Applicability of power law for describing the rheology of soils of different origins and characteristics

2009 ◽  
Vol 46 (9) ◽  
pp. 1011-1023 ◽  
Author(s):  
Sueng Won Jeong ◽  
Serge Leroueil ◽  
Jacques Locat
Keyword(s):  
Strain Rate ◽  
Power Law ◽  
Debris Flows ◽  
Rheological Behaviour ◽  
Strain Rate Range ◽  
Rate Dependent ◽  
Different Origins ◽  
Power Law Index ◽  
Soil Behaviour ◽  
Low Activity

The rate-dependent rheological behaviour of soils of different origins and characteristics was studied and the applicability of the power law model was examined. The studied soils were divided into three groups: (i) low-activity soils, (ii) high-activity soils, and (iii) silt-rich soils. The results show that the power law applies to all these soils and is representative of soil behaviour in a strain rate range corresponding to debris flows, which is generally not the case with the Bingham model. For low-activity clays, the power law index, n, is typically equal to 0.12 and seems to increase with the plasticity index; it is larger (i.e., in the range of 0.2–0.6) for silt-rich soils. Comparison of n values for tests performed on intact and remoulded low-activity clay specimens indicates that the power law index is possibly strain-rate dependent.

scholarly journals Extension of Flow Behaviour and Damage Models for Cast Iron Alloys with Strain Rate Effect

2020 ◽  
Author(s):  
Chuang Liu ◽  
Dongzhi Sun ◽  
Xianfeng Zhang ◽  
Florence Andrieux ◽  
Tobias Gerster
Keyword(s):  
Cast Iron ◽  
Constitutive Model ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Damage Model ◽  
Iron Alloys ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Damage Models ◽  
Rate Dependent

Abstract Cast iron alloys with low production cost and quite good mechanical properties are widely used in the automotive industry. To study the mechanical behavior of a typical ductile cast iron (GJS-450) with nodular graphite, uni-axial quasi-static and dynamic tensile tests at strain rates of 10− 4, 1, 10, 100, and 250 s− 1 were carried out. In order to investigate the effects of stress state, specimens with various geometries were used in the experiments. Stress–strain curves and fracture strains of the GJS-450 alloy in the strain-rate range of 10− 4 to 250 s− 1 were obtained. A strain rate-dependent plastic flow law based on the Voce model is proposed to describe the mechanical behavior in the corresponding strain-rate range. The deformation behavior at various strain rates is observed and analyzed through simulations with the proposed strain rate-dependent constitutive model. The available damage model from Bai and Wierzbicki is extended to take the strain rate into account and calibrated based on the analysis of local fracture strains. The validity of the proposed constitutive model including the damage model was verified by the corresponding experimental results. The results show that the strain rate has obviously nonlinear effects on the yield stress and fracture strain of GJS-450 alloys. The predictions with the proposed constitutive model and damage models at various strain rates agree well with the experimental results, which illustrates that the rate-dependent flow rule and damage models can be used to describe the mechanical behavior of cast iron alloys at elevated strain rates.

scholarly journals Modeling of the Strain Rate Dependency of Polycarbonate’s Yield Stress: Evaluation of Four Constitutive Equations

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Abdullah A. Al-Juaid ◽  
Ramzi Othman
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Yield Stress ◽  
Power Law ◽  
Constitutive Relations ◽  
Stress Sensitivity ◽  
Strain Rate Range ◽  
Rate Dependency ◽  
Rate Range ◽  
Strain Rate Dependency

The main focus of this paper is in evaluating four constitutive relations which model the strain rate dependency of polymers yield stress. Namely, the two-term power-law, the Ree-Eyring, the cooperative, and the newly modified-Eyring equations are used to fit tensile and compression yield stresses of polycarbonate, which are obtained from the literature. The four equations give good agreement with the experimental data. Despite using only three material constants, the modified-Eyring equation, which considers a strain rate-dependent activation volume, gives slightly worse fit than the three other equations. The two-term power-law and the cooperative equation predict a progressive increase in the strain rate sensitivity of the yield stress. Oppositely, the Ree-Eyring and the modified-Eyring equations show a clear transition between the low and high strain rate ranges. Namely, they predict a linear dependency of the yield stress in terms of the strain rate at the low strain rate range. Crossing a threshold strain rate, the yield stress sensitivity sharply increases as the strain rate increases. Hence, two different behaviors were observed though the four equations fit well the experimental data. More experimental data, mainly at the intermediate strain rate range, are needed to conclude which, of the two behaviors, is more appropriate for polymers.

Rate-Dependent Behavior and Constitutive Model of Polycarbonate at Strain Rate from 10-5 to 103 S-1

2011 ◽  
Vol 117-119 ◽  
pp. 434-437
Author(s):  
Wen Jun Hu ◽  
Xi Cheng Huang ◽  
Fang Ju Zhang ◽  
Cheng Jun Chen
Keyword(s):  
Constitutive Model ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Temperature Dependent ◽  
Static Tests ◽  
Rate Range ◽  
Rate Dependent ◽  
Dependent Behavior

Uni-axial quasi-static tests at strain rates 10-5, 10-4, 10-3,10-2 and 10-1 s-1 and dynamic compressive tests at strain rates 1679, 2769,5000 and 8200 s-1 have been carried out to study the mechanical behavior for polycarbonate used in the avigation industry. The stress–strain curves of polycarbonate in the strain-rate range from 10-5 to 8200 s-1 have been obtained. The effects of the strain rate on yield phenomenon and rate-dependent mechanical behavior are discussed. A plastic flow law based on the DSGZ rate-temperature-dependent constitutive model was used to describe the mechanical behavior of polycarbonate in the strain-rate range from 10-5 to 103 s-1. The results at the six strain rates are in excellent agreement with the experimental data, which illustrates that the constitutive model can describe the mechanical behavior for polycarbonate at low and high strain rates perfectly.

