Tensile stress/strain characterization of non-linear materials

1981 ◽  
Vol 16 (2) ◽  
pp. 107-110 ◽  
Author(s):  
J Margetson
Keyword(s):  
Strain Curve ◽  
Uniaxial Stress ◽  
Aerodynamic Heating ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Strain Characterization ◽  
Least Squares Fit ◽  
Experimental Values ◽  
Good Agreement

A uniaxial stress/strain curve is represented empirically by a modified Ramberg-Osgood equation ∊=(σ/E) + (σ/σo)m. Firstly E is extracted then σo and m are determined from two points on the experimental curve. These values are improved iteratively by a least squares fit using all the experimental points on the curve. The procedure is used to generate stress/strain relationships for a variety of materials and there is good agreement with the experimental values. The method is also applied to a simulated aerodynamic heating experiment.

scholarly journals Effects of layer shift and yarn path variability on mechanical properties of a twill weave composite

2016 ◽  
Vol 51 (7) ◽  
pp. 913-925 ◽  
Author(s):  
MY Matveev ◽  
AC Long ◽  
LP Brown ◽  
IA Jones
Keyword(s):  
Numerical Analysis ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Element Analysis ◽  
Damage Propagation ◽  
Macro Scale ◽  
Twill Weave ◽  
Modulus Reduction ◽  
Good Agreement

Experimental and numerical analyses of a woven composite were performed in order to assess the effect of yarn path and layer shift variability on properties of the composite. Analysis of the geometry of a 12 K carbon fibre 2 × 2 twill weave at the meso- and macro-scales showed the prevalence of the yarn path variations at the macro-scale over the meso-scale variations. Numerical analysis of yarn path variability showed that it is responsible for a Young’s modulus reduction of 0.5% and CoV of 1% which makes this type of variability in the selected reinforcement almost insignificant for an elastic analysis. Finite element analysis of damage propagation in laminates with layer shift showed good agreement with the experiments. Both numerical analysis and experiments showed that layer shift has a strong effect on the shape of the stress–strain curve. In particular, laminates with no layer shift tend to exhibit a kink in the stress–strain curve which was attributed solely to the layer configuration.

Influence of Uniaxial Stress on the Stress-Strain Curve Measured by Nanoindentation

2014 ◽  
Vol 597 ◽  
pp. 17-20
Author(s):  
Ikuo Ihara ◽  
Kohei Ohtsuki ◽  
Iwao Matsuya
Keyword(s):  
Compressive Stress ◽  
Strain Curve ◽  
Uniaxial Stress ◽  
Local Area ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Compressive Stresses ◽  
Multiple Loading ◽  
Tip Radius ◽  
Uniaxial Compressive Stress

A nanoindentation technique with a spherical indenter of tip radius 10 μm is applied to the evaluation of stress-strain curve at a local area of a pure iron under the uniaxial compressive stress exerted through the iron, and the influence of the compressive stress on the estimated stress-strain curve has been examined. A continuous multiple loading method is employed to determine the stress-strain curve. In the method, a set of 21 times of loading/unloading sequences with increasing terminal load are made and load-displacement curves with the different terminal loads from 0.1 mN to 100 mN are then continuously obtained and converted to a stress-strain curve. To examine the stress dependence of the stress-strain curve, the estimation by the nanoindentetion is performed under different uniaxial compressive stresses up to 250 MPa. It has been found that the stress-strain curve determined by the nanoindentation shifts upward as the compressive stress increases and the quantity of the shift is almost equal to the uniaxial stress acting on the iron specimen. It is also noted that the yield stress (0.2 % proof stress) estimated from the stress-strain curve increases almost proportionally to the uniaxial stress and the increase ratio tends to decrease as the stress reaches around 200 MPa.

Tension-compression stress-strain curves from bending tests

1971 ◽  
Vol 6 (4) ◽  
pp. 286-292 ◽  
Author(s):  
P W J Oldroyd
Keyword(s):  
Strain Curve ◽  
Bending Moment ◽  
Uniaxial Stress ◽  
Bending Test ◽  
Compression Stress ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Bending Tests ◽  
Original Length ◽  
Annealed Copper

A formula—Nadai's bending formula—is derived which enables the tension (or compression) stress-strain curve for a material to be obtained from the curve relating bending moment to curvature for a beam of solid rectangular section. The method is extended to give a formula which covers deformations in which reversals of plastic strain occur. The results obtained from a unidirectional bending test made on annealed copper are compared with those obtained from a tensile test made on the same material and the accuracy of the stress-strain values obtained from the bending test is discussed. The results obtained from a reversed bending test are also compared with those obtained from a tension-compression test in which a specimen was first stretched and then compressed to its original length. The limitations imposed by this method of obtaining the stress-strain curve for a material are examined and the advantages its presents in the study of the behaviour of materials under uniaxial stress are outlined.

