High Strain Rate Test of a Steel Plate under Blast Loading from High Explosive

In this study, a high strain rate test method of a steel plate under blast loading from high explosive was designed and was conducted by a combined experimental/numerical approach to facilitate the estimation process for the dynamic stress-strain curve under practical strain rate conditions. The steel plate was subjected to a blast load, which was generated by Composition C4 explosive and the dynamic deformation of the plate was observed with a high-speed video camera. Time-deformation relations were acquired by image analysis. A numerical simulation for the dynamic behaviors of the plate identical to the experimental condition was conducted using a coupling analysis of finite element method (FEM) and discrete particle method (DPM). Explosives were modeled by discrete particles and the steel plate and other materials were modeled by finite element. The blast load on the plate was described fluid-structure interaction (FSI) between DPM and FEM. As inverse analysis scheme to estimate dynamic stress-strain curve, an evaluation using a quasistatic data was conducted. In addition, two types of approximations for stress-strain curve were assumed and optimized by least square method. One is a 2-piece approximation, and was optimized by least squares method using a yield stress and a tangent modulus as parameters. The other is a continuous piecewise linear approximation, in which a stress-strain curve was divided into some segments based on experimental time-deformation relation, and was sequentially optimized using youngs modulus or yield stress as parameter. The results showed that the piecewise approximation can gives reasonably agreement with SS curve obtained from the experiment.

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The High Strain Rate Dynamic Stress-Strain Curve for OFHC Copper

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.52.9appendix_187 ◽

2003 ◽

Vol 52 (9Appendix) ◽

pp. 187-195

Author(s):

Michael. E. STEVENSON ◽

Stanley. E. JONES ◽

Richard. C. BRADT

Keyword(s):

High Strain Rate ◽

Strain Rate ◽

Dynamic Stress ◽

High Strain ◽

Strain Curve ◽

Ofhc Copper ◽

Stress Strain Curve ◽

Stress Strain ◽

Rate Dynamic

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Dynamic Constitutive Equations and Behaviour of Brass at High Strain Rates

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/pime_proc_1995_209_155_02 ◽

1995 ◽

Vol 209 (4) ◽

pp. 287-293 ◽

Cited By ~ 5

Author(s):

L-Y Li ◽

T C K Molyneaux

Keyword(s):

Flow Stress ◽

Strain Rate ◽

Yield Stress ◽

Constitutive Equations ◽

High Strain ◽

Strain Curve ◽

Strain Rates ◽

Stress Strain Curve ◽

High Strain Rates ◽

Stress Strain

This paper presents an experimental study of the mechanical properties of brass at high strain rates. The brass tested is the copperzinc alpha-beta and beta two-phase alloy in the cold-worked state. Experiments were conducted using an extended tension split Hopkinson bar apparatus. It is found that, at lower strain rates, the stress-strain curve is smooth, exhibiting no well-defined yield stress, but at higher strain rates the stress-strain curve not only shows a well-defined yield stress but also displays a very pronounced drop in stress at yield. The flow stress is found to increase with increasing strain rate, but the increase is more significant for the yield stress than for the flow stress, showing that the yield stress is more sensitive to the strain rate than the flow stress away from the yield point. Based on the experimental results, empirical strain-rate-dependent constitutive equations are recommended. The suggested constitutive equations provide a reasonable estimate of the strain-rate-sensitive behaviour of materials.

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Simulation study of the effect of strain rate on the mechanical properties and tensile deformation of gold nanowire

Modern Physics Letters B ◽

10.1142/s0217984917502475 ◽

2017 ◽

Vol 31 (27) ◽

pp. 1750247 ◽

Cited By ~ 4

Author(s):

Guo-Jie Shi ◽

Jin-Guo Wang ◽

Zhao-Yang Hou ◽

Zhen Wang ◽

Rang-Su Liu

Keyword(s):

