Compressive Stress-Strain Relations and Shock Hugoniot Curves of Flexible Foams

1995 ◽  
Vol 117 (3) ◽  
pp. 278-284 ◽  
Author(s):  
E. Zaretsky ◽  
G. Ben-Dor
Keyword(s):  
Porous Materials ◽  
Relative Density ◽  
Compressive Stress ◽  
Functional Dependence ◽  
General Function ◽  
Stress Strain ◽  
Stress Strain Relation ◽  
Wide Range ◽  
Shock Hugoniot ◽  
Hugoniot Curves

Based on the general shape of the curves describing experimental compressive stress-strain relations of flexible porous materials (e.g., flexible foams) which are known to depend on their relative density, a general mathematical functional dependence of the stress on the strain is proposed. The general function includes two constants. Using experimental and empirical information the values of these constants are determined, so that a final compressive stress-strain relation, in which the relative density is a parameter, is obtained. Good agreement is found when the presently developed empirical stress-strain relations are compared to experimental ones for a wide range of relative densities. The proposed compressive stress-strain relations are then used to derive shock Hugoniot relations for flexible porous materials. With the aid of these relations one can investigate the dynamic behavior of foams struck head-on by shock waves. The finally obtained empirical shock Hugoniot relations are found to be similar to experimental relations which are proposed in the literature. In addition, a mathematical investigation of the asymptotic behavior of the shock Hugoniot relations is conducted. The results of this investigation are found to agree excellently with actual experimental data.

A Three-Stage Explicit Stress-Strain Relations for Stainless Steel Alloys Applicable in Tension and Compression at Elevated Temperatures

2012 ◽  
Vol 730-732 ◽  
pp. 691-696
Author(s):  
Abdella Kenzu
Keyword(s):  
Stainless Steel ◽  
Elevated Temperatures ◽  
Full Range ◽  
Elastic Behaviour ◽  
Stress Strain ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Wide Range ◽  
Tension And Compression ◽  
Linear Elastic Behaviour

Presented in this paper is an explicit full-range stress-strain relation for stainlesssteel alloys applicable at normal and elevated temperatures. The relation utilizes an approxima-tion of the closed form inversion of a highly accurate three-stage stress-strain relation recentlyobtained from the Ramberg-Osgood equation. The three stage inversion is formulated using anappropriate rational function assumption to approximate the fractional deviation of the actualstress-strain relation from an idealized linear elastic behaviour. The temperature dependenceon the stress-strain relation is then introduced by modifying the basic mechanical propertiesof stainless steel to account for the temperature e ects. The proposed approximate inversionis applicable over the full-range of the stress well beyond the elastic region up to the ultimatestress. Moreover, the inversion can be applied to both tensile and compressive stresses. Theproposed approximate inversion is tested over a wide range of material parameters as well as awide range of temperatures. It is shown that the new expression results in stress-strain curveswhich are both qualitatively and quantitatively in excellent agreement with experimental re-sults and the fully iterated numerical solution of the full-range stress-strain relation for normalas well as elevated temperatures

High Strain-Rate Compressive Behavior and Constitutive Modeling of Selected Polymers Using Modified Ramberg-Osgood Equation

2014 ◽  
Vol 566 ◽  
pp. 80-85
Author(s):  
Kenji Nakai ◽  
Takashi Yokoyama
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Compressive Stress ◽  
Constitutive Modeling ◽  
High Strain ◽  
Strain Rates ◽  
Stress Strain ◽  
Strain Behavior ◽  
Least Squares Fit ◽  
Wide Range

The present paper is concerned with constitutive modeling of the compressive stress-strain behavior of selected polymers at strain rates from 10-3 to 103/s using a modified Ramberg-Osgood equation. High strain-rate compressive stress-strain curves up to strains of nearly 0.08 for four different commercially available extruded polymers were determined on the standard split Hopkinson pressure bar (SHPB). The low and intermediate strain-rate compressive stress-strain relations were measured in an Instron testing machine. Six parameters in the modified Ramberg-Osgood equation were determined by fitting to the experimental stress-strain data using a least-squares fit. It was shown that the monotonic compressive stress-strain behavior over a wide range of strain rates can successfully be described by the modified Ramberg-Osgood constitutive model. The limitations of the model were discussed.

