摘要
由于热弹塑性效应的存在,使得材料在低周疲劳载荷作用下发生的力学变形将导致材料温度发生变化,因而可通过观测温度变化判明材料的累积疲劳损伤。基于此,采用叠加各向同性强化模型的非线性随动强化模型作为循环载荷下的材料力学本构模型,以有限元软件ANSYS为平台,对SS304不锈钢平板试件在控制应变循环载荷作用下的热弹塑性效应进行数值模拟,着重分析一个载荷周期内导致材料温度发生变化的各种机制。结果表明,在一个载荷周期内,若材料处于弹性变形范围内,则引起材料温度变化的只有弹性拉伸和弹性压缩两种机制,且弹性拉伸引起温降,弹性压缩引起温升;若材料处于弹塑性变形范围内,则塑性拉伸、弹性压缩和塑性压缩导致材料温度上升,弹性拉伸导致温度降低。在整个载荷周期内,热弹性效应导致材料温度发生波动,热塑性效应导致材料平均温度升高。此外,若将材料温度的变化信息叠加到应力-应变变化的信息上,还可判明材料的屈服强度以及材料在载荷作用下所处的应力状态,如弹性拉伸、塑性拉伸、弹性压缩以及塑性压缩等状态。
Due to the thermal-elastic-plastic effect, the temperature of specimen will be changed during low cycle fatigue loading, and the temperature can be utilized to reveal the accumulation of fatigue damage. A constitutive model composed of isotropic and nonlinear kinematic hardening model is used to predict the mechanical responses of material subjected to cyclic deformation, the ANSYS software is adopted to simulate temperature evolution of SS304 stainless steel fiat plate specimen during strain controlled cyclic loading, and the mechanisms causing the temperature change are analyzed. The results show that, in the elastic region, when a material is subjected to tensile loading, the material undergoes cooling and when a material is subjected to compressive loading, it undergoes heating. While in the elastic-plastic region, plastic tension, elastic compression and plastic compression correspond to temperature increase and only elastic tension corresponds to temperature decrease. During the whole loading period, the thermal-elastic effect caused the temperature to oscillate, and the thermal-plastic effect caused the mean temperature to increase. The results also show that, from the temperature evolution and the stress-strain curve data, the yield points can be identified, and it is possible to identify the state of stress of material during cyclic loading, such as elastic tension, plastic tension, elastic compression and plastic compression from the thermal data.
出处
《机械工程学报》
EI
CAS
CSCD
北大核心
2013年第4期64-69,共6页
Journal of Mechanical Engineering
基金
国家自然科学基金资助项目(50906099)
关键词
低周疲劳
热弹塑性效应
有限元法
Low-cycle fatigue
Thermal-elastic-plastic effect
Finite element method
