Effect of Specimen Thickness on Fatigue Limit in Carbon Composites

2015 ◽  
Vol 1110 ◽  
pp. 13-18 ◽  
Author(s):  
Chobin Makabe ◽  
Takuya Nakayama ◽  
Masaki Fujikawa ◽  
Kazuo Arakawa ◽  
Ding Ding Chen
Keyword(s):  
Carbon Fiber ◽  
Fatigue Limit ◽  
Fracture Behavior ◽  
Crack Growth Behavior ◽  
Carbon Composites ◽  
Fiber Direction ◽  
Specimen Thickness ◽  
Shear Damage ◽  
Notched Specimens ◽  
Specimen Axis

The fracture behavior and fatigue limit in notched specimens of C/C composites were investigated. Also, the effect of specimen thickness on fatigue limit was discussed. Two plates of different thicknesses of plates of C/C composites using fine-woven carbon fiber laminates with α=0°/90° direction were used for testing. α is the angle between the carbon fiber direction and specimen axis. The crack growth behavior and failure mechanism of specimens are derived from the shear damage in the fiber bundle and matrix. Slits of several sizes were cut on both sides of a test section and different geometries of the specimens were prepared. Specimens with slits and blunt-notches were used to compare the fatigue strength. The fatigue limit is related to the method of making the plate of carbon composites. Large sizes of voids are observed in the case of specimens of thinner thickness. The fatigue limit was related to the void fraction, and thinner specimens showed a lower fatigue limit.

Effect of Fiber Direction and Stress Ratio on Fatigue Property in Carbon Fiber Reinforced Epoxy Composites

2018 ◽  
Vol 940 ◽  
pp. 79-83 ◽  
Author(s):  
Md. Shafiul Ferdous ◽  
S.M. Moshiar Rahman ◽  
Chobin Makabe
Keyword(s):  
Carbon Fiber ◽  
Epoxy Resin ◽  
Fatigue Limit ◽  
Fatigue Property ◽  
Epoxy Composites ◽  
Crack Growth Behavior ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Load Axis ◽  
Carbon Fiber Reinforced

The fatigue limit and crack growth behavior of slit specimens of carbon fiber reinforced epoxy composites were investigated. The fatigue limit was defined by the maximum stress amplitude that the specimen endured 106 times repeated stress when S-N curve was used. The highest fatigue limit was obtained when all the fiber directions were parallel to the load axis. The fatigue limits were evaluated in the cases of composites using alternately parallel and perpendicular to the load axis and compared with the result of the specimen having all the carbon fiber orientations were parallel to the load axis. When the measured value of the fatigue limit was lower, shear damage to the epoxy resin and peeling of fiber from epoxy resin occurred clearly. According to those results, it was expected that the fatigue limit of smooth specimens of carbon composites with long fibers can be evaluated from the results of the slit specimens.

Fatigue and fracture behavior in notched specimens of C/C composite with fine-woven carbon fiber laminates

Carbon ◽  
2009 ◽  
Vol 47 (14) ◽  
pp. 3355-3364 ◽  
Author(s):  
Anggit Murdani ◽  
Chobin Makabe ◽  
Masaki Fujikawa
Keyword(s):  
Carbon Fiber ◽  
Fracture Behavior ◽  
Notched Specimens ◽  
Fatigue And Fracture

Effect of Shear Damage on the Fracture Behavior of Carbon-Carbon Composites

2004 ◽  
Vol 84 (6) ◽  
pp. 1327-1333 ◽  
Author(s):  
Ken Goto ◽  
Hiroshi Hatta ◽  
Hirotsugu Takahashi ◽  
Hiroyuki Kawada
Keyword(s):  
Fracture Behavior ◽  
Carbon Composites ◽  
Shear Damage

Notch Sensitivity on Fatigue Behavior of Carbon-Carbon Composites

2020 ◽  
Vol 858 ◽  
pp. 89-94
Author(s):  
Sobahan Mia ◽  
Md. Shafiul Ferdous
Keyword(s):  
Fatigue Limit ◽  
Critical Stress ◽  
Fatigue Behavior ◽  
Notch Sensitivity ◽  
Experimental Result ◽  
Shear Mode ◽  
Carbon Composites ◽  
Notched Specimens ◽  
Damage Condition ◽  
The Impact