Mechanical Properties ◽

Strain Rate ◽

High Strain ◽

Strain Curve ◽

Deformation Mechanisms ◽

Strain Rates ◽

Stress Strain Curve ◽

Stress Strain ◽

Au Nanowire ◽

Plastic Process

The mechanical properties and deformation mechanisms of Au nanowire during the tensile processes at different strain rates are revealed by the molecular dynamics method. It is found that the Au nanowire displays three distinct types of mechanical behaviors when tensioning at low, medium and high strain rates, respectively. At the low strain rate, the stress–strain curve displays a periodic zigzag increase–decrease feature, and the plastic deformation is resulted from the slide of dislocation. The dislocations nucleate, propagate, and finally annihilate in every decreasing stages of stress, and the nanowire always can recover to FCC-ordered structure. At the medium strain rate, the stress–strain curve gently decreases during the plastic process, and the deformation is contributed from sliding and twinning. The dislocations formed in the yield stage do not fully propagate and further escape from the nanowire. At the high strain rate, the stress-strain curve wave-like oscillates during the plastic process, and the deformation is resulted from amorphization. The FCC atoms quickly transform into disordered amorphous structure in the yield stage. The relative magnitude between the loading velocity of strain and the propagation velocity of phonons determines the different deformation mechanisms. The mechanical behavior of Au nanowire is similar to Ni, Cu and Pt nanowires, but their deformation mechanisms are not completely identical with each other.

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Understanding Dynamic Recrystallization Behavior through a Delay Differential Equation Approach

Materials Science Forum ◽

10.4028/www.scientific.net/msf.558-559.441 ◽

2007 ◽

Vol 558-559 ◽

pp. 441-448 ◽

Cited By ~ 3

Author(s):

Jong K. Lee

Keyword(s):

Differential Equation ◽

Strain Rate ◽

Critical Strain ◽

Strain Curve ◽

Single Peak ◽

Strain Rates ◽

Stress Strain Curve ◽

Stress Strain ◽

Strain Behavior ◽

Delay Differential

During hot working, deformation of metals such as copper or austenitic steels involves features of both diffusional flow and dislocation motion. As such, the true stress-true strain relationship depends on the strain rate. At low strain rates (or high temperatures), the stress-strain curve displays an oscillatory behavior with multiple peaks. As the strain rate increases (or as the temperature is reduced), the number of peaks on the stress-strain curve decreases, and at high strain rates, the stress rises to a single peak before settling at a steady-state value. It is understood that dynamic recovery is responsible for the stress-strain behavior with zero or a single peak, whereas dynamic recrystallization causes the oscillatory nature. In the past, most predictive models are based on either modified Johnson-Mehl-Avrami kinetic equations or probabilistic approaches. In this work, a delay differential equation is utilized for modeling such a stress-strain behavior. The approach takes into account for a delay time due to diffusion, which is expressed as the critical strain for nucleation for recrystallization. The solution shows that the oscillatory nature depends on the ratio of the critical strain for nucleation to the critical strain for completion for recrystallization. As the strain ratio increases, the stress-strain curve changes from a monotonic rise to a single peak, then to a multiple peak behavior. The model also predicts transient flow curves resulting from strain rate changes.

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Dynamic Stress-Strain Relations for Annealed 2S Aluminum Under Compression Impact

Journal of Applied Mechanics ◽

10.1115/1.4010759 ◽

1953 ◽

Vol 20 (4) ◽

pp. 523-529

Author(s):

J. E. Johnson ◽

D. S. Wood ◽

D. S. Clark

Keyword(s):

Dynamic Stress ◽

Strain Curve ◽

Stress Strain Curve ◽

Stress Strain ◽

Impact Stress ◽

Stress Strain Relation ◽

Final Strain ◽

Dynamic Relations ◽

Single Stress ◽

The Impact

Abstract This paper presents the results of an experimental study of the stress-strain relation of annealed 2S aluminum when subjected to compression impact. Two methods of securing a dynamic stress-strain curve are considered, namely, from the measurement of impact stress as a function of maximum plastic strain, and impact stress as a function of the impact velocity. The dynamic stress-strain curves obtained by these methods lie considerably above the static curve. The elevation in stress of the dynamic relations above the static relation increases progressively from zero at the elastic limit to about 20 per cent at a strain of 4.5 per cent. However, the two dynamic relations are not coincident which indicates that the behavior of the material cannot be described by a single stress-strain curve for all impact velocities. A family of stress-strain curves which differ slightly from each other and which depend upon the final strain is postulated in order to correlate both sets of data adequately.

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