CAJ | 학술논문

本文以曲线拟合方法，分析AZ31B-H24镁合金的单轴拉伸试验，针对材料在400°C温度下，应变率ε&=10-5-10-2 s-1范围之应力-应变关系曲线，找出一个以应变、应变率为函数的应力流方程式之本构模型，并将此模型掺入有限元(FEM)建构一合理的数值分析模式，仿真该单轴拉伸试验，以验证其可靠性。有限元分析(FEA)时以固体力学的弹-塑性理论来运算材料塑性流演化行为的应力增量-应变增量之关系。分析结果显示，FEA与单轴拉伸试验的应力-应变关系曲线，在各变形阶段上，二者皆具有相当不错的吻合性；且实验与FEA在极限应变状态下之杆件的变形形状，二者结果亦相当接近；本文并以此FEM分析模式预测固定速率之单轴拉伸案例，对该材料的吹制成型试验进行仿真，结果亦验证了本文所提出的本构模型拥有超塑性成型力学分析的实用性。本文对AZ31镁合金之超塑性力学分析提供了一个数值分析模式之参考。
본문이곡선의합방법，분석AZ31B-H24미합금적단축랍신시험，침대재료재400°C온도하，응변솔ε&=10-5-10-2 s-1범위지응력-응변관계곡선，조출일개이응변、응변솔위함수적응력류방정식지본구모형，병장차모형참입유한원(FEM)건구일합리적수치분석모식，방진해단축랍신시험，이험증기가고성。유한원분석(FEA)시이고체역학적탄-소성이론래운산재료소성류연화행위적응력증량-응변증량지관계。분석결과현시，FEA여단축랍신시험적응력-응변관계곡선，재각변형계단상，이자개구유상당불착적문합성；차실험여FEA재겁한응변상태하지간건적변형형상，이자결과역상당접근；본문병이차FEM분석모식예측고정속솔지단축랍신안례，대해재료적취제성형시험진행방진，결과역험증료본문소제출적본구모형옹유초소성성형역학분석적실용성。본문대AZ31미합금지초소성역학분석제공료일개수치분석모식지삼고。
A constitutive law is offered for an AZ31B-H24 Mg alloy within a strain rate range of 10-5-10-2 s-1 at a temperature of 400 °C. The constitutive law, which is developed by curve fitting the tensile tests data, is expressed as a flow stress function of strain and strain rate. Furthermore, the constitutive law is embedded into a proper FE model to simulate the tensile experiments for the purpose of verifying reliability, where the incremental stress-strain relationships are calculated by an elastic-plastic theory in the finite element analysis (FEA). The results show that the stress-strain characteristics and the final deformed shapes in the FEA agree well with the experiments. In addition, the predicting analysis of constant-velocity stretch conditions and the verification of a free bulge forming experiment show that the proposed FE model is practicable for mechanical analysis on superplastic forming problems. A selective numerical method is offered for advanced superplastic analysis on AZ31 Mg alloys.