Elastic-Plastic Stress Distribution in a Compressed Ring

1968 ◽  
Vol 90 (4) ◽  
pp. 435-440
Author(s):  
K. T. Chang ◽  
P. M. Leopold
Keyword(s):  
Stress Distribution ◽  
Strain Curve ◽  
Experimental Results ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Strain Gages ◽  
Stress Strain ◽  
Theoretical Predictions ◽  
Strain Relationship ◽  
Plastic Stress

This investigation was conducted to define the plastic stress distribution at a section 90 degrees from the point of load application on a ring. The elastic and plastic stress distribution was determined experimentally by using postyield strain gages and the stress-strain relationship obtained from a uniaxial tensile test. The experimental results in the elastic range were found to agree with presently available theoretical predictions. A theoretical plasticity analysis of the ring was made by assuming that it deforms to the shape of an ellipse and that plane sections remain plane. The strains determined in this manner were used to calculate stresses off the tensile stress-strain curve. The experimental results indicated that this initial analysis gave a good approximation of the stress distribution for large deflections of the ring.

Fracture Assessment of Pipes Having Multiple Flaws Based on Ramberg–Osgood-Type Stress–Strain Relationships

2011 ◽  
Author(s):  
Hideo Machida ◽  
Tetsuya Hamanaka ◽  
Yoshiaki Takahashi ◽  
Katsumasa Miyazaki ◽  
Fuminori Iwamatsu ◽  
...  
Keyword(s):  
Flow Stress ◽  
Stress Concentration ◽  
Fracture Strength ◽  
Strain Curve ◽  
Assessment Method ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Relationship ◽  
Fracture Assessment

This paper describes a fracture assessment method for a pipe having multiple circumferential flaws. According to Fitness-for-Service (FFS) codes for nuclear facilities published by the Japanese Society of Mechanical Engineers (JSME), the fracture strength of a high-ductility pipe having a circumferential flaw is evaluated using the limit load assessment method assuming the elastic–perfectly-plastic stress–strain relationship. In this assessment, flow stress is used as a proportional stress. However, previous experimental results [1, 2, 3] show that a crack penetrates before the entire flawed pipe section reaches the flow stress. Therefore, stress concentration at a flaw was evaluated on the basis of the Dugdale model [4], and the fracture strength of the crack-ligament was evaluated. This model can predict test results with high accuracy when the ligament fracture strength is assumed to be tensile strength. Based on this examination, a fracture assessment method for pipes having multiple flaws was developed considering the stress concentration in the crack-ligament by using the realistic stress–strain relationship (Ramberg–Osgood-type stress–strain curve). The fracture strength of a multiple-flawed pipe estimated by the developed method was compared with previous experimental results. When the stress concentration in the crack-ligament was taken into consideration, the fracture strength estimated using the Ramberg–Osgood-type stress–strain curve was in good agreement with experimental results, confirming the validity of the proposed method.

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.

scholarly journals Ability of Constitutive Models to Characterize the Temperature Dependence of Rubber Hyperelasticity and to Predict the Stress-Strain Behavior of Filled Rubber under Different Defor Mation States

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 369
Author(s):  
Xintao Fu ◽  
Zepeng Wang ◽  
Lianxiang Ma
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Mechanical Response ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Chain Model ◽  
Stress Strain ◽  
Filled Rubber ◽  
Yeoh Model

In this paper, some representative hyperelastic constitutive models of rubber materials were reviewed from the perspectives of molecular chain network statistical mechanics and continuum mechanics. Based on the advantages of existing models, an improved constitutive model was developed, and the stress–strain relationship was derived. Uniaxial tensile tests were performed on two types of filled tire compounds at different temperatures. The physical phenomena related to rubber deformation were analyzed, and the temperature dependence of the mechanical behavior of filled rubber in a larger deformation range (150% strain) was revealed from multiple angles. Based on the experimental data, the ability of several models to describe the stress–strain mechanical response of carbon black filled compound was studied, and the application limitations of some constitutive models were revealed. Combined with the experimental data, the ability of Yeoh model, Ogden model (n = 3), and improved eight-chain model to characterize the temperature dependence was studied, and the laws of temperature dependence of their parameters were revealed. By fitting the uniaxial tensile test data and comparing it with the Yeoh model, the improved eight-chain model was proved to have a better ability to predict the hyperelastic behavior of rubber materials under different deformation states. Finally, the improved eight-chain model was successfully applied to finite element analysis (FEA) and compared with the experimental data. It was found that the improved eight-chain model can accurately describe the stress–strain characteristics of filled rubber.

Definition of the yield point in plasticity and its effect on the shape of the yield locus

1966 ◽  
Vol 1 (4) ◽  
pp. 331-338 ◽  
Author(s):  
T C Hsu
Keyword(s):  
Yield Point ◽  
Experimental Work ◽  
Strain Curve ◽  
Yield Locus ◽  
Experimental Results ◽  
Stress Strain Curve ◽  
Proportional Limit ◽  
Stress Strain ◽  
Small Section ◽  
Definition Of

Three different definitions of the yield point have been used in experimental work on the yield locus: proportional limit, proof strain and the ‘yield point’ by backward extrapolation. The theoretical implications of the ‘yield point’ by backward extrapolation are examined in an analysis of the loading and re-loading stress paths. It is shown, in connection with experimental results by Miastkowski and Szczepinski, that the proportional limit found by inspection is in fact a point located by backward extrapolation based on a small section of the stress-strain curve, near the elastic portion of the curve. The effect of different definitions of the yield point on the shape of the yield locus and some considerations for the choice between them are discussed.

