晶体塑性理论是将晶体微观尺度的位错运动与宏观尺度的塑性形变相结合的重要理论,提供了在细观尺度内研究材料力学行为的有效方法。位错的密度变化对金属晶体的硬化行为有着重要的影响。该文在晶体塑性理论的基础上引入位错运动理论,建立基于位错密度的体心立方晶体(body center cubic,BCC)塑性本构模型,研究BCC的力学行为;并借助ABAQUS有限元软件,编写UMAT子程序,实现对BCC结构的铁单晶及多晶单轴拉伸试验的数值模拟。结果表明:该本构模型能有效地模拟铁单晶及多晶单轴拉伸的力学行为。 The theory of plastic plasticity is an important theory that combines the dislocation motion at the microscopic scale with the plastic deformation at the macro scale and provides an effective method to study the mechanical behavior of the material at the mesoscopic scale. The density of dislocations has an important influence on the hardening behavior of metal crystals. Based on the theory of plastic plasticity, this dissertation introduces the theory of dislocation motion and establishes a plastic center constitutive model of body center cubic (BCC) based on dislocation density. The mechanical behavior of BCC is studied. With ABAQUS finite element software, The UMAT subroutine was programmed to simulate the uniaxial tensile test of iron single crystal and polycrystalline BCC structure. The results show that this constitutive model can effectively simulate the mechanical behavior of iron single crystal and polycrystalline uniaxial tension.