Numerical Analysis on Usability of SHPB to Characterize Dynamic Stress–Strain Relation of Metal Foam

2017 ◽  
Vol 09 (05) ◽  
pp. 1750075 ◽  
Author(s):  
Beixin Xie ◽  
Liqun Tang ◽  
Yiping Liu ◽  
Zhenyu Jiang ◽  
Zejia Liu
Keyword(s):  
Strain Rate ◽  
Dynamic Stress ◽  
Metal Foam ◽  
Test Method ◽  
Specimen Thickness ◽  
Strain Rates ◽  
Stress Strain ◽  
Deformation Localization ◽  
Strain Relation ◽  
Stress Strain Relation

Split Hopkinson pressure bar (SHPB) technique is the most important test method to characterize dynamic stress–strain relations of various materials at different strain rates, and this technique requires uniform deformation of specimen during the experiment. However, some studies in recent years have found obvious deformation localization within metal foam specimens in SHPB tests, which may significantly affect the reliability of the results. Usability of SHPB to characterize dynamic stress–strain relation of metal foam becomes doubtful. In this paper, based on experimental verification, we carried out numerical simulative SHPB tests to study the problem, in which the metal foam specimens were modeled to have 3D meso structures with properties of their matrix material. Numerical simulative SHPB tests of aluminum foam specimens with varying thickness at different strain rates were performed. Deformation distribution in each local region of the specimen was examined and a concept of “effective specimen” was presented. Appropriate specimen thickness and range of testing strain rate were suggested based on quantitative analysis. Finally, we recommended a method how to revise the nominal strain and strain rate measured by traditional SHPB method to acquire the reliable dynamic stress–strain relation.

Tensile Mechanical Properties of AM50A Alloy by Hopkinson Bar

2007 ◽  
Vol 340-341 ◽  
pp. 247-254 ◽  
Author(s):  
Dong Wei Shu ◽  
Wei Zhou ◽  
Guo Wei Ma
Keyword(s):  
Mechanical Properties ◽  
Magnesium Alloy ◽  
Tensile Stress ◽  
Strain Rate ◽  
Automotive Industry ◽  
Dynamic Stress ◽  
Hopkinson Bar ◽  
Strain Rates ◽  
Stress Strain ◽  
Stress Strain Relation

An ultralight magnesium alloy AM50A has been investigated for its potential to be used in aerospace and automotive industry. The dynamic stress strain relation of aluminum 6061 T6 and the magnesium alloy AM50A have been obtained by using the Hopkinson bar apparatus. The strain rates range between 600 s-1 and 1300 s-1. The Al 6061 T6 results tally well with those in literature. The magnesium alloy AM50A displays about 50% higher tensile stress at the strain rate of about 1300 s-1 than at static.

One-Dimensional Dynamic Compressive Behavior of EPDM Rubber

2003 ◽  
Vol 125 (3) ◽  
pp. 294-301 ◽  
Author(s):  
B. Song ◽  
W. Chen
Keyword(s):  
Strain Rate ◽  
High Speed ◽  
Dynamic Stress ◽  
Split Hopkinson Pressure Bar ◽  
Constant Strain Rate ◽  
Strain Rates ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Epdm Rubber ◽  
One Dimensional

Dynamic compressive stress-strain curves at various strain rates of an Ethylene-Propylene-Diene Monomer Copolymer (EPDM) rubber have been determined with a modified split Hopkinson pressure bar (SHPB). The use of a pulse-shaping technique ensures that the specimen deforms at a nearly constant strain rate under dynamically equilibrated stress. The validity of the experiments was monitored by a high-speed digital camera for specimen edge deformation, and by piezoelectric force transducers for dynamic stress equilibrium. The resulting dynamic stress-strain curves for the EPDM indicate that the material is sensitive to strain rates and that the strain-rate sensitivity depends on the value of strain. Based on a strain energy function theory, a one-dimensional dynamic constitutive equation for this rubber was modified to describe the high strain-rate experimental results within the ranges of strain and strain rates presented in this paper.

