ME 212 EXPERIMENT SHEET #2 TENSILE TESTING OF MATERIALS (original) (raw)
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7.1 STRESS-STRAIN BEHAVIOUR OF MATERIAL
All engineering materials do not show same sort of behaviour when subjected to tension as well as compression. There exist some materials like metals, alloys etc., which are more or less equally strong in both tension and compression. And these materials are generally tested in tension again concrete, stones, bricks etc., are such type of materials which are weaker in tension and stronger in compression. Hence, these materials are tested in compression. Now the stress-strain characteristics of mild steel are of specific importance to the community dealing with basic engineering science.
Correlation between Engineering Stress-Strain and True Stress-Strain Curve
American Journal of Civil Engineering and Architecture, 2014
The most commonly accepted method in evaluation of the mechanical properties of metals would be the tension test. Its main objective would be to determine the properties relevant to the elastic design of machines and structures. Investigation of the engineering and true Stress-strain relationships of three specimens in conformance with ASTM E 8 -04 is the aim of this paper. For the purpose of achieving this aim, evaluation of values such as ultimate tensile strength, yield strength, percentage of elongation and area reduction, fracture strain and Young's Modulus was done once the specimens were subjected to uniaxial tensile loading. The results indicate that the properties of steel materials are independent from their thickness and they generally yield and fail at the same stress and strain values. Also, it is concluded that the maximum true stress values are almost 15% higher than that of the maximum engineering stress values while the maximum true strain failure values are 1.5% smaller than the maximum engineering strain failure values.
Determine Steel Properties for Large Strain from a Standard Tension Test
An accurate modelling of the material true stress-true strain relationship up to the instant of fracture is required in carrying out finite element analyses of structural connections and in regions of geometric discontinuity. In a standard tension material test of steel, the measurement of the axial deformation of the gauge length versus the load only allows the material true stress-true strain relationship to be calculated up to the peak load. This paper will present the experimental and finite element study of the A516 pressure vessel steel and X70 pipeline steel tension coupon tests, and recommend a simple procedure to obtain an approximate true stress-true strain relationship using the combination pre-peak load axial deformation-load relationship and the post-peak load transverse deformation-load relationship from a standard tension material test. Both cylindrical and rectangular coupons were investigated in this study. Axial deformation-load measurement after reaching the peak load varies significantly between specimens of the same material and dimension, but not the transverse deformation-load relationship.
Tensile Test: Comparison Experimental, Analytical and Numerical Methods
—The objective of this work is to study and analyze the stress-strain curves obtainedthrough the experimental tensile test and the comparison of thedata obtainedwith the analytical and numerical methods. For the development of the analytical method, we proposed equations for the stress-strain curve of the material, using MS-EXCEL 2016. For the numerical method, a modeling of the test specimen was elaborated using the ANSYS Workbench® version 16 software. The steel selected for the studies was ABNT 1020.
All engineering materials do not show same sort of behaviour when subjected to tension as well as compression. There exist some materials like metals, alloys etc., which are more or less equally strong in both tension and compression. And these materials are generally tested in tension again concrete, stones, bricks etc., are such type of materials which are weaker in tension and stronger in compression. Hence, these materials are tested in compression. Now the stress-strain characteristics of mild steel are of specific importance to the community dealing with basic engineering science.
Bogazici University Materials Science Course - Tensile Test Lab Report
The application of tensile load in increments until the failure of the material was the main purpose of this test. Change in the material's length was recorded after every increment. The data until the failure was recorded and used to find the material's yielding strength, ductility, tensile strength, toughness, true tensile strength, fracture strength, true fracture strength, modulus of elasticity and estimate its toughness. Then, an engineering stress-strain graph was plotted. Finally the conversion formulas were used to come up with the true stress-strain curve. The material's mechanic features were also compared with the theoretical results. The physical properties were in the expected interval.
Behaviour of Stress Strain Relationship of Few Metals
Journal of Intelligent Mechanics and Automation
The aim of this study is to examine the uniaxial tensile strength of three specimens of mild steel, brass and aluminium is examined. Tension tests enable the determination and prediction of the deformation/deflection response of the material properties and elastic modulus. The values of Young’s Modulus for Elasticity (E) for mild steel, brass, and aluminium have been successfully determined from laboratory experiments. Also, the stress and strain of the materials were graphically shown to have good correlations between theory and experimental values and compositions. The results further show that steel is more suitable for structural application than brass and aluminium respectively, because of their high E Modulus rating. It therefore implies that steel can withstand more tension. The result obtained from the study such as tensile strength, yield strength etc. have been recorded. Also, the related theory has been indicated.
