scholarly journals Fatigue of Rubber

1964 ◽  
Vol 37 (5) ◽  
pp. 1341-1364 ◽  
Author(s):  
J. R. Beatty
Keyword(s):  
Heat Generation ◽  
Vibration Isolation ◽  
Dynamic Stress ◽  
Static Loads ◽  
Cyclic Stresses ◽  
Large Samples ◽  
Rubber Compounds ◽  
Compression Springs ◽  
Torsion Springs ◽  
Fatigue Failures

Abstract The long-range elastic properties of rubber suit it ideally to dynamic service applications. Vibration isolation, suspension, and force transmittal are examples of such uses of rubber compounds. Common examples illustrating these uses are isolation devices of all types, e.g., motor mounts, torsion, shear and compression springs, and tires—just to name a few. While fatigue failures may occur under static loads, they are generally accelerated by cyclic stresses. In most applications of rubber, a failure is critical in that the device depends for its functioning on the properties of the rubber and ceases to function when fatigue or other types of failure occur. Examples of fatigue failures are groove cracking in tires, tread and ply separations in tires, failures in torsion springs and motor mounts, etc. This review is concerned with fatigue of rubber under conditions of dynamic stress. Two specific areas are treated, the case where frequency of stressing is low enough and the samples are small enough that heat generation is not an important factor in failure and, to a lesser extent, the case where heat generation due to large samples and high frequency load application builds up temperatures which contribute to failure. Both of these cases of fatigue failure are encountered widely in service. For example, the first is found in vibration isolation devices such as motor mounts, and the latter in the shoulder area of heavy duty tires.

Energy dissipation characteristics of crosslinks in natural rubber: an assessment using low and high-frequency analyzer

2018 ◽  
Vol 38 (8) ◽  
pp. 723-729 ◽  
Author(s):  
K. Anas ◽  
Samson David ◽  
R.R. Babu ◽  
M. Selvakumar ◽  
S. Chattopadhyay
Keyword(s):  
Energy Dissipation ◽  
Natural Rubber ◽  
Heat Generation ◽  
High Frequency ◽  
Crosslink Density ◽  
Vibration Isolation ◽  
Very High Frequency ◽  
Rubber Compounds ◽  
Lower Heat ◽  
Very High

AbstractThe dynamic deformation of a viscoelastic material can cause heat generation. This heat generation is an aspect of energy dissipation. The present paper investigates the contribution of crosslink type and density on energy dissipation mechanism in natural rubber compounds. The influences of these elements are investigated using a very high frequency (VHF) analyzer (VHF 104) and a dynamical mechanical analyzer (DMA). The VHF 104 analyzer follows transmissibility and vibration isolation principle, whereas DMA works on dynamical mechanical the deformation principle. Higher crosslink density promotes lower heat generation in rubber compounds. Tanδinterpretation for energy dissipation characteristics of rubbery compounds should be done judiciously to avoid wrong interpretations. Polysulfidic linkages show higher damping ratios (ζ) than monosulfidic or disulfidic linkages due to their dissipative nature. The natural frequency (ωn) of a system at a given mass is the function of its crosslink density.

Design and Amplitude Dependence of Resonance Frequency of Origami-Inspired Vibration Isolators With Quasi-Zero-Stiffness Characteristic

2020 ◽  
Author(s):  
Kouya Yamaguchi ◽  
Sachiko Ishida
Keyword(s):  
Vibration Isolation ◽  
Amplitude Dependence ◽  
Vibration Isolators ◽  
Stiffness Characteristic ◽  
Resonance Frequencies ◽  
Tensile Forces ◽  
Linear Spring ◽  
Compression Springs ◽  
Mechanical Elements ◽  
Vibration Isolation Performance

Abstract This study aims to design two types of vibration isolators, with different spring mechanisms, using a foldable structure that is based on a cylinder torsional buckling pattern, and evaluate the vibration isolation performance of each design. Vibration isolation is achieved through nonlinear spring characteristics of the isolators, which have zero spring stiffness, achieved by attaching a linear spring to the foldable isolator structure. The two vibration isolators differ in the mechanical elements that constitute the foldable structure, which undergo tensile forces as the structure folds. For the first isolator, the mechanical elements are represented only by tension springs, which appropriately undergo tension. For the second isolator, the mechanical elements are designed so that embedded compression springs within the elements compress under tension, thus enabling the elements to work as tension springs. The excitation experiment results revealed that the different spring mechanisms produced equivalent resonance frequencies but different damping effects at the resonance and higher frequencies. When oscillations with multiple amplitudes were input, larger input amplitudes were found to correspond to lower resonance frequencies for both isolators. This trend contradicts that described in the nonlinear vibration theory modeled by the Duffing equation, and was determined to be caused by hysteresis of the spring phenomena in the vibration isolators.

