Fatigue Strength of Welded Tubular T Joints Under Variable Amplitude Loading

1983 ◽  
Vol 105 (2) ◽  
pp. 184-188
Author(s):  
M. Kawahara ◽  
A. Katoh ◽  
T. Iwasaki
Keyword(s):  
Fatigue Strength ◽  
Large Scale ◽  
Fatigue Tests ◽  
Load Spectrum ◽  
Random Loading ◽  
T Joints ◽  
Crack Penetration ◽  
Sequence Patterns ◽  
Load Sequence ◽  
The Difference

This paper describes an experimental study on fatigue strength of welded tubular T joints, performed in small and large-scale models fabricated from mild steel tubes. Fatigue tests were conducted under three kinds of loading patterns: constant amplitude loading, block programmed loading and random loading. In block programmed loading tests, the period of load sequence was varied, while the load spectrum was the same. Thus, the effects of the difference in load sequences upon fatigue lives were examined independently from the effect of load spectrum. Crack initiation life was hardly affected by the load sequence patterns. However, the crack penetration life or failure life were largely affected by types and periods of load sequences. The limit of validity of the Miner’s rule are discussed together with possible interpretations on the effects of the difference in load sequence patterns.

Fatigue Capacity of Stiffener to Web Frame Connections

2009 ◽  
Author(s):  
Torbjo̸rn Lindemark ◽  
Inge Lotsberg ◽  
Joong-Kyoo Kang ◽  
Kwang-Seok Kim ◽  
Narve Oma
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
Large Scale ◽  
Fatigue Tests ◽  
Life Assessment ◽  
Shear Stresses ◽  
Test Model ◽  
The Difference ◽  
Marine Engineering ◽  
Plate Connections

Daewoo Shipbuilding & Marine Engineering Co., Ltd. (DSME), StatoilHydro and DNV established a common project to investigate the reason for the difference between calculated fatigue lives and the in-service experience and to assess the fatigue capacity of stiffener web connections subjected mainly to web frame shear stresses. The main objective of the work was to establish fatigue test data and perform numerical analysis of collar plate connections in order to provide improved confidence in analysis methodology for fatigue life assessment. Large scale fatigue tests of different types of connections were carried out to obtain fatigue test data of collar plate connections. Finite element analyses were carried out for comparison with fatigue test data and with measured stresses on the test model. Based on this work recommendations on fatigue design analysis of connections between stiffeners and web frames have been derived. The background for this is presented in this paper.

Exploratory Tests on the Effects of Random Loading and Corrosive Environment on the Fatigue Strength of Fillet-Welded Lap Joints

1975 ◽  
Vol 17 (4) ◽  
pp. 181-185 ◽  
Author(s):  
K. J. Marsh ◽  
T. Martin ◽  
J. McGregor
Keyword(s):  
Fatigue Strength ◽  
Mild Steel ◽  
Narrow Band ◽  
Fatigue Tests ◽  
Lap Joints ◽  
Corrosive Environment ◽  
Test Frequency ◽  
Constant Amplitude ◽  
Random Loading ◽  
Loading Tests

Fatigue tests on simple, fillet-welded, mild steel lap joints have been carried out to determine the effects of a corrosive environment and random loading. At normal testing frequencies, a brine-drip environment had no effect on the constant-amplitude fatigue strength at short endurances. At stresses less than the in-air fatigue limit, the corrosive environment was sufficient to allow crack growth at very low stress levels. In these corrosive environment tests, reducing the test frequency by a factor of 50 halved the life. The results of narrow-band random loading tests could be predicted reasonably accurately either by a fracture mechanics method or by Miner's rule.

scholarly journals INFLUENCE OF CARBON CONTENT ON FATIGUE STRENGTH OF DRAWN STEEL TUBES FOR SMALL ONCE-THROUGH BOILER

2012 ◽  
Vol 06 ◽  
pp. 361-366
Author(s):  
DAISUKE YONEKURA ◽  
YUTA FUJIE ◽  
RI-ICHI MURAKAMI ◽  
YUKIHIRO TOKUNAGA
Keyword(s):  
Heat Treatment ◽  
Fatigue Strength ◽  
Carbon Content ◽  
Steel Tube ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Post Heat Treatment ◽  
Steel Tubes ◽  
Heat Treated ◽  
The Difference

Tension-tension fatigue tests were performed to examine the influence of carbon content on the fatigue properties of drawn specific steel tube (STB340) with/without post heat treatment for small once-through boiler. Two different carbon content steel tubes, C =0.06 and 0.12% were prepared. The as-received, as-drawn and post drawing heat treated series for each carbon content tube were prepared for fatigue test. The hardness, grain size and residual stress were measured for each series. As a result, the fatigue strength of as-received and as-drawn series showed a small difference between C =0.06 and 0.12% specimens. However, the post drawing heat treatment series showed obvious difference in the fatigue strength. The fatigue strength of higher carbon content tubes significantly decreased by the post drawing heat treatment, whereas the decrease of fatigue strength was little for lower carbon content heat treated tubes. The difference of fatigue strength was mainly caused by the degree of relaxation of work hardening by post heat treatment.

