报告人：Prof. Yoshihiro Mizutani （Tokyo Institute of Technology, Japan）
时间：2017年3月6日14：00
地点：A18-529
报告摘要：FRPs are widely used in engineering fields and UT and AT are utilized for evaluating itssoundness. Since FRPs are anisotropic materials, velocity of elastic wave is changed withpropagation angle. On the other hand, it is known that packet of elastic wave skews awayfrom the normal direction of wave fronts when the wave does not propagate along anisotropicprincipal axes. As the results, amplitude of the waves are changed by angles even the wavesare detected with same propagation distance. This phenomenon causes serious problemswhen soundness of CFRP structure are evaluated by amplitude based algorithms.In this study, we first proposed simplified method to calculate velocity of elastic wave inlaminated FRP plates. Then, amplitude correction method to cancel the effect of wavepacket skew is discussed. We will also show the behavior of elastic waves when the wavepropagates along structures with curved-reinforcement (carbon fiber).
报告2：Electric conductivity of laminated Carbon Fiber Reinforced Polymer composites
报告人：Prof. Akira Todoroki（Tokyo Institute of Technology, Japan）
时间：2017年3月6日14：50
地点：A18-529
报告摘要：Laminated Carbon Fiber Reinforced Polymer (CFRP) composites have orthotropicelectric conductivity. The fiber direction has the highest electric conductivity. Thetransverse direction has lower conductivity, and the conductivity comes from fibercontacts in the prepreg sheet. The lowest conductivity is the through-thickness direction.The conductivity in the through-thickness direction comes from the carbon fiber contactbetween plies. The present study shows the measurements of the electric conductivity oflaminated CFRP, and the scatter of the conductivity is discussed. The frequency effecton the conductivity is also measured. The mechanism of the electric conductivity in thethrough-thickness direction is experimentally investigated. The steady electric current oflaminated CFRP is analytically shown in the present study.
报告3：Eddy current technique for carbon fiber composite: visualization of process-induced fibermisalignment
报告摘要：Carbon fiber reinforced plastics (CFRPs) have been increasingly adopted as structuralmaterials in aerospace industries. Assurance of part quality after manufacture is stronglydemanded in those fields. Fiber misalignment is one of the process-induced defects in CFRPthat causes degradation of the mechanical property. In this study, new eddy current techniqueis developed to visualize fiber misalignment. Although anisotropic electrical properties ofCFRP makethe use of eddy current nondestructive technique difficult, the anisotropy canbe effectively utilized for detection and visualization of misaligned carbon fiber. Distributionof carbon fiber orientation in CFRP can be successfully visualized through the experiment ofthe developed technique.
