多亚层柔性节点模型及其在双材料4ENF试件界面分析中的应用

提出了多亚层柔性节点模型用于分析双材料裂纹尖端的应力和变形。该模型考虑了胶层的变形,各亚层视为独立的剪切变形梁,采用两个界面柔度系数考虑界面应力对各亚层界面变形的影响,界面变形包括双材料界面和胶层的变形。通过对FRP-混凝土末端切口四点弯试件(Four-point bending end-notched flexure specimen,简称4ENF)进行界面分析,并与其他模型和有限元分析对比表明:刚性节点模型忽略了裂纹尖端的应力和变形集中,只能粗略地估计构件的整体变形和界面应力;半刚性节点容许裂纹尖端的转动,对裂纹尖端的变形估计优于刚性节点模型,但精度依然不高;多亚层柔性节点模型反映了裂纹尖端的应力和变形集中,与数值分析结果吻合很好,该研究对进行双材料结构的工程设计具有理论指导和参考价值。

Multi-layer flexible joint model and its application to 4ENF specimen analysis of bi-material interface

In this study,based on shear deformable and interface deformable multi-layer beam theory,a new flexible joint model accounting for deformation of adhesive layer is developed to model the crack tip deformation.As an application,closed-form solutions of interface stresses and deformation of a four-point bending end-notched flexure(4ENF) specimen are obtained.Comparisons of interface stresses and deformation using the rigid,semi-rigid and flexible models in the 4ENF specimen show three distinct accuracy levels of the solutions when compared to the finite element analysis,and the best accuracy is achieved by the multi-layer flexible joint model,as indicated by its remarkable agreements with the results of numerical analysis.Therefore,the proposed multi-layer flexible joint model is more accurate and applicable for delamination evaluation of hybrid composites,determination of fracture parameters,and data reduction analysis of fracture experiment.