of damage resistance in composite materials under in-situ effects
To study the enhancement strategies for damage resistance,particularly the delamination resistance,of lightweight CFRP composites,a parametric analysis of in-situ transverse tensile and shear strength of composites was conducted,indicating that the enhancement of in-situ strength has a positive impact on mitigating material damage.Subsequently,through short-beam shear experiments,the expansion of in-plane shear-type cracks under external loading was a significant cause of internal delamination in laminates.A material damage model was constructed based on the classical Hashin criterion,taking into account the in-situ effect.This material model was applied to conduct simulation analysis on the bending failure behavior of short beams.Finally,the application of this damage model and material enhancement scheme to the analysis of delamination damage in laminates under local impact loads was extended.The results show that when the single-layer thickness of orthogonally laid short beams is reduced to one-fourth of the original thickness,the bending strength significantly increases by 48%,and structural failure is significantly delayed.The mechanism of inhibiting interlayer delamination and enhancing structural strength lies in the significant delay of crack initiation and propagation in the matrix.The significant difference in delamination area under impact loads suggests that adopting a thin-ply design has tremendous potential to enhance the local impact delamination resistance of CFRP composites.
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