Fatigue Characteristics of Open-End Thick-Walled Cylinders Under Cyclic Internal Pressure

1963 ◽  
Vol 85 (4) ◽  
pp. 555-565 ◽  
Author(s):  
T. E. Davidson ◽  
R. Eisenstadt ◽  
A. N. Reiner
Keyword(s):  
Fatigue Crack ◽  
Internal Pressure ◽  
Stress Level ◽  
Cyclic Stress ◽  
Diameter Ratio ◽  
Tensile Fatigue ◽  
Stress Levels ◽  
Fatigue Characteristics ◽  
Using Data ◽  
Rate Of Improvement

Thick-walled cylinder fatigue data due to cyclic internal pressure for open-end cylinders in the range of 103 to 105 cycles to failure and having a diameter ratio of 1.4 to 2.0 at a nominal yield strength of 160,000 pounds per square inch is presented. Discussed and also presented are the effects of autofrettage on the fatigue characteristics of thick-walled cylinders. Autofrettage substantially enhances fatigue characteristics at stress levels below the corresponding overstrain pressure, the degree of improvement increasing the decreasing stress levels. The rate of improvement in fatigue characteristics increases significantly with diameter ratio in autofrettaged cylinders up to a diameter ratio of 1.8–2.0 and to a much smaller degree in the nonautofrettaged condition. The rate of improvement of fatigue characteristics above 2.0 is the same for both the autofrettaged and nonautofrettaged cases. It is shown that thermal treatment of 675 F for 6 hours after autofrettage does not affect fatigue characteristics and that there is a correlation between the cyclic-stress level and the area and depth of the fatigue crack to the point of ductile rupture. The depth of the fatigue crack decreases with increasing cyclic-stress level. A means for using data from a unidirectional tensile fatigue test to predict the fatigue characteristics of thick-walled cylinders is discussed.

scholarly journals Study on the Influence of Different Prophase Stress Levels on the Fatigue Damage Characteristics of Granite

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Tianzuo Wang ◽  
Mengya Xue ◽  
Peng Sha ◽  
Fei Xue ◽  
Linxiang Wang
Keyword(s):  
Fatigue Damage ◽  
Stress Level ◽  
Development Trend ◽  
Cyclic Stress ◽  
Tangent Modulus ◽  
Dissipated Energy ◽  
Upper Limit ◽  
Stress Levels ◽  
Number Of Cycles ◽  
The Development Trend

In order to reveal the influence of prophase stress levels on the fatigue damage characteristics of granite, uniaxial fatigue tests of granite with different prophase stress levels were carried out on the basis of the MTS 815.04 rock mechanics test system. The results show that, under the same number of cycles, the failure degree increases with the increase of the prophase stress level. Under the low upper limit of cyclic stress, the tangent modulus and dissipated energy increase significantly with the increase of prophase stress level at the early stage of the cycle loading, while the increasing trend is not obvious with the increase of prophase stress level at the late stage. Under the high upper limit of cyclic stress, the tangent modulus and dissipated energy are less affected by the prophase stress level. The development trend of elastic release energy is not obvious with the increase of prophase stress level, which is less affected by the number of cycles. From the damage parameters defined by dissipative energy, under the low upper limit of cyclic stress, the initial damage is less affected by the prophase stress level. With the increase of the number of cycles, the influence of the prophase stress level on the development trend of the damage variable increases gradually. And the development trend of damage variables shows “C-shaped” damage.