Analysis of Hot Tension Test Data to Obtain Stress-Strain Curves to High Strains
J of Testing and Evaluation , v13, 1985
High strain rate hot tension tests have been carried out on AISI 1020 (Unified Numbering System [UNS] G10200) steel using a Gleeble ® testing machine, Tests have been terminated at a series of strains and the specimen geometries measured. From these measurements, local areas, strains, and strain rates are derived and are used to obtain the local true stress-true strain curves. These are corrected for the change in strain rate with strain using an equation of state. The corrected curves are in good agreement with published curves on similar steels determined by compression or torsion testing. Under the present testing conditions, the maximum strain to which correction can be applied is-1.5. This is imposed by the onset of rapid local deformation heating. Up to this strain, no stress correction of the Bridgmann type for necking appears to be necessary. A knowledge of the stress-strain behavior of materials at high temperatures and strain rates typical of hot working operations is essential for the calculation of working forces and power requirements. Such data may be obtained from laboratory tests carried out in tension , compression, or torsion [1-3], but tension tests are frequently considered to be unsatisfactory because the onset of necking occurs at relatively low strains compared with those of interest in working operations. Once necking starts, local strains and strain rates in the neck become progressively higher than the average values for the gage section. If testing is carded out using a Gleeble ® machine, the direct resistance heating leads to a temperature gradient along the specimen, which encourages the early onset of necking. Recent work [4-6] has shown that if strain rate or temperature or both do not change too rapidly with strain, the stress-strain behavior of steels is closely described by an equation of state. Thus, if local strain and strain rate can be determined for material in the neck during a tension test, it should be valid to correct the measured stresses for the variation in strain rate caused by progressive necking by using an equation of state and hence to derive the stress-strain curve expected for a constant strain rate. The purpose of this paper is to describe a procedure by which this analysis can be carded out from the results of tension tests performed tHead of thermomechanical process group, IPT, Cidade Universitaria, Sao Paulo, Brazil 05508. 2Professor, Department of Metallurgy, University of Sheffield, Sheffield S1 3JD, England. on a Gleeble machine, to obtain results that compare favorably with those produced by other test methods up to true strains of ~ 1.5. Experimental Procedure Experiments have been carried out on AISI 1020 (Unified Numbering System [UNS] G10200) steel of composition 0.2% carbon, 0.5% manganese, 0.15% silicon, 0.008% phosphorus, and 0.009% sulfur, received in the form of hot rolled rod. Specimens of 12.7-mm (V2-in.) diameter by 152.4 mm (6 in.) long with threaded ends were machined from this material, for hot tension testing in a Gleeble machine , Model 510. Initially, calibration of the temperature readings from the ultraviolet (UV) recorder (Visicorder ®) on the Gleeble machine was made by applying a series of millivolt signals across the thermocouple input terminals and recording these simultaneously on a direct reading oscillograph (Rapicorder®). Temperature gradients along the specimen length were then determined using a specimen onto which ther-mocouples had been welded at the center of the length and at points 5 and 10 mm on each side of the center. These thermocouples were welded along a line on the surface 90 ° away from the point at which the control thermocouple was welded to the specimen centerline. The specimen was positioned between the two copper grips set-60 mm apart, and measurements were made for four different set temperatures without deforming the specimen. The change in specimen centerline temperature during deformation was also examined for both "current on" and "current off" conditions during a test. In the latter case the current was turned off 0.2 s before the start of tension testing. Results showed that "current on" conditions gave the more nearly constant temperature, and this condition was used for all subsequent tests. Tension tests were performed at temperatures of about 1050, 1100, and 1200°C after heating specimens direct to the test temperature and holding for 15 s. All tests were carried out using a crosshead speed of 6.3 mm/s and a series of specimens was tested at each temperature. In each series, one test was taken to fracture and the others were terminated at different lower strains by use of a "stopping block" placed between the moving crosshead and the piston head to restrict the displacement to a predetermined value. Load-time and displacement-time curves were recorded for each test. The profiles of all the tested specimens were determined using an optical comparitor (Jones and Lamson, Model Epic 214) at ×10 magnification to measure the diameter at the neck and at a series of different positions along the specimen length. From these measurements the local areas were determined, and these were used to derive local stress-strain curves, as described in the next section.