A Yield Criterion for Porous Ductile Media at High Strain Rate

1997 ◽  
Vol 64 (3) ◽  
pp. 503-509 ◽  
Author(s):  
Ze-Ping Wang ◽  
Qing Jiang
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Yield Surface ◽  
High Strain ◽  
Yield Criterion ◽  
Matrix Material ◽  
Yield Function ◽  
Inertial Effects ◽  
The Matrix ◽  
Dynamic Yield

An approximate yield criterion for porous ductile media at high strain rate is developed adopting energy principles. A new concept that the macroscopic stresses are composed of two parts, representing dynamic and quasi-static components, is proposed. It is found that the dynamic part of the macroscopic stresses controls the movement of the dynamic yield surface in stress space, while the quasi-static part determines the shape of the dynamic yield surface. The matrix material is idealized as rigid-perfectly plastic and obeying the von Mises yield. An approximate velocity field for the matrix is employed to derive the dynamic yield function. Numerical results show that the dynamic yield function is dependent not only on the rate of deformation but also on the distribution of initial micro-damage, which are different from that of the quasi-static condition. It is indicated that inertial effects play a very important role in the dynamic behavior of the yield function. However, it is also shown that when the rate of deformation is low (≤103/sec), inertial effects become vanishingly small, and the dynamic yield function in this case reduces to the Gurson model.

scholarly journals Влияние гигантской магнитострикции на динамический предел текучести в условиях высокоскоростной деформации

2021 ◽  
Vol 63 (12) ◽  
pp. 2070
Author(s):  
В.В. Малашенко
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Yield Stress ◽  
High Strain ◽  
Dynamic Yield Stress ◽  
High Strain Rate Deformation ◽  
Dynamic Yield ◽  
Giant Magnetostriction

The high-strain rate deformation of crystals with giant magnetostriction is theoretically analyzed. It is shown that giant magnetostriction has a significant effect on the dynamic yield stress of crystals.

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.

Dynamic Tensile Properties of TiCp/Ti Composite

2008 ◽  
Vol 385-387 ◽  
pp. 873-876
Author(s):  
Fang Jiang ◽  
Dong Zhao ◽  
Jian Guo Ning
Keyword(s):  
Titanium Alloy ◽  
High Strain Rate ◽  
Strain Rate ◽  
Tensile Properties ◽  
Strain Rate Sensitivity ◽  
High Strain ◽  
Volume Fraction ◽  
Rate Sensitivity ◽  
The Matrix ◽  
High Strain Rate Sensitivity

The tensile properties of a titanium alloy reinforced with 3% by volume fraction of TiC particles and of an unreinforced titanium alloy are studied over a range of strain rates from 0.0001s-1 to 1300s-1 using quasi-static material testing system (MTS810) and split Hopkinson tensile bar apparatus. The experimental results show that both the TiCp/Ti composite and its matrix alloy exhibit an obvious strain-rate hardening property. But the high strain-rate sensitivity of the TiCp/Ti composite is significantly higher than that of the matrix. The high strain-rate sensitivity of the TiCp/Ti composite is considered to be originated from the high dislocation accumulation rate during dynamic deformation and the constraint of TiC particles on the surrounding matrix, which dramatically enhances rate of the matrix. Finally, a phenomenological dynamic constitutive relation is established considering the composite is elastic-perfectly plastic material.

A Yield Criterion for Pressure-Sensitive Materials

2011 ◽  
Vol 117-119 ◽  
pp. 493-497
Author(s):  
Chen Hua Lu ◽  
Bo Liu ◽  
Jian Bing Sang ◽  
Yan Hui Qie ◽  
Jing Yuan Wang
Keyword(s):  
Yield Surface ◽  
Yield Criterion ◽  
Matrix Material ◽  
Yield Condition ◽  
Upper Bound Theorem ◽  
Pressure Sensitive ◽  
The Matrix ◽  
Plastic Limit Analysis ◽  
Bound Theorem ◽  
Two Parameter

Following the modified Gurson model in meso-mechanics, the models with spherical holes are established by the assumption which the matrix meets the two-parameter elliptic yield condition. The macroscopic stress expression which contains micro structure parameters and the material equation of yield surface are given by the upper bound theorem of plastic limit analysis. The parameters of the matrix material and damage(porosity) which impact on macroscopic yield surface equation are discussed. These works provide theory foundations for material damage and design.

scholarly journals THE EFFECT OF NANOSCALE DEFECTS ON THE DYNAMIC YIELD STRESS OF ALLOYS

2020 ◽  
pp. 136-141
Author(s):  
Вадим Викторович Малашенко ◽  
Татьяна Ивановна Малашенко
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Yield Stress ◽  
Point Defects ◽  
High Strain ◽  
Analytical Expression ◽  
Dynamic Yield Stress ◽  
High Strain Rate Deformation ◽  
Dynamic Yield

Теоретически проанализирована высокоскоростная деформация состаренных сплавов, содержащих зоны Гинье-Престона. Получено аналитическое выражение вклада зон Гинье-Престона в величину динамического предела текучести. Показано, что динамическое торможение дислокаций наноразмерными дефектами существенно отличается от торможения точечными дефектами. The high strain rate deformation of aged alloys containing Guinier-Preston zones is theoretically analyzed. The analytical expression for the contribution of the Guinier-Preston zones to the value of the dynamic yield stress has been obtained. It is shown that the dynamic drag of dislocations by nanoscale defects differs significantly from the drag by point defects.

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