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Composite tubes may be subjected to impact loads during placement or operation. By determining the impact properties of composite tubes and using them in the design process, the accuracy of the behavior of these structures in the loading condition is guaranteed. In this study, the behavior of glass/epoxy composite tubes under dynamic axial loading was experimentally investigated. Also, the effects of parameters such as fiber density, fiber alignment angle, internal diameter of the tube and impact energy on the amount of pipe damage were also studied. To prepare composite specimens, E-type glass fiber was used with two different densities of 200 gr⁄m^2 and 400 gr⁄m^2 . The specimens were placed on a drop weight machine of Tafresh University by a fixture, and the Impactor was released from the height of 2 meters. The force -displacement diagrams for each test were extracted and compared with each other. Also, a parameter called specific energy absorption was calculated for all samples in order to compare the efficiency of the samples as energy absorber. The results of this study showed that increasing the fiber density, number of layers and diameter of the tube increases the specific energy absorption. It was also observed that with the increase of the axial dynamic impact energy, the mechanical properties of the specimen will be changed and the specimen will be firmly established.

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Thin-walled composite structures are increasingly used in vehicles where light weight and high energy absorption capacity are important. Fiber reinforced composites, such as glass/fiber reinforced polymers, have attracted attention in automotive engineering due to their properties such as light weight and high mechanical properties. Fiber reinforced composites use the energy in various ways to damage their structure, which in terms of structural failure; delamination, fiber breakage, and matrix cracking are the predominant conditions. According to the literature, design parameters and optimal dimensions of glass/epoxy composite tubes were determined. After that, by using experimental testing, acoustic emission technique, and finite element method, various failure mechanisms of 45 ° filament wound composite tube were investigated. Examination of failure by acoustic emission method showed that the predominant mechanism for 45 ° samples is fiber breakage. In order to simulate the behavior of the samples, the VUMAT subroutine was used with the help of 3D Hashin criteria for the onset of damage and the continuous damage criterion was used to simulate the spread of failure. The agreement of the obtained experimental diagrams with the subroutine developed for the composite simulation confirmed the ability of the model to predict the behavior of the composite sample even after the maximum tolerable force. By comparing the force-displacement diagrams with the energy data obtained from the acoustic emission method, it was found that the acoustic emission method can be used to predict the behavior of composite pipes under lateral loading.