Dynamic behavior and constitutive modeling of magnesium alloys AZ91D and AZ31B under high strain rate compressive loading

2014 ◽  
Vol 28 (08) ◽  
pp. 1450063 ◽  
Author(s):  
Jing Xiao ◽  
Iram Raza Ahmad ◽  
D. W. Shu
Keyword(s):  
Strain Rate ◽  
Magnesium Alloys ◽  
Dynamic Stress ◽  
Elevated Temperatures ◽  
High Strain ◽  
Compressive Loading ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Cook Model

The dynamic stress–strain characteristics of magnesium alloys have not been sufficiently studied experimentally. Thus, the present work investigated compressive dynamic stress–strain characteristics of two representative magnesium alloys: AZ91D and AZ31B at high strain rates and elevated temperatures. In order to use the stress–strain characteristics in numerical simulations to predict the impact response of components, the stress–strain characteristics must be modeled. The most common approach is to use accepted constitutive laws. The results from the experimental study of the response of magnesium alloys AZ91D and AZ31B under dynamic compressive loading, at different strain rates and elevated temperatures are presented here. Johnson–Cook model was used to best fit the experimental data. The material parameters required by the model were obtained and the resultant stress–strain curves of the two alloys for each testing condition were plotted. It is found that the dynamic stress–strain relationship of both magnesium alloys are strain rate and temperature dependent and can be described reasonably well at high strain rates and room temperature by Johnson–Cook model except at very low strains. This might be due to the fact that the strain rate is not strictly constant in the early stage of deformation.

Analytical Formulation of a Rate and Temperature Dependent Stress-Strain Relation

1979 ◽  
Vol 101 (3) ◽  
pp. 254-257 ◽  
Author(s):  
A. Merzer ◽  
S. R. Bodner
Keyword(s):  
Plastic Strain ◽  
Strain Rate ◽  
Uniaxial Stress ◽  
Plastic Strain Rate ◽  
Isotropic Hardening ◽  
Stress Strain ◽  
Rate Dependent ◽  
Strain Relation ◽  
Strain And Strain Rate ◽  
Stress Strain Relation

The equation for plastic strain rate in the Bodner-Partom viscoplastic formulation is integrated under conditions of uniaxial stress, constant plastic strain rate, and isotropic hardening to give an analytical expression for the stress as a function of plastic strain and strain rate. Temperature dependence is introduced which leads to a general relationship between stress, strain, strain rate, and temperature. The resulting equation indicates an asymptotic saturation stress whose dependence on strain rate and temperature appears to agree with experimental results. Strain hardening given by the analytical equation also seems to be consistent with experiments. A possible new definition of yield stress is a consequence of the rate dependent stress-strain relation.

Finite Element Analysis of Adhesive-Bonded Single-Lap Joints

2002 ◽  
Author(s):  
Charles Yang ◽  
Zhidong Guan ◽  
John S. Tomblin ◽  
Wenjun Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Lap Joints ◽  
Test Method ◽  
Stress Strain ◽  
Element Analysis ◽  
Lap Shear ◽  
Strain Relation ◽  
Stress Strain Relation ◽  
Tension Loading

Finite element analyses were conducted using commercial software ABAQUS to analyze the mechanical behavior of single-lap adhesive-bonded joints. Adhesive was characterized for the stress-strain relation by comparing the apparent shear-strain relations obtained from finite element analysis and experiments following ASTM D 5656 “Standard Test Method for Thick-Adherend Metal Lap-Shear Joints for Determination of the Stress-Strain Behavior of Adhesives in Shear by Tension Loading.” With the established stress-strain relation, two failure criteria using equivalent plastic strain and J-integral were used to predict the failure load for joint specimens following ASTM D 5656 and ASTM D 3165 (Strength Properties of Adhesives in Shear by Tension Loading of Single-Lap-Joint Laminated Assemblies), respectively. Bondline thicknesses of 0.013”, 0.04”, 0.08”, and 0.12” were used in the investigation. Good correlation was found between the finite element results and the experimental results.

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