A Generalized Deformation Law

1948 ◽  
Vol 15 (3) ◽  
pp. 237-240
Author(s):  
E. A. Davis
Keyword(s):  
The Other ◽  
Strain Diagram ◽  
Strain Rates ◽  
Combined Stress ◽  
Creep Tests ◽  
Stress Strain ◽  
Tension Tests ◽  
Independent Functions ◽  
Deformation Law ◽  
Elastic Strains

Abstract According to Hooke’s law the magnitude of infinitesimal elastic strains depends upon two independent constants. In this paper equations are developed which express the magnitude and the distribution of the strains in terms of two independent functions of the stresses. One function is related to the stress-strain diagram while the other is concerned with the distribution of the strains in a state of combined stress. The equations are easily adaptable to the relations between the strain rates and the stresses in combined stress-creep tests. It is the opinion of the author that two independent functions are necessary and that the behavior under a state of combined stress cannot be predicted from data obtained in pure-tension tests.

A Quantitative Comparison of Flow and Deformation Theories of Plasticity

1950 ◽  
Vol 17 (2) ◽  
pp. 180-184
Author(s):  
P. G. Hodge ◽  
G. N. White
Keyword(s):  
Hollow Cylinder ◽  
Yield Condition ◽  
Quantitative Comparison ◽  
The Other ◽  
Stress Strain ◽  
Flow Type ◽  
Deformation Law

Abstract The stresses and displacements in a partly plastic, infinitely long, hollow cylinder are obtained according to the flow type of stress-strain law of Prandtl-Reuss and to the deformation law of Hencky. In both cases the Mises yield condition is used and the compressibility of the material is taken into account. It is shown that under these assumptions the two theories yield substantially the same results for this particular problem, but that one theory or the other may be preferable for computing purposes in certain cases. The results are compared with those of other investigations in which different combinations of stress-strain law, yield condition, compressibility, and end loading were assumed.

Tension Tests at Constant True Strain Rates

1945 ◽  
Vol 12 (4) ◽  
pp. A217-A227
Author(s):  
C. W. MacGregor ◽  
J. C. Fisher
Keyword(s):  
Strain Rate ◽  
True Strain ◽  
Testing Temperature ◽  
True Stress ◽  
Strain Rates ◽  
Stress Strain ◽  
True Strain Rate ◽  
Influence Of Temperature ◽  
Tension Tests ◽  
Strain Type

Abstract Tension tests of the true stress-strain type are reported for which the true strain rate is maintained constant throughout each test. Several metals are investigated under testing temperatures ranging from −183 C to 665 C. The influence of temperature and strain velocity on the true stress-strain properties is described. A single variable called the velocity-modified temperature is used to represent the combined influences of true strain rate and testing temperature.

Watertightness, cracking resistance, and self-healing of asphalt concrete used as a water barrier in dams

2013 ◽  
Vol 50 (3) ◽  
pp. 275-287 ◽  
Author(s):  
Yingbo Zhang ◽  
Kaare Höeg ◽  
Weibiao Wang ◽  
Yue Zhu
Keyword(s):  
Asphalt Concrete ◽  
Leakage Rate ◽  
Strain Rates ◽  
Self Healing ◽  
Test Results ◽  
Direct Tension ◽  
Coefficient Of Permeability ◽  
Tension Tests ◽  
Laboratory Test Results ◽  
Cracked Specimens

The coefficient of permeability of hydraulic asphalt concrete is in the range 10−8–10−10 cm/s. Laboratory test results show that triaxial specimens in axial compression can undergo axial strains up to 18% without any significant increase in permeability until approaching the compressive strength. For temperatures between 5 and 20 °C and strain rates between 2 × 10−3%/s and 5 × 10−3%/s, conventional hydraulic asphalt concrete can tolerate 1%–3% tensile strains before cracking in direct tension tests and strains up to 3%–4% in bending. At 20 °C the tensile and bending strains at cracking are 2–4 times higher than those at 0 °C, and at −20 °C they are approximately 0.2% and 0.8%, respectively. Asphalt concrete possesses pronounced crack self-healing properties. In the experiments, the crack leakage rate dropped 1–4 orders of magnitude within a few hours and the cracked specimens regained 55% of the intact tensile strength after only 1 day of self-healing. In summary, the comprehensive series of laboratory tests documents that asphalt concrete has characteristics that make the material extremely well suited for use in impervious barriers in dams, and the test results reported herein can be of great use in barrier design.

