Predicting strain rate dependent deformation of carbon fiber cylinders under impact internal pressure

This study aims to investigate the dynamic response and accurately predict the macroscopic structural deformation of carbon fiber reinforced polymer (CFRP) composite cylinders under transient impact internal pressure such as deflagration. First, quasi-static and dynamic loading experiments were conducted to determine the strain rate dependent properties of M40 CFRP. Subsequently, a macroscopic phenomenological theoretical model incorporating a strain rate correction matrix was established to efficiently evaluate elastic deformation. To validate this model, an innovative closed-bomb impact testing system was independently developed for real-time, synchronous monitoring of transient internal pressure and dynamic hoop strain. The results reveal a pronounced strain rate strengthening effect under both tension and compression, particularly in the fiber reinforced direction. Experimental validation demonstrates that the proposed model captures the dynamic expansion, maintaining the prediction error for the maximum hoop strain within 16%. Parametric analyses further demonstrate that larger cylinder sizes and shorter pressure loading durations significantly amplify strain rate effects, proving that relying on traditional quasi-static parameters leads to unsafe underestimations of deformation risks. Consequently, this model and testing method provide a practical engineering reference for the preliminary anti-impact design of composite pressure-bearing structures, such as composite cartridge cases and high-pressure vessels.