Masaru Ishibashi

Evaluation of adhesively bonded joint strength of CFRP with laser treatment

Pulsed laser surface treatment was applied to carbon fiber-reinforced plastics (CFRPs) to enhance the work efficiency as well as to establish the stable clean process of surface pre-treatment during the bonding process of CFRP structures. Surface analyses were conducted to CFRP treated by various laser conditions in order to find the optimal laser process. Adhesively bonded specimens were fabricated using CFRPs subjected to laser treatment, and adhesive lap shear strength of CFRPs bonded with adhesive films was evaluated compared with the abrasive paper treatment. Surface conditions, adhesive strength, and adhesive fracture mode depended on the treatment parameters, and adhesive strength similar to abrasive paper treatment could be obtained in the specimens with appropriate laser treatment. It was concluded that laser surface treatment can be applied to the surface treatment process of CFRP bonded structures.

Fabrication of CNT-Dispersed CFRP Using Length-Controlled CNTs: Measurement of CNT Length and Characterization of Mechanical Properties

Abstract The incorporation of carbon nanotubes (CNTs) into polymers is expected to improve the physical properties of polymers and fiber-reinforced plastics. Moldability of CNT-dispersed polymers is the key technology for the successful improvement of properties. As CNT length has great impact on the moldability (e.g., viscosity) as well as physical performance of nanocomposites, length control of CNT by milling process is focused on in this study. The CNTs and CNT-dispersed compounds were subject to milling process and length distribution of CNTs was measured using SEM and rheological properties of the compounds were discussed. Finally, carbon-fiber reinforced plastics (CFRP) using length-controlled CNT-dispersed epoxy was successfully fabricated and its mechanical properties were measured too. Improvement of mechanical properties of CNT-dispersed CFRP is demonstrated by the comparison to CFRP without CNTs.

Characterization of Nonlinear Behaviors of CSCNT/Carbon Fiber-Reinforced Epoxy Laminates

Nonlinear mechanical behaviors of unidirectional carbon fiber-reinforced plastic (CFRP) laminates using cup-stacked carbon nanotubes (CSCNTs) dispersed epoxy are evaluated and compared with those of CFRP laminates without CSCNTs. Off-axis compression tests are performed to obtain the stress–strain relations. One-parameter plasticity model is applied to characterize the nonlinear response of unidirectional laminates, and nonlinear behaviors of laminates with and without CSCNTs are compared. Clear improvement in stiffness of off-axis specimens by using CSCNTs is demonstrated, which is considered to contribute the enhancement of the longitudinal compressive strength of unidirectional laminates and compressive strength of multidirectional laminates. Finally, longitudinal compressive strengths are predicted based on a kink band model including the nonlinear responses in order to demonstrate the improvement in longitudinal strength of CFRP by dispersing CSCNTs.