Non-Destructive Evaluation of Impacted CFRP by IR Thermography.

Waldemar Swiderski,Pawel Hlosta

doi:10.3390/ma12060956

Abstract

The aim of the article is to present a new technique providing an increase in the reliability of standard destructive tests of light ballistic shields. During the ballistic impact (i.e., of projectiles or fragments) on the material and its penetration by these incoming items, the absorbed kinetic energy is transformed into heat. In particular, the material regions that are damaged generate heat, and around and above the damage, on particular areas of the surface of the sample, the temperature signal increases. While registering, thermal cameras can process the impact and penetration of a material by a projectile and can accurately determine the area of the material (around the point of impact and the area of penetration) that has been damaged. Two infrared cameras were used for our testing work. One recorded the changes to the temperature field on the surface with the ballistic impact and the second one on the opposite surface. These results were compared with those obtained by optical active thermography performed by the reflection approach. Selected results from all the tests are presented in this paper.

Highlights

In military applications, laminates reinforced with aramid, carbon, and glass fibers are used for the construction of protective products against light ballistics
Changes in the temperature fields on both the surface impacted by the projectile and the rear surface were recorded by two thermal cameras
When fired at a speed of 300 m/s, the kinetic energy of a projectile is about 50 J, with some of this energy being converted into heat energy in the destruction area of the material

Summary

Introduction

Laminates reinforced with aramid, carbon, and glass fibers are used for the construction of protective products against light ballistics. As a result of the impact, fibers stretch and break to absorb the kinetic energy of the projectile casing. The stretching of fibers in the fabric transfers the projectile’s energy to adjacent fibers and in this way, disperses the energy over a large area [1]. This creates a subsurface defect in the composite structure with a much greater area than the caliber of the projectile [2]. During the ballistic impact (i.e., of projectiles or fragments) on the material and its penetration by these incoming objects, the absorbed kinetic energy is transformed into heat

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Conclusion