Large Strain, High Strain Rate Testing of Copper

1980 ◽  
Vol 102 (4) ◽  
pp. 376-381 ◽  
Author(s):  
U. S. Lindholm ◽  
A. Nagy ◽  
G. R. Johnson ◽  
J. M. Hoegfeldt
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Large Strain ◽  
Shear Banding ◽  
Testing Machine ◽  
Shear Instability ◽  
Large Strains ◽  
Rate Dependent ◽  
Torsional Testing ◽  
Strain Hardening Behavior

This paper describes the development of a high-speed torsional testing machine and results obtained on the strain-rate dependent strength of copper at large shear strains. Test techniques and data obtained are intended to be useful in applications such as ballistics and machining. For copper, the results indicate positive strain hardening behavior to very large strains under low rate, isothermal conditions and the transition to adiabatic thermal softening, shear instability and localization (shear banding) at high rates.

Analytical Solutions for Circular Bars Subjected to Large Strain Plastic Torsion

1990 ◽  
Vol 57 (2) ◽  
pp. 298-306 ◽  
Author(s):  
K. W. Neale ◽  
S. C. Shrivastava
Keyword(s):  
Closed Form ◽  
Analytical Solutions ◽  
Large Strain ◽  
Kinematic Hardening ◽  
Flow Theory ◽  
Constitutive Laws ◽  
Isotropic Hardening ◽  
Large Strains ◽  
Inelastic Behavior ◽  
Rate Dependent

The inelastic behavior of solid circular bars twisted to arbitrarily large strains is considered. Various phenomenological constitutive laws currently employed to model finite strain inelastic behavior are shown to lead to closed-form analytical solutions for torsion. These include rate-independent elastic-plastic isotropic hardening J2 flow theory of plasticity, various kinematic hardening models of flow theory, and both hypoelastic and hyperelastic formulations of J2 deformation theory. Certain rate-dependent inelastic laws, including creep and strain-rate sensitivity models, also permit the development of closed-form solutions. The derivation of these solutions is presented as well as numerous applications to a wide variety of time-independent and rate-dependent plastic constitutive laws.

Investigation of the axial compressive behavior of Kevlar fibers using the dynamic loop test

2019 ◽  
Vol 89 (18) ◽  
pp. 3825-3838
Author(s):  
Ahmad Abuobaid ◽  
Raja Ganesh ◽  
John W Gillespie
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Failure Strain ◽  
Kink Band ◽  
Test Method ◽  
Strain Rates ◽  
Compressive Failure ◽  
Band Formation ◽  
Rate Dependent ◽  
Strain And Strain Rate

A dynamic loop test method for measuring strain rate-dependent fiber properties was developed. During dynamic loop testing, the fiber ends are accelerated at constant levels of 20.8, 50 and 343 m/s2. The test method is used to study Kevlar® KM2-600, which fails in axial compression due to kink band formation. The compressive failure strain and strain rate at the onset of kink band formation is calculated from the critical loop diameter ( D C), which is monitored throughout the test using a high-speed camera. The results showed that compressive failure strain increases with strain rates from quasi-static to a maximum strain rate of 116 s−1 by a factor of ∼3. Kink angles (φ) and kink band spacing ( D S) were 60 ° ± 2 ° and 16 ± 3 μm, respectively, over the strain rates tested. Rate-dependent mechanisms of compressive failure by kink band formation were discussed.

Crystal Plasticity

1983 ◽  
Vol 50 (4b) ◽  
pp. 921-934 ◽  
Author(s):  
R. J. Asaro
Keyword(s):  
Crystallographic Texture ◽  
Inelastic Deformation ◽  
Constitutive Behavior ◽  
Large Strains ◽  
Significant Progress ◽  
Crystalline Materials ◽  
Hardening Behavior ◽  
The Past ◽  
Rate Dependent ◽  
Strain Hardening Behavior

Significant progress has been made during the past decade in incorporating micromechanics in continuum descriptions of inelastic deformation. This has led to the development of a rather comprehensive constitutive theory for rate-dependent and idealized rate-independent crystalline materials that deform plastically by crystalline slip. This theory is reviewed in some detail and examples are presented which illustrate how complex slip phenomena involving localized plastic flow and nonuniform crystallographic texture can be analyzed. The paper concludes by suggesting that it is now possible to develop accurate models for rate-dependent polycrystals undergoing arbitrarily large strains. Such models would have as principal aims the prediction of texture development and the rigorous assessment of such anisotropy on constitutive behavior. An example of how this would be of immediate value in analyzing strain-hardening behavior of metal polycrystals at large strains is provided.

scholarly journals Characterization of Flow Induced Anisotropy in Sheet Metal at Large Strain

2021 ◽  
Author(s):  
F. Gutknecht ◽  
H. Traphöner ◽  
T. Clausmeyer ◽  
A. E. Tekkaya
Keyword(s):  
Strain Rate ◽  
Sheet Metal ◽  
Strain Path ◽  
Large Strain ◽  
High Strength ◽  
Bulge Test ◽  
Large Strains ◽  
Steel Grades ◽  
Strain Path Change ◽  
Cross Hardening

