Biaxial Fatigue Testing Of Vulcanizates

1961 ◽  
Vol 34 (2) ◽  
pp. 506-526 ◽  
Author(s):  
S. D. Gehman ◽  
P. Rohall ◽  
D. I. Livingston
Keyword(s):  
Fatigue Life ◽  
Carbon Black ◽  
Natural Rubber ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Biaxial Fatigue ◽  
Wide Range ◽  
Different Types ◽  
Extreme Probability ◽  
General Service

Abstract Extensive fatigue tests of vulcanizates of natural rubber and SBR were carried out using a cycle of alternate stretching in two perpendicular directions. It is shown that the data can be best handled statistically by assuming a lognormal distribution or by the use of extreme probability techniques. Illustrative results are given to compare the fatigue life of different types of SBR ; to show the value of the method for studying the effects of processing variations on fatigue life ; to determine the effect of various loadings of different types of carbon black; and to evaluate the effectiveness of anitoxidants and antiozonants. Exploratory tests using ozone instead of pinholes to initiate the failure eliminated the wide range in fatigue life between natural rubber and SBR, and in this respect gave a result which is more consistent with general service experience. This type of biaxial fatigue testing has many areas of usefulness for developing good endurance qualities in vulcanizates.

scholarly journals Fatigue Testing of Wearable Sensing Technologies: Issues and Opportunities

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4070
Author(s):  
Andrea Karen Persons ◽  
John E. Ball ◽  
Charles Freeman ◽  
David M. Macias ◽  
Chartrisa LaShan Simpson ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Wearable Sensors ◽  
Fatigue Tests ◽  
Proof Of Concept ◽  
Cycle Fatigue ◽  
Wearable Sensing ◽  
Failure Data

Standards for the fatigue testing of wearable sensing technologies are lacking. The majority of published fatigue tests for wearable sensors are performed on proof-of-concept stretch sensors fabricated from a variety of materials. Due to their flexibility and stretchability, polymers are often used in the fabrication of wearable sensors. Other materials, including textiles, carbon nanotubes, graphene, and conductive metals or inks, may be used in conjunction with polymers to fabricate wearable sensors. Depending on the combination of the materials used, the fatigue behaviors of wearable sensors can vary. Additionally, fatigue testing methodologies for the sensors also vary, with most tests focusing only on the low-cycle fatigue (LCF) regime, and few sensors are cycled until failure or runout are achieved. Fatigue life predictions of wearable sensors are also lacking. These issues make direct comparisons of wearable sensors difficult. To facilitate direct comparisons of wearable sensors and to move proof-of-concept sensors from “bench to bedside,” fatigue testing standards should be established. Further, both high-cycle fatigue (HCF) and failure data are needed to determine the appropriateness in the use, modification, development, and validation of fatigue life prediction models and to further the understanding of how cracks initiate and propagate in wearable sensing technologies.

scholarly journals Experimental Design and Validation of an Accelerated Random Vibration Fatigue Testing Methodology

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Jiang ◽  
Gun Jin Yun ◽  
Li Zhao ◽  
Junyong Tao
Keyword(s):  
Fatigue Life ◽  
Stress Responses ◽  
Life Prediction ◽  
Random Vibration ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Power Spectral ◽  
Vibration Fatigue ◽  
Non Gaussian

Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a notched specimen structure were measured under different base random excitations. According to the measured stress responses, the structural fatigue lives corresponding to the different vibrational excitations were predicted by using the WAFO simulation technique. Second, a couple of destructive vibration fatigue tests were carried out to validate the accuracy of the WAFO fatigue life prediction method. After applying the proposed experimental and numerical simulation methods, various factors that affect the vibration fatigue life of structures were systematically studied, including root mean squares of acceleration, power spectral density, power spectral bandwidth, and kurtosis. The feasibility of WAFO for non-Gaussian vibration fatigue life prediction and the use of non-Gaussian vibration excitation for accelerated fatigue testing were experimentally verified.

scholarly journals Ultrasonic fatigue testing under multiaxial loading conditions on a railway wheel

2019 ◽  
Vol 300 ◽  
pp. 18003 ◽  
Author(s):  
Pedro R. da Costa ◽  
Henrique Soares ◽  
Luís Reis ◽  
Manuel Freitas
Keyword(s):  
Stress Ratio ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Cycle Frequency ◽  
Railway Wheel ◽  
Material Specimen ◽  
Hydraulic Machines ◽  
Wide Range ◽  
Ultrasonic Fatigue ◽  
Very High

