• Journal of the Korean Society for Nondestructive Testing
• /
• v.29 no.4
• /
• pp.323-330
• /
• 2009

The objective of this research was to develop a practical integrated approach using extracted features from electrical resistance measurements and coupled electromechanical models of damage, for in-situ damage detection and sensing in carbon fiber reinforced plastic(CFRP) composites. To achieve this objective, we introduced specific known damage (in terms of type, size, and location) into CFRP laminates and established quantitative relationships with the electrical resistance measurements. For processing of numerous measurement data, an autonomous data acquisition system was devised. We also established a specimen preparation procedure and a method for electrode setup. Coupon and panel CFRP laminate specimens with several known damage were tested. Coupon specimens with various sizes of artificial delaminations obtained by inserting Teflon film were manufactured and the resistance was measured. The measurement results showed that increase of delamination size led to increase of resistance implying that it is possible to sense the existence and size of delamination. A quasi-isotropic panel was manufactured and electrical resistance was measured. Then three different sizes of holes were drilled at a chosen location. The panel was prepared using the established procedures with six electrode connections on each side making a total of twenty-four electrodes. Vertical, horizontal, and diagonal pairs of electrodes were chosen and the resistance was measured. The measurement results showed the possibility of the established measurement system for an in-situ damage detection method for CFRP composite structures.

• Composites Research
• /
• v.29 no.1
• /
• pp.24-32
• /
• 2016

Ballistic impact analyses have been performed with the Kevlar fabric impregnated with STF(shear thickening fluid). Multi-layer laminates modeled with 3D isoparametric shell elements were used for the performance analysis and their results are compared with experimental results. Both experiments and numerical analyses have been done to verify the usefulness of STF to enhance the impact resistance performance. The results showed that STF increases friction within a bundle of fiber, and this phenomena is more apparent in the velocity range of under near 450 m/s. In this research, it is emphasized that FEA analyses of STF impregnated Kevlar fabric laminate were successfully conducted using shell elements. Moreover, the effectiveness of the technique and accuracy were verified through the comparison with reliable experimental data.