Biomimetic composite structural T-joints

Biological structural fixed joints exhibit unique attributes, including highly optimized fiber paths which minimize stress concentrations. In addition, since the joints consist of continuous, uncut fiber architectures, the joints enable the organism to transport information and chemicals from one part of the body to the other. To the contrary, sections of man-made composite material structures are often joined using bolted or bonded joints, which involve low strength and high stress concentrations. These methods are also expensive to achieve. Additional functions such as fluid transport, electrical signal delivery, and thermal conductivity across the joints typically require parasitic tubes, wires, and attachment clips. By using the biomimetic methods, we seek to overcome the limitations which are present in the conventional methods. In the present work, biomimetic co-cured composite sandwich T-joints were constructed using unidirectional glass fiber, epoxy resin, and structural foam. The joints were fabricated using the wet lay-up vacuum bag resin infusion method. Foam sandwich T-joints with multiple continuous fiber architectures and sandwich foam thickness were prepared. The designs were tested in quasi-static bending using a mechanical load frame. The significant weight savings using the biomimetic approaches is discussed, as well as a comparison of failure modes versus architecture is described.