A nanoscale study of size scale, strain rate, temperature, and stress state effects on damage and fracture of polyethylene

2021 ◽  
pp. 104008
Author(s):  
A.L. Bowman ◽  
S. Mun ◽  
B.D. Huddleston ◽  
S.R. Gwaltney ◽  
M.I. Baskes ◽  
...  
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Size Scale ◽  
Damage And Fracture

scholarly journals Effects of Spatially Varying Seismic Ground Motions and Incident Angles on Behavior of Long Tunnels

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Yundong Zhou ◽  
Yongxin Wu ◽  
Ziheng Shangguan ◽  
Zhanbin Wang
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Ground Motions ◽  
Pure Shear ◽  
Radial Strain ◽  
Complex Stress State ◽  
Asymmetric Effect ◽  
Principal Stresses ◽  
Input Motion ◽  
Spatially Varying

Seismic behavior of long circle tunnels is significantly influenced by the nature of input motion. This study, based on the 3D finite-element method (FEM), evaluates the effects of spatially varying seismic ground motions and uniform input seismic ground motions and their incident angles on the diameter strain rate and tensive/compressive principal stresses under different strata. It is found that (1) the spatially varying seismic ground motions induced larger diameter strain rate (radially deformation) than the uniform input seismic motion, (2) the spatially varying seismic ground motions had an asymmetric effect on the radial strain rate distributions, and (3) the rising incident angles changed the pure shear stress state into a complex stress state for tunnels under specified input motion.

Stress-State, Temperature, and Strain Rate Dependence of Vintage ASTM A7 Steel

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
S. A. Brauer ◽  
W. R. Whittington ◽  
H. Rhee ◽  
P. G. Allison ◽  
D. E. Dickel ◽  
...  
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Rate Sensitivity ◽  
Rate Dependence ◽  
Maximum Strength ◽  
Strain Rate Dependence ◽  
Dynamic Strain ◽  
Strength Increase ◽  
Negative Strain Rate Sensitivity

The structure–property relationships of a vintage ASTM A7 steel is quantified in terms of stress state, temperature, and strain rate dependence. The microstructural stereology revealed primary phases to be 15.8% ± 2.6% pearlitic and 84.2% ± 2.6 ferritic with grain sizes of 13.3 μm ± 3.1 μm and 36.5 μm ± 7.0 μm, respectively. Manganese particle volume fractions represented 0.38–1.53% of the bulk material. Mechanical testing revealed a stress state dependence that showed a maximum strength increase of 85% from torsion to tension and a strain rate dependence that showed a maximum strength increase of 38% from 10−1 to 103 s−1at 20% strain. In tension, a negative strain rate sensitivity (nSRS) was observed in the quasi-static rate regime yet was positive when traversing from the quasi-static rates to high strain rates. Also, the A7 steel exhibited a significant ductility reduction as the temperature increased from ambient to 573 K (300 °C), which is uncommon for metals. The literature argues that dynamic strain aging (DSA) can induce the negative strain rate sensitivity and ductility reduction upon a temperature increase. Finally, a tension/compression stress asymmetry arises in this A7 steel, which can play a significant role since bending is prevalent in this ubiquitous structural material. Torsional softening was also observed for this A7 steel.

Temperature, strain rate, stress state and the failure of HY-100 steel

2001 ◽  
Vol 302 (2) ◽  
pp. 197-205 ◽  
Author(s):  
V. Jablokov ◽  
D.M. Goto ◽  
D.A. Koss ◽  
J.B. McKirgan
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Temperature Strain

Dynamic fracture under impact and high-strain-rate loading

1995 ◽  
Vol 73 (5-6) ◽  
pp. 315-323 ◽  
Author(s):  
M. J. Worswick ◽  
J. A. Clarke ◽  
R. J. Pick
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Ductile Fracture ◽  
Damage Evolution ◽  
High Strain ◽  
Yield Criterion ◽  
Damage And Fracture ◽  
Split Hopkinson ◽  
Strain Rate Loading ◽  
Dynamic Loading Conditions

A constitutive model based on a pressure-dependent yield criterion is used to predict damage evolution and ductile fracture under dynamic loading conditions. The model predicts the influence of porosity on plastic flow in metals and the nucleation, growth, and coalescence of internal microvoids to cause ductile fracture. The constitutive equations have been implemented in the DYNA2D finite-element code and have been used to simulate three high-strain-rate experiments: (i) the symmetric Taylor cylinder impact, (ii) the plate impact, and (iii) the tensile split Hopkinson bar experiments. In each case, the model is shown to capture qualitatively the damage and fracture within the experiments modelled. Comparison with recent symmetric Taylor impact experiments on leaded brass suggests that the model over-predicts the rate of damage evolution under the high-strain rate, high-triaxiality conditions associated with impact.

scholarly journals ANALYSIS OF INFLAMMABLE STATE OF PURCHASE AT THE WALKING

2019 ◽  
pp. 80-85
Author(s):  
Irina Bubnovska
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Stress Tensor ◽  
Plane Strain ◽  
Equilibrium Equation ◽  
State Parameter ◽  
Strain Rate Tensor ◽  
Workpiece Material

