Elastic Stability of Rubber Compression Springs

1965 ◽  
Vol 38 (2) ◽  
pp. 415-430 ◽  
Author(s):  
A. N. Gent
Keyword(s):  
Classical Theory ◽  
Shear Stiffness ◽  
Elastic Stability ◽  
Buckling Load ◽  
Theoretical Treatment ◽  
Experimental Measurements ◽  
Loading Conditions ◽  
Good Accord ◽  
Compressive Loads ◽  
Compression Springs

Abstract Experimental measurements are described of the critical (buckling) compressive loads for columns of rubber springs under various loading conditions. They are shown to be in good accord with the theoretical treatment of Haringx, in which the classical theory of buckling is modified to take into account the shear deflection of column elements. Measurements are also described of the shape of the buckled column and of the shear stiffness of columns under compressive loads smaller than the buckling load. They are found to be satisfactorily described by the theory also.

Pull-Out and Push-Out Tests for Rubber-to Metal Adhesion

1989 ◽  
Vol 62 (4) ◽  
pp. 757-766 ◽  
Author(s):  
A. N. Gent ◽  
S. Y. Kaang
Keyword(s):  
Large Fraction ◽  
Theoretical Treatment ◽  
Total Force ◽  
Compression Tests ◽  
Cross Sectional ◽  
Pull Out ◽  
Good Accord ◽  
Compressive Loads ◽  
And Control ◽  
Push Out

Abstract A study has been carried out of adhesive failure forces for a steel rod embedded in and bonded to a rubber block. Emphasis has been placed on comparing tension (pull-out) and compression (push-out) forces. A fractional contribution to the pull-out force appeared to be significant for rods having a diameter greater than about 0.5 mm in the present experiments. Indeed, it became a large fraction of the total force when the rod diameter was 1 mm or more. On the other hand, it was negligibly small in push-out experiments. They would therefore be preferred on this basis for measuring the strength of adhesion. But experimental difficulties in carrying out compression tests are considerable. Tall blocks become unstable under large compressive loads, and short ones are markedly stiffer than long ones, due to restraints on their lateral expansion, which are difficult to specify and control. Thus, although measurements of push-out force for a wide variety of samples have been shown to be in good accord with a simple theoretical treatment of debonding, ignoring friction, it is recommended that pull-out tests be retained for assessing the strength of adhesive bonds. Caution is necessary to minimize the effect of friction. The theoretical treatment indicates that the product aL of the rod radius a and the embedded length L should be held smaller than the cross-sectional area of the block in which the rod is embedded.

A Cohesive Model with Frictional Effects on Strength and Stiffness under Transverse Compression

2014 ◽  
Vol 553 ◽  
pp. 649-654
Author(s):  
Irene Guiamatsia ◽  
Giang Dinh Nguyen
Keyword(s):  
Loading Conditions ◽  
Transverse Compression ◽  
Engineering Structures ◽  
Cohesive Model ◽  
Damage Propagation ◽  
Discrete Fracture ◽  
Compressive Loads ◽  
Constitutive Response ◽  
Strength And Stiffness ◽  
Push Out

Failure develops and propagates through a structure via a complex sequence of competing micro-mechanisms occurring simultaneously. While the active mechanism of surface debonding is the source of loss of stiffness and cohesion, friction between cracked surfaces, upon their closure, acts as a passive dissipation mechanism behind the quasi-brittleness and hence can increase the toughness of the material under favorable loading conditions. In order to numerically study damage propagation, the constitutive response must be able to faithfully capture, both qualitatively and quantitatively, one of the signature characteristic of failure: the energy dissipation. In this paper, we present an interface decohesive model for discrete fracture that is able to capture the apparent enhancement of interfacial properties that is observed when transverse compressive loads are applied. The model allows to seamlessly account for the additional frictional dissipation that occurs when the loading regime involves transverse compression, whether during debonding or after full delamination. This constitutive model is then used to successfully predict the response of realistic engineering structures under generalized loading conditions as demonstrated with the numerical simulation of a fiber push-out test.

scholarly journals The straggling of β-particles

1929 ◽  
Vol 125 (798) ◽  
pp. 420-445 ◽  
Keyword(s):  
Classical Theory ◽  
Experimental Investigations ◽  
Theoretical Treatment ◽  
A Value ◽  
Thin Foils ◽  
New Ideas ◽  
The Subject ◽  
The Individual ◽  
Individual Particles ◽  
Α Particles

When a beam of electric particles is passed through a sheet of matter the energy of the individual particles is reduced. The loss of energy is not the same for all the particles so that particles incident on the foil with the same energy emerge with different energies. This dispersion of the energy caused by the foil is known as the "straggling" of the particles. The straggling of α-particles has been the subject of several experimental investigations, and the theory in this case was adequately developed by Bohr in 1915. In the case of β-particles, however, the straggling was not experimentally investigated until quite recently and no theoretical treatment of the phenomenon has been given, the calculations of Bohr being, as he showed, applicable only to α-particles. The purpose of the work described in this paper is to develop a theory of the straggling of β-particles by thin foils and by means of it to interpret the results of experiment. The paper is arranged as follows. In 2 an account is given of the state of the experimental work on the subject, and in particular the effect of the complications introduced by "scattering" are considered. The formula derived by Bohr for the straggling of electric particles is given in 3 and its inapplicability to β-particles demonstrated. The present calculations of the straggling of β-particles are given in 4. The theory of the straggling of electric particles resolves itself into two parts. The first deals with the dynamics of collisions between electric particles and atoms, and is the same whether we are concerned with the straggling or some other phenomena such as ionisation of "stopping power." This may be called the fundamental theory and its requirements may be summarised in the function ϕ (Q) which express the frequency of collisions in which the electric particle loses energy of amount Q. The second part of the theory is the process of calculating the straggling by means of probability theory from the function ϕ . This may be regarded as the straggling theory proper and it is the main subject of 4. When the present calculations were started it was intended to calculate the straggling on the basis of classical theory only, the value of the function ϕ on this theory being definitely known. However, after some practice with the type of calculation involved it was decided to calculate the straggling for other forms of ϕ . From the results obtained it is possible to deduce the straggling corresponding to any form which ϕ may reasonably have, and if a new theory leads to a value of ϕ different from the classical value, the straggling on the new theory may readily be determined. Alternatively this fuller treatment may be used for the reverse process of calculating from the observed straggling the value of ϕ to which it corresponds. This is considered to be the most convenient procedure and in 5 the form of ϕ which explains the experimental results is deduced. this is compared in 6 with the value of ϕ on classical theory. A brief outline is given in 7 of certain new ideas concerning the nature of collisions of electric particles with electrons and atoms.

