Damage detection versus heat dissipation under dynamic compression

What is it about?

In this investigation, a new experimental technique in which the deformation, damage mode, and the temperature are measured simultaneously during a high strain rate on laminated composites materials. The composites consist of unidirectional E-glass fibers reinforced epoxy polymer composites used in industrial applications. The experimental setup consists of a compression Split Hopkinson Pressure Bar (SHPB), a high-speed infrared camera and a high-speed Fastcam rapid camera. Specimens, with cubic like a shape, are impacted at different strain rates ranging from 200 to 2000 s−1. During impact test, the specimen surface is controlled and monitored with the infrared camera which provides thermal images in time sequence and with high-speed camera which acquires the damage progressive in specimens. Experimental results show that the damage throughout specimens differs and the temperature change depending on the damage mode and their maximum exceed 219 °C.

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Why is it important?

An experimental setup in which simultaneous full-field deformation, damage and temperature measurements were done on the surface of a specimen during dynamic compression tests conducted at different strain rates using Hopkinson bars. The infrared thermal camera was used to detect defects and damage in [±60]20 glass fibers reinforced epoxy polymer composites. With lock-in thermography and the rapid camera shows a satisfactory agreement and allows for a correct identification of size, location and shape of the created area of damage. V-letter like shape is the principle damage form observed in specimens. For the thermal camera, a hot spot with V-shape is also observed during the test with Hopkinson bars. The hot area was localized in the intersection of the two branches of the V with maximum temperature exceeds 219 °C.

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