On the basis of the equilibrium equation, the plasticity conditions in the zones of plane strain, the equation of the connection of the components of the stress tensor and the strain rate tensor, an expression was obtained for determining the stress state parameter, which makes it possible to estimate the deformity of the workpiece material during rolling.

scholarly journals Study on the Dynamic Mechanical Properties of Metamorphic Limestone under Impact Loading

Lithosphere ◽  
2021 ◽  
Vol 2021 (Special 4) ◽  
Author(s):  
Zhiyu Zhang ◽  
Qingyun Qian ◽  
Hao Wang ◽  
Yonghui Huang ◽  
Jianguo Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Energy Dissipation ◽  
Strain Rate ◽  
Failure Modes ◽  
Fractal Theory ◽  
Sudden Change ◽  
Mining Area ◽  
Strain Rates ◽  
Damage And Fracture ◽  
Corner Cracks

Abstract To study the dynamic damage and fracture of metamorphic limestone under explosive load and the stability of the surrounding rock, the stress-strain curve, fracture morphology, and energy dissipation characteristics of metamorphic limestone in the Dahongshan mining area under different strain rates were studied by the Hopkinson pressure bar (SHPB), stress wave analysis, and fractal theory. The experimental results show that the crushing form and degree are significantly affected by the loading strain rate. There are several typical failure modes. When the strain rate is 17.56 s−1, there is no obvious failure except corner cracks. When the strain rate is between 26.92 s−1 and 56.18 s−1, the failure mode of the specimen is axial splitting failure, and when the strain rate is 67.34 s−1, splitting and shearing failure occur. With the increase of the strain rate, the growth rate of the dynamic compressive strength slows down. Compared with static compressive strength, the strength factor increases from 1.15 to 4.19. Also, the fractal dimension shows a gentle increase. When Df is in the range of 1.82~2.24, there is a sudden change in fragmentation when the strain rate is in the range of 34.70 s−1~56.18 s−1. Energy dissipation density increases logarithmically with the strain rate. The results reveal the dynamic breaking and energy consumption laws of metamorphic limestone under impact loads with different strain rates and could provide some reference value for the safe and efficient construction in the Dahongshan mining area and similar engineering projects.

A quantitative criterion for predicting solid-state disordering during biaxial, high strain rate deformation

2021 ◽  
Author(s):  
Michael Becker ◽  
Desiderio Kovar
Keyword(s):  
Stress State ◽  
Strain Rate ◽  
Strain State ◽  
Biaxial Loading ◽  
High Strain ◽  
Md Simulations ◽  
Strain Rates ◽  
Critical Strain Rate ◽  
Wide Range ◽  
High Strain Rate Deformation

Abstract A criterion to predict the onset of disordering under biaxial loading based on a critical potential energy per atom was studied. In contrast to previous theories for disordering, this criterion incorporates the effects of strain rate and strain state. The strain state (or stress state) is defined by the combination of strain (or stress) magnitudes and directions that are applied to each sample during the simulation. Τhe validity of this criterion was studied using molecular dynamic (MD) simulations of Ag conducted over a wide range of biaxial strain rates, strain configurations, and crystal orientations with respect to the applied stress state. Biaxial strains were applied in two different planes, (112 ̅) and (001) in eight directions in each plane. Results showed that, when larger strain rates were applied, there was a transition from plastic deformation driven by the nucleation and propagation of dislocations to disordering and viscous flow. Although the critical strain rate to initiate disorder was found to vary in the range of ε ̇ = 1×1011 s-1 to ε ̇ = 4×1011 s-1, a consistent minimum PE/atom of -2.7 eV was observed over a broad range of strain states and for both crystallographic orientations that were studied. This indicates that the critical PE/atom is a material property that can be used to predict the onset of disordering under biaxial loading. Further, the results showed that this criterion can be applied successfully even when non-uninform strain states arise in the crystal.  

The Stress-State in the Shear Zone During Steady State Machining

1979 ◽  
Vol 101 (2) ◽  
pp. 211-216 ◽  
Author(s):  
J. H. L. The´ ◽  
R. F. Scrutton
Keyword(s):  
Flow Stress ◽  
Stress State ◽  
Strain Rate ◽  
Shear Zone ◽  
Deformation Mode ◽  
Deformation Pattern ◽  
Line Field ◽  
Strain And Strain Rate ◽  
Theoretical Predictions ◽  
Simple Shear Deformation

In order to calculate the stress state at any point in the shear zone, a new method has been developed which incorporates the effects of strain—hardening, strain-rate and temperature. Previous attempts have employed a modified slip-line field technique. The method is based on an empirical formula derived from published experimental data over a period of fifteen years relating flow stress values with values of strain, strain-rate, and temperature. From an experimentally derived deformation pattern, the strain and strain-rate distributions may be determined assuming a simple shear deformation mode. By using the empirical flow stress formula, the stresses and temperatures in the plastic zone may be calculated easily. Theoretical predictions agree well with experimentally observed values. The method is applied to a parallel-sided zone.

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