Ultrasonic fatigue testing is a relative recent fatigue methodology that uses resonant principles for the induction of stress cycles in a specific designed material specimen. This experimental method can apply very high cycle frequency, the most common frequency being 20 kHz, and was created with the main purpose of studying material fatigue life in the Very High Cycle Fatigue regime between 107 and 109 cycles with a higher performance of time and energy wise in comparison to conventional servo-hydraulic machines. In this study an improvement of an already built multiaxial ultrasonic fatigue machine in the Instituto Superior Técnico laboratories was carried out to specific designed specimens and afterwards a fatigue study was made for a material of a worn-out railway wheel. The particular design of the specimen was achieved by numerical and experimental analysis based on previous experiments and components. Thermographic imaging and the application of rosette strain gauges to the main throat of the specimens were conducted in order to validate the improved specimen design and to understand the real induced stresses on the specimen. Afterwards fatigue tests were conducted for several specimens for a wide range of stresses with a stress ratio R=-1 and an axial vs shear stress ratio of around 0.58. Results were analysed and fracture analysis was also carried out.

QUANTIFICATION OF THE CONTRIBUTION OF FILLER CHARACTERISTICS TO NATURAL RUBBER REINFORCEMENT USING PRINCIPAL COMPONENT ANALYSIS

2018 ◽  
Vol 91 (1) ◽  
pp. 79-96 ◽  
Author(s):  
Cindy S. Barrera ◽  
Alfred B. O. Soboyejo ◽  
Katrina Cornish
Keyword(s):  
Principal Component Analysis ◽  
Carbon Black ◽  
Natural Rubber ◽  
Polymer Composites ◽  
Principal Component ◽  
Component Analysis ◽  
Specific Product ◽  
Industrial Residues ◽  
Explanatory Variables ◽  
Wide Range

ABSTRACT Practical statistical models were developed to quantify individual contributions from characteristics of conventional and non-conventional fillers and predict resulting mechanical properties of both hevea and guayule natural rubber composites. Carbon black N330 and four different agro-industrial residues, namely, eggshells, carbon fly ash, processing tomato peels, and guayule bagasse, were used in this study. Filler characteristics were used as explanatory variables in multiple linear regression analyses. Principal component analysis was used to evaluate correlations among explanatory variables based on their correlation matrices and to transform them into a new set of independent variables, which were then used to generate reliable regression models. Surface area, dispersive component of surface energy, carbon black, and waste-derived filler loading were found to have almost equal importance in the prediction of composite properties. However, models developed for ultimate elongation poorly explained variability, indicating the dependence of this property on other variables. Agro-industrial residues could potentially serve as more sustainable fillers for polymer composites than conventional fillers. This new modeling approach for polymer composites allows the performance of a wide range of different waste-derived fillers to be predicted with minimum laboratory work, facilitating the optimization of compound recipes to address specific product requirements.

Relationship Between Fatigue Life Distribution, Notch Configuration, and S-N Curve of a 2024-T4 Aluminum Alloy

1985 ◽  
Vol 107 (3) ◽  
pp. 214-220 ◽  
Author(s):  
T. Shimokawa ◽  
Y. Hamaguchi
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Life ◽  
Stress Amplitude ◽  
Fatigue Tests ◽  
Test Results ◽  
Notched Specimens ◽  
Wide Range ◽  
Life Distributions ◽  
The Relationship ◽  
Test Stress

The objective of this study is to identify the most closely related variable to the distribution of fatigue life in unnotched and three kinds of notched 2024-T4 aluminum alloy specimens. Carefully designed fatigue tests under a constant temperature and humidity condition provided fatigue life distributions over a wide range of stress amplitude. This study used about 1000 specimens. On the basis of the test results, the dependence of the scatter in fatigue life on notch configuration, the period to crack initiation, the level of stress amplitude, the median fatigue life, and the slope of the median S-N curve is investigated, and the relationship between the distributional form of fatigue life and the shape of the median S-N curve is discussed. It is concluded that the slope and shape of the median S-N curve in the vicinity of the test stress level are closely related to the scatter and distributional form of fatigue life respectively. This is common to the unnotched and three kinds of notched specimens. A variability hypothesis to correlate the median S-N curve with fatigue life distributions is examined.

