Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 46 2 2015 02 20 An Experimental Study on Ratcheting Behavior of Polyacetal Tube Under Uniaxial Ioading and Internal Pressure An Experimental Study on Ratcheting Behavior of Polyacetal Tube Under Uniaxial Ioading and Internal Pressure 13 21 351 10.22060/mej.2015.351 FA Mahmoud Shariati Javad Yazdannejad Journal Article 2015 02 21 In this study, the experimental tests are designed and carried out to analyze the behavior of polyacetal ratcheting under both uniaxial loading and internal pressure. Experimental tests are performed by an accurate servo-hydraulic machine, Instron 8802. Three group tests were presented in which two of the stress amplitude, mean stress or internal pressure was constant to observe the effect of another factor. The effect of stress amplitude, mean stress and internal pressure on ratcheting strain and softening behavior of the polyacetal tube are investigated. Graphs of ratcheting strain, ratcheting strain range, hysteresis loops of group tests were drawn. By using these graphs, some results such as softening behavior obtained. A suitable hardening factor was presented and its relation with the polyacetal fatigue life was examined. In a specific loading cycle for the specimen, whose hardening factor is more than the others, a lower fatigue life predicted. Softening behavior of the material, increases with increasing the loading cycles. The results show that the specimen with the high ratcheting strain value has lower fatigue life. In this study, the experimental tests are designed and carried out to analyze the behavior of polyacetal ratcheting under both uniaxial loading and internal pressure. Experimental tests are performed by an accurate servo-hydraulic machine, Instron 8802. Three group tests were presented in which two of the stress amplitude, mean stress or internal pressure was constant to observe the effect of another factor. The effect of stress amplitude, mean stress and internal pressure on ratcheting strain and softening behavior of the polyacetal tube are investigated. Graphs of ratcheting strain, ratcheting strain range, hysteresis loops of group tests were drawn. By using these graphs, some results such as softening behavior obtained. A suitable hardening factor was presented and its relation with the polyacetal fatigue life was examined. In a specific loading cycle for the specimen, whose hardening factor is more than the others, a lower fatigue life predicted. Softening behavior of the material, increases with increasing the loading cycles. The results show that the specimen with the high ratcheting strain value has lower fatigue life. https://mej.aut.ac.ir/article_351_efe937780e95574250dabe07151bdc23.pdf