Analysis of thermoplastic prepreg bending stiffness during manufacturing and of its influence on wrinkling simulations

Bending properties of thermoplastic prepregs used in aerospace are investigated at representative thermoforming temperatures. The influence of temperature is of principal importance because prepreg manufacturing is performed close to the resin’s melting point. A cantilever test performed in an environmental chamber is presented. Bending properties of PEEK-carbon satin and PPS-carbon satin prepregs are measured in a range of temperature including manufacturing temperatures. It is shown that the bending stiffness of the fore-mentioned thermoplastic prepregs are greatly influenced by temperature. The measured bending properties are used to simulate a thermoforming process. The impact of these properties on the simulation results is shown as well. Particularly, bending stiffness during forming determines the size of wrinkles that may appear. The sensitivity of wrinkle size with regards to the measured bending stiffness is analysed.