Block-Programme Fatigue Testing of Automobile Wheel Spindles

1973 ◽  
Vol 187 (1) ◽  
pp. 295-299 ◽  
Author(s):  
J. D. Tedford ◽  
B. Crossland
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Normal Load ◽  
Mean Value ◽  
Fatigue Tests ◽  
Test Sequence ◽  
Testing Time ◽  
Constant Frequency ◽  
Stress Levels ◽  
Life Function

The paper reports the results of fatigue tests carried out on Ford Capri wheel spindle bodies. The first three programmes were aimed at investigating the effect of the sequence in which the loads were applied in a multilevel constant-frequency block programme. A further programme was carried out to investigate the effect on the fatigue life of removing the low-load cycles from the test sequence. The first three programmes demonstrated that the sequence in which individual blocks were applied had no significant effect on the fatigue life. From the fourth programme it was concluded that the removal of stress levels equal to and less than 1·75 times the r.m.s. (root mean square) value of the normal load frequency distribution had no effect on the fatigue damage. If these stress levels are removed there is an 87 1/2 per cent reduction in testing time. The slopes of the life function curves for all four programmes were nearly identical, and gave a mean value of 6·9 which is in agreement with other workers. Lastly it was concluded that tests on small notched cantilever specimens led to very similar conclusions, and that such specimens could be used for proving and developing testing programmes.

A Study on Fatigue Behavior of SM490A Steel under Low Temperature

2007 ◽  
Vol 353-358 ◽  
pp. 142-145 ◽  
Author(s):  
Ki Weon Kang ◽  
Byeong Choon Goo ◽  
J.H. Kim ◽  
Heung Seob Kim ◽  
Jung Kyu Kim
Keyword(s):  
Fatigue Life ◽  
Low Temperature ◽  
Test Temperature ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Testing Machine ◽  
Fatigue Tests ◽  
Static Strength ◽  
Experimental Results ◽  
Railway Vehicle

This paper deals with the fatigue behavior and its statistical properties of SM490A steel at various temperatures, which is utilized in the railway vehicle. For these goals, the tensile ad fatigue tests were performed by using a servo-hydraulic fatigue testing machine at three temperatures: +20°C, -10°C and -40°C. The static strength and fatigue limits of SM490A steel were increased with decreasing of test temperature. The probabilistic properties of fatigue behavior are investigated by means of probabilistic stress-life (P-S-N) curve and they are well in conformance with the experimental results regardless of temperature. Also, based on P-S-N curves, the variation of fatigue life is investigated and as the temperature decreases, the variation of fatigue life increases moderately.

Modeling of Carbon Black Filled Natural Rubber Vulcanizates by the Standard Triboelastic Solid

1999 ◽  
Vol 72 (4) ◽  
pp. 673-683 ◽  
Author(s):  
V. A. Coveney ◽  
D. E. Johnson
Keyword(s):  
Mathematical Modeling ◽  
Carbon Black ◽  
Natural Rubber ◽  
Dynamic Behavior ◽  
Low Frequency ◽  
Specific Reference ◽  
Published Data ◽  
General Terms ◽  
Wide Range ◽  
Natural Rubber Vulcanizates

Abstract Mathematical modeling of the dynamic behavior of vulcanizates is reviewed with the emphasis on carbon black filled natural rubber (NR). The 3 constant standard triboelastic solid (STS) model and its behavior are described, in general terms and with specific reference to low frequency shear data for a wide range of filled NR vulcanizates. Good general agreement is found between model and experiment for the data obtained at strain amplitudes down to 0.01; there is also acceptably good correlation between carbon black loading and values of STS constants. For previously published data down to very low strain amplitudes (1×10−4), agreement is much less satisfactory.

Fatigue Properties of a Ck45 Steel Coated with a Post-Heat Treated Ni-Cu-P Electroless Deposit

2006 ◽  
Vol 514-516 ◽  
pp. 574-578
Author(s):  
Sasan Yazdani ◽  
N. Parvini-Ahmadi ◽  
Tohid Saeid
Keyword(s):  
Fatigue Life ◽  
Fatigue Testing ◽  
Crack Nucleation ◽  
Fatigue Cracks ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Interfacial Cracks ◽  
Heat Treated ◽  
Base Steel ◽  
Surface Notch

The Fatigue tests under rotating bending conditions have been conducted on samples of a quenched and tempered Ck45 steel in two different conditions: (a) uncoated, (b) coated with an electroless Ni-Cu-P deposit, followed by a post-heat treatment (PHT) at 673 K for 1 h. Such a deposit had a thickness of approximately 10µm, with Cu and P contents of 6wt.% and 13.7wt.% respectively. The results indicate that plating the base steel with this kind of deposit leads to a reduction of the fatigue life of the material. The reduction in fatigue life has been quantified in terms of the Basquin parameters of the materials tested under different conditions. The microscopic observation of the fracture surfaces of the samples indicates that the reduction in fatigue life is associated with the nucleation of fatigue cracks on the coating-substrate interface and the deposit remains well adhered to substrate during fatigue testing since interfacial cracks have been very rarely observed. It is therefore concluded that, in the present case, the interface acts as a surface crack source or surface notch, which decreases the fatigue life of the coated material by reducing the crack nucleation stage.

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