科研之友
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摘要
The goal of this research is to optimize the design of single-lap joints made by joining composite material to metals. The single-lap joint under both out-of-plane load and tensile load was examined. It is observed that designing a joint for one kind of load is not always satisfactory because for other load cases, different stresses would govern the design. Local stress peaks were investigated in order to find ways to decrease these peaks. An approach for optimizing the joint was chosen so the stress peaks at each end could be minimized (peel, axial and shear stress). By tapering the titanium adherend inside and outside, the stress distribution in the adhesive can be significantly changed at the tapered end and all three important stresses that governed the design (peel, axial and shear stress) are decreased for a joint under tension and out-of-plane load. For dissimilar adherends, the numerically largest stresses always occur in the adhesive at the edge of the overlap adjacent to the adherend with the lower value of flexural stiffness and the relative difference in these peaks is a function of the relative flexural stiffness of two adherends. Using an outer bead of adhesive decreases the stress peak at composite edge. Thus, two methods are used to reduce adhesive stresses: tapering and addition of adhesive beads. Having completed a finite element stress analysis, the results are used to predict the strength of a given joint. A strain energy based on failure criteria was evaluated, which addressed the problem of stress singularities in the finite element method. Three point bending tests were performed using different bonding configurations to verify the strength of the adhesive joint and to evaluate the failure criterion. Optimization of the parameters of the joint geometry was achieved from the results of this study.
- 出版日期2007-5