High Strain-Rate Compressive Stress-Strain Loops for Structural Adhesive

2011 ◽  
Vol 83 ◽  
pp. 130-135 ◽  
Author(s):  
Takashi Yokoyama ◽  
Kenji Nakai ◽  
Norfazrina Hayati Mohd Yatim
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Compressive Stress ◽  
High Strain ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Dissipation Energy ◽  
Wide Range ◽  
Structural Adhesive

The high strain-rate compressive stress-strain loops for bulk specimens of an epoxy structural adhesive are determined on the standard split Hopkinson pressure bar. The compressive stress-strain data including unloading curves are obtained over a wide range of strain rates from 10-3to 103/s. The effects of strain rate on the initial (secant) modulus, flow stress, dissipation energy and hysteresis loss ratio are discussed. The experimental results show that the bulk structural adhesive exhibits dynamic viscoelastic behavior like polymers.

scholarly journals Novel Ring Compression Test Method to Determine the Stress-strain Relations and Mechanical Preperties of Metallic Materials

2021 ◽  
Author(s):  
Guang-Zhao Han ◽  
lixun Cai ◽  
Chen Bao ◽  
Bo Liang ◽  
Yang Lv ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Test Method ◽  
Metallic Materials ◽  
Compression Tests ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Ring Compression ◽  
Wide Range

Abstract Although there are methods for testing the stress–strain relation and strength, which are the most fundamental and important properties of metallic materials, their application to small size specimens is limited. In this study, a new dimensionless elastoplastic load–displacement (EPLD-Ring) model for compressed metal rings with isotropy and constitutive power law is proposed to describe the relation between the geometric dimensions, Hollomon law parameters, load, and displacement based on energy density equivalence. Furthermore, a novel test method for the rings is developed to obtain the elastic modulus, stress–strain relation, yield strength, and tensile strength. The universality and accuracy of the model are verified within a wide range of imaginary materials via finite element analysis (FEA), and the results show that the stress–strain relations obtained with the model are more consistent with those inputted in the FEA software. Additionally, for seven metallic materials, a series of ring compression tests with various dimensions were performed. It was found that the stress–strain relations and mechanical properties predicted by the model are in agreement with the normal tensile test results. It is believed that the new method is reliable and effective for testing the mechanical properties of small size materials and tube components.

Dynamic Plastic Response of the Mg-Gd-Y Alloy over a Wide Range of Temperatures

2010 ◽  
Vol 146-147 ◽  
pp. 623-630
Author(s):  
Qing Yu Hou ◽  
Jing Tao Wang
Keyword(s):  
Constitutive Model ◽  
Reference Temperature ◽  
Stress Strain ◽  
Impact Compression ◽  
New Model ◽  
Stress Strain Relation ◽  
Wide Range ◽  
Compression Data ◽  
Pressure Bar ◽  
The Impact

In this paper, a new phenomenological and empirically based constitutive model was proposed to change the temperature term in the original Johnson-Cook constitutive model. The new model can be used to describe or predict the stress-strain relation of the metals deformed over a wide range of temperatures even though the current temperatures are lower than the reference temperature. Based on the impact compression data obtained by split Hopkins pressure bar (SHPB) apparatus about one hot-extrudedMg-10Gd-2Y-0.5Zr alloy, the material constants in the new model can be experimentally determined using isothermal and adiabatic stress-strain curves at different strain rates and temperatures. Good agreement is obtained between the predicted and the experimental flowcurves for the hot-extrudedMg-10Gd-2Y-0.5Zr alloy at both quasi-static and dynamic loadings under a wide range of temperatures ever though the current temperatures are lower than the reference temperature.

Isochronous Stress-Strain Relationship in Compressive Stress Relaxation of Vulcanizates

1977 ◽  
Vol 50 (5) ◽  
pp. 915-921 ◽  
Author(s):  
B. Stenberg ◽  
J. F. Jansson
Keyword(s):  
Stress Relaxation ◽  
Mechanical Behavior ◽  
Compressive Stress ◽  
Heterogeneous Systems ◽  
Stress Strain ◽  
Vital Importance ◽  
Suspension Systems ◽  
Stress Strain Relation ◽  
Relaxation Measurements ◽  
Strain Relationship

Abstract The mechanical and other properties of natural and synthetic rubbers can be regulated by the incorporation of fillers. The mechanical behavior of the resulting complicated heterogeneous systems is often difficult to describe theoretically. These vulcanizates have wide and useful applications under conditions of multiaxial stresses. In many cases, however, the stresses act mainly in compression, for instance, in gaskets, seals, suspension systems for vibration insulation, etc. Thus the stress relaxation properties in compression are of vital importance. In spite of this, very few studies have given attention to the stress-strain relations in compression, and the results reported in the literature concentrate mainly on the mechanical behavior of rubbers in tension. We now report a study of the isochronous stress-strain relation in compression for some rubbers at 295 K, based on stress relaxation measurements. A comparison is made between the behavior of samples which have been greased and of samples which have been glued to the deformation plates.

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