Application of Model-based Design Approach on Dynamic Tensile Testing of Carbon/Epoxy Composites at Intermediate Strain Rates

Abstract

The reliable strain rate-dependent material properties at intermediate strain rate levels (1-200 s-1 ) are crucial for an accurate crashworthy design of fibre-reinforced polymer (FRP) composite structures. However, the presence of unacceptable oscillations in measured force signals hinders the precise identification of the dynamic mechanical response of materials. The current work reports the results of gained in an initial study using a novel numerical model developed through a Model-based Design (MBD) approach. A multi-degree of-freedom (MDOF) mass-spring-damper model is employed to investigate the dynamic characteristics of a whole experimental test setup to gain insights into the dynamic interaction between the test machine and the test specimen. The developed model was calibrated by the results from dynamic tension testing of Aluminium Alloy 2024-T3. Then, the model parameters were optimised using a genetic algorithm (GA). Subsequently, the adaptability of the developed model to carbon/epoxy composites, IM7/8552, was examined. The proposed model is promising to identify the influence of the test setup on the measurements and effectively distinguish excessive oscillations caused by its inertial effect at intermediate strain rate levels. The model will offer a robust solution to identify oscillations and, therefore, expand the testing capabilities to a broader range of strain rates.

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