On the Determination of the Cholesteric Screw Sense by the Grandjean-Cano-Method

1980 ◽  
Vol 35 (6) ◽  
pp. 619-622 ◽  
Author(s):  
Paul R. Gerber
Keyword(s):  
Theoretical Treatment ◽  
Experimental Measurements ◽  
Polarizing Microscope

A theoretical treatment is presented for the determination of the screw sense of a cholesteric substance in a Grandjean-Cano-wedge by observing the sample in a polarizing microscope. For comparison some experimental measurements are given

Buckling and Vibration of Circular Auxetic Plates

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Teik-Cheng Lim
Keyword(s):  
Poisson’S Ratio ◽  
Dynamic Properties ◽  
Elastic Stability ◽  
Buckling Load ◽  
Poisson's Ratio ◽  
Circular Plates ◽  
Critical Buckling Load ◽  
Various Boundary Conditions ◽  
Load Factors ◽  
Auxetic Materials

This paper evaluates the elastic stability and vibration characteristics of circular plates made from auxetic materials. By solving the general solutions for buckling and vibration of circular plates under various boundary conditions, the critical buckling load factors and fundamental frequencies of circular plates, within the scope of the first axisymmetric modes, were obtained for the entire range of Poisson's ratio for isotropic solids, i.e., from −1 to 0.5. Results for elastic stability reveal that as the Poisson's ratio of the plate becomes more negative, the critical bucking load gradually reduces. In the case of vibration, the decrease in Poisson's ratio not only decreases the fundamental frequency, but the decrease becomes very rapid as the Poisson's ratio approaches its lower limit. For both buckling and vibration, the plate's Poisson's ratio has no effect if the edge is fully clamped. The results obtained herein suggest that auxetic materials can be employed for attaining static and dynamic properties which are not common in plates made from conventional materials. Based on the exact results, empirical models were generated for design purposes so that both the critical buckling load factors and the frequency parameters can be conveniently obtained without calculating the Bessel functions.

Initial Postbuckling Behavior of Imperfect, Antisymmetric Cross-Ply Cylindrical Shells Under Torsion

1987 ◽  
Vol 54 (1) ◽  
pp. 174-180 ◽  
Author(s):  
David Hui ◽  
I. H. Y. Du
Keyword(s):  
Cylindrical Shells ◽  
Elastic Stability ◽  
Buckling Load ◽  
Postbuckling Behavior ◽  
Imperfection Sensitivity ◽  
Torsional Buckling ◽  
Buckling Mode ◽  
Young’S Moduli ◽  
Coupling Behavior ◽  
Parameter Variations

This paper deals with the initial postbuckling of antisymmetric cross-ply closed cylindrical shells under torsion. Under the assumptions employed in Koiter’s theory of elastic stability, the structure is imperfection-sensitive in certain intermediate ranges of the reduced-Batdorf parameter (approx. 4 ≤ ZH ≤ 20.0). Due to different material bending-stretching coupling behavior, the (0 deg inside, 90 deg outside) two-layer clamped cylinder is less imperfection sensitive than the (90 deg inside, 0 deg outside) configuration. The increase in torsional buckling load due to a higher value of Young’s moduli ratio is not necessarily accompanied by a higher degree of imperfection-sensitivity. The paper is the first to consider imperfection shape to be identical to the torsional buckling mode and presents concise parameter variations involving the reduced-Batdorf paramter and Young’s moduli ratio.

Instability of a Hollow Elastic Cylinder Under Tension, Torsion, and Inflation

2007 ◽  
Vol 75 (1) ◽  
Author(s):  
Leonid M. Zubov ◽  
Denis N. Sheidakov
Keyword(s):  
Hollow Cylinder ◽  
Stability Region ◽  
Three Dimensional ◽  
Elastic Stability ◽  
Elastic Cylinder ◽  
Elastic Instability ◽  
Incompressible Medium ◽  
Compressive Loads ◽  
Thin Walled ◽  
External Loads

Background. Many papers on the elastic stability of both thin-walled and massive (three-dimensional) bodies regard the bifurcation of equilibrium in the case of compressive loads. Although, the elastic instability may also occur under tensile stresses. Method of Approach. In the present paper on the basis of three-dimensional equations of the nonlinear elasticity the instability of a stretched infinite hollow cylinder under torsion and inflation is investigated. The bifurcational method of stability analysis is used. Results. The critical surfaces and stability region in the space of loading parameters are defined for a Biderman material and special model of incompressible medium, which possess essential material nonlinearity. The influence of a wall thickness on the instability of a hollow cylinder is analyzed. Conclusions. Based on the obtained results, a simple and efficient practical criterion of stability under tension is formulated. This criterion can be represented in the form of the Drucker postulate, given in terms of external loads.

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