In the automotive industry, trial and error systems are adopted to the design. This system is disadvantageous concerning cost and time. Therefore, the simulation technology with the reliability has been required. The objective of this study is to establish the simulation technology for impact response behavior of rectangular CFRP tubes under full-lap collision. We adopted drop weight impact tests to investigate response behavior and energy absorption characteristics of the rectangular CFRP tubes. The impact test was carried out by dropping the impactor from height of 12 m. The speed was approximately 55 km/h just before the impact. The weight of the impactor was 105 kg. The same tendency of the impact response was observed for the five specimens. A finite element (FE) model was also developed by using a nonlinear, explicit dynamic code LS-DYNA to simulate the progressive failure behavior and to calculate the absorbed energy of the rectangular CFRP tubes under impact load. The maximum load, absorbed energy and maximum displacement calculated by FEM model were in good agreement with the average values of the test results.
This study demonstrates the ultrasonic technique that visualizes the wave propagation with the use of a pulsed laser for a nondestructive testing of CFRP composite laminates. In order to verify the technique, we visualized the Lamb-wave propagation in an intact CFRP cross-ply laminate. The S0 mode and the A0 mode were identified in the snapshots of the wave propagation through the calculated dispersion curves. Furthermore, we applied the technique to the damage detection in the CFRP laminate subjected to the impact loading. Although the impact damage was barely visible, the wave scattering due to the delamination was clearly observed in the snapshots as well as the S0 and A0 Lamb-modes. We also addressed the quantitative evaluation of the delamination using the B-scope image and concluded that the reliable detection and evaluation of the impact-induced delamination by the proposed technique are applicable to inspections of composite laminates.