FE fracture analysis, using the integral J and tearing energy T parameters, of a natural rubber NR

2021 ◽  
Author(s):  
Adel Hamdi ◽  
Abdelkader Boulenouar ◽  
Zaineb Baccouch
Keyword(s):  
Natural Rubber ◽  
Fracture Analysis ◽  
Tearing Energy

COMPARISON OF SINE VERSUS PULSE WAVEFORM EFFECTS ON FATIGUE CRACK GROWTH BEHAVIOR OF NR, SBR, AND BR COMPOUNDS

2010 ◽  
Vol 83 (4) ◽  
pp. 391-403 ◽  
Author(s):  
G. Andreini ◽  
P. Straffi ◽  
S. Cotugno ◽  
G. Gallone ◽  
G. Polacco
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Natural Rubber ◽  
Crack Growth ◽  
Fine Tuning ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Pulse Waveform ◽  
Tearing Energy ◽  
Styrene Butadiene

Abstract Fatigue crack growth experiments on carbon black-filled rubber compounds have been carried out to evaluate the influence of testing conditions over different compound formulations. Investigations on the influence of waveform, data acquisition, and compound formulation have been performed on strip-tensile specimens reproducing the mode I of crack opening. The response of three different compound formulations (based on either natural rubber, butadiene rubber, or styrene-butadiene rubber) to the application of two different waveforms, pulse and sine, has been analyzed, showing significant differences in fatigue behavior and ranking of the various compounds. Compared to the sinusoidal waveform, the use of a pulse waveform provided an improved correlation of the tearing energy with the crack propagation speed. This difference was particularly evident in the case of natural rubber and butadiene rubber, while it resulted negligible in the case of styrene-butadiene rubber. Such a different behavior could be attributed to differences in macromolecular chains orientation. Fine-tuning of video acquisition parameters provided an accurate observation of the crack growth process, as confirmed by the low standard deviation of the estimated tearing energy and crack growth rate.

Effect of Epoxidized Oil on Tensile and Tear Strength of NR Vulcanizate and its Comparison with Aromatic Oil NR Vulcanizates

2013 ◽  
Vol 812 ◽  
pp. 204-209 ◽  
Author(s):  
Mohamed Rahmah ◽  
Wan Zain Norazira ◽  
Ahmad Faiza Mohd ◽  
Mohd Nurazzi Norizan
Keyword(s):  
Tensile Strength ◽  
Natural Rubber ◽  
Rubber Compound ◽  
Tear Strength ◽  
Green Component ◽  
Strength Tests ◽  
Tearing Energy ◽  
Polymer Industry ◽  
Natural Rubber Vulcanizates

Epoxidized oil (EO) is a sustainable oil that can be obtained form edible or non-edible naturals oil. The incorporation of epoxidized oil can increase the green component in rubber compound. It can contributes to worldwide technology specially in green tyre manufacturing. Epoxidized oil has the potential to replace aromatic oil (AO) to rubber and polymer industry. The effect of incorporation of EO and AO into natural rubber vulcanizates (NR) was studied via tensile and tear strength tests according to ISO 31-1977 and ISO 6133, respectively. Tensile strength of AO value showed greather value compared to EO. Gradual increases of elongation were observed form both AO and EO. Both moduli at 100% and 300% elongation, showed reductions as oil loading were increased. The tear strength results showed that tearing energy insignificantly increased with oil loading. EO compound was found to possess higher tearing energy compared to AO compound for most composition except for 15 pphr EO.

Role of Ozone in Dynamic Cut Growth of Rubber

1966 ◽  
Vol 39 (4) ◽  
pp. 1053-1064
Author(s):  
G. J. Lake ◽  
P. B. Lindley
Keyword(s):  
Natural Rubber ◽  
Test Piece ◽  
Critical Value ◽  
Rate Of Growth ◽  
Tearing Energy

Abstract The effect of ozone on the growth of cuts in rubber strips subjected to repeated tensile deformations has been investigated. At tearing energies below a critical value ozone accounts for all the cut growth, and in this region the rate of growth is substantially independent of tearing energy. At higher tearing energies, cut growth also occurs due to mechanico-oxidative rupture, the rate of this type of growth increasing rapidly with increasing tearing energy so that the effects of ozone are normally slight. For vulcanizates of natural rubber and SBR unprotected by anti-ozonant, the characteristics of dynamic ozone cut growth can be deduced from static measurements. If a natural rubber test piece is not allowed to relax to zero strain on each cycle, the effects of ozone are important over a wider range of tearing energy.

Rupture of Rubber. VI. Further Experiments of the Tear Criterion

1961 ◽  
Vol 34 (1) ◽  
pp. 66-75
Author(s):  
A. G. Thomas
Keyword(s):  
Natural Rubber ◽  
Test Piece ◽  
Fundamental Property ◽  
Elastic Strain Energy ◽  
Test Pieces ◽  
Tearing Energy ◽  
Different Shapes ◽  
Materials Used ◽  
T Values ◽  
Energy Balance Approach