PROBABILISTIC SPECIMEN PROPERTY-FATIGUE LIFE MAPPING AND P-S-N CURVE FITTING

2013 ◽  
Vol 20 (05) ◽  
pp. 1350020
Author(s):  
LIYANG XIE ◽  
JIANZHONG LIU ◽  
NINGXIANG WU ◽  
WENXUE QIAN
Keyword(s):  
Fatigue Life ◽  
Test Data ◽  
Stress Level ◽  
Curve Fitting ◽  
Cyclic Stress ◽  
Small Sample ◽  
Test Method ◽  
Life Distribution ◽  
Stress Levels ◽  
Curve Fitting Method

Fitting P-S-N curve with small-size sample of fatigue test data is significant in engineering applications. Although several small sample-based P-S-N curve fitting methods have been developed, complexity in mathematics and/or the unrealistic assumption of the methods hinder their application seriously. Based on the principle of probabilistically mapping from the probability distribution of specimen property to that of fatigue life of the specimen, this paper presents a new, easy to apply P-S-N curve fitting method. By collecting the life distribution information dispersed in several small-size samples of fatigue lives tested under different cyclic stress levels, a large-size sample of equivalent fatigue life data can be built based on the mapping mechanism as well as the uniqueness of the relationship between fatigue life standard deviation and cyclic stress level. The basic viewpoint is that the fatigue lives tested at any cyclic stress levels can be equivalently converted to an arbitrary baseline stress level according to the life distribution–stress relationship, and this principle can be applied to determine the P-S-N curves with a limited number of test data. Test results illustrate that the P-S-N curves obtained by such methods with 30, 24 or 20 samples, respectively, are close to those obtained by the conventional test method with 60 or 40 samples.

Conjectures, Hypotheses, and Theories of Drumlin Formation (In memory of Stanislaw Baranowski)

1981 ◽  
Vol 27 (97) ◽  
pp. 503-505 ◽  
Author(s):  
Ian J. Smalley
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Stress Level ◽  
Critical Stress ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Glacial Till ◽  
Forming Process ◽  
Stress Levels

AbstractRecent investigations have shown that various factors may affect the shear strength of glacial till and that these factors may be involved in the drumlin-forming process. The presence of frozen till in the deforming zone, variation in pore-water pressure in the till, and the occurrence of random patches of dense stony-till texture have been considered. The occurrence of dense stony till may relate to the dilatancy hypothesis and can be considered a likely drumlin-forming factor within the region of critical stress levels. The up-glacier stress level now appears to be the more important, and to provide a sharper division between drumlin-forming and non-drumlin-forming conditions.

scholarly journals Corrosion Fatigue Characteristics of 316L Stainless Steel Fabricated by Laser Powder Bed Fusion

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1046
Author(s):  
Balachander Gnanasekaran ◽  
Jie Song ◽  
Vijay Vasudevan ◽  
Yao Fu
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Corrosion Fatigue ◽  
Fatigue Properties ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Corrosion Properties ◽  
Powder Bed ◽  
Fatigue Characteristics

Laser powder bed fusion (LPBF) has been increasingly used in the fabrication of dense metallic structures. However, the corrosion related properties of LPBF alloys, in particular environment-assisted cracking, such as corrosion fatigue properties, are not well understood. In this study, the corrosion and corrosion fatigue characteristics of LPBF 316L stainless steels (SS) in 3.5 wt.% NaCl solution have been investigated using an electrochemical method, high cycle fatigue, and fatigue crack propagation testing. The LPBF 316L SSs demonstrated significantly improved corrosion properties compared to conventionally manufactured 316L, as reflected by the increased pitting and repassivation potentials, as well as retarded crack initiation. However, the printing parameters did not strongly affect the pitting potentials. LPBF samples also demonstrated enhanced capabilities of repassivation during the fatigue crack propagation. The unique microstructural features introduced during the printing process are discussed. The improved corrosion and corrosion fatigue properties are attributed to the presence of columnar/cellular subgrains formed by dislocation networks that serve as high diffusion paths to transport anti-corrosion elements.

