On the Determination of Stress, Strain, Strain-Rate Relations From Dynamic Beam Tests

1969 ◽  
Vol 36 (3) ◽  
pp. 632-634 ◽  
Author(s):  
P. P. Gillis ◽  
J. M. Kelly
Keyword(s):  
Strain Rate ◽  
Dynamic Testing ◽  
Direct Method ◽  
Bending Moment ◽  
Experimental Results ◽  
Stress Strain ◽  
Analytical Technique ◽  
Flexural Response ◽  
Flexural Tests

A direct method is proposed for the determination of stress, strain, strain-rate relations from dynamic flexural tests in which bending moment is given in terms of curvature and curvature rate, or any other suitable deformation parameter and deformation rate parameter. The method is demonstrated by application to published experimental results. It is found that the stress, strain, strain-rate relations that are derived from the flexural test data are in significantly better accord with uniaxial data on the same material, than moment, curvature, curvature-rate relations predicted from the uniaxial data correspond with the experimental results. It appears that the process of reducing flexural data to uniaxial relations by the method proposed is much less sensitive than that of predicting flexural response from uniaxial data. Since flexural tests have many experimental advantages over uniaxial tests this analytical technique seems to open up possibilities for improved dynamic testing methods.

Uniaxial Constitutive Equation of Ice From Beam Tests

1985 ◽  
Vol 107 (4) ◽  
pp. 511-515 ◽  
Author(s):  
P. C. Xirouchakis ◽  
T. Wierzbicki
Keyword(s):  
Strain Rate ◽  
Direct Method ◽  
Elastic Beam ◽  
Bending Moment ◽  
Uniaxial Stress ◽  
Analytical Technique ◽  
Linear Elastic ◽  
Beam Depth ◽  
Tension And Compression ◽  
Extensional Strain

A method is proposed to obtain ice uniaxial stress, strain, strain-rate relations from beam tests. The basic advantage of the proposed analytical technique is that it is a direct method of reducing beam test data. So, no assumption is made with regard to the ice constitutive behavior. The proposed method is an extension of Gillis and Kelly’s procedure to account for different ice response in tension and compression. It is also an extension of the procedure reported by Mayville and Finnie to account for ice response dependence on strain rate. Furthermore, it is shown that the expressions presented by Mayville and Finnie are only valid when the bending moment, with respect to the zero strain axis, is assumed independent of the centroidal extensional strain. A simple example of a linear elastic beam with a Young’s modulus that varies linearly with the beam depth is worked out to show that these earlier given expressions are not applicable in that case.

scholarly journals A Strain Rate-Dependent Damage Evolution Model for Concrete Based on Experimental Results

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Bin Xu ◽  
Xiaoyan Lei ◽  
P. Wang ◽  
Hui Song
Keyword(s):  
Strain Rate ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Damage Model ◽  
Evolution Model ◽  
Experimental Results ◽  
Strain Rates ◽  
Compression Tests ◽  
Stress Strain ◽  
Actual Damage

There are various definitions of damage variables from the existing damage models. The calculated damage value by the current methods still could not well correspond to the actual damage value. Therefore, it is necessary to establish a damage evolution model corresponding to the actual damage evolution. In this paper, a strain rate-sensitive isotropic damage model for plain concrete is proposed to describe its nonlinear behavior. Cyclic uniaxial compression tests were conducted on concrete samples at three strain rates of 10−3s−1, 10−4s−1, and 10−5s−1, respectively, and ultrasonic wave measurements were made at specified strain values during the loading progress. A damage variable was defined using the secant and initial moduli, and concrete damage evolution was then studied using the experimental results of the cyclic uniaxial compression tests conducted at the different strain rates. A viscoelastic stress-strain relationship, which considered the proposed damage evolution model, was presented according to the principles of irreversible thermodynamics. The model results agreed well with the experiment and indicated that the proposed damage evolution model can accurately characterize the development of macroscopic mechanical weakening of concrete. A damage-coupled viscoelastic constitutive relationship of concrete was recommended. It was concluded that the model could not only characterize the stress-strain response of materials under one-dimensional compressive load but also truly reflect the degradation law of the macromechanical properties of materials. The proposed damage model will advance the understanding of the failure process of concrete materials.

Experimental Determination of the Ultimate Strength of Box Girder Specimens

2016 ◽  
Author(s):  
Thomas Lindemann ◽  
Patrick Kaeding ◽  
Eldor Backhaus
Keyword(s):  
Finite Element ◽  
Experimental Determination ◽  
Ultimate Strength ◽  
Progressive Collapse ◽  
Bending Moment ◽  
Element Model ◽  
Experimental Results ◽  
Bending Test ◽  
Box Girder

The Finite Element Method (FEM) is a feasible tool to perform progressive collapse analyses of large structural systems. Despite enormous developments in finite element formulations and computer technologies the results of structural analyses should be validated against experimental results. In this paper the collapse behaviour of two identical box girder specimens is determined experimentally for the load case of pure longitudinal bending. The specimens are composed of stiffened plate panels and connected at either ends to a loading structure. Within a 4-point bending test a constant bending moment is applied to each specimen to determine the collapse behaviour even in the post-ultimate strength range. The results of the experimental determination of the ultimate strength are presented for the box girder specimens. To simulate the collapse behaviour a finite element model is used and validated against experimental results.

