考虑复合材料层合板就地效应的强度理论

Theoretical Methodology for Laminated Composite Strength Including In-situ Effect

为了能准确预测复合材料层合板的失效起始和破坏过程,发展了一种考虑层合板就地效应(In-situ Effect)的强度理论,方法包括就地强度的确定、失效起始判定和材料性能退化。介绍并推导了基于断裂力学假设的就地强度计算方法,将层合板内的铺层分为内嵌厚层、内嵌薄层和外表面层3种类型,不同类型的层分别对应不同的计算方法。建立了一种考虑就地强度的面内失效起始准则,提出了相应的强度分析方法流程。对单向和多向层合板的失效包线进行了预测,计算结果表明发展的强度理论能很好地预测结构的失效起始,充分反映材料从失效起始到最终破坏的试验现象和规律,与传统Hashin准则相比预测精度明显提高。通过对准各向同性层合板失效包线预测发现,在进行层合板强度分析时考虑就地强度能明显提高预测失效起始的准确性和精度,在复合材料结构强度分析过程中考虑层合板的就地效应十分必要。

In order to accurately predict the failure initiation and propagation for composite laminates,a strength theory including in-situ effect is developed.The method deals with the determination of in-situ strength,damage initiation and material properties degradation.The theory of the in-situ strength,based upon the principle of fracture mechanics and certain assumptions,divides the laminate into embedded thick ply,embedded thin ply and outer surface ply and provides them with different calculation methods.An intralaminar failure initiation criterion including in-situ strength is proposed and the corresponding failure analysis procedure is developed.The predictions of failure envelopes for unidirectional and multidirectional laminates are conducted.The results show that the developed method predicts the structural failure initiation and captures the experimental phenomena from the initiation to the final failure pretty well.The prediction accuracy is significantly improved compared to the wide applied Hashin criterion.The strength analysis result for a quasi-isotropic laminate shows that the failure onset envelope agrees well with the experiment when in-situ strength is used,which necessitates the consideration of insitu effect in composites structural strength analysis.