Quantitative Characterization of Cure. I. Relationship between Modulus and Strain of Pure-Gum Natural-Rubber Vulcanizates

1952 ◽  
Vol 25 (3) ◽  
pp. 430-439 ◽  
Author(s):  
R. F. Blackwell
Keyword(s):  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Quantitative Characterization ◽  
Strain Data ◽  
Tentative Explanation ◽  
Natural Rubber Vulcanizates ◽  
The Relationship ◽  
Mooney Equation

Abstract The object of this investigation was to determine whether the relationship between strain (elongation) and modulus is sufficiently close for one to be calculated from the other. Stress-strain data have been recorded for loads of 2–10 kg. per sq. cm. for a series of ACS1 and other pure-gum compounds. It is shown that the strain at a fixed stress (5 kg. per sq. cm.) is uniquely related to the load required to produce an elongation of 100 per cent. A tentative explanation of this observation is given in terms of the Mooney equation for the stress-strain curve. It is shown that the second constant of this equation does not vary greatly from rubber to rubber.

A Contribution to the Characterization of the Plastic-Elastic State

1939 ◽  
Vol 12 (4) ◽  
pp. 799-804 ◽  
Author(s):  
E. Rohde
Keyword(s):  
Characteristic Property ◽  
Strain Curve ◽  
The Other ◽  
Elastic State ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Other Hand ◽  
Puzzling Problem

Abstract The manner in which vulcanized rubber can be deformed and yet return almost completely to its original dimensions after the stress is released is a unique and characteristic property. Technically the problem in testing rubber is to evaluate this property and to define it in terms of the factors which are concerned. To define completely this property of rubber whereby it is susceptible to deformation, it is necessary to know the stress, the elongation, the energy expended, the energy lost, the time and the temperature. The stress, elongation and energy expended are closely related and are characterized by the stress-strain curve, which in turn depends on the time and temperature. In addition, it must be borne in mind that rubber can be deformed either by tension or by pressure, but this will not be discussed further here. On the other hand a rather puzzling problem will be considered, the solution of which brings out the fact that the three variables involved in any deformation, viz.: (1) The time or frequency. (2) The temperature. (3) The interrelated factors: stress, elongation and energy expended, must be varied considerably in order to characterize the phenomena of deformation and that when this is done, unexpected results are obtained.

scholarly journals A Simplified Uniaxial Stress-strain Curve of Concrete and Its Application in Numerical Simulation

2021 ◽  
Vol 283 ◽  
pp. 01045
Author(s):  
Lou Yafei ◽  
Zou Tao ◽  
Yang Jie ◽  
Jiang Tao ◽  
Zhang Qingfang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Constitutive Model ◽  
Computational Efficiency ◽  
Concrete Beams ◽  
Strain Curve ◽  
Uniaxial Stress ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Good Convergence ◽  
High Computational Efficiency

Detennining the constitutive model is a key procedure in numerical simulation of concrete structures. The uniaxial stress-strain curve is important information to determine the concrete constitutive model. This paper provided a simplified stress-strain curve of concrete that can be used in simulation. The comparison between Chinese Code and the simplified curve shows that the simplified curve of uniaxial compression is close to the code value. Numerical simulation of concrete beams show that the simplified curve proposed has high computational efficiency and good convergence.

Experimental Study on Stress-Strain Relationship of New-Old Concrete

2006 ◽  
Vol 302-303 ◽  
pp. 536-542
Author(s):  
Jian Yin ◽  
Yi Jin Li ◽  
Xiong Zhang ◽  
Shi Qiong Zhou
Keyword(s):  
High Performance ◽  
Full Range ◽  
Strain Curve ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Rapid Repair ◽  
Strain Relationship ◽  
Relationship Of ◽  
Good Agreement

In this paper, full-range compression tests were conducted on prisms of Old concrete, New-Old concrete and High-Performance Rapid Repair Concrete (HPRRC) prisms The complete stress-strain curve of HPRRC incorporating PFAC (pulverized fly ash composite), Old concrete and New-Old concrete were obtained and compared with each other. The essential uniform deformation capacity of three kinds of concrete was verified with the experimental results. At the same time, the unified numerical expressions of the compressive complete stress-strain curves of the three kinds of concrete are put forward. The theoretical curves from calculation are in good agreement with the experimental curves.

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