scholarly journals Longitudinal Strain Pulse Propagation in Wide Rectangular Bars: Part 2—Experimental Observations and Comparisons With Theory

1963 ◽  
Vol 30 (1) ◽  
pp. 61-69 ◽  
Author(s):  
O. E. Jones ◽  
A. T. Ellis
Keyword(s):  
Plane Stress ◽  
Pulse Propagation ◽  
Step Function ◽  
Pressure Loading ◽  
Stress Theory ◽  
Second Mode ◽  
Fringe Patterns ◽  
Strain Pulse ◽  
Thickness Mode ◽  
Theory And Experiment

The plane-stress theory presented in Part 1 is shown to predict qualitatively the warping of plane sections observed in transient fringe patterns obtained using birefringent coatings and in dynamic photoelastic pictures obtained in other investigations. Measurements using conventional techniques are described in which wide rectangular bars were subjected to a longitudinal step-function pressure loading produced by a shock tube. Comparisons show that the gross features of the experimental records for the head of the pulse are qualitatively predicted by the theory. Both theory and experiment show that short-wavelength, second-mode disturbances arrive very early. Experimentally it is observed that these disturbances are accomplished by thickness-mode activity which cannot be accounted for by the plane-stress theory.

Pulse Propagation in Straight and Curved Beams—Theory and Experiment

1974 ◽  
Vol 41 (1) ◽  
pp. 71-76 ◽  
Author(s):  
F. B. Crowley ◽  
J. W. Phillips ◽  
C. E. Taylor
Keyword(s):  
Method Of Characteristics ◽  
Pulse Propagation ◽  
Curved Beam ◽  
Curved Beams ◽  
Dimensional Theory ◽  
One Dimensional ◽  
Isochromatic Fringe ◽  
Fringe Patterns ◽  
Theory And Experiment ◽  
Good Agreement

The equations from Morley’s one-dimensional theory governing the motion of a curved beam subjected to an arbitrary pulse are solved numerically using the method of characteristics. Propagation of initially longitudinal pulses in beam assemblages with both straight and curved sections is investigated. Simulated isochromatic fringe patterns are constructed by a Calcomp plotter and are compared with actual photoelastic patterns. Remarkably good agreement is found between theory and experiment in all the cases investigated. It is concluded that Morley’s theory can be applied to pulse propagation problems of the type investigated.

scholarly journals Longitudinal Strain Pulse Propagation in Wide Rectangular Bars: Part 1—Theoretical Considerations

1963 ◽  
Vol 30 (1) ◽  
pp. 51-60 ◽  
Author(s):  
O. E. Jones ◽  
A. T. Ellis
Keyword(s):  
Elastic Strain ◽  
Longitudinal Strain ◽  
Pulse Propagation ◽  
Equations Of Motion ◽  
Step Function ◽  
Infinite Strip ◽  
Asymptotic Expressions ◽  
Theoretical Considerations ◽  
Strain Pulse ◽  
Function Time

The propagation of a longitudinal elastic strain pulse in a wide rectangular bar is considered on the basis of approximate plane-stress equations of motion. Asymptotic expressions are obtained which, for large distances of travel, describe the pulse propagation in a semi-infinite strip with stress-free lateral edges, subject to the conditions that a uniform normal stress with a step-function time dependence is applied to the end and that the end is laterally constrained. Particular emphasis is given to describing the warping of plane sections during passage of the strain pulse.

Strain pulse propagation in composite elastic rods

Composites ◽  
1970 ◽  
Vol 1 (3) ◽  
pp. 190
Author(s):  
V.K Varatharajulu ◽  
I Kayek Sabih
Keyword(s):  
Pulse Propagation ◽  
Elastic Rods ◽  
Strain Pulse

Material Testing & Computational Mechanics — A New Philosophy for Architectural Fabrics

2008 ◽  
Vol 23 (4) ◽  
pp. 215-232 ◽  
Author(s):  
P. D. Gosling ◽  
B. N. Bridgens
Keyword(s):  
Test Data ◽  
Elastic Constants ◽  
Plane Stress ◽  
Computational Mechanics ◽  
Material Testing ◽  
Woven Fabrics ◽  
Stress Theory ◽  
Young’S Moduli ◽  
Functional Representation ◽  
New Perspective

This paper proposes a new perspective on the analysis of fabric structures – the concept that material testing and computational mechanics are mutually dependent and, by implication, not to be considered as independent. Current representations of fabric stress-strain behaviour are based on plane-stress assumptions, and tend to simplify the available data (e.g. use of secant elastic moduli). Young's moduli and Poisson's ratios were determined for each test so as to provide the best fit plane to the scattered data points. These planar representations provided limited correlation with test data. The elastic constants do not comply with plane stress theory since coated woven fabrics are not homogeneous materials: They are composites with the interaction of orthogonal yarns making them act as a constrained mechanism. A new approach to incorporating fabric test data in structural analysis is proposed here: Use of direct correlation between pairs of stresses and strains. This avoids the inherent approximation in defining elastic constants or other parameters to quantify the fabric behaviour. A simple triangular interpolation scheme is recommended which is robust and avoids the risk of unreliable interpolation and extrapolation when using a functional representation of the data.

