Further Investigation of the Hydrostatic Bulge Test in a Plasticity Laboratory

2009 ◽  
Vol 37 (2) ◽  
pp. 159-174
Author(s):  
O. Ifedi ◽  
Q. M. Li ◽  
Y. B. Lu
Keyword(s):  
Tensile Test ◽  
Effective Stress ◽  
Strain Curve ◽  
Plasticity Theory ◽  
Loading Path ◽  
Uniaxial Tensile ◽  
Bulge Test ◽  
Uniaxial Tensile Test ◽  
Stress Strain Curve ◽  
Stress Strain

In plasticity theory, the effective stress–strain curve of a metal is independent of the loading path. The simplest loading path to obtain the effective stress–strain curve is a uniaxial tensile test. In order to demonstrate in a plasticity laboratory that the stress–strain curve is independent of the loading path, the hydrostatic bulge test has been used to provide a balanced biaxial tensile stress state. In our plasticity laboratory we compared several different theories for the hydrostatic bulge test for the determination of the effective stress–strain curve for two representative metals, brass and aluminium alloy. Finite element analysis (FEA) was performed based on the uniaxial tension test data. It was shown that the effective stress–strain curve obtained from the biaxial tensile test (hydrostatic bulge test) had a good correlation with that obtained in the uniaxial tensile test and agreed well with the analytical and FEA results. This paper may be used to support an experimental and numerical laboratory in teaching the concepts of effective stress and strain in plasticity theory.

scholarly journals Mechanical Properties of Compact Bone Defined by the Stress-Strain Curve Measured Using Uniaxial Tensile Test: A Concise Review and Practical Guide

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4224
Author(s):  
Che-Yu Lin ◽  
Jiunn-Horng Kang
Keyword(s):  
Mechanical Properties ◽  
Tissue Engineering ◽  
Tensile Test ◽  
Bone Tissue Engineering ◽  
Strain Curve ◽  
Compact Bone ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Stress Strain Curve ◽  
Stress Strain

Mechanical properties are crucial parameters for scaffold design for bone tissue engineering; therefore, it is important to understand the definitions of the mechanical properties of bones and relevant analysis methods, such that tissue engineers can use this information to properly design the mechanical properties of scaffolds for bone tissue engineering. The main purpose of this article is to provide a review and practical guide to understand and analyze the mechanical properties of compact bone that can be defined and extracted from the stress–strain curve measured using uniaxial tensile test until failure. The typical stress–strain curve of compact bone measured using uniaxial tensile test until failure is a bilinear, monotonically increasing curve. The associated mechanical properties can be obtained by analyzing this bilinear stress–strain curve. In this article, a computer programming code for analyzing the bilinear stress–strain curve of compact bone for quantifying the associated mechanical properties is provided, such that the readers can use this computer code to perform the analysis directly. In addition to being applied to compact bone, the information provided by this article can also be applied to quantify the mechanical properties of any material having a bilinear stress–strain curve, such as a whole bone, some metals and biomaterials. The information provided by this article can be applied by tissue engineers, such that they can have a reference to properly design the mechanical properties of scaffolds for bone tissue engineering. The information can also be applied by researchers in biomechanics and orthopedics to compare the mechanical properties of bones in different physiological or pathological conditions.

Determination of Flow Curve Using Bulge Test and Calibration of Damage for Ito-Goya Models

2013 ◽  
Vol 554-557 ◽  
pp. 182-189 ◽  
Author(s):  
Bruno Martins ◽  
Abel D. Santos ◽  
Pedro Teixeira ◽  
K. Ito ◽  
N. Mori
Keyword(s):  
Tensile Test ◽  
Damage Model ◽  
Strain Curve ◽  
Uniaxial Tensile ◽  
Bulge Test ◽  
Uniaxial Tensile Test ◽  
Damage Prediction ◽  
Damage Models ◽  
Material Information

The standard uniaxial tensile test is the widely accepted method to obtain relevant properties of mechanical characterization of sheet metal materials. However the range of strain obtained from tensile test is limited. The bulge test is an alternative to obtain ranges of deformation, higher than tensile test, thus permitting a better characterization for material behaviour. This paper presents a sensitivity analysis for some influencing variables used in bulge measurements, thus giving some guidelines for the evaluation of the stress-strain curve from experimental results using a developed experimental mechanical system. Additionally, using bulge test up to fracture shall give material information regarding damage, which in turn may be used to evaluate and calibrate damage models. A methodology is presented to be used for evaluation and calibration of Ito-Goya damage model of damage prediction.

