Fatigue in Rubber. Part II

1939 ◽  
Vol 12 (2) ◽  
pp. 332-343 ◽  
Author(s):  
W. J. S. Naunton ◽  
J. R. S. Waring
Keyword(s):  
Carbon Black ◽  
Internal Friction ◽  
High Frequency ◽  
Strain Curve ◽  
Power Input ◽  
Viscous Resistance ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Wide Range ◽  
Rubber Part

Abstract 1. An apparatus is described for measuring the modulus and resilience of rubber over a wide range of frequencies. 2. These measurements can be made at any point in the stress-strain curve of the sample. 3. By increasing the power input, the same apparatus can be used to induce high frequency fatigue in the sample. 4. The earlier work with the torsion head apparatus has been confirmed, namely, that internal friction is greatest near zero strain. 5. High frequency resilience is more independent of degree of vulcanization than tripsometer resilience. 6. Modulus tends to increase with frequency. The effect is least with a rubber gum stock and is greater with compounds containing gas black. 7. Resilience decreases with frequency both in gum and gas black compounds. The decrease is more rapid in the gum compounds. 8. Viscous resistance decreases with frequency and becomes constant at higher frequencies. 9. The modulus of both rubber and Neoprene carbon black compounds decreases with fatigue. 10. The change in modulus with frequency in fatigued stocks is exactly analogous to the change before fatigue in rubber, but there is a slight divergence in the case of Neoprene.

Reinforcement of Butyl with Carbon Black. II. Thermally vs. Chemically Oxidized Blacks

1964 ◽  
Vol 37 (4) ◽  
pp. 1034-1048 ◽  
Author(s):  
A. M. Gessler
Keyword(s):  
Carbon Black ◽  
Chemical Reactivity ◽  
Preceding Paper ◽  
Strain Curve ◽  
Convincing Evidence ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Carbon Particles ◽  
Vulcanized Rubber ◽  
Oxygen Functionality

Abstract The effect of oxidized blacks on the stress-strain properties and bound-rubber content of butyl and SBR was discussed in the preceding paper. Oxidized blacks, when compared with similar untreated blacks, were shown to have a greatly increased reinforcing capacity in butyl. Oxygen functionality on carbon black, it was therefore concluded, is essential in butyl to produce the chemical reactivity which is required between polymer and black if high-order reinforcement is to be obtained. Oxygen functionality on carbon black, it was also demonstrated, is not only not required for enhanced reinforcement in SBR, but it is in fact a deterrent, because it exerts severe restraining effects on the cure of the resulting vulcanizates as well. These interesting results were proposed to provide qualitative but convincing evidence that carbon-polymer bonding, which we believe is requisite to reinforcement, is achieved by different mechanisms in butyl and SBR. In butyl, the unique sensitivity of the stress-strain curve to reinforcing effects was used to speculate on the disposition of carbon blacks in “filled” and reinforced vulcanizates, respectively. With oxidized blacks, reinforcement effects were pictured as stiffening effects which, starting with the gum vulcanizates, caused the stress-strain curve to be shifted without intrinsic changes in its shape. The resulting “reinforced gum,” it was suggested, derived its physical characteristics from the fact that carbon black was included in the vulcanized rubber network. With untreated blacks, in “filled” systems, carbon black was pictured as being enmeshed or entangled in an independently formed vulcanized rubber network. The stiffening effects in this case were attributed to viscous contributions arising from steric restrictions which the occluded carbon particles were thought to impose on both initial movements and the subsequent orientation of network chains when the sample was extended.

scholarly journals Modification of Charpy machine for the acquisition of stress-strain curve in thermoplastics

DYNA ◽  
2020 ◽  
Vol 87 (213) ◽  
pp. 52-60
Author(s):  
Luis Miguel Zabala Gualtero ◽  
Ulises Figueroa López ◽  
Andrea Guevara Morales ◽  
Alejandro Rojo Valerio
Keyword(s):  
Strain Rate ◽  
Strain Curve ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Static Tests ◽  
Wide Range ◽  
Plastic Components ◽  
Impact Simulations

Simulations of impact events in the automotive industry are now common practice. Vehicle crashworthiness simulations on plastic components cover a wide range of strain rates from 0.01 to 500 s-1. Because plastics mechanical properties are very dependent on strain rate, developing experimental methods for generating stress-strain curves at this strain rate range is of great technological importance. In this paper, a modified Charpy machine capable of acquiring useful information to obtain the stress-strain curve is presented. Strain rates between 300 to 400 s-1 were achieved. Three thermoplastics were tested: high-density polyethylene, polypropylene-copolymer and polypropylene-homopolymer. Impact simulations using LS-DYNA were performed using the acquired high-strain rates stress-strain curves and compared with experimental data. Simulations using stress-strain curves from quasi-static tests were also performed for comparison. Very good agreement between the simulation and experimental results was found when the ASTM D1822 type S specimen was used for testing each material.

Use of Chip Tension to Obtain a Stress-Strain Curve From Metal Cutting Tests

1963 ◽  
Vol 85 (4) ◽  
pp. 351-355 ◽  
Author(s):  
I. Finnie ◽  
J. Wolak
Keyword(s):  
Metal Cutting ◽  
Strain Curve ◽  
Commercial Purity ◽  
Compression Tests ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Wide Range ◽  
Shear Strains ◽  
The Difference ◽  
Commercial Purity Aluminum

By pulling the chip at various angles during metal cutting, it has been possible to greatly decrease the shear strains and thus to obtain a wide range of shear strains with a single tool. Using this technique, stress-strain curves for commercial purity aluminum have been obtained at −320 deg F (78 deg K) and 68 deg F (293 deg K). These results lie above those obtained from compression tests on the same material and the difference is ascribed largely to strain rate. Limits are imposed on the chip-pulling technique by an instability which appears when the direction of pulling makes too great an angle with the tool face and by fracture.

