Characterization of Impact Damage Resistance of CF/PEEK and CF/Toughened Epoxy Laminates under Low and High Velocity Impact Tests

Abstract

In order to use composite materials in aeronautical turbo engines, their resistance to impact damage must be understood. In this work the subperforation flat-wise impact resistance of three kinds of high resistance material systems were evaluated under low and high velocity impact tests. Tested systems were AS4/PEEK (APC-2/AS4, ICI-Fiberite), AS4/PEEK + IL, which consists of APC-2 prepreg and PEEK film inserted between layers as an interleave, and toughened epoxy system T800/#3900 (Toray). To investigate the effects of stacking sequence on resistance, three lay-ups (0/ + 30/0/ -30)s, (0/ + 60/0/ -60)s, and (0/ + 45/90/ -45)s-were tested. A drop weight system was used for the low velocity tests, where the velocity ranged from 1.5 to 3.1 m/s. An air gun system was used for the high velocity tests, where the velocity range was between 50 and 100 m/s. Both velocity impact tests used the same specimens geometries, support structures, impactor head geometries, and incident energy range. The projected damage area was measured with an ultrasonic C-Scan. The relation between damage area (DA) and impact energy (IE) was linear, and the ratio of the DA/IE quantified the impact resistance of each specimen. The value of DA/IE for the high velocity tests was larger than the value for low velocity tests. To estimate the lay-up effect, a stacking parameter,B, which indicates the difference of the inplane stiffness between the adjacent laminae, was proposed. A proportional relation between the DA/IE and the f was obtained. The value of (DA/IE)/3, which was independent of stacking sequence, indicated the impact resistance of the tested material systems for both velocity levels. The ratio of (DA/IE)/3 for the high velocity to the value for the low velocity changed with material systems.