Fracture Energy of Reactive Powder Concrete Based on Uniaxial Tensile Test

2011 ◽  
Vol 306-307 ◽  
pp. 519-522
Author(s):  
Hai Yan Yuan ◽  
Ming Zhe An ◽  
Fang Fang Jia ◽  
Zhi Gang Yan
Keyword(s):  
Tensile Test ◽  
Fracture Energy ◽  
Testing Machine ◽  
Strain Curve ◽  
Reactive Powder Concrete ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Stress Strain Curve ◽  
Concentration Problem ◽  
Reactive Powder

Based on uniaxial tensile test, the complete uniaxal tensile stress-strain curve of Reactive Powder Concrete (the steel fiber content by volume is Vf =1%, 2%) was obtained, and the fracture energy of RPC specimens with cross-section of 100mm by 100mm was calculated. The test was finished through Universal Testing Machine without any stiffness-strengthen devices. In order to solve the stress concentration problem, a self-designed uniaxial tensile test equipment was developed, and a dumbbell-shaped specimen was used in the test. The results indicate that the fracture energy of RPC increased as well as the increasing of Vf.

Study of True Stress-Strain Curve after Necking for Application in Ductile Fracture Criteria in Tube Hydroforming of Aerospace Material

2012 ◽  
Vol 504-506 ◽  
pp. 95-100 ◽  
Author(s):  
Mehdi Saboori ◽  
Henri Champliaud ◽  
Javad Ghoulipor ◽  
Augustin Gakwaya ◽  
Jean Savoie ◽  
...  
Keyword(s):  
Tube Hydroforming ◽  
Strain Curve ◽  
True Stress ◽  
Material Behavior ◽  
Loading Path ◽  
Burst Pressure ◽  
Uniaxial Tensile ◽  
Aerospace Materials ◽  
Stress Strain Curve ◽  
Stress Strain

Tube hydroforming (THF) is an advanced metal forming process that is used widely in automotive industry, but the application of the THF process in aerospace field is comparatively new with many challenges due to high strength and limited formability of aerospace materials. The success of THF process largely depends on many factors, such as mechanical properties of the material, loading path during the process, tool geometry and friction condition. Due to complexity of this process, finite element modeling (FEM) can largely reduce the production cost. One of the important input in FEM is the material behavior during hydroforming process. The true stress-strain curve before necking can be easily determined, using either tensile testing or bulge testing, but for an accurate failure prediction in a large deformation, such as hydroforming, the study of true stress-strain curve after necking is important because it improves the quality of the analysis due to utilizing a real extended stress-strain curve. Hence, the objective of this research was to establish a methodology to determine the true stress-strain curve after necking in order to predict burst pressure in the THF of aerospace materials. Uniaxial tensile tests were performed on standard tensile samples (ASME E8M-04) to determine the true stress-strain before and after necking, using an analytical method presented in this study. To validate the approach, burst pressure in the THF process was predicted using the extended stress-strain curve in conjunction with Brozzo's decoupled fracture model. The approach was evaluated using data obtained from the free expansion (tube bulging) tests performed on stainless steel 321 tubes with 2 inches diameter and two different thicknesses, 0.9 mm and 1.2 mm. The comparison of the predicted and measured burst pressures was promising, indicating that the approach has the potential to be extended to predict formability limits in THF of complex shapes.

scholarly journals The influence of rate of deformation on the tensile test with special reference to the yield point in iron and steel.

1938 ◽  
Vol 165 (923) ◽  
pp. 568-592 ◽  
Author(s):  
C. F. Elam ◽  
Henry Cort Harold Carpenter
Keyword(s):  
Tensile Test ◽  
Special Reference ◽  
Yield Point ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Iron And Steel ◽  
Plastic Distortion

The following experiments were carried out with two principal objects in view: (1) to investigate the deformation of those metals, particularly iron and steel, in which the stress-strain curve does not immediately rise at the onset of plastic distortion; (2) to determine the effect of rate of deformation on the yield and subsequent stress-strain curve. It is impossible to give an adequate summary of the literature which deals with this subject, but a bibliography is included in an appendix and some of the most important results are referred to briefly below.

Strain Localisation during a Tensile Test of Metallic Plates: Experimental and Numerical Results

2009 ◽  
Vol 417-418 ◽  
pp. 569-572
Author(s):  
D.A. Cendón ◽  
Jose M. Atienza ◽  
Manuel Elices Calafat
Keyword(s):  
Tensile Test ◽  
Strain Curve ◽  
Maximum Load ◽  
Surface Strain ◽  
Displacement Curve ◽  
Strain Localisation ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Fields ◽  
Developed Surface

The stress-strain curve of a material is usually obtained from the load-displacement curve measured in a tensile test, assuming no strain localisation up to maximum load. However, strain localisation and fracture phenomena are far from being completely understood. Failure and strain localisation on plane tensile specimens has been studied in this work. A deeply instrumented experimental benchmark on steel specimens has been developed. Surface strain fields have been recorded throughout the tests, using an optical extensometer. This allowed characterisation of the strain localisation and failure processes. Tests have been numerically modelled for a more detailed analysis. Preliminary results show a substantial influence of geometrical specimen defects on the strain localisation phenomena that may be critical on the stress-strain curves obtained and in the failure mechanisms.

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