汽车工程 ›› 2024, Vol. 46 ›› Issue (12): 2164-2172.doi: 10.19562/j.chinasae.qcgc.2024.12.003

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考虑缺陷的一体压铸铝合金弹塑性本构及断裂准则研究

翟强强1,2,吴迪1,2,张涵寓1,2,刘钊3,朱平1,2()   

  1. 1.上海交通大学,机械系统与振动全国重点实验室,上海 200240
    2.上海交通大学,汽车动力与智能控制国家工程研究中心,上海 200240
    3.上海交通大学设计学院,上海 200240
  • 收稿日期:2024-07-01 修回日期:2024-08-24 出版日期:2024-12-25 发布日期:2024-12-20
  • 通讯作者: 朱平 E-mail:pzhu@sjtu.edu.cn
  • 基金资助:
    国家自然科学基金(52375256);上海市自然科学基金(23ZR1431600)

Study on Constitutive Model and Fracture Criterion of Megacasting Aluminum Alloy Considering Defects

Qiangqiang Zhai1,2,Di Wu1,2,Hanyu Zhang1,2,Zhao Liu3,Ping Zhu1,2()   

  1. 1.Shanghai Jiao Tong University,State Key Laboratory of Mechanical System and Vibration,Shanghai 200240
    2.Shanghai Jiao Tong University,National Engineering Research Center of Automotive Power and Intelligent Control,Shanghai 200240
    3.School of Design,Shanghai Jiao Tong University,Shanghai 200240
  • Received:2024-07-01 Revised:2024-08-24 Online:2024-12-25 Published:2024-12-20
  • Contact: Ping Zhu E-mail:pzhu@sjtu.edu.cn

摘要:

一体压铸零件在快速的填充和冷却过程中不可避免地会产生缺陷,且缺陷对铸件力学性能的影响不可忽视。然而,现有力学分析模型难以准确预测含缺陷铸件的力学性能,给铸件结构安全性设计带来巨大困难。针对此问题,本研究提出了一套考虑缺陷的铸铝弹塑性本构和断裂模型。从一体压铸后地板的不同位置裁剪出5种不同形状的样件,并开展了试验测试。利用扫描电镜统计了断面上的缺陷信息。基于标准拉伸样件的应力-应变曲线,提出了考虑缺陷和饱和应力的弹塑性本构,准确描述了其应变硬化特性。基于现有的Modified Mohr-Coulomb (MMC)断裂准则,提出了考虑缺陷和应力状态的改进MMC模型,并通过4种不同形状的样件进行了参数标定。为了验证所提模型的有效性,进行了试验和仿真的对比分析。结果表明,相比于传统硬化模型,所提弹塑性本构具有很高的拟合精度(R2>0.994)。不同样件试验和仿真的载荷-位移曲线吻合度较高,验证了所提断裂模型的有效性。本研究为一体压铸铝合金力学性能的高精度预测提供了新的思路。

关键词: 一体压铸, 免热处理铝合金, 本构模型, 断裂准则

Abstract:

Megacasting during rapid filling and cooling processes inevitably generates defects, which significantly impact the mechanical properties of castings. However, it is difficult for existing mechanical analysis models to accurately predict the properties in defective castings, posing substantial challenges to the design of structurally safe castings. To solve the problem, a constitutive model and a fracture criterion of cast aluminum considering defects are proposed in this paper. Five different shapes of samples are cut from different locations of the megacasting floor, and experimental tests are carried out. The defect information on the fracture sections is statistically analyzed using scanning electron microscopy. Based on the stress-strain curves of the standard tensile samples, a constitutive model considering defects and saturating stresses is proposed to accurately characterize the strain-hardening properties. Based on the existing Modified Mohr-Coulomb (MMC) fracture criterion, an improved MMC model considering defects and stress states is proposed, and the parameters are calibrated by four different shaped samples. To validate the effectiveness of the proposed model, a comparative analysis between experimentation and simulation is conducted. The results show that the proposed constitutive model has a high fitting accuracy compared with the traditional hardening model. The load-displacement curves of the tests and simulation of different samples are in good agreement, which verifies the validity of the proposed fracture model. This study provides a novel approach to accurately predicting the mechanical properties of megacasting aluminum alloys.

Key words: megacasting, non-heat-treated alloy, constitutive model, fracture criterion