PSI - Issue 80

Seiji Mitsubayashi et al. / Procedia Structural Integrity 80 (2026) 431–442 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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To evaluate the presence of internal voids and verify the positioning of carbon fiber cloth along the tooth surface, X-ray computed tomography (X-ray CT) was performed. CFRP gears containing 0.2 wt% chopped carbon fiber were examined under two conditions: with one layer and with two layers of surface-applied carbon fiber cloth. 3. Results and discussions 3.1. Fabrication result of CFRP gears N co o n . F d 3 i i g t in i u o r T n e a s b 4 , l t e s h h 2 e o , w g in e s a w a r n h s i e w c x h e a 0 r m e .2 p s l w u e c t o % c f e a s o s f f f a c u b h l r l o y ic p a m p t e e o d d ld c C e a F d r R b t o P o n g m e fi a a b r t e . c r T h s h w t e h e g e r e e s a h m r a s i p x h e e o d w o i f n n t t i h o n e t F h i m e g u o e r l p d e o , 4 x c y c u o r r e r e r s d e i n s p . p r U o o n n p d d e e s rl r t y o a , l a c l o n m n d o d l w i d ti e i o n r n g e de me mb eo dl ddeedd iwn i tt hh eo uetp osxi gynrief isci ann, ti n dd ai cma tai gneg. t hTahtet hcea rrbe os inn hf iabde rs ucflfoi ct ihe npt ll ya ci emdp rael og nn ga t et dh et hteo roet ihn fsour rc fi ancgef i wb earss . f u l l y

Fig. 4. Example of a fabricated CFRP gear photographed from (a) the front and (b) the side. Figure 5(a) shows an X-ray CT image of the tooth root of the CFRP gear reinforced with a single layer of carbon fiber cloth. While the cloth was properly aligned along the tooth root, it detached from the tooth surface near the tooth tip, indicating incomplete conformity. Several voids were also observed around the tooth root. Figure 5(b) presents an X-ray CT image of the tooth root of the CFRP gear reinforced with two layers of carbon fiber cloth. As with the single-layer case, the cloth did not conform fully to the tooth tip, and voids were observed. No significant differences were found in the size or number of voids between the two conditions.

Fig. 5. X-ray CT images of the tooth root of the CFRP gear with (a) a single layer and (b) two layers of carbon fiber cloth.

3.2. Tooth bending strength of CFRP gears Figure 6 shows the relationship between rotation angle of tension arm and tooth bending stress. Figure 6(a) presents the results for gears fabricated using neat epoxy resin, while Figure 6(b) shows the results for gears reinforced with