Application of the R-Curve Concept to Fatigue Crack Growth

1978 ◽  
Vol 100 (4) ◽  
pp. 416-420 ◽  
Author(s):  
D. P. Wilhem ◽  
M. M. Ratwani
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Extension ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Crack Growth Resistance ◽  
Resistance Curve ◽  
Cyclic Stress Ratio ◽  
Wide Range

Crack growth resistance for both static (rising load) and for cyclic fatigue crack growth has been shown to be a continuous function over a range of 0.1 μm to 10 cm in crack extension for 2024-T3 aluminum. Crack growth resistance to each fatigue cycle of crack extension is shown to approach the materials ordinary undirectional static crack resistance value when the cyclic stress ratio is zero. The fatigue crack extension is averaged over many cycles and is correlated with the maximum value of the crack tip stress intensity, Kmax. A linear plot of crack growth resistance for fatigue and static loading data shows similar effects of thickness, stress ratio, and other parameters. The effect of cyclic stress ratio on crack growth resistance for 2219 aluminum indicates the magnitude of differences in resistance when plotted to a linear scale. Prediction of many of these trends is possible using one of several available crack growth data correlating techniques. It appears that a unique resistance curve, dependent on material, crack orientation, thickness, and stress/physical environment, can be developed for crack extensions as small as 0.076 μm (3 μ inches). This wide range, crack growth resistance curve is seen of immense potential for use in both fatigue and fracture studies.

Fatigue crack growth of filament wound GRP pipes with a surface crack under cyclic internal pressure

2008 ◽  
Vol 43 (16) ◽  
pp. 5569-5573 ◽  
Author(s):  
Ahmet Samanci ◽  
Ahmet Avci ◽  
Necmettin Tarakcioglu ◽  
Ömer Sinan Şahin
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Internal Pressure ◽  
Crack Growth ◽  
Surface Crack ◽  
Filament Wound

الضغوط المهنية لدى معلمي ومعلمات التربية المهنية في الأردن في ضوء بعض المتغيرات

2019 ◽  
Vol 7 (2) ◽  
pp. 59-67
Author(s):  
Sameer Shdaifat ◽  
Jaafar Abusaa
Keyword(s):  
Public Schools ◽  
Occupational Stress ◽  
Stress Level ◽  
Primary Teachers ◽  
Male Teachers ◽  
Ministry Of Education ◽  
Occupational Education ◽  
The Public ◽  
Significant Difference ◽  
Stress Levels

The present study aimed to identify the occupational stress level of occupational education female and male teachers. It also aimed to identify whether there is any difference between the respondents’ occupational stress levels which can be attributed to their (gender, experience or school stage). The study’s population consists from all the all the occupational education female and male teachers who work at the public schools affiliated with the first and second directorates of education in Irbid (i.e. 320 teachers). As for the sample, it consists from 100 female and male teachers. Those teachers were selected through using the random stratified sampling method. Those teachers were selected from the public schools affiliated with the first and second directorates of education in Irbid. The researchers chose a descriptive survey research design. They developed an instrument (i.e. a questionnaire) for measuring the occupational stress level of teachers. It was found that the occupational stress level of the occupational education female and male teachers is high. It was found that there is a statistically significant difference between the respondents’ occupational stress levels which can be attributed to gender. The latter difference is for the favor of males.  It was found that there is a statistically significant difference between the respondents’ occupational stress levels which can be attributed to experience. The latter difference is for the favor of the ones who possess moderate experience. It was found that there is a statistically significant difference between the respondents’ occupational stress levels which can be attributed to the school stage. The latter difference is for the favor of the lower primary teachers. In the light of the aforementioned results, the researchers recommend exerting effort to reduce the occupational stress level of occupational education female and male teachers. Such efforts include creating convenient psychological and occupational environments. The researchers also recommend providing the lower primary teachers with attention by the Ministry of Education in Jordan. That can be done through providing those teachers with training & development programs. That can be also done through raising their socio-economic levels and providing them with financial & moral incentives & rewards.

