Damage of Composite Laminates by Low-Velocity Impact

J. Ocean Eng. Technol. 2005;19(1):39-43.

AHN SEOK-HWAN;KIM JIN-WOOK;DO JAE-YOON;KIM HYUN-SOO;NAM KI-WOO;

College of Engineering, Pukyong National University;Korea Institute of Machinery and Materials;Busan Polytechnic college;College of Engineering, Pukyong National University;College of Engineering, Pukyong National University;

저속충격에 의한 복합재료 적층판의 손상

안석환;김진욱;도재윤;김현수;남기우;

부경대학교 공과대학;한국기계연구원;부산기능대학;부경대학교 공과대학;부경대학교 공과대학;

Keywords: Low-velocity Impact, Composite Laminate, Elastic Wave Velocity, Ultrasonic Scans, Damaged Area, Delamination

핵심용어: 저속충격, 복합재료 적층판, 탄성파 속도, 초음파 주사, 손상영역, 박리

Abstract

The study investigated the nondestructive characteristics of damage, caused by law-velocity impact, on symmetric cross-ply laminates, composed of [0o/90o]16s, 24s, 32s, 48s. The thickness of the laminates was 2, 3, 4 and 6 mm, respectively. The impact machine used, Model 8250 Dynatup Instron, was a drop-weight type that employed gravity. The impact velocities used in this experiment were 0.75, 0.90, 1.05, 1.20 and 1.35 m/sec, respectively. Both the load and the deformation increased when the impact velocity was increased. Further, when the load increased with the laminate thickness in the same impact velocity, the deformation still decreased. The extensional velocity was quick, as the laminate thickness increased in the same impact velocity and the impact velocity increased in the same laminate thickness. In the ultrasonic scans, the damaged area represented a dimmed zone. This is due to the fact that the wave, after the partial reflection by the deflects, does not have enough energy to touch the opposite side or to come back from it. The damaged laminate areas differed, according to the laminate thickness and the impact velocity. The extensional velocities are lower in the 0o direction and higher in the 90o direction, when the size of the defect increases. However, it was difficult to draw any conclusion for the extensional velocities in the 45o direction.