共查询到17条相似文献,搜索用时 500 毫秒
1.
拉—扭复合加载下不锈钢的弹塑性本构关系——Ⅰ.实验 总被引:1,自引:2,他引:1
讨论了1Cr18Ni9Ti不锈钢薄壁圆管试件沿三段折线、不同曲率的圆形和椭圆应变路径承受拉-扭复合载荷的实验,在塑性应变空间中,观察加载路径的内蕴几何参数对应力矢量大小、方向影响的规律。结果表明:响应的延迟角、瞬时软化和重新强化性质与的内蕴几何学密切相关,Lensky的“局部确定性”假设不完全符合事实;变形历史和应变分量相互间的耦合效应对响应存在显著的影响,初步的电镜实验表明,材料中位错组态和塑料 相似文献
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40钢非比例循环塑性行为研究 总被引:1,自引:0,他引:1
对40钢在拉扭循环复杂应变路径下的硬化特性和流动特性进行了实验研究。研究表明:40钢材料的循环硬/软化不但依赖于应变路径形状,而且依赖于等效应变幅值,还具有路径历史效应;材料的塑性流动几乎不受先前路径历史的影响,仅依赖于当前应变路径形状和等效奕变幅值。 相似文献
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本文求得单向拉伸和平面应变轴对称问题的解析解,并说明:不同应变率下的应力响应相差不是一常数;该文的方法还能用于求解其它弹 粘塑性问题. 相似文献
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提出应力是塑性应变空间内蕴几何学参数的泛函.一般情况下,塑性应变空间是非欧几何空间,而其度量张量是塑性应变和其历史的函数,但在初始各向同性和不可压的情况下可取成欧氏空间.本文在Ilyushin理论,和Valanis理论的基础上,提出在拉-扭复合加载下的εp1-εp3空间中新的积分型弹塑性本构关系,所建理论预测的结果和实验[1]相当一致,表明理论是合理的 相似文献
6.
拉-扭复合加载下不锈钢的弹塑性本构关系——Ⅱ.理论 总被引:2,自引:1,他引:2
提出应力是塑性应变空间内蕴几何学参数的泛函.一般情况下,塑性应变空间是非欧几何空间,而其度量张量是塑性应变和其历史的函数,但在初始各向同性和不可压的情况下可取成欧氏空间.本文在Ilyushin理论,和Valanis理论的基础上,提出在拉-扭复合加载下的εp1-εp3空间中新的积分型弹塑性本构关系,所建理论预测的结果和实验[1]相当一致,表明理论是合理的 相似文献
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考虑路径相关性的非比例循环塑性本构模型 总被引:2,自引:0,他引:2
根据非比例加载下金属材料响应的延迟特性及加载路径相关性,选取沿应力迹法向的塑性应变的累积量作为非比例加载影响的度量,相应给出反映非比例附加强化的变量,并假设其模量和强化率与加载路径的几何参数相关.为反映由于非比例加载而引起的材料强化的异向效应,在Valanis的塑性内时响应方程中引入与加载路径几何性质有关的应力项,构成非比例循环塑性本构关系.对316和304不锈钢材料在一些典型非比例循环加载路径下的应力响应进行了理论预测,与Benallal等及McDowell的实验结果取得了良好的一致. 相似文献
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弹塑性本构关系的Ilyushin应变空间理论研究进展 总被引:1,自引:0,他引:1
Ilyushin提出五维偏应变矢量空间中的一般弹塑性本构理论,将应力表示为变形迹内蕴几何学参数的泛函,适合于描写复杂加载下金属材料的塑性响应特性。本文对其实验和理论两方面的研究进展作了综述,涉及关于塑性响应矢量特性的“局部确定性”假设,标量特性的“延心原理”假设及Ilyushin关于矢量空间的“特殊各向同性”假设等的实验研究和验证,微分型和积分型本构模型的建立及所含本构泛函的形式和确定。 相似文献
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率相关非比例循环塑性内时本构模型 总被引:3,自引:0,他引:3
将材料响应的总应力表示为平衡态应力和非平衡成过应力的和,分别定义描述率无关和率相关变形过程的内时,在平衡态响应的描写中,假定反映非比例加载效应的附加等等向强化和异向强化函数与沿应力迹法向的塑性应变分量的累积量相关,并在其中考虑加载路径几何性质变化的影响,建立一组率相关非比例循环塑性内时本构方程,对XCrNi18.9不锈钢在不同加载率下的单轴比例和多轴非比例响应进行预测,与Haupt和Lion的实验 相似文献
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《International Journal of Plasticity》2005,21(11):2174-2190
An experimental study was conducted on the inhomogeneous cyclic plastic deformation of 1045 steel under multiaxial cyclic loading. Thin-walled tubular specimens were used and small strain gages were bonded on the specimen surface to characterize the local deformation. The controlled loading paths included cyclic tension–compression, cyclic torsion, proportional axial-torsion, 90°-out-of-phase axial-torsion, and fully reversed torsion with a constant axial stress. The maximum stress in each experiment was lower than the lower yield stress of the material. It was found that the cyclic plastic deformation within the gage section of the specimen under multiaxial stress state followed the three-stage process that was observed from uniaxial loading, namely, incubation, propagation, and saturation. The plastic deformation was significantly inhomogeneous during the propagation stage, and the inhomogeneity continued through the saturation stage. The duration of each stage and the saturated strains were dependent on the cyclic stress amplitude and the loading path. Multiaxial stress state reduced the incubation stage. With identical equivalent stress magnitude, the nonproportional loading path resulted in the shortest incubation and propagation stages, and the saturated equivalent plastic strain magnitude was the smallest. Although the deformation over the gage section was inhomogeneous, the plastic deformation in a given local area was found to be practically isotropic. 相似文献
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The total stress response of material is decomposed into a sum of an equilibrium stress response and a non-equilibrium overstress
response. Correspondingly, the rate-independent intrinsic time and the rate-dependent intrinsic time are defined respectively.
