Monitoring Three-point Bending Behavior of Carbon/Carbon Composites Using Electrical Resistance Change Methods

Damage behavior of unidirectional carbon fiberreinforced carbon(C/C)composites underthree-point bending load by electrical resistancechange(ERC)methods was presented.Staticbending tests and ERC tests were exam-ined simultaneously to obtain the relationship be-tween damage types and electrical resistance chang-es.In order to identify the occurring time and

Numerical simulation on thermal expansion coefficient of 3D braided C/C composites

To effectively get the thermal expansion coef- ficient （CTE） of three-dimensional （3D） braided C/C composites and study the variations, a VC＋＋ program with graphical user interfaces was obtained, based on the yam unit model and numerical analysis. With the limited basic properties of carbon fibers and carbon matrix, CTE of 3D braided C/C composites is obtained at 85 ~C. The deviation between the simulated and exl^erimental axial CTE of 3D braided C/C composites is no more than 11%. The effects of different parameters （including the braiding angle of 3D braided preform, the fiber volume fraction and the porosity of 3D braided C/C composites, and the elastic modulus, Poisson＇s ratio and CTEs of carbon fibers and carbon matrix） were analyzed with the program. The results show that the axial CTE of C/C composites decreases with the increase of the braiding angle, the fiber volume fraction, and the porosity of 3D braided C/C composites. The transverse elastic modulus of carbon fibers has the greatest effect on the axial CTE among the studied mechanical parameters, followed by the elastic modulus and Poisson＇s ratio of carbon matrix.

Effect of matrix sub-layer interfacial fracture on residual strength improvement of the fatigued carbon/carbon composites

In the present study, flexural behavior of carbon fber reinforced pyrolytic carbon matrix composites （C/C composites） before and after fatigue tests had been studied. The results showed that the residual flexural strengths of the samples had been improved after fatigue tests, and the fracture mechanisms of the original and post-fatigue specimens had some differences. Fracture mechanism of the original specimens could be described as fiber/matrix interfacial de-bonding, and the dominant damage of the post-fatigue specimens could be regarded as pyrolytic carbon sub-layers＇ step-delamination. The degradation of matrix sub-layer interfacial bonding strength was beneficial to improve the mechanical properties of C/C composites.2017 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science ＆ Technology.