The Influence of Plasticizer Content and Type on the Rheological Behaviour of Plastisol Used in Coated Fabrics

2000 ◽  
Vol 30 (1) ◽  
pp. 50-50
Author(s):  
A. Zadhoush ◽  
M. A. Alsharif
Keyword(s):  
Statistical Analysis ◽  
Power Law ◽  
Research Work ◽  
Rheological Behaviour ◽  
Flow Properties ◽  
Newtonian Flow ◽  
Plasticizer Content ◽  
Rheological Measurements ◽  
Coated Fabrics ◽  
Power Law Index

Coating pastes need to have very specific rheological properties because of the methods in which they are applied. Composition of the paste can be formulated in such a manner to achieve the desired rheological behaviour. In this research work rheological measurements of paste with nine various plasticizer content using DOP and DOA, and PVC-E with three k-values (69, 70, 75) were studied. The results indicate that pastes are characterized by a non-Newtonian pseudoplastic flow under the studied conditions. The power-law index ( n) values of the pastes show that the flow properties of pastes change to Newtonian flow above 50 phr plasticizer content. It was also found that the consistency index (k) of the pastes were decreased with increasing plasticizer content. Statistical analysis carried out show very good correlation between the studied parameters.

Modeling and Testing Strain Rate-Dependent Tensile Strength of Carbon/Epoxy Composites

2007 ◽  
Vol 353-358 ◽  
pp. 1418-1421 ◽  
Author(s):  
Gui Ping Zhao ◽  
Zheng Hao Wang ◽  
Jian Xin Zhang ◽  
Qiao Ping Huang
Keyword(s):  
Tensile Strength ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Split Hopkinson Tensile Bar ◽  
Rate Dependent ◽  
Dependent Behavior ◽  
Split Hopkinson ◽  
Rate Experiment ◽  
Epoxy Matrix Composite ◽  
Dependent Model

Tensile strength is an important material property and usually can be determined experimentally. The strain rate dependent behavior of T300 carbon/epoxy matrix composite was characterized over a wide strain rate range (10×10-5 s-1to10×104s-1). The low to moderate strain rate experiments were carried out on a MTS machine, while the high strain rate experiment was conducted with a split Hopkinson tensile bar. A rate dependent model was introduced to simulate the material response. Two kinds of stacking sequence of composite specimens [(45/-45)4]s and [(0/45/90/-45)2]s were tested at different strain rates, and the results were used to determine parameters of the model. The predictions of the model showed to agree fairly well with the experimental results. The tensile strength and initial elastic modulus of the composites increase when the strain rate increases.

AZ31 Magnesium Alloy Parameters Identification through Inverse Analysis at 713 K

2012 ◽  
Vol 504-506 ◽  
pp. 643-646 ◽  
Author(s):  
Gillo Giuliano
Keyword(s):  
Strain Rate ◽  
Power Law ◽  
Inverse Analysis ◽  
Constant Pressure ◽  
Az31 Alloy ◽  
Equivalent Strain ◽  
Strain Rate Range ◽  
Displacement Curve ◽  
Material Constants ◽  
Equivalent Strain Rate

This paper introduces a fast and accurate procedure for determining the constants of magnesium AZ31 alloy at 713 K. The material behaviour is modelled by means of the power law relationship between the equivalent flow stress, the equivalent strain and the equivalent strain-rate within a narrow equivalent strain-rate range. Bulging tests were carried out in isothermal conditions (713 K) and at constant pressure in order to determine the material constants. It is necessary to evaluate the displacement and the thickness evolutions at the dome apex of the metal sheet. The time-displacement curve was obtained by laser measurements whereas a large number of bulging tests, interrupted at preset time intervals, were carried out to evaluate the thickness. The thickness was measured directly using a two-digit micrometer. The material constants, m, n and K were obtained in the power law relationship by means of constant pressure bulging tests coupled with the use of an inverse analysis technique. The results of comparison between experimental and numerical tests are shown and they indicate that the material constants can be accurately evaluated.

Preliminary Results of Stainless Steel Impact Bending Tests

2006 ◽  
Author(s):  
Spencer D. Snow ◽  
D. Keith Morton ◽  
Tommy E. Rahl ◽  
Robert K. Blandford ◽  
Thomas J. Hill
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Spent Nuclear Fuel ◽  
National Laboratory ◽  
Strain Rate Range ◽  
Impact Testing ◽  
Radioactive Material ◽  
304L Stainless Steel ◽  
Rate Dependent ◽  
Tensile Impact

Stainless steels are used for the construction of numerous spent nuclear fuel or radioactive material containers that may be subjected to high strains and moderate strain rates during accidental drop events. Mechanical characteristics of these materials under dynamic (impact) loads in the strain rate range of concern are not well documented. However, two previous papers [1, 2] reported on impact tensile testing and analysis results performed at the Idaho National Laboratory using 304L and 316L stainless steel specimens that began the investigation of these characteristics. The goal of the work presented herein is to: (1) add the results of additional tensile impact testing for 304L stainless steel specimens, and (2) show that the application of the strain rate-dependent material curves (determined through that tensile impact testing) to specimens designed to respond in bending during impact loading would yield accurate deformation and strain predictions.

Strain-rate dependent material properties of selective laser melted AlSi10Mg and AlSi3.5Mg2.5

2020 ◽  
Vol 62 (6) ◽  
pp. 573-583
Author(s):  
Andreas Lutz ◽  
Lukas Huber ◽  
Claus Emmelmann
Keyword(s):  
Strain Rate ◽  
Material Properties ◽  
Rate Dependent
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