Design and failure prediction of insert for composite sandwich structures
Date Issued
2009
Date
2009
Author(s)
Fong, Rey-Yie
Abstract
Insert is usually used as a local reinforcement in composite sandwich structure to transfer concentrated load to structure and avoid failure and excess local deformation. Insert load capacity requirement for vehicle suspension connection point depends on suspension type, geometry and vehicle weight. In traditional design method, the interface between insert and sandwich are always under perfectly connected assumption. However, experiments show that the first failure mode is mostly interface peel not face fracture or core shear in traditional sandwich causing load capacity overestimated. In other words, insert load capacity is dominated by interface adhesive strength. In this research, an interface behavior characterizing method is proposed and simulated by finite element cohesive element that is applied to predict insert load capacity and improved the traditional method that wholly depends on experiments. The method of characterizing interface behavior depends on two fundamental experiments, flatwise tensile and single lap shear test, to obtain strength, stiffness and fracture toughness behavior. FEA model is verified by comparing the result with climbing drum peel rest which contains normal and shear force simultaneously on the interface. The load capacity under different failure modes are recorded and predicted by FEA. Three designs and material configurations in revolution successful increased the load and specific load capacity, adapting for different load and manufacturing process requirements. The method was based on increasing sandwich stiffness to prevent interface peel and proofed by experiments; also an adaptive insert design can both have the characteristics with high load and high specific load capacity to reach the target in effective reinforcement and light weight.
Subjects
composite sandwich structure
insert
load capacity
specific load capacity
cohesive element
interface behavior
Type
thesis
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