Investigating flow mechanics within a novel non-destructive injectability measurement for fibre preforms

Abstract

Current trends in the field of Fibre Reinforced Plastics (FRP) are exceeding the capabilities of classical, recognised inspection and test methods. Novel non-destructive measurement methods to easily assess the quality assurance within an industrial mass production are required. The research undertaken by the Centre for Advanced Composite Materials is focused on a novel method to assess properties of textile reinforcements employed in Liquid Composite Moulding (LCM) processes. This method non-destructively measures the resistance provided by textiles, stacks and preforms to compressive deformation and fluid flow. These two material properties are indicative for the success of a subsequent resin injection process and are therefore a crucial and characteristic quality control values. On this basis a simple, mobile device is envisaged to support BMW Technology and Production staff to evaluate the injectability and compressibility properties of stacks and preforms. Such a device gives instant feedback, to identify changes in properties from batch to batch. Compaction response has been studied extensively in the literature, with measurements being conceptually simple, and easily applicable in a non-destructive format. Flow resistance of fibre reinforcements, or “injectability”, is commonly quantified by permeability. Rather than calculating permeability using traditional methods (destructive preparation of samples, infusion with a liquid), simple measures of injectability of textile reinforcements are determined using an air pulse applied within the stack or preform. The air pulse provides reliable and immediate information about injectability, enabling fast and accurate measurement methods with simple sensor requirements, suitable for quality assessments within an industrial production environment. Advancing techniques for material characterisation and material failure detection is the main goal of this research.