A Note on the Determination of an Upper Bound on Displacement Rates for Steady Creep Problems

1966 ◽  
Vol 33 (1) ◽  
pp. 216-217 ◽  
Author(s):  
J. B. Martin
Keyword(s):  
Strain Rate ◽  
Upper Bound ◽  
Displacement Rate ◽  
Steady Creep ◽  
Nonlinear Case ◽  
Stress Strain

A method is described whereby the displacement rate at any point on the surface of a body undergoing steady creep may be bounded from above. The method is restricted to n-power stress-strain rate relations, and is of most significance in the nonlinear case.

Propagation of glacier surges

1969 ◽  
Vol 6 (4) ◽  
pp. 969-977 ◽  
Author(s):  
G. de Q. Robin ◽  
P. Barnes
Keyword(s):  
Shear Stress ◽  
Melting Point ◽  
Strain Rate ◽  
Experimental Results ◽  
Shear Stresses ◽  
Rate Data ◽  
Stress Strain ◽  
Glacier Surface ◽  
Glacier Surges ◽  
Tensile Zone

Propagation of glacier surges has been discussed in terms of stresses acting in the three major zones of the surge. The steeply sloping front of a surge appears sufficient to explain the thickening of a glacier and the rise in velocity of ice motion which takes place across this zone in terms of accepted stress–strain rate data for ice. Explanation of the high velocities which occur in the next zone in spite of little change in the available shear stress is more difficult, but the experimental results of Barnes and Tabor on ice close to the melting point appear to offer an explanation of the unusually high rates of flow. In the tensile zone, where velocities slow down, the net lowering of the glacier surface after the surge has passed is explained in terms of the depth of crevassing and easier flow of ice at melting point when under tensile and shear stresses.

Experimental Study on the Plastic Collapse Load of Elbows Subjected to In-Plane Opening Bending Moment

2011 ◽  
Vol 204-210 ◽  
pp. 1755-1758
Author(s):  
Cha Xiu Guo ◽  
Xin Li Wei
Keyword(s):  
Bending Moment ◽  
Limit Load ◽  
Experimental Results ◽  
Piping System ◽  
Plastic Collapse ◽  
Test Results ◽  
Collapse Load ◽  
Critical Components ◽  
Collapse Behavior

Pipe elbows are the most critical components in any piping system. However, the earlier experiments on cracked elbows were focused mainly on the determination of limit load of through wall cracked elbow. The experimental results of plastic collapse load of seven carbon steel 900 elbows, subjected to in-plane opening bending moment, are reported in this work. Among the selected specimens, three were defect-free elbows and six had axial surface cracks at the intrados, crown or at extrados. Test arrangement and the collapse behavior with and without cracks were presented. The plastic collapse loads were then obtained on the basis of experimental results. Reasonably good matching between test results and existing estimation formulae has been observed.

scholarly journals High-Strain-Rate Compressive Behavior of UHMWPE Fiber Laminate

2020 ◽  
Vol 10 (4) ◽  
pp. 1505 ◽  
Author(s):  
Yihui Zhu ◽  
Xiaoyun Zhang ◽  
Benyuan Xue ◽  
Hengsha Liu ◽  
Yaoke Wen ◽  
...  
Keyword(s):  
Strain Rate ◽  
Fracture Stress ◽  
Maximum Stress ◽  
Dynamic Testing ◽  
Numerical Models ◽  
Test Machine ◽  
Stress Strain ◽  
Uhmwpe Fiber ◽  
Out Of Plane ◽  
Plane Direction

Ultra-high-molecular-weight polyethylene (UHMWPE) fiber laminate is currently widely used in ballistic protection for its exceptional physical and mechanical properties. However, the dynamic compressive mechanism of UHMWPE laminate remains poorly understood. Therefore, the stress–strain relationship, the influence of different thickness, area, and shape, and the maximum stress and fracture stress are studied in both out-of-plane and in-plane directions under quasi-static and dynamic loading using a universal test machine, Split Hopkinson pressure bar (SHPB), and high-speed camera. Furthermore, numerical models with cohesive elements are developed. The results indicate a dependency on strain rate and loading direction. Firstly, the stress–strain curve of dynamic testing can be divided into different zones according to different loading directions and strain rates. Secondly, with the increase of the strain rate in the dynamic testing, the maximum stress and fracture stress increase as well; relatively speaking, the fracture stress in the out-of-plane direction is greater than the fracture stress in the in-plane direction. Thirdly, both experiment and simulation indicate that the thickness does not influence the modulus clearly the in out-of-plane direction but influences the modulus in the in-plane direction. Fourthly, the fracture stress of dynamic testing is higher than the fracture stress of quasi-static testing in both directions. Finally, the numerical results show good agreement with the experiment in terms of the maximum stress and failure form.

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