The fatigue strengths in notched specimens of carbon-carbon composites were investigated. Slits of different length were cut on both sides of a test section to investigate the impact of notch sensitivity on fatigue life. Specimens with blunt-notches on the both side of the specimen, and center hole were also used to compare the critical stress, sw. The fatigue limit was measured using S-N curves. From the experimental result, it was found that specimens with blunt-notches have lowest fatigue limit. The relationships between critical stress, sw and specimen geometry were investigated by stress concentration factor, Kt and stress intensity factor, KI which was done two dimensional body forced methods. Consequently, it was discussed that the damage condition in the vicinity of the notch or slit, and the crack initiation behavior affects the fatigue strength. Also, the S-N curve and fatigue limit was related to the crack growth in shear mode.

scholarly journals Prediction of Effective Thermal Conductivities of Four-Directional Carbon/Carbon Composites by Unit Cells with Different Sizes

2021 ◽  
Vol 11 (3) ◽  
pp. 1171
Author(s):  
Chang Xu ◽  
Zhihong Sun ◽  
Guowei Shao
Keyword(s):  
Carbon Fiber ◽  
Longitudinal Direction ◽  
Unit Cell ◽  
Carbon Composites ◽  
Temperature Boundary ◽  
The Matrix ◽  
Unit Cells ◽  
Experimental Values ◽  
Different Diameters ◽  
Thermal Conductivities

Two-unit cells developed to predict the effective thermal conductivities of four-directional carbon/carbon composites with the finite element method are proposed in this paper. The smaller-size unit cell is formulated from the larger-size unit cell by two 180° rotational transformations. The temperature boundary conditions corresponding to the two-unit cells are derived, and the validity is verified by the temperature and heat flux distributions at specific positions of the larger-size unit cell and the smaller-size unit cell. The thermal conductivities of the carbon fiber bundles and carbon fiber rods are measured firstly. Then, combined with the properties of the matrix, the effective thermal conductivities of the four-directional carbon/carbon composites are numerically predicted. The results in transverse direction predicted by the larger-size unit cell and the smaller-size unit cell are both higher than experimental values, which are 5.8 to 6.2% and 7.3 to 8.2%, respectively. In longitudinal direction, the calculated thermal conductivities of the larger-size unit cell and the smaller-size unit cell are 6.8% and 6.2% higher than the experimental results, respectively. In addition, carbon fiber rods with different diameters are set to clarify the influence on the effective thermal conductivities of the four-directional carbon/carbon composites.

scholarly journals Comparison of Mode Shapes of Carbon-Fiber-Reinforced Plastic Material Considering Carbon Fiber Direction

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 311
Author(s):  
Chan-Jung Kim
Keyword(s):  
Carbon Fiber ◽  
Modal Analysis ◽  
Dynamic Behavior ◽  
Mode Shapes ◽  
Modal Parameters ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic

Previous studies have demonstrated the sensitivity of the dynamic behavior of carbon-fiber-reinforced plastic (CFRP) material over the carbon fiber direction by performing uniaxial excitation tests on a simple specimen. However, the variations in modal parameters (damping coefficient and resonance frequency) over the direction of carbon fiber have been partially explained in previous studies because all modal parameters have only been calculated using the representative summed frequency response function without modal analysis. In this study, the dynamic behavior of CFRP specimens was identified from experimental modal analysis and compared five CFRP specimens (carbon fiber direction: 0°, 30°, 45°, 60°, and 90°) and an isotropic SCS13A specimen using the modal assurance criterion. The first four modes were derived from the SCS13A specimen; they were used as reference modes after verifying with the analysis results from a finite element model. Most of the four mode shapes were found in all CFRP specimens, and the similarity increased when the carbon fiber direction was more than 45°. The anisotropic nature was dominant in three cases of carbon fiber, from 0° to 45°, and the most sensitive case was found in Specimen #3.

Fracture Behavior of Ceramics Used in Multilayer Capacitors

1986 ◽  
Vol 72 ◽  
Author(s):  
Theresa L. Baker ◽  
Stephen W. Freiman
Keyword(s):  
Crack Growth ◽  
Fracture Behavior ◽  
Ceramic Materials ◽  
Fatigue Tests ◽  
Internal Stresses ◽  
Crack Growth Behavior ◽  
Multilayer Capacitors ◽  
Materials Used ◽  
Aging Phenomena

AbstractThis study involved the determination of the effects of composition and microstructure on the fracture toughness and susceptibility to environmentally enhanced crack growth of several ceramic materials used in multilayer capacitors. Indentation-fracture procedures were used to measure KIC as well as to assess the possible effects of internal stresses on the fracture behavior of these materials and to correlate dielectric aging phenomena with strength. The environmentally enhanced crack growth behavior of these materials was determined by conducting dynamic fatigue tests in water.

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