Natural Rubber Compounds for Truck Tires

1985 ◽  
Vol 58 (4) ◽  
pp. 740-750 ◽  
Author(s):  
D. Barnard ◽  
C. S. L. Baker ◽  
I. R. Wallace
Keyword(s):  
Stearic Acid ◽  
Heat Generation ◽  
Rolling Resistance ◽  
Synthetic Compound ◽  
Wear Performance ◽  
Test Pieces ◽  
Truck Tire ◽  
Truck Tires ◽  
Rubber Compounds ◽  
Lower Severity

Abstract An 80 NR/20 BR truck tread compound containing a semi-EV cure system and modified with a 6.0 phr level of stearic acid has been shown to exhibit excellent resistance to reversion when compared to a similar compound containing a normal 2.0 phr level of stearic acid. Improvements in the retention of laboratory abrasion resistance, heat generation, and most physical properties have been identified on test pieces subjected to typical truck retread overcure conditions. In highway fleet testing trials of 1100 × 22.5 truck retreads fitted to both third and fourth drive axles of tipper trucks, the modified compound displayed a 42% improvement in treadwear performance over the normal compound in the lower severity third axle positions while performance in the higher severity fourth axle positions was inferior by 20%. In comparison to a 55 SBR/45 BR truck tread, both NR compounds displayed superior wear performance on the fourth axles while some further adjustments of the modified compound are required to match the synthetic compound on the third axles. The reversal of wear performances for all compounds between third and fourth axles is due to the different abrasion mechanisms encountered. Laboratory abrasion rankings do not correlate with wear performances of compounds on the fourth drive axle of trucks, but they do correlate with wear performances on third drive axles. Despite the reversion characteristics of the normal semi-EV compound, no significant adverse effect on treadwear performance was evident at the start of tire life. The low heat generation of the modified compound in laboratory tests is confirmed in actual tire testing. Advantages in rolling resistance characteristics are also evident for the modified compound. Current studies at MRPRA suggest that further modifications of cure system design, in combination with the optimization of NR/BR ratios and mixing methods, will potentially provide NR dominant truck tread compounds which will exhibit superior wear performance in both the higher and lower abrasion severities encountered in heavy-duty truck tire service conditions.

Thermal Properties of Rubber Compounds. II. Heat Generation of Pigmented Rubber Compounds

1935 ◽  
Vol 8 (1) ◽  
pp. 138-149 ◽  
Author(s):  
C. E. Barnett ◽  
W. C. Mathews
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Laboratory Test ◽  
Heat Generation ◽  
The Other ◽  
Moving Plate ◽  
Rubber Compounds ◽  
Time Required ◽  
Two Machines ◽  
Rubber Block

Abstract THE first paper (1) of this series discussed thermal conductivity of rubber and a number of compounding ingredients which were measured using the electric current as the source of heat. In this article the fundamental factors controlling the generation of heat and the variations possible by pigmentation are being studied. Results obtained for pigmented rubber in the pendulum and flexometer will be discussed and correlated. In the writers' laboratory two machines have been used extensively in studying the temperature developed in rubber compounds subjected to distortion by compressive forces. The first of these is a flexometer described by Cooper (2), and the second a compression machine in which a rubber block 14 cm. (5.5 inches) in diameter and 9.53 cm. (3.75 inches) high is pounded with a definite load a specified number of times per minute. The laboratory test block used in the flexometer is in the shape of a frustrum of a rectangular pyramid, of which the base is 5.4 × 2.86 cm. (2.126 × 1.125 inches), the top 5.08 × 2.54 cm. (2 × 1 inches), and the altitude 3.81 cm. (1.5 inches). This block of rubber is compressed between two plates under definite load, one of the plates being stationary while the other travels in a circular motion of definite magnitude. After the sample has been placed in the machine, the moving plate is set to one side of the center. Both the loading and the amount of offset may be varied within wide limits. With this machine one may study either the temperature developed over a period of flexing or the time required to compress the sample a predetermined amount.

