Effect of strain hardening behavior on forming limit stresses of steel tube subjected to nonproportional loading paths
Effect of strain hardening behavior on forming limit stresses of steel tube subjected to nonproportional loading paths
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DOI：
10.1016/j.ijplas.2006.11.008
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发表时间：
2007-07
影响因子：
9.8
通讯作者：
Kengo Yoshida;T. Kuwabara
中科院分区：
文献类型：
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作者：
Kengo Yoshida;T. Kuwabara
利用拉力-内压试验机研究了线性应力路径和复合应力路径下钢管在轴向载荷和内压联合作用下的成形极限应变和应力的应变路径相关性。组合应力路径由两个(第一和第二)线性应力路径组成，并包括第一和第二加载之间的卸载。根据等效应力-等效塑性应变(σ‘-ε’)曲线观察了钢管在许多线性和组合应力路径下的应变硬化行为。当给定应力路径的相应σ-ε曲线在一条曲线上时，线性应力路径和某些组合应力路径的成形极限应力落在应力空间中的一条曲线上，而与应力路径无关。另一方面，当试件在应力路径改变后立即表现出较低的应变硬化率时，某些组合应力路径的成形极限应力低于线性应力路径的成形极限应力。由此得出结论：钢管的成形极限应力不是完全路径无关的，在给定的加载路径下，成形极限应力的路径依赖性受材料的应变硬化行为的强烈影响。
The strain path dependence of forming limit strains and stresses of a steel tube subjected to combined axial load and internal pressure are investigated for linear and combined stress paths using a tension–internal pressure testing machine. The combined stress paths consist of two (first and second) linear stress paths and include unloading between the first and second loadings. The strain hardening behavior of the steel tube for many linear and combined stress paths is observed in terms of equivalent stress–equivalent plastic strain (σ¯–ε¯) curves. The forming limit stresses for the linear and some combined stress paths fall on a single curve in stress space irrespective of the stress paths when the corresponding σ¯–ε¯ curves observed for the given stress paths are on a single curve. On the other hand, the forming limit stresses for some combined stress paths are lower than those for the linear stress paths when the specimen exhibits a low strain hardening rate immediately after the change in stress paths. It is, therefore, concluded that the forming limit stress of the steel tube is not fully path-independent, and that the path dependence of forming limit stress is strongly affected by the strain hardening behavior of the material for given loading paths.