Relationship of Fiber Intake, Stress Level, Physical Activity with Blood Pressure of Pre Elderly and Elderly in Lubang Buaya and Kampung Tengah

2021 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Eti Cahya Fitrianti ◽  
Sintha Fransiske Simanungkalit
Keyword(s):  
Physical Activity ◽  
Blood Pressure ◽  
Stress Level ◽  
Blood Pressure Measurement ◽  
Bivariate Analysis ◽  
P Value ◽  
Fiber Intake ◽  
Chi Square ◽  
Stress Levels ◽  
Chi Square Test

High blood pressure is defined as systolic blood pressure that is equal to or above 140 mm Hg or diastolic blood pressure equal to or above 90 mm Hg (JNC VIII, 2013). In 2018, the prevalence of hypertension in Indonesia is based on the characteristics of the age 45-75 years and above with an average of 58.33% (Riskesdas, 2018). The aimed of this study was to determine of fiber intake, stress levels, and physical activity with blood pressure in pre elderly and elderly at RW 03 Lubang Buaya and RW 09 Kampung Tengah, East Jakarta. This research method is observational with cross sectional approach followed by 80 respondents with simple random sampling technique Data collection was taken, namely blood pressure measurement using a Sphygmomanometer, fiber intake using the Food Recall form 2 x 24 hours (Weekend and Weekday), stress levels with the DASS-14 questionnaire, and physical activity with the Baecke questionnaire. Data processing was analyzed by univariate and bivariate using Chi-Square test. The results of bivariate analysis with chi-square test showed a significant relationship between fiber intake (p value = 0.007), stress level (p value = 0,000), and physical activity (p value = 0.022) with blood pressure. There is a relationship between fiber intake, stress level, and physical activity with blood pressure in the elderly and elderly in Lubang Buaya and Kampung Tengah.

scholarly journals The Relationship between Nutritional Status, Sleep Duration, Stress Level with Blood Pressure of Nurse Night Shift in the Hospital: Cohort Study

2019 ◽  
Vol 4 (1) ◽  
pp. 55
Author(s):  
Salmawati Salmawati ◽  
Ari Natalia Probandari ◽  
Sapja Anantanyu
Keyword(s):  
Blood Pressure ◽  
At Risk ◽  
Nutritional Status ◽  
Sleep Duration ◽  
Stress Level ◽  
Night Shift ◽  
Anthropometric Measurement ◽  
Short Sleep Duration ◽  
Stress Levels ◽  
The Relationship

Objective: Hypertension as a cardiovascular disease occurs due to an uncontrolled increase in blood pressure. Night shift nurses with more overweight, short sleep duration, and excessive stress levels are at risk of increase blood pressure. This study aims to analyze how the relationship between obesity, nutritional status, sleep duration and stress level influence the blood pressure of the night shift nurses.Materials and methods: The subjects in this study were night shift nurses in four hospitals. The dependent variable was blood pressure and the independent variables were nutritional status, sleep duration, and stress levels. This study was an observational analysis with a perspective cohort design in which the subjects were 312 night shift nurses. Nutritional status were identified from Body Mass Index (BMI) through anthropometric measurement, sleep duration by looking at average hours of sleep during the night service, stress levels through the Perceived Stress Scale (PSS-10) questionnaire. Blood pressure was measured using a mercury sphygmomanometer. Data were analyzed by Chi-square test and Logistic Regression.Results and Discussion: There was a significant relationship between nutritional status, sleep duration, and stress levels with blood pressure. The results of the multivariate analysis showed that the shift nurses with overweight (obesity) nutritional status are at a risk of having disorder 1.97 times, the shift nurses with sleep duration < 6 hours are at risk of having disorder 3.78 times and shift nurses with intermediate stress level at risk of having disorder 2.08 times with enhancement blood pressure.Conclusion: There is a relationship between nutritional status, sleep duration and stress level with blood pressure. Sleep duration mostly influences the blood pressure.International Journal of Human and Health Sciences Vol. 04 No. 01 January’20 Page : 55-59

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