Dynamic compressive mechanical response of a soft polymer material

• A transparent polymer with a static softness and a dynamic stiffness was reported.
• The advanced impact resistant properties with rate dependency were revealed.
• Temperature rise was determined, implying the contribution to dynamic strain energy.
• Crazes and microcracks for enabling plastic deformation were characterised.
• Considerable plastic zone ahead of crack indicates the dynamic fracture toughness.

The dynamic mechanical behaviour of a soft polymer material (Clear Flex 75) was studied using a split Hopkinson pressure bar (SHPB) apparatus. Mechanical properties have been determined at moderate to high strain rates. Real time deformation and fracture were recorded using a high-speed camera. Fracture micrographs were examined to explore the deformation and fracture mechanisms. Crazing and microcracking mechanisms were indicated to be decisive for the dynamic response and impact resistance of this soft polymer material. The stress–strain curves at various strain rates were derived to investigate the strain rate sensitivity. The yield stress shows a rate-dependent behaviour. Temperature rise was also measured by an infrared radiation (IR) camera to investigate the transformation of strain energy at different strain rates. It is of crucial significance to understand the deformation and fracture mechanisms, to study the rate-dependent behaviour as well as to develop a new impact-resistant framework for real engineering application.

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