Combined-Stress Tests on 24S-T Aluminum-Alloy Tubes

1947 ◽  
Vol 14 (2) ◽  
pp. A147-A153
Author(s):  
W. R. Osgood
Keyword(s):  
Aluminum Alloy ◽  
Hoop Stress ◽  
Axial Stress ◽  
Axial Strain ◽  
Maximum Deviation ◽  
Shearing Stress ◽  
Stress Tests ◽  
Combined Stress ◽  
Stress Strain ◽  
Shearing Strain

Abstract Combined-stress tests were made on five 24S-T aluminum-alloy tubes, 1 3/4 in. ID × 0.05 in. thick. The ratios of circumferential (hoop) stress to axial stress were 0, 1/2, 1, 2, and ∞. The tubes were tested to failure and sufficient measurements of circumferential strain and axial strain were taken to plot stress-strain curves almost up to rupture. The results are presented in the form of two sets of stress-strain curves for each ratio of stresses, namely, maximum shearing stress plotted against maximum shearing strain, and octahedral shearing stress plotted against octahedral shearing strain. In each plot the maximum deviation of the curves is about ± 5 per cent. A method of evaluating small octahedral shearing strains from the data is given which does not assume Poisson’s ratio to be 1/2.

INVESTIGATING THE INFLUENCE OF ENVIRONMENTAL CONDITIONING ON EPOXY RESINS AT QUASISTATIC AND HIGH STRAIN RATES FOR MATERIAL OPERATING LIMIT

2021 ◽  
Author(s):  
SAGAR M. DOSHI, SAGAR M. DOSHI, ◽  
NITHINKUMAR MANOHARAN ◽  
BAZLE Z. (GAMA) HAQUE, ◽  
JOSEPH DEITZEL ◽  
JOHN W. GILLESPIE, JR.
Keyword(s):  
Mechanical Properties ◽  
Epoxy Resin ◽  
Yield Stress ◽  
High Strain ◽  
Operating Conditions ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Wide Range ◽  
Environmental Aging

Epoxy resin-based composite panels used for armors may be subjected to a wide range of operating temperatures (-55°C to 76°C) and high strain rates on the order of 103-104 s-1. Over the life cycle, various environmental factors also affect the resin properties and hence influence the performance of the composites. Therefore, it is critical to determine the stress-strain behavior of the epoxy resin over a wide range of strain rates and temperatures for accurate multi-scale modeling of composites and to investigate the influence of environmental aging on the resin properties. Additionally, the characterization of key mechanical properties such as yield stress, modulus, and energy absorption (i.e. area under the stress-strain curve) at varying temperatures and moisture can provide critical data to calculate the material operating limits. In this study, we characterize mechanical properties of neat epoxy resin, SC-15 (currently used in structural armor) and RDL-RDC using uniaxial compression testing. RDL-RDC, developed by Huntsman Corporation, has a glass transition temperature of ~ 120°C, compared to ~ 85°C of SC-15. A split Hopkinson pressure bar is used for high strain rate testing. Quasistatic testing is conducted using a screw-driven testing machine (Instron 4484) at 10-3 s-1 and 10-1 s-1 strain rates and varying temperatures. The yield stress is fit to a modified Eyring model over the varying strain rates at room temperature. For rapid investigation of resistance to environmental aging, accelerated aging tests are conducted by immersing the specimens in 100°C water for 48 hours. Specimens are conditioned in an environmental chamber at 76 °C and 88% RH until they reach equilibrium. Tests are then conducted at five different temperatures from 0°C to 95°C, and key mechanical properties are then plotted vs. temperature. The results presented are an important step towards developing a methodology to identify environmental operating conditions for composite ground vehicle applications.

Determination of stress-strain characteristics at very high strain rates

1970 ◽  
Vol 10 (9) ◽  
pp. 370-376 ◽  
Author(s):  
C. K. H. Dharan ◽  
F. E. Hauser
Keyword(s):  
High Strain ◽  
Strain Rates ◽  
High Strain Rates ◽  
Stress Strain ◽  
Very High
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