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Zhu Y.,Jiangsu Fasten Hopesun Group Co. | Zhu Y.,Nanjing Southeast University | Wen W.,Nanjing University of Aeronautics and Astronautics | Liu L.,Jiangsu Fasten Hopesun Group Co. | And 2 more authors.
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2016

The longitudinal tensile-tensile fatigue characteristics and in-plane shear tensile-tensile fatigue characteristics of unidirectional C/C composites and the longitudinal tensile-tensile fatigue characteristics of three-dimensional and four-directional braided C/C composites were researched through tests. The interface residual strength between fiber bundle and matrix was measured. The residual stiffness degradation model and the residual strength degradation model under longitudinal and in-plane shear tensile-tensile fatigue loading of unidirectional C/C composites were fitted by the least square method, and the interface residual strength model between fiber bundle and matrix was established. The results show that the biggest stiffness degradation of the unidirectional C/C composites at the fatigue load stress level of 87.5% is only about 8.8%, whereas, the biggest in-plane shear stiffness degradation goes to about 30% at the fatigue load stress level of 70.0%. The strength and stiffness of three-dimensional and four-directional braided C/C composites are both improved after fatigue loading. The interface strength between fiber bundle and matrix of the three-dimensional and four-directional braided C/C composites decrease gradually with the increase of fatigue loading cycles. © 2016, BUAA Culture Media Group Ltd. All right reserved.


Zhu Y.,Jiangsu Fasten Hopesun Group Co. | Zhu Y.,Nanjing Southeast University | Liu L.,Jiangsu Fasten Hopesun Group Co. | Zhang J.,Nanjing Southeast University | And 3 more authors.
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2015

The numerical analysis of adhesive anchorage system for carbon fiber reinforced plastics (CFRP) tendon was conducted, of which including influence of different friction coefficients between anchor wall and anchorage agglomerant, influence of different cone angles and with or without straight transition section in front of anchorage and end blocking constraint to the stress state of tendons. The reason of tendons that fail near the front end of the anchorage was found out, relevant strength analysis method and anchorage improvement methods were proposed, the effectiveness of the method were verified by test results. The analysis results show that radial extrusion stress peak values of tendons at 0.7 friction coefficient are 45.01% of the radial extrusion stress peak values at 0.3 friction coefficient. Radial extrusion stress peak values of CFRP tendons at anchorage cone section decrease with the increase of cone angles, while shear stress peak values gradually increase. The addition of straight transition section at cone section ends can relieve radial extrusion stress and shear stress peak values of tendons. Mitigation coefficients are 76.78% and 52.90%, respectively. The existence of end blocking constraint leads an obviously stress concentration phenomenon at the front end of anchorage, which results in the failure of tendon near the front end of anchorage. ©, 2015, Beijing University of Aeronautics and Astronautics (BUAA). All right reserved.


Liu L.,Jiangsu Fasten Hopesun Group Co. | Sun J.,Jiangsu Fasten Hopesun Group Co. | Wang H.,Jiangsu Fasten Hopesun Group Co.
13th International Conference on Fracture 2013, ICF 2013 | Year: 2013

Failure analysis procedure of steel wire drawing fracture process was introduced, which includes background information collection, visual inspection and low magnification test, microscopic analysis, metallographic examination, etc. The importance of each step on fracture failure analysis results was also explained. In accordance with the stress condition in drawing process of steel wire, the typical characteristics of the mainly drawing fracture failure modes including pencil-point shaped, plane shaped and inclined shaped were investigated. The process of microscopic analysis and metallographic examination were optimized with macro morphology characteristics, and a faster and more precise analytical approach of metallic wire drawing fracture failure was proposed which was of important engineering significance and practical value to improve product competitiveness. [1] H. Uchikawa, S. Hanehara, T. Shirasaka, D. Sawaki, Effect of water curing. Cem Concr Res, 22 (1992) 115-120.

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