Failure Modes and Load Transfer in Sandwich T-Joints

Various T-joints of composite sandwich panels were investigated. The corresponding modes of failure at the joint were identified. The key modes of failure include debonding between the two sandwich components to be joined, debonding between the attachment and the sandwich panel, and cracking in the core of the sandwich. A new type of T-joint incorporating an aluminum U-channel in the web sandwich was found to provide much improvement over the conventional circular fillet T-joint. Two types of bolted joints were also studied to investigate the effectiveness of using bolts for suppressing debonding at the joint. It was shown that using bolts in a circular fillet joint could cause early failure in the core and would not help much to increase the ultimate joint strength. The experimental failure modes of the tested joints were explained with the help of FE analysis.