Abstract In previous papers (I to V of this series), a tear criterion for rubbers has been proposed based on an energy balance approach. This equates the energy required to form new surfaces (the tearing energy) with the loss of elastic strain energy in the test piece. The tearing energy T is assumed to be characteristic of the material and so independent of the overall shape of the test piece. It is thus the fundamental property controlling tear behavior. The correctness of this approach was investigated by making tear measurements on test pieces of different shapes but of the same material and examining the constancy of the T values obtained. The results were consistent with the theory but not wholly conclusive, due primarily to the particular tearing behavior of the materials used (natural rubber gum vulcanizates). Another limitation was that accurate T values could be obtained only if they could be calculated directly from the measured tearing forces or elongations, and the required relationships were known for only two types of test piece. Clearly, the more test pieces available for comparison and the more they differ from each other in shape, the more stringent the test of the basic theory. In the present paper a third test piece is described, the necessary theory given, and experimental results presented on the three test pieces. By comparing the results from these test pieces, which are of widely different shapes, a critical test of the theory is possible. The choice of the experimental material is influenced by several factors. Previous measurements have been made on natural rubber gum compounds, which have the advantage of possessing excellent elastic properties but whose rupture characteristics are such that tearing occurs at a critical load. In contrast, a gum GR-S tears more or less steadily at a rate depending on the load, a characteristic which is experimentally advantageous for the particular test pieces described here. It was therefore used in this investigation.

scholarly journals Knotty Tear Phenomena and Effect of Maturation Time on Knotty Tear in Filled Natural Rubber Latex Films

2019 ◽  
Vol 8 (4) ◽  
pp. 7013-7017
Keyword(s):  
Natural Rubber ◽  
Protein Content ◽  
Natural Rubber Latex ◽  
Latex Films ◽  
Rubber Latex ◽  
Maturation Time ◽  
Tearing Energy

Knotty tearing is a phenomena normally observed in reinforced black-filled natural rubber (NR) vulcanizate but not in gum NR vulcanizate. Unfortunately the underlying cause of knotty tear is still not fully understood and need to be unraveled. Many factors contribute to knotty tear behavior which include suppression of strain-induce crystallization, protein content of latex, vulcanization temperature and pre-vulcanization and post-vulcanization of latex. In this study, we concentrate on varying the maturation time during compounding process in filled NR latex (NRL) to study knotty tear behavior. The maturation time were varied in the range (0 – 72) hrs; and the tear deviation were measured to determine the extent of knotty tear phenomena. It was found that at the optimum maturation time of 24 hrs samples show highest tearing energy and show knotty tear phenomena with the least angle of tear deviation

Cut Growth and Fatigue of Rubbers. II. Experiments on A Noncrystallizing Rubber

1965 ◽  
Vol 38 (2) ◽  
pp. 301-313 ◽  
Author(s):  
G. J. Lake ◽  
P. B. Lindley
Keyword(s):  
Natural Rubber ◽  
Fatigue Failure ◽  
Fatigue Behavior ◽  
Time Dependent ◽  
Fourth Power ◽  
Dynamic Conditions ◽  
Tensile Fatigue ◽  
Different Temperatures ◽  
Tearing Energy ◽  
Energy Theory

Abstract Tensile fatigue failure of a gum vulcanizate of noncrystallizing SBR can be accounted for by the growth of small flaws initially present in the rubber. Fatigue of crystallizing natural rubber was shown in Part I to be attributable to the same cause. Cut growth results are interpreted in terms of the tearing energy theory of Rivlin and Thomas. SBR exhibits cut growth under both static and dynamic conditions; in each case the rate is approximately proportional to the fourth power of the tearing energy. Variation of the dynamic cut growth rate with frequency can be explained by the summation of a time-dependent static component of growth and a cyclic component not dissimilar to that occurring in natural rubber. Fatigue failure, under both static and dynamic conditions, is predicted from the cut growth results. These predictions are found to account quantitatively for experimentally observed fatigue lives when a suitable value is assumed for the initial flaw size. Fatigue lives at different temperatures correlate well with cut growth results obtained by Greensmith and Thomas over the same temperature range. The results are compared to those obtained previously for natural rubber, and possible reasons for the differences in fatigue behavior of crystallizing and non-crystallizing rubbers are discussed.

Extraction and identification of fillers and pigments from pyrolyzed rubber and tire samples

1996 ◽  
Vol 54 ◽  
pp. 174-175
Author(s):  
P. Sadhukhan ◽  
J. B. Zimmerman
Keyword(s):  
Zinc Oxide ◽  
Electron Microscope ◽  
Carbon Black ◽  
Natural Rubber ◽  
Transmission Electron Microscope ◽  
Rolling Resistance ◽  
Synthetic Polymers ◽  
Nitrogen Atmosphere ◽  
Transmission Electron ◽  
Curing Agents

Rubber stocks, specially tires, are composed of natural rubber and synthetic polymers and also of several compounding ingredients, such as carbon black, silica, zinc oxide etc. These are generally mixed and vulcanized with additional curing agents, mainly organic in nature, to achieve certain “designing properties” including wear, traction, rolling resistance and handling of tires. Considerable importance is, therefore, attached both by the manufacturers and their competitors to be able to extract, identify and characterize various types of fillers and pigments. Several analytical procedures have been in use to extract, preferentially, these fillers and pigments and subsequently identify and characterize them under a transmission electron microscope.Rubber stocks and tire sections are subjected to heat under nitrogen atmosphere to 550°C for one hour and then cooled under nitrogen to remove polymers, leaving behind carbon black, silica and zinc oxide and 650°C to eliminate carbon blacks, leaving only silica and zinc oxide.

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