Parametric study of stress concentration in bolted lap joints between particulate metal matrix composite materials

by Katepalli, Nagababu.

A composite is defined as a material that constitutes of at least two constituents, which are bonded together along the interface in the composite. Metal Matrix Composite (MMC) is a composite material in which one constituent is a metal or alloy forming at least one percolating network. The other constituent is embedded in this metal matrix. The particulate metal matrix composites when compared to metal alloys exhibit higher strength, wear resistance and stiffness. Because of their high plastic modulus, they exhibit higher buckling and compressive strength. They have high electrical conductivity, better thermal conductivity and low thermal expansion. More over their isotropic behavior and formability by conventional methods makes them good choice for low cost applications. Optimization of the design of structural joints leads to increase in their load carrying capacity, minimizing weight and cost. Extensive knowledge of multiple parameters that effect the behavior of the structural joints is required for reliable and effective design of joints. The aim of this research is to predict the stress concentration around the hole in the lap joint made of MMC and to investigate the effects of the different parameters on the stress around the hole. A three dimensional finite element model has been developed to study the effects of various design parameters on the structural performance of such joints. The model is validated by comparing the results with a closed form solution for a simple problem of determining the stress around the hole in a flat plat. The present study quantifies relationship between stress concentration around the hole and the bolt diameter; distance between the holes, Young’s modulus, fastener pre-tension and the axial load. v