scholarly journals Forming limit diagram prediction of 6061 aluminum by GTN damage model

2018 ◽  
Vol 19 (2) ◽  
pp. 202 ◽  
Author(s):  
Rasoul Safdarian
Keyword(s):  
Damage Model ◽  
Forming Limit Diagram ◽  
Numerical Results ◽  
Experimental Results ◽  
Correct Selection ◽  
Forming Limit ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Gtn Model ◽  
Gtn Damage Model

Forming limit diagram (FLD) is one of the formability criteria which is a plot of major strain versus minor strain. In the present study, Gurson-Tvergaard-Needleman (GTN) model is used for FLD prediction of aluminum alloy 6061. Whereas correct selection of GTN parameters’ is effective in the accuracy of this model, anti-inference method and numerical simulation of the uniaxial tensile test is used for identification of GTN parameters. Proper parameters of GTN model is imported to the finite element analysis of Nakazima test for FLD prediction. Whereas FLD is dependent on forming history and strain path, forming limit stress diagram (FLSD) based on the GTN damage model is also used for forming limit prediction in the numerical method. Numerical results for FLD, FLSD and punch’s load-displacement are compared with experimental results. Results show that there is a good agreement between the numerical and experimental results. The main drawback of numerical results for prediction of the right-hand side of FLD which was concluded in other researchers’ studies was solved in the present study by using GTN damage model.

scholarly journals Stress-strain model for grade 275 reinforcing steel with cyclic loading

1978 ◽  
Vol 11 (2) ◽  
pp. 101-109 ◽  
Author(s):  
K. J. Thompson ◽  
R. Park
Keyword(s):  
Axial Loading ◽  
Strain Curve ◽  
Cyclic Stress ◽  
Stress Strain ◽  
Reinforcing Bar ◽  
Strain Behaviour ◽  
Strain Relationship ◽  
Reversed Loading ◽  
Relationship Of ◽  
Strain Model

The stress-strain relationship of Grade 275 steel reinforcing bar under cyclic (reversed) loading is examined using experimental results obtained previously from eleven test specimens to which a variety of axial loading cycles has been applied. A Ramberg-Osgood function is fitted to the experimental stress-strain curves to follow the cyclic stress-strain behaviour after the first load run in the plastic range. The empirical constants in the function are determined by regression analysis and are found to depend mainly on the plastic strain imposed
in the previous loading run. The monotonic stress-strain curve for the steel, with origin of strains suitably adjusted, is assumed to be the envelope curve giving the upper limit of stress. The resulting Ramberg-Osgood expression and envelope is found to give good agreement with the experimentally measured cyclic stress-strain curves.

scholarly journals Constant Strain-Rate Tensile Testing of Natural Snow

1980 ◽  
Vol 26 (94) ◽  
pp. 519 ◽  
Author(s):  
H. Singh ◽  
F.W. Smith
Keyword(s):  
Strain Rate ◽  
Strain Gage ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Strain Rates ◽  
Strain Gages ◽  
Compression Tests ◽  
Snow Sample ◽  
Stress Strain ◽  
Natural Snow

Abstract In conducting tension and compression tests on snow samples, strains and strain-rates are usually determined from the displacements of the ends of the samples. In this work, a strain-gage which mounts directly onto the snow sample during testing, was developed and was found to give accurate and direct measurements of strain and strain-rates. A commercially available 0-28 pF variable capacitor was modified to perform the required strain measurements. It is a polished metallic plunger sliding inside a metal-coated glass tube. The plunger and tube were each soldered to the end of a spring-steel wire arm. To the other end of these arms were soldered to 10 mm square pads made of thin brass shim stock. The whole device weighs 2.5 g and the low coefficient of friction in the capacitor resulted in a very low actuation force. To mount the strain gage, the pads are wetted and frozen onto the snow sample. A high degree of sensitivity was achieved through the use of “phase-lock-loop” electronic circuitry. The capacitance change caused by the strain in the sample, changes the frequency of output signal from an oscillator and thus causes the change in output from the system. In the locked state, to which the system is constantly driven by a feed-back loop, the system output is almost ripple free. The strain gages were calibrated in the field in order to take into account the effects of very low field temperatures. The calibration curves were almost linear over the travel of 15 mm, the maximum limit. The sensitivity of the system is 4 mV per strain unit, but this could be increased by an order of magnitude by minor adjustments in the circuit. Constant strain-rate tensile tests were performed on natural snow at Berthoud Pass, Colorado, U.S.A., in the density range of 140-290 kg m-3. Four strain gages were mounted onto the samples to sense any non-uniform deformation which otherwise would have gone unnoticed or caused scatter in the data. The average indication of these gages was used to construct stress—strain curves for various types of snow at different strain-rates. The effect of strain-rate on the behavior of snow was studied. “Ratcheting” in the stress-strain curve in the region where the snow becomes plastic was observed first by Kinosita in his compression tests. A similar phenomenon was observed in these tension tests. It was found that directly measured strain is quite different from that which would be calculated from sample end movement. Strain softening was not observed in these tests up to total strains of 8%. The strain-rate effects found were comparable to the results of other investigators.

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