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应变强化是不锈钢压力容器结构实现轻型化的重要途径,而应变强化内压的确定则是应变强化技术的核心。为了能够更准确有效地达到结构应变强化的目的,对循环加载的应变强化方式进行了研究。通过304不锈钢材料的室温单轴棘轮试验,建立了应力比R0条件下的棘轮安定曲线。根据Mises等效原理,利用该曲线通过一次弹塑性有限元分析直接获得结构在循环载荷作用下的强化内压和产生的塑性应变,与试验结果吻合较好,说明运用循环加载的应变强化方式可以有效地达到应变强化的目的。在达到相同的应变强化程度要求下,该方法降低了强化内压,因此可以减小过载加压的风险。
Strain hardening is an important way to achieve lightweighting of stainless steel pressure vessel structure, while strain hardening is the core of strain hardening technology. In order to achieve the purpose of strengthening the structure strain more accurately and effectively, the strain hardening method of cyclic loading was studied. Through the ratcheting test of 304 stainless steel at room temperature, the ratchet stability curve under the stress ratio R0 was established. According to the principle of Mises equivalence, this curve can be used to directly obtain the strengthened internal pressure and the plastic strain caused by the cyclic loading through an elasto-plastic finite element analysis. The results are in good agreement with the experimental results, indicating that the strain hardening method by cyclic loading can Effectively achieve the purpose of strengthening the strain. This method reduces the enhanced internal pressure as required to achieve the same level of strain-hardening, thereby reducing the risk of over-pressurization.