Dynamic materials testing and constitutive modeling of structural sheet steel for automotive applications. Final progress report

Cady, Carl M.; Chen, S.R.; Gray, G. T.

doi:10.2172/380343

Cited by 3 publications

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“…High strain rate analysis on DQSK GI steel and other steels for automotive applications was done by Cady et al [22]. However, they only studied discrete strain rates of 0.001 s .…”

Section: Introductionmentioning

confidence: 99%

High Strain Rate Properties of DQSK GI Steel Spot Welds

Khanna¹

2014

SOJMSE

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IntroductionSteel is one of the most widely used metals in modern industries due to its high strength and ductility, low cost, greater design flexibility and wider spans, dimensional stability and compatibility with most manufacturing techniques [1]. There has been a significant advancement in steel industry in recent years. This advancement resulted in the development of Advanced High Strength Steel (AHSS) and High Strength Low Alloy Steel (HSLA) materials that are finding increasing use in cars, trucks, cranes, bridges, and other structures that are designed to handle high static and dynamic stresses. The combination of strength, ductility, formability, positive strain-rate sensitivity and strain hardening characteristics of AHSS and HSLA steels indicates their potential to absorb significantly higher amounts of energy during crashes than conventional low-carbon steels, while reducing the overall weight of a vehicle [2].The mechanical behavior of materials at high strain rate is very different when compared to quasi-static (low strain rate) behavior. Usually materials are much stronger at higher rate of strain, such as caused by an impact. In recent years, the interest of researchers on high strain rate response of materials has gained momentum due to developments in various industries such as nuclear, space, military, automobile, etc. that need a better understanding of the material behavior at high strain rates to enable the proper selection of materials with desired properties [3].In automobiles low carbon steel such as DQSK GI and AISI1020 are widely used and primarily joined by spot welding, and a typical automobile may contain about 5000 spot welds. Hence the durability of these welds is an important area for research. For this we need to know the constitutive laws of the parent metal and the welded metal, their fatigue behavior and their high strain rate behavior. In this research, we have determined the high strain rate behavior of DQSK GI spot welds and compared the results with the original base metal. The split Hopkinson pressure bar apparatus was used to investigate the high strain rate behavior of spot welds.Although material data and joint design data is readily available under static loading conditions [4,5], the information regarding the high strain rate behavior of welded joints is not so extensively available. There are very few references [6][7][8] that can be found in open sources on high strain data on spot welded joints. This lack of available data has resulted in the ignorance of the differences in the dynamic strength of the base and weld materials. In many finite element models and other analysis, the weld is considered as having the same material properties as the base metal.The main interest in our investigation is to compare dynamic strength of DQSK GI steel base metal with the spot weld metal under high strain rate loading conditions. The dynamic strength can be derived from the stress strain curves at different strain rates. There are many experimental techniques to investigate dy...

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“…High strain rate analysis on DQSK GI steel and other steels for automotive applications was done by Cady et al [22]. However, they only studied discrete strain rates of 0.001 s .…”

Section: Introductionmentioning

confidence: 99%

High Strain Rate Properties of DQSK GI Steel Spot Welds

Khanna¹

2014

SOJMSE

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Simulation of Fracture Behavior of Elastomer Modified Polypropylene Based on Elastoviscoplastic Constitutive Equation With Craze and Tensile Softening Law

Mae

2005

Applied Mechanics

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The strong strain-rate dependence, neck propagation and craze evolution characterize the large plastic deformation and fracture behavior of polymer. In the latest study, Kobayashi, Tomii and Shizawa suggested the elastoviscoplastic constitutive equation based on craze evolution and annihilation and then applied it to the plane strain issue of polymer. In the previous study, the author applied their suggested elastoviscoplastic constitutive equation with craze effect to the three dimensional shell issue and then showed that the load displacement history was in good agreement with the experimental result including only microscopic crack such as craze. For the future industrial applications, the macroscopic crack had to be taken into account. For instance, an airbag deployment simulation needed the macroscopic crack prediction. Thus, the main objective of this study was to propose the tensile softening equation and then add it to the elastoviscoplastic constitutive equation with craze effect so that the load displacement history could be roughly simulated during the macroscopic crack propagation. The tested material in this study was the elastomer blended polypropylene used in the interior and exterior of automobiles. First, the material properties were obtained based on the tensile test results at wide range of strain rates: 10−4 – 102 (1/sec). Next, the fast compact tension test was conducted and then the tensile softening parameters were fixed. Then, the fast bending test and the dart impact test were carried out in order to obtain the load displacement history and also observe the macroscopic crack propagation at high strain rate. Finally, the fracture behavior was simulated and then compared with the experimental results. It was shown that the predictions of the constitutive equation with the proposed tensile softening equation were in good agreement with the experimental results.

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Modeling and Simulation of Impact Failure Characteristic of Polypropylene by Elastoviscoplastic Constitutive Law

Mae

Kishimoto

2007

JMMP

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Dynamic materials testing and constitutive modeling of structural sheet steel for automotive applications. Final progress report

Cited by 3 publications

References 0 publications

High Strain Rate Properties of DQSK GI Steel Spot Welds

High Strain Rate Properties of DQSK GI Steel Spot Welds

Simulation of Fracture Behavior of Elastomer Modified Polypropylene Based on Elastoviscoplastic Constitutive Equation With Craze and Tensile Softening Law

Modeling and Simulation of Impact Failure Characteristic of Polypropylene by Elastoviscoplastic Constitutive Law

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