Effect of Carbon Black on Dynamic Properties of Rubber Vulcanizates

1978 ◽  
Vol 51 (3) ◽  
pp. 437-523 ◽  
Author(s):  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Vibration Isolation ◽  
Power Transmission ◽  
Dynamic Properties ◽  
Engineering Application ◽  
Mullins Effect ◽  
Rubber Compounds ◽  
Background Material ◽  
Power Transmission Belts ◽  
Transient Forces

Abstract The term dynamic properties as applied to elastomers refers to the response to periodic or transient forces which do not cause failure or appreciable fatigue (permanent change of properties) during the investigation. Generally this is limited to vulcanizates subjected to deformations not exceeding about 25%; and generally the dynamic properties are measured after several cycles or (in a transient experiment such as resilience) after several preconditioning transients, so that the Mullins effect or difference between first and second strain cycles is not of consequence. Thus, dynamic properties represent the viscoelastic properties of vulcanizates at deformations below about 25%, after reaching a pseudo-equilibrium state. The dynamic properties of rubber are altered tremendously by the addition of a filler. The scope of this article is restricted to the dynamic properties of rubber vulcanizates with carbon black as a filler. The effect covered in this article are important in designing rubber compounds to be used under dynamic conditions, such as tires, power transmission belts, vibration isolation mountings, etc. However, the engineering application of dynamic properties, which has been treated in detail elsewhere, is outside the scope of this review. A certain amount of background material is needed. We will first define the terms used in describing dynamic properties. The methods and instruments used for measuring these properties will be described briefly, and the nature of carbon black will be reviewed. Finally, some historical material is given, together with the dynamic behavior of typical compounds, as a preface to the review of more recent work in this field.

scholarly journals A Novel Ring Spring Vibration Isolator for Metro Superstructure

2021 ◽  
Vol 11 (18) ◽  
pp. 8422
Author(s):  
Yuhong Ling ◽  
Shan Wu ◽  
Jingxin Gu ◽  
Hongtao Lai
Keyword(s):  
Vibration Isolation ◽  
Common Knowledge ◽  
Displacement Curve ◽  
Vibration Isolator ◽  
Spring Stiffness ◽  
Dynamic Simulations ◽  
Theoretical Derivation ◽  
Vibration Isolators ◽  
Good Energy ◽  
Compression Springs

Due to the serious impact of metro vibration on people’s lives, it is important to design vibration isolators. In this study, the dynamic characteristics of a thick-walled ring spring are studied first. Through theoretical derivation, a new formula suitable for thick-walled ring springs is proposed. Finite element numerical analysis was performed to study the load–displacement curve and stress of the ring spring and verified the correctness of the formula. According to the studied mechanic characteristics, a novel ring spring isolator is proposed for vibration isolation of the metro superstructure. With the help of a ring spring, the proposed isolator has good energy absorption and self-reset function. The dynamic simulations were conducted in a multi-story building with the ring spring isolator as the isolator to study the vibration performance. It is common knowledge that the vertical natural frequency of the superstructure that is isolated by compression springs is given by the mass of the superstructure and the spring stiffness. In order to obtain vibration attenuation and control the vertical deformation, the spring stiffness needs to be 500–1000 kN/mm. Hence, it is clear that the vibration isolator does reduce the vertical eigenfrequency. By comparing the isolated structure with the non-isolated structure, it is proved that the new isolator can effectively improve a building’s serviceability.

Influence of Processing Oil Based on Modified Epoxidized Vegetable Oil with N-Phenyl-p-Phenylenediamine (PPD) on Extrusion Process Behaviors of Natural Rubber Compounds

2015 ◽  
Vol 659 ◽  
pp. 423-427 ◽  
Author(s):  
Chalida Moojea-Te ◽  
Adisai Rungvichaniwat ◽  
Kannika Sahakaro
Keyword(s):  
Natural Rubber ◽  
Heat Generation ◽  
Extrusion Process ◽  
Die Swell ◽  
Rubber Compound ◽  
Output Rate ◽  
Extrusion Rate ◽  
Rubber Compounds ◽  
Filler Dispersion ◽  
Mooney Viscosity

