Transverse loading of bolted joints in discontinuous ceramic cored sandwich structures
Date
2012
Authors
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Publisher
University of Delaware
Abstract
The present study involves the transverse static and fatigue loading of bolted joints in a discontinuous ceramic cored sandwich structure (DCCSS). DCCSS structures are commonly used in armored vehicle applications. The DCCSS is a hybrid symmetric composite laminate made up of a face sheet, adhesive interlayer, and a discontinuous tile array core infused with FCS 2 epoxy resin. Static tests were performed with the varying of support conditions from simply supported, pinned, and torqued bolts. The goal was to understand the change in strength and failure modes due to the joint under transverse loading. Optimization of the joint was also involved, thus the torque levels were also varied to conclude t he best torque level for performance of the joint. It was found out that the bolted joint improved the performance and strength of the DCCSS in comparison to the simply supported and pinned support conditions. The failure mode of the DCCSS changed with each support condition, but ultimate failure was consistently due to delamination between the adhesive interlayer and face sheet. The optimal torque level of 90 ft-lbs. was determined from static testing. The influence of fatigue on stiffness retention, residual strength and damage were also conducted for both pinned and torqued support conditions to study durability. The bolted joint helped maintain the strength of the joint and stiffness of the structure in comparison to the pinned condition.