Additional hardening functions for describing the isotropic and anisotropic nonproportional effects are assumed to be related
to the accumulation of plastic strain component along the normal of equilibrium stress trajectory, in which the effects of
geometry of the loading path are included. An endochronic constitutive model for rate-dependent, nonproportional cyclic plasticity
is formulated and applied to simulate the stress responses of stainless steel XCrNi18.9 for some typical loading programs
at different loading rates. A comparison between predicted results and experimental ones by Haupt and Lion shows that the
former are in agrreement with the latter. 相似文献
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利用有限元法,考虑材料反复滚压条件下棘轮效应和局部滑动的影响,研究了非稳态机车和车辆车轮载荷作用下轮轨滚动接触的弹塑性应力、应变和变形,进而分析了塑性流动型钢轨波浪形磨损的形成和发展过程以及波谷和波峰处材料的力学行为.结果表明:在非稳态载荷作用下,钢轨接触表面产生不均匀塑性变形引起的波磨,波磨发展速率呈衰减趋势,最终趋于稳定状态;在相同载荷下,与车辆车轮相比,机车车轮对钢轨波磨影响较大;波谷处的残余应力、应变和变形大于波峰处. 相似文献
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George Z. Voyiadjis S.H. Hoseini G.H. Farrahi 《International Journal of Solids and Structures》2012,49(13):1541-1556
Recent research studies on ductile fracture of metals have shown that the ductile fracture initiation is significantly affected by the stress state. In this study, the effects of the stress invariants as well as the effect of the reverse loading on ductile fracture are considered. To estimate the reduction of load carrying capacity and ductile fracture initiation, a scalar damage expression is proposed. This scalar damage is a function of the accumulated plastic strain, the first stress invariant and the Lode angle. To incorporate the effect of the reverse loading, the accumulated plastic strain is divided into the tension and compression components and each component has a different weight coefficient. For evaluating the plastic deformation until fracture initiation, the proposed damage function is coupled with the cyclic plasticity model which is affected by all of the stress invariants and pervious plastic deformation history.For verification and evaluation of this damage-plasticity constitutive equation a series of experimental tests are conducted on high-strength steel, DIN 1.6959. In addition finite element simulations are carried out including the integration of the constitutive equations using the modified return mapping algorithm. The modeling results show good agreement with experimental results. 相似文献
17.
为了得到试件的粘聚力和内摩擦角随轴向塑性压应变变化的曲线提出本方法。试件的弹塑性本构关系遵循相关联的Mohr-Coulomb强度准则;对常规三轴试验,试件受力进入塑性状态后,处在棱椎状屈服面的棱上,加载过程遵循Koiter流动法则。按经典塑性力学理论,推导得到轴向塑性压应变与轴向应力与轴向应变的关系;在常规三轴试验机上获得不同围压下试件的全程应力-应变曲线,进而可得到各自围压下轴向塑性压应变随加载过程的变化曲线;把来自不同围压下对应同一轴向塑性压应变的应力分别代入屈服面方程,即可求得对应的粘聚力和内摩擦角。结果表明,Mohr-Coulomb材料的两个强度参数的变化由轴向塑性压应变确定。轴向塑性压应变可以作为塑性变形的状态参数,它和试件的受力过程可以唯一确定试件的变形过程。 相似文献