Abstract Background Many metals exhibit a stress overshoot, the so-called cross-hardening when subjected to a specific strain-path change. Existing tests for sheet metals are limited to an equivalent prestrain of 0.2 and show varying levels of cross-hardening for identical grades. Objective The aim is to determine cross-hardening at large strains, relevant for forming processes. Mild steel grades (DC04, DC06, DX56) and high strength steel grades (BS600, DP600, ZE800) are investigated to quantify the level of cross-hardening between different grades and reveal which grades exhibit cross-hardening at all. Method A novel test setup for large prestrain using hydraulic bulge test and torsion of curved sheets is developed to achieve an orthogonal strain-path change, i.e. the strain rate tensors for two subsequent loadings are orthogonal. The influence of strain rate differences between the tests and clamping of curved sheets on the determined cross-hardening are evaluated. The results are compared to experiments in literature. Results Cross-hardening for sheet metal at prestrains up to 0.6 true plastic strain are obtained for the first time. For DX56 grade the maximum cross-hardening for all prestrains have a constant level of approximately 6%, while the maximum cross-hardening for DC04 and DC06 grades increases, with levels between 7 and 11%. The high strength grades BS600 and ZE800 do not show cross-hardening behavior, while, differencing from previous publications, cross-hardening is observed for dual phase steel DP600. Conclusion Depending on the microstructure of the steel grade the cross-hardening increases with large prestrain or remains constant.

Incorporation of the effect of strain rate in Mie-Gruneisen equation of state for polyethylene

2021 ◽  
pp. 030932472199403
Author(s):  
Gholam Hossein Majzoobi ◽  
Niloufar Zarei
Keyword(s):  
Numerical Simulation ◽  
Equation Of State ◽  
Strain Rate ◽  
Volume Change ◽  
Optimization Technique ◽  
Testing Machine ◽  
High Rate ◽  
Compression Tests ◽  
Rate Dependent ◽  
Load Volume

Volume change versus pressure is expressed through an equation of state (EOS) such as the well-known Mie-Gruneisen equation. Equation of state is an essential requirement to be defined for numerical simulation of high rate events such as impact. All EOSs have some coefficients which are identified by experiment and are usually considered constant and strain rate independent. In this study, the effect of strain rate on the coefficients of Mie-Gruneisen equation is obtained for polyethylene by experiment and numerical simulation. The low and high strain rate compression tests are conducted using Instron testing machine and Hopkinson bar, respectively. The load-displacement and load-volume change curves are obtained from the experiments. The strain rate dependent constants of Mie-Gruneisen equation of state are obtained through a combined experimental/numerical/optimization technique. The compression test is simulated using Ls-dyna hydrocode. The results show that the coefficient γ is not affected by strain rate but the coefficients C and S1 are severely strain rate dependent. The latter varies with strain rate in a linear fashion and the former varies cubically with strain rate.

Dynamic Mechanical Behavior of Two Fiber-Reinforced Composites

2012 ◽  
Vol 525-526 ◽  
pp. 261-264
Author(s):  
Y.Z. Guo ◽  
X. Chen ◽  
Xi Yun Wang ◽  
S.G. Tan ◽  
Z. Zeng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Rate Dependent ◽  
Dynamic Loadings ◽  
Axial Splitting

The mechanical behavior of two composites, i.e., CF3031/QY8911 (CQ, hereafter in this paper) and EW100A/BA9916 (EB, hereafter in this paper), under dynamic loadings were carefully studied by using split Hopkinson pressure bar (SHPB) system. The results show that compressive strength of CQ increases with increasing strain-rates, while for EB the compressive strength at strain-rate 1500/s is lower then that at 800/s or 400/s. More interestingly, most of the stress strain curves of both of the two composites are not monotonous but exhibit double-peak shape. To identify this unusual phenominon, a high speed photographic system is introduced. The deformation as well as fracture characteristics of the composites under dynamic loadings were captured. The photoes indicate that two different failure mechanisms work during dynamic fracture process. The first one is axial splitting between the fiber and the matrix and the second one is overall shear. The interficial strength between the fiber and matrix, which is also strain rate dependent, determines the fracture modes and the shape of the stress/strain curves.

Response and failure of fiber metal laminates subjected to high strain rate tensile loading

2018 ◽  
Vol 53 (11) ◽  
pp. 1489-1506 ◽  
Author(s):  
Ankush P Sharma ◽  
Sanan H Khan ◽  
Venkitanarayanan Parameswaran
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Glass Fiber ◽  
High Speed ◽  
High Strain ◽  
Image Correlation ◽  
Fiber Metal Laminates ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Fiber Metal

The tensile behavior of fiber metal laminates consisting of layers of aluminum 2024-T3 alloy and glass fiber reinforced composites under high strain rate loading is investigated. Fiber metal laminates having four different layups, but all having the same total metal layer thickness, were fabricated using a combined hand lay-up cum vacuum bagging method. The fiber metal laminate specimens were loaded in high strain rate tension using a split Hopkinson tensile bar. The rate-dependent behavior of the glass fiber composite was also obtained as baseline data. The strain on the gage area of the specimen was measured directly using high-speed digital image correlation. Another high-speed camera was used to capture the sequence of damage by viewing the specimen edgewise. The results indicated that the strength of the fiber metal laminates increased at high strain rates primarily due to the rate-dependent behavior of the composite used. The response was also influenced by the distribution of the metallic layers in the fiber metal laminates. The failure in the case where the individual composite layers were separated by metallic layers was more progressive in nature.

