Validation of Macroscopic Forming Simulations of a Unidirectional Pre-Impregnated Material through Optical Measurements

Abstract

Presenting interesting aspects such as a high strength-to-weight ratio, Carbon Fibre Reinforced Plastic components are frequently used in the aerospace industry. The forming step, which conforms the reinforcement to a specific geometry, is a sensitive phase of the manufacturing process. In order to detect the occurrence of defects prior to any trial, forming methods are often simulated via finite element software. The presented work will detail the simulation validation of a double curved helicopter frame forming out of a unidirectional carbon fibre pre-impregnated material (M21E, Hexcel®). The finite element model was based on an explicit approach at a macroscopic level and developed via the commercially available software Visual-Crash PAM (ESI®) [1]. The validation was carried out on six different preforms. Measurements of the top layers were performed by an enhanced version of a 4D measuring system, originally developed for non-woven fabric [2], able to make reproducible photographic and height measurements (Fig. 1). Experimental results were then compared to simulated ones. Due to material specificities, the photo quality reached for non-crimp fabrics could not be achieved [2]. After hardware and software modifications, measurements and analyses were eventually successfully completed. The validation of the simulation reached an accuracy of 1° to 3° depending on the geometrical features of the preform (Fig. 2).