A study on the constitutive equation of HC420LA steel subjected to high strain rates
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, Qiong Wang1, Dongying Dong1, Hao Jiang1, Xu Zhang2
, Guangyao Li1,a)
1
State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha 410082, China College of Automotive and Mechanical Engineering, Changsha University of Science and Technology, Changsha 410114, China a) Address all correspondence to this author. e-mail: [email protected] 2
Received: 17 September 2018; accepted: 30 October 2018
In this paper, the influence of strain rate on the mechanical behavior of high-strength low-alloy (HC420LA) steel were studied. Quasi-static and dynamic tensile experiments were performed with strain rates ranging from 0.001 to 500 s1 at room temperature. The digital image correlation technique was used to obtain the full-field strain. The experimental results showed that HC420LA steel exhibited positive strain rate sensitivity. Based on experimental results, the modified Johnson–Cook (J–C) model was used to model the constitutive behavior of HC420LA steel. Predictions of the standard and modified J–C models were compared using standard statistical parameters. The modified J–C model showed better agreement with the experimental data. Then, numerical simulation of the representative tensile test at a strain rate of 100 s1 was performed using the finite element code LS-DYNA. Good correlation between the experimental and numerical simulation results was achieved.
Introduction High-strength steels have wide-ranging applications in the transportation industry due to their excellent energy absorption, light weight, and low fuel consumption. High-strength low-alloy steels have high yield strength, high ratio of yield stress to ultimate tensile stress, and good resistance to deformation. They are usually used as structural parts and reinforcements such as longitudinal beam, crossbeams of the body in white. Many studies [1, 2, 3, 4] have been conducted on high-strength low-alloy steels that possess high strength, good cold formability, and good weldability. In recent years, describing the tensile properties of materials at elevated strain rates is gaining increasing attention. Since deformation of materials during the impact is a dynamic response, studying and simulating the mechanical response of materials at elevated strain rates have a guidance role on optimizing the structural design, reasonably selecting the materials, and improving the vehicle body safety. The mechanical behavior of materials at high strain rates is considerably different from that observed at quasi-static loads because of the strain rate sensitivity of materials [5, 6, 7, 8, 9, 10]. Wang et al. [7] reported on investigations into the dynamic tensile properties of high-strength 600–1000-MPa dual-phase steel and
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1200 MPa fully martensitic (MS) steel under elevated strain rates. The research results indicated that all investigated dualphase steels had a positive strain rate dependency. However, negative strain rate dependency was observed for 1200 MPa MS. Qin et al. [8] studied the mecha
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