Failure mechanism of epoxy polymer: transition from ductile to brittle failure

The failure processes of an epoxy polymer (Epicote 21506) were studied by using a high speed camera evolving over a range of strain rates from 0.0001s(-1) to 668s(-1). The front surface of the specimen was monitored by the high speed camera to capture the deformation and cracking processes. A split Hopkinson pressure bar (SHPB) was utilized to examine the dynamic response of the material, and the uniaxial compression test was applied for its quasi-static behavior. The microstructure of the specimen fracture surface after quasi-static and dynamic compression was also investigated by using a Scanning Electron Microscope (SEM) to look insight into the failure mechanism of the material. With the coupled analysis of stress-strain curves and captured images, the behaviors of the specimen under static and dynamic loading can be determined precisely with sufficient details. The specimen under static loading displayed ductile failure, while that under dynamic loading revealed different brittle damage behaviors.