Rubber processing oil based on modified epoxidized vegetable oils (m-EVO) was prepared by a reaction of epoxidized palm oil EPO) or epoxidized soybean oil (ESBO) with N-Phenyl-ρ-phenylenediamine (PPD) at a mole ratio of 1:0.5. The comparison of m-EVO with aromatic oil (Treated distillate aromatic extract, TDAE) on extrusion process behaviors (output rate, extrusion rate, screw efficiency, heat generation, die swell, extrudate appearance) of carbon black (N330) filled natural rubber (NR) compound was made. It was found that the mooney viscosity of m-EVO based natural rubber compounds are slightly higher than that of the TDAE based natural rubber compound (ML(1+4)100°C: m-ESBO 65.5±0.7; m-EPO 59.7±0.2; TDAE 56.5±1.0), which probably due to the poorer filler dispersion in the compounds. The extrusion process behaviors for output rate (g/min: m-ESBO 191.0±0.6; m-EPO 191.2±0.4; TDAE 195.5±0.6), extrusion rate (cm3/min: m-ESBO 179.6±0.6; m-EPO 183.2±0.4; TDAE 186.4±0.6) and screw efficiency (%: m-ESBO 30.8±0.6; m-EPO 31.4±0.4; TDAE 32.0±0.6). All the three compounds show similar extrusion process behaviors in which the TDAE based compounds shows a marginal higher values than the m-EVO as its lower mooney viscosity lead to a better flow. The m-EPO and m-ESBO based natural rubber compounds show very similar extrusion process behaviors. The heat generation (°C: m-ESBO 61.0±0.8; m-EPO 62.1±0.4; TDAE 63.1±1.0) and die swell (%: m-ESBO 11.0±0.7; m-EPO 11.0±0.5; TDAE 12.7±0.3) of the m-EVO based natural rubber compounds are slightly lower than those of the TDAE based natural rubber compound. As there are no significant differences in the extrusion process behaviors, with respect to extrusion process, m-EVO can be used to replace TDAE oil.

scholarly journals Investigations into the Potential Abrasive Release of Nanomaterials due to Material Stress Conditions-Part A: Carbon Black Nano-Particulates in Plastic and Rubber Composites

2019 ◽  
Vol 9 (2) ◽  
pp. 214 ◽  
Author(s):  
Johannes Bott ◽  
Roland Franz
Keyword(s):  
Carbon Black ◽  
Dynamic Stress ◽  
Laser Light ◽  
Stress Test ◽  
Stress Conditions ◽  
Rubber Composites ◽  
Test Protocol ◽  
Rubber Compounds ◽  
Plastic Materials ◽  
Surface Particle

Plastic and rubber based composites containing carbon black (CB) were investigated for the potential to release CB nano-particulates under stress conditions into food simulants. Nanocomposites were exposed to thermal, chemical, and mechanical stress, followed by mechanical abrasion of their surface. Particle sensitive asymmetric flow field-flow fractionation (AF4) with multi angle laser light scattering (MALLS) detection was used to detect and quantify CB nano-particulates. This study demonstrates that, even under dynamic stress conditions, CB nano-particulates are not released from the plastic or rubber compounds into food. This study intends also to propose a general nano-release stress test protocol for plastic materials coming into contact with foodstuff.

The Relationship Between Design, Processing and Shot Peening on Wheel Plate Failures

2014 ◽  
Author(s):  
Steven L. Dedmon
Keyword(s):  
Fatigue Life ◽  
Residual Stresses ◽  
Cold Rolling ◽  
Shot Peening ◽  
Cyclic Stresses ◽  
Compressive Stresses ◽  
Freight Car ◽  
The Relationship ◽  
Fatigue Failures ◽  
Improve Fatigue

Wheel plate failures occur rarely in North American freight car service. When they do occur, derailments are a likely result. Shot peening has been used to improve fatigue life for more than 80 years and the efficacy of the process is now undisputed in reducing fatigue failures of parts subjected to high levels of cyclic stresses. The introduction of residual compressive stresses from shot peening is acknowledged as the reason for the improvement in fatigue life; comparable processes such as cold rolling, are successful for the same reason. Since residual stresses are so important to fatigue life, then design and processing prior to shot peening should have an equally important role. This investigation demonstrates some of the variables which are important to producing wheels resistant to plate fatigue failures.

The Goodrich Flexometer

1938 ◽  
Vol 11 (1) ◽  
pp. 249-262 ◽  
Author(s):  
E. T. Lessig
Keyword(s):  
Heat Generation ◽  
Test Piece ◽  
Applied Load ◽  
Structural Changes ◽  
Elevated Temperatures ◽  
Simple Design ◽  
Test Pieces ◽  
Rubber Compounds ◽  
Rubber Fabric

Abstract The Goodrich flexometer is of simple design and is easily operated at ordinary or elevated temperatures. Test pieces procured from laboratory specimens or from finished rubber or rubber-fabric products may be tested, using moderate loads that produce equilibrium temperatures during flexure or larger loads that rupture the test piece. This machine may be used to study the effects on heat generation of the time of cure, the magnitude of the applied load, changes in pigmentation, and variations caused by anisotropy in rubber compounds. It is so designed that the structural changes such as softening or stiffening may be followed during the period of flexure.

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