Influence of Large Static Deformation on the Dynamic Properties of Polymers Part II. Influence of Carbon Black Loading

1981 ◽  
Vol 54 (4) ◽  
pp. 857-870 ◽  
Author(s):  
E. A. Meinecke ◽  
S. Maksin
Keyword(s):  
Carbon Black ◽  
Energy Loss ◽  
Amplification Factor ◽  
Complex Modulus ◽  
Dynamic Properties ◽  
Strain Curve ◽  
Static Stress ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Static Modulus

Abstract The influence of carbon black loading on the dynamic properties of statically deformed elastomers has been investigated. The energy loss per cycle was found to increase according to the square of the strain amplification factor as expressed by the Guth-Gold-Einstein equation. The dynamic complex modulus |E*| is approximately equal to the static modulus obtained from the slope of the static stress-strain curve. The influence of carbon black loading on E* can, therefore, be predicted from its influence on the static stress-strain curve which was found to be governed by the first power of the strain amplification factor. The tangent of the loss angle can thus be predicted from |E*| and the energy loss per cycle. It does not only depend upon the dynamic viscosity of the material; it also depends upon the shape of the stress-strain curve as well.

Reinforcement of Butyl with Carbon Black. I. Effect of Oxidized Blacks on Stress-Strain Properties and Bound Rubber

1964 ◽  
Vol 37 (4) ◽  
pp. 1013-1033 ◽  
Author(s):  
A. M. Gessler
Keyword(s):  
Carbon Black ◽  
Chemical Properties ◽  
Strain Curve ◽  
Critical Factor ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Bound Rubber ◽  
Oxygen Functionality ◽  
Physical And Chemical ◽  
Initial Movement

Abstract The increased reinforcing capacity of oxidized blacks in butyl is illustrated, and the results are discussed in terms of the relationships which exist between polymer and black. Oxygen functionality on the black, it is shown, is the critical factor controlling the extent to which butyl is reinforced by the black. The lesser effects of decreased aggregate structure in the black are also demonstrated. These results are obtained using blacks which, though similar to attrited blacks, derive both their physical and chemical properties without the use of comminution. A much more unambiguous approach to the questions of black structure and oxygen content is therefore provided. In butyl, the unique sensitivity of the stress-strain curve to reinforcing effects is attributed to low unsaturation in the polymer. This sensitivity is used to qualify the nature of the reinforcement which is obtained. With oxidized blacks, true reinforcement is pictured as a stiffening effect which, starting with the gum vulcanizate, shifts the stress-strain curve without essentially changing its shape. The result is a “reinforced gum” which, it is suggested, derives its physical characteristics through the bonding of carbon black in the rubber network. With untreated black, carbon black is pictured as being enmeshed or entangled in an independently formed rubber network. Changes in the shape of the stress-strain curve are therefore attributed to steric restrictions which this arrangement imposes on the initial movement and subsequent orientation of network chains when the sample is extended.

scholarly journals Behaviour of longitudinally stiffened stainless-steel plate girder under combined bending and shear

2021 ◽  
Author(s):  
Sajith Chandran T ◽  
Ajith M S
Keyword(s):  
Stainless Steel ◽  
Carbon Steel ◽  
Steel Plate ◽  
Strain Curve ◽  
Stainless Steel Plate ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Longitudinal Stiffener ◽  
Wide Range ◽  
Plate Girder

Due to the high corrosion resistance, the use of stainless steel is increased in a wide range of environment in the last two decades. The behaviour of stainless steel is different from that of carbon steel, especially in a stress-strain relationship. Stainless steel has a rounded stress-strain curve, whereas carbon steel exhibits a sharp yield point in the stress-strain curve. Stainless steel has better strain hardening capacity and possesses high ductility. Stiffeners are generally utilised in plate girder for increasing the load-carrying capacity by providing better resistance against buckling of web panels. The existing study related to austenitic stainless steel plate girder studied the effect of longitudinal stiffener placed at the centre of the web panel alone. Present work uses to optimise position of longitudinal stiffener in stainless steel plate girder subjected to combined bending and shear. The behaviour is analysed by using finite element software ABAQUS. The optimum location for longitudinal stiffener in long-span stainless steel plate girder under combined bending and shear was identified and compared the results with the standard design codes.

The Stress-Strain Relationships of Vulcanized India-Rubber. Part I. The Inflection Point

1933 ◽  
Vol 6 (4) ◽  
pp. 486-503 ◽  
Author(s):  
Cecil Wilson Shacklock
Keyword(s):  
Inflection Point ◽  
Applied Load ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Vulcanized Rubber ◽  
Rubber Part ◽  
The Many

Abstract Definition.—The relation between applied load and the resulting extension of vulcanized or unvulcanized rubber may be represented graphically as a curve which is “s” shaped, and there is a point of inflection in the curve. If a load W grams be applied to the rubber, and the resulting length be L, the point of inflection is defined as the point on the curve where the second differential becomes zero and changes sign. More simply, the point of inflection is where the tangent to the curve crosses the curve. It is well known that the point of inflection exists, but there appears to be no reference in the literature to any attempts to determine precisely its position. It is also apparent from the many stress-strain curves of rubber which have been published that the point of inflection varies with both the period of cure and the compounding of the rubber. What follows is an account of some experiments made to investigate the position of the point of inflection in the stress-strain curve of vulcanized rubber.

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