Flow-speed-controlled quality optimisation for one-shot-hybrid RTM parts

Abstract

This work describes a model-based methodology to improve the bonding quality between the metal and composite constituents of one-shot-hybrid resin transfer moulding (OSH-RTM) parts. In order to reduce void induced defects in the interface an ideal flow front velocity needs to be achieved. This ideal flow front velocity is characterised by capillary rise experiments at the used carbon fibre textile. The flow front velocity during mould filling is controlled by the use of pressure sensors and Darcy's law. Therefore, viscosity characterisation of the resin system and permeability measurements of the preform were carried out. The interface of the produced OSH-RTM roof bar for a car is tested on a component test rig imitating the load of a side impact at a car. A t-test was carried out to prove that the flowspeed-controlled injection strategy is advantageous compared to a constant mass flow injection by means of a higher maximum load transferable by the interface of the hybrid part.

Capillary Driven Saturation of Textile Reinforcing Structures Proposal for an Extension of Lucas-Washburn Equation

“…Whether inter-yarn or intra-yarn void formation is dominant, depends mainly on the average flow front velocity during saturation. Accordingly, void formation can be minimized by infiltration with an optimized flow front velocity resulting in comparable timely saturation development in the yarns and in between [7]. For complex shaped geometries such approach will not work since a controlled and defined flow front velocity in all regions is hardly reachable.…”

Quality Control Approach for the Detection of Internal Lower Density Areas in Composite Disks in Industrial Conditions Based on a Combination of NDT Techniques

“…Their appearance is typical for all manufacturing methods being used for polymeric and PMC structures. The reasons for such phenomenon are usually related to inappropriate processing parameters; for example, incorrectly set temperature and pressure cycles (causing boiling of a polymer), a flow speed of a liquid polymer and its viscosity during resin infusion (RI) or resin transfer molding (RTM) manufacturing techniques [1][2][3][4][5], the cumulation of entrapped gas bubbles, an unevenly distributed temperature field in the volume of an injected liquid polymer [6], etc. Moreover, connecting the mentioned reasons with the manufacturing process, the appearance of voids in polymeric and PMC structures can be also related to the specificity of a processed polymer, i.e., nucleation processes occurring during crystallization or solidification, the influence of residual volatiles, dissolving or absorption of moisture and other gases during the manufacturing process, etc.…”