Case Study: Monitoring the Surface Temperature on Curing Epoxy Resin Samples

High‐end thermography with the VarioCAM® HD research 800

During the curing process, a polymer with a strongly cross‐linked structure – also called a thermoset – is formed. Polymers generally have low thermal conductivity. Particularly in the case of thick‐walled components, these properties lead to an inhomogeneous temperature distribution with hotspots. This entails the risk that the material properties of the polymers deteriorate, for example, their strength decreases, porosity increases, or they even ignite. In addition, the cross‐linking curing reaction of epoxy resins is accompanied by a volumetric shrinkage of the material. This can sometimes cause strong mechanical residual stresses in the material, which can lead to the failure of the component before the actual loading. A precise numerical prediction of the temperature development in components is essential in order to develop suitable temperature controls in the manufacturing process of fibre composite components.

The Institute of Applied Mechanics of Clausthal University of Technology develops mathematical models based on a wide range of experimental studies. These material models reflect the mechanical, thermal, and in this case, the chemical behaviour of the polymer. Implemented in finite element software, they enable the prediction of the process or component behaviour. Against the background of the aforementioned challenges to process control in the production of fibre composite components, Dipl.‐Ing. Chris Leistner and his colleagues at the Institute of Applied Mechanics, among other topics, examined the pure epoxy resin system as part of their tests. They use temperature measurements on epoxy resin samples during curing in order to validate the model.

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