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When a piezoelectric film is glued on the surface of a structure member subjected to mechanical load, a distribution of electric potential is induced. In the existence of defects in the member, a characteristic variation of electric potential is observed. Based on this phenomenon, the passive electric potential CT (computed tomography) method is developed for detecting and identifying defects in a structure. In this study, the applicability of the passive electric potential CT method to the identification of a delamination in a CFRP laminate was experimentally examined. CFRP laminate specimens, which have an artificial interlaminer delamination, with a piezoelectric film on their surface were subjected to three-point bending. The electric potential distribution on the piezoelectric film was measured by a non-contact voltmeter. Characteristic variation reflecting the location and the size of the delamination is observed in the measured electric potential distributions. To identify the delamination, an inverse method was constructed based on the least-squares residual evaluated between the measured and computed electric potential distributions. The location and size of the delamination were estimated accurately. It was shown that the passive electric potential CT method using a piezoelectric film was useful for the quantitative identification of interlaminar delamination in laminated composite materials. [ABSTRACT FROM AUTHOR]

A CD shell was preimploded by two counter-propagating green beams from the GEKKO laser system GXII (based at the Institute of Laser Engineering, Osaka University), forming a dense core. The core was predominantly heated by energetic ions driven by the laser for fast-ignition-fusion experiment, an extremely energetic ultrashort pulse laser, that is illuminated perpendicularly to the GXII axis. Consequently, we observed the D(d, n)3 He-reacted neutrons (DD beam-fusion neutrons) at a yield of n sr. The beam-fusion neutrons verified that the ions directly collided with the core plasma. Whereas the hot electrons heated the whole core volume, the energetic ions deposited their energies locally in the core. As evidenced in the spectrum, the process simultaneously excited thermal neutrons with a yield of n sr, raising the local core temperature from 0.8 to 1.8 keV. The shell-implosion dynamics (including the beam fusion and thermal fusion initiated by fast deuterons and carbon ions) can be explained by the one-dimensional hydrocode STAR 1D. Meanwhile, the core heating due to resistive processes driven by hot electrons, and also the generation of fast ions were well-predicted by the two-dimensional collisional particle-in-cell code. Together with hot electrons, the ion contribution to fast ignition is indispensable for realizing high-gain fusion. By virtue of its core heating and ignition, the proposed scheme can potentially achieve high-gain fusion. [ABSTRACT FROM AUTHOR]