Experiments on Dispersive Pulse Propagation in Laminated Composites and Comparison With Theory

1969 ◽  
Vol 36 (3) ◽  
pp. 485-490 ◽  
Author(s):  
J. S. Whittier ◽  
J. C. Peck
Keyword(s):  
Pulse Propagation ◽  
Laminated Composites ◽  
Rear Surface ◽  
Step Function ◽  
Surface Velocity ◽  
Flat Plates ◽  
Theoretical Predictions ◽  
Long Time ◽  
Capacitance Gauge ◽  
High Degree

Transient stress-wave experiments on laminated composites are described, and the results are compared with theoretical predictions. The composites are laminated from alternating layers of high and low-modulus material, which cause a high degree of geometric dispersion of waves propagating in the composite. Experiments were conducted in which waves propagated parallel to the laminations. Flat plates were subjected on one face to a uniform pressure with step-function time dependence induced by a gas-dynamic shock wave. Under this loading, the central portion of the specimen initially responds as if it were laterally unbounded. The average velocity over a 3/8-in-dia area of the backface of the plate was measured with a capacitance gauge. The results are in good agreement with theoretical predictions made with a long-time asymptotic approximation called the head-of-the-pulse approximation. The theory isolates the dominant character of the response and predicts timing and amplitude of oscillations in normalized rear surface velocity within a few percent.

Study on Constitutive Relation and Permeable Coefficient Tensor of Rocks under Tensile Stress Loading with Micromechanics

2006 ◽  
Vol 324-325 ◽  
pp. 899-902
Author(s):  
Llide Wei ◽  
Cong Xin Chen ◽  
Chun He Yang
Keyword(s):  
Tensile Stress ◽  
Constitutive Relation ◽  
Effective Stress ◽  
Plane Stress ◽  
Fracture Criterion ◽  
Damage Model ◽  
Hydraulic Pressure ◽  
Pressure Loading ◽  
Microcrack Growth ◽  
Damaged Rocks

In the present paper, a micromechanical based damage model and corresponding permeable coefficient tensor are developed for rocks under tensile stress and hydraulic pressure loading based on the concept of the domain of microcrack growth (DMG) . After choosing an appropriate fracture criterion for microcracks, we obtain the equations from which the DMG under a monotonically increasing proportional plane stress and an invariable hydraulic pressure loading is obtained. Then the overall effective stress-strain relations and the permeable coefficient tensor of damaged rocks are calculated. The theory is verified by test.

Reinforcement of a Small Circular Hole in a Plane Sheet Under Tension

1948 ◽  
Vol 15 (2) ◽  
pp. 160-168
Author(s):  
Samuel Levy ◽  
A. E. McPherson ◽  
F. C. Smith
Keyword(s):  
Experimental Investigation ◽  
Stress Concentration ◽  
Circular Hole ◽  
Plane Stress ◽  
Median Surface ◽  
Stress Theory ◽  
State Of Stress ◽  
Uniform Tension ◽  
Plane Sheet ◽  
Plane Stress Analysis

Abstract This paper presents a theoretical and experimental investigation of the effect of various reinforcements on the stresses and displacements near a small circular hole in a plane sheet under load in its plane. The first part of the paper gives a plane-stress analysis for a reinforcement of variable thickness when the load is a uniform tension in all directions. It is found that a reinforcement which crowds most of the material close to the edge of the hole is most effective in reducing the stress concentration at the hole. The next part presents the principal results of earlier plane-stress analyses for reinforcement by a “doubler plate” when the load is tension in one direction only. The last part describes tests in the elastic range of riveted doubler-plate reinforcements of several sizes and with several rivet arrangements. Details of a test to failure of one reinforcement riveted to one side of the sheet only are given. The tests indicate that the plane-stress theory gives a good estimate of the state of stress outside the reinforcement, and that it may be used for computing median-surface stresses and average elongations of the hole in the specimen, provided that the reinforcement is attached to the sheet by more than one row of rivets.

Creep Lifetime Under Constant Load and Constant Stress: Theory and Experiment

1996 ◽  
Vol 24 (4) ◽  
pp. 212 ◽  
Author(s):  
DR Petersen ◽  
RE Link ◽  
J Aktaa ◽  
B Schinke
Keyword(s):  
Constant Load ◽  
Constant Stress ◽  
Stress Theory ◽  
Theory And Experiment

scholarly journals Pulse Propagation in a Helix—Theory and Experiment

1974 ◽  
Vol 41 (4) ◽  
pp. 1047-1051 ◽  
Author(s):  
J. W. Phillips
Keyword(s):  
Experimental Model ◽  
Strain Gage ◽  
Method Of Characteristics ◽  
Pulse Propagation ◽  
Numerical Results ◽  
Interface Problem ◽  
One Dimensional ◽  
The Method Of Characteristics ◽  
Theory And Experiment

Wittrick’s general one-dimensional equations governing the propagation of small elastic disturbances in a helical waveguide are solved by the method of characteristics, and numerical results for a particular interface problem are compared with strain gage records from an impacted experimental model. The agreement between theory and experiment is found to be excellent for the type of pulse considered, namely, an initially longitudinal compressive pulse approximately seventy rod-diameters in length.

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