CrMnFeCoNi纳米晶温度相关的拉伸行为研究

摘要：高熵合金是一种由多种主元元素组成的新型合金。实验研究表明等原子比CrMnFeCoNi高熵合金在低温下具有比室温更高的拉伸强度和断裂韧性。本文针对这一现象，利用分子动力学模拟对平均晶粒尺寸为6 nm的CrMnFeCoNi纳米晶在300、200和77 K下分别进行拉伸模拟。模拟研究揭示了纳米尺度CrMnFeCoNi高熵合金力学行为的温度效应和强韧机理。微结构演化分析表明：低温下，塑性变形阶段，滑移系开动的较少，位错滑移所受的阻力越大，屈服强度和抗拉强度越大；模型破坏时，孔洞缺陷形核较慢，更多孔洞缺陷演化成断口，更多的断口分摊拉伸应变，使得高熵合金纳米晶的低温韧性更好。

A SECOND-ORDER CONE LINEAR COMPLEMENTARITY APPROACH FOR CONTACT PROBLEMS WITH ORTHOTROPIC FRICTION LAW

A second-order cone linear complementarity formulation for contact problems with orthotropic friction law is proposed by the parametric variational principle.Employing the concept of second-order cone complementarity,the contact condition with orthotropic friction law is formulated as a linear second-order cone complementarity condition through the analogy with the elastic-perfectly plastic constitutive model.Then,the governing equations of the contact problem can be reformulated as a linear second-order cone complementarity problem (SOCCP) via the parametric variational principle and the finite element method.The SOCCP formulation avoids the polyhedral approximation to the elliptical Coulomb friction cone so that the problem under consideration has much smaller size and the solution has better accuracy.Numerical results confirm the effectiveness and robustness of the SOCCP formulation.