MECHANICAL BEHAVIOR AND FAILURE ANALYSIS OF RTM-BRAIDED FLAT PANEL LAMINATES

Hakan Kilic, Som R. Soni, William Grissom

ABSTRACT

Coupon tests are investigated to characterize the mechanical behavior of resin transfer molded (RTM) braided flat panels. The tested composite system is made from carbon fiber braids and polylite matrix constituents. Coupons were cut from two different RTM-braided flat panel laminates with [±30]s and [±60]s lay-ups. The overall linear elastic properties are identified along with the stress-strain behavior of coupons under in-plane tension loading. Different failure modes, lower initial elastic moduli and softer stress-strain responses were observed for [±60]s compared to those of [±30]s. In addition, RTM-braided flat plates of [±30]s and [±60]s lay-ups with water-jet cut holes (¼ and 3/8”) were tested to investigate the material response and the failure mode under axial bolt loads. The experimentally obtained failure modes and loads are compared with the predicted ones obtained from a boundary value problem representing a double lap bolted joint implemented into a computer code for the analysis of bolted joints. The elastic properties and ultimate stresses obtained from coupon tests are used for predictions. Good agreement is shown when comparing the experimental results and the predictions.