IMPACT RESPONSE OF THICK GLASS-FIBER-REINFORCED POLYESTER LAMINATES

Thick glass/polyester woven roving laminated plates subject to low-vel ocity impact have been investigated using a guided drop-weight test ri g in ascending energy order up to 1500 J. The impact response and ener gy-absorbing characteristics have been determined by impact-force and absorbed-energy histories, and by force-displacement relationships. Im pact damage is examined by visual inspection, ultrasonic C-scan and an optical microscope so that a three-staged sequential damage model is proposed to characterize damage growth. Static tests are also conducte d to examine strain rate effect. It is demonstrated that the maximum i mpact forces are increased by 36% for the thin plates and by 22% for t he thick plates, although the initial threshold forces are less strain -rate sensitive. Two thicknesses of laminated plates are used to study the thickness effect, and the scaling rules are developed for the del aminated plates. It is shown that both the maximum static and impact f orces, and the incident kinetic energy can be scaled by the thickness ratio if these laminates have the same diameter arid their behaviour i s dominated by shear. The finite element modelling is carried out for relatively low energy cases, the impact structural response is well ca ptured by linear elastic solution.