Hassan Sayar - MSc, Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
Mohammad Azadi - Assistant Professor, Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
Mohsen Alizadeh - MSc, Faculty of Aerospace Engineering, Semnan University, Semnan, Iran

In the present article, the maximum stress and the strain at the maximum stress of carbon fibers, the epoxy resin and carbon/epoxy laminated composites have been investigated. For experiments, tensile tests, including 4 different loading rates, were performed on specimens for the pure resin, the pure fiber and open-hole standard composite samples. The sensitivity analysis was performed to study effects of the tensile loading rate on mechanical properties of mentioned materials, in the MINITAB software. For such objective, the logarithmic scale of the tensile loading rate was selected in the regression analysis, in which a linear function for fittingexperimental data by the predicting model was considered. Obtained results showed that by increasing the tensile loading rate, the maximum stress decreased, in pure resin and pure fiber specimens and increased in open-hole standard composite samples. In addition,when the tensile loading rate increased, the strain at the maximum stress was constant in pure resin and pure fiber samples and was sensitive for composite specimens. Besides, a reverse trend was observed for the maximum stress versus the loading rate in pure resinand pure fiber specimens. The sensitivity analysis demonstrated that the loading rate had a significant effect on the maximum stress in pure resin and the pure fiber specimens and had no effect on that of composite samples.

Laminated composite, Carbon fibers, Epoxy resin, Tensile loading rate, Sensitivity analysis, Mechanical properties