The Influence of Strain Rate on the Passive and Stimulated Engineering Stress–Large Strain Behavior of the Rabbit Tibialis Anterior Muscle

1998 ◽  
Vol 120 (1) ◽  
pp. 126-132 ◽  
Author(s):  
B. S. Myers ◽  
C. T. Woolley ◽  
T. L. Slotter ◽  
W. E. Garrett ◽  
T. M. Best
Keyword(s):  
Strain Rate ◽  
Tibialis Anterior ◽  
High Speed ◽  
Large Strain ◽  
Strain Rates ◽  
Average Strain ◽  
Stress Strain ◽  
Engineering Stress ◽  
Average Strain Rate ◽  
Strain Responses

The passive and stimulated engineering stress–large strain mechanical properties of skeletal muscle were measured at the midbelly of the rabbit tibialis anterior. The purpose of these experiments was to provide previously unavailable constitutive information based on the true geometry of the muscle and to determine the effect of strain rate on these responses. An apparatus including an ultrasound imager, high-speed digital imager, and a servohydraulic linear actuator was used to apply constant velocity deformations to the tibialis anterior of an anesthetized neurovascularly intact rabbit. The average isometric tetanic stress prior to elongation was 0.44 ± 0.15 MPa. During elongation the average stimulated modulus was 0.97 ± 0.34 MPa and was insensitive to rate of loading. The passive stress–strain responses showed a nonlinear stiffening response typical of biologic soft tissue. Both the passive and stimulated stress–strain responses were sensitive to strain rate over the range of strain rates (1 to 25 s−1). Smaller changes in average strain rate (1 to 10, and 10 to 25 s−1) did not produce statistically significant changes in these responses, particularly in the stimulated responses, which were less sensitive to average strain rate than the passive responses. This relative insensitivity to strain rate suggests that pseudoelastic functions generated from an appropriate strain rate test may be suitable for the characterization of the responses of muscle over a narrow range of strain rates, particularly in stimulated muscle.

scholarly journals Strain rate dependence of plastic flow in Ce-based bulk metallic glass during nanoindentation

2007 ◽  
Vol 22 (2) ◽  
pp. 258-263 ◽  
Author(s):  
B.C. Wei ◽  
L.C. Zhang ◽  
T.H. Zhang ◽  
D.M. Xing ◽  
J. Das ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Loading Rate ◽  
Shear Banding ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Serrated Flow ◽  
Rate Dependent

The strain rate dependence of plastic deformation of Ce60Al15Cu10Ni15 bulk metallic glass was studied by nanoindentation. Even though the ratio of room temperature to the glass transition temperature was very high (0.72) for this alloy, the plastic deformation was dominated by shear banding under nanoindentation. The alloy exhibited a critical loading rate dependent serrated flow feature. That is, with increasing loading rate, the alloy exhibited a transition from less prominent serrated flow to pronounced serrated flow during continuous loading but from serrated to smoother flow during stepped loading.

Dynamic Tensile Characteristics of DP600 Steel Sheets for Automotive Applications

2012 ◽  
Vol 509 ◽  
pp. 40-45
Author(s):  
Dan Yang Dong ◽  
Yang Liu ◽  
Lei Wang ◽  
Chang Sheng Liu
Keyword(s):  
Strain Rate ◽  
Tensile Testing ◽  
High Speed ◽  
Greenhouse Gas Emission ◽  
Testing Machine ◽  
Fracture Mechanisms ◽  
Strain Rates ◽  
Automotive Applications ◽  
Tensile Testing Machine ◽  
Steel Sheets

To reduce fuel consumption and greenhouse gas emission, dual phase (DP) steels have been considered for automotive applications due to their higher tensile strength, better initial work hardening along with larger elongation compared to conventional grade of steels. In such applications, which would create potential safety and reliability issues under dynamic loading, the mechanical behavior of DP steel considering the strain rate must be examined. In the present study, the dynamic tensile behavior of DP600 steel sheets was investigated using a high-speed tensile testing machine at various strain rates. And the quasi-static tensile testing was also conducted on the steel to understand the effect of the strain rate on the tensile property. The fracture mechanisms of the steel were also analyzed. The results show that the mechanical properties of DP600 steel are noticeably influenced by the strain rates. As the strain rate increases, the strength of the steel increases and the obvious yield phenomenon can be observed when the strain rate is above 0.01 s-1. The fracture elongation of DP600 steels decreases with increasing strain rate from 0.001 to 1 s-1, then increases up to the strain rate of 100 s-1 and reaches the lowest value at the strain rate of 1000 s-1. DP600 steel sheet exhibit typical ductile fracture characteristics with dimples morphology of the facture surface when tensile deformed at various strain rates.

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