Effect of Humidity on Fatigue Strength of Age-Hardened Al Alloy

2009 ◽  
Vol 417-418 ◽  
pp. 373-376
Author(s):  
T. Fukudome ◽  
Norio Kawagoishi ◽  
K. Kariya
Keyword(s):  
Fatigue Strength ◽  
Fracture Mechanism ◽  
Fatigue Tests ◽  
Shear Mode ◽  
Al Alloy ◽  
Bending Fatigue ◽  
Rotating Bending Fatigue ◽  
Ultrasonic Fatigue ◽  
Rotating Bending ◽  
The Difference

Ultrasonic and rotating bending fatigue tests were carried out using plain specimens and specimens with a small blind hole for an extruded and age-hardened Al alloy 7075-T6 in different environments in order to investigate the effect of humidity on fatigue strength and fracture mechanism. Fatigue strength was decreased by high humidity under both tests. The effect of humidity on fatigue strength was larger in ultrasonic fatigue. The humidity affected both of crack initiation and propagation processes. Crack propagated in tensile mode then changed to shear mode macroscopically in all environments under ultrasonic fatigue, though it was only in tensile mode under rotating bending fatigue. These differences in fracture mechanism related to the difference in environmental effect on fatigue strength in both tests.

Probabilistic Properties of Fatigue Damage and an Equivalent Damage Simplification Model for Multi-Level Load Spectra

2016 ◽  
Vol 08 (02) ◽  
pp. 1650017 ◽  
Author(s):  
X. R. Liu ◽  
Q. Sun
Keyword(s):  
Fatigue Damage ◽  
Damage Model ◽  
Fatigue Tests ◽  
Al Alloy ◽  
Test Results ◽  
Load Spectrum ◽  
Load Spectra ◽  
Multi Level ◽  
Load Sequence ◽  
Good Agreement

An equivalent fatigue damage simplification model for multi-level load spectrum is proposed. On the basis of the probabilistic fatigue damage model which takes load sequence effect into account and the constant amplitude fatigue tests, probabilistic properties of damage accumulated in one loading block are achieved quantitatively by statistical methods. The new simplification model can ensure that, for the original spectrum and simplified spectrum, the probabilistic properties of fatigue damage are almost the same. Fatigue tests for Al-alloy straight plates are performed to test the validity of the model. The test results are in good agreement with predicted results.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

TO THE PROBLEMS OF COMBATING CORRUPTION IN MODERN RUSSIA AND INTERNATIONAL COOPERATION IN THE FIELD OF ANTI-CORRUPTION

2020 ◽  
Author(s):  
Angela Dranishnikova
Keyword(s):  
Large Scale ◽  
The State ◽  
Point Of View ◽  
Modern Life ◽  
Existing Problems ◽  
Moral Point ◽  
Material Goods ◽  
The Russian Federation ◽  
The Difference ◽  
The Government

In the article, the author reflects the existing problems of the fight against corruption in the Russian Federation. He focuses on the opacity of the work of state bodies, leading to an increase in bribery and corruption. The topic we have chosen is socially exciting in our days, since its significance is growing on a large scale at all levels of the investigated aspect of our modern life. Democratic institutions are being jeopardized, the difference in the position of social strata of society in society’s access to material goods is growing, and the state of society is suffering from the moral point of view, citizens are losing confidence in the government, and in the top officials of the state.

Modeling a random sequence of extremes of loads for fatigue tests under irregular loading

2020 ◽  
pp. 13-19
Author(s):  
N.A. Mahutov ◽  
I.V. Gadolina ◽  
S.G. Lebedinskiy ◽  
E.S. Oganyan ◽  
A.A. Bautin
Keyword(s):  
Random Sequence ◽  
Fatigue Tests ◽  
Linear Hypothesis ◽  
Resource Estimation ◽  
Transition Matrices ◽  
Random Loading ◽  
Markov Transition ◽  
Random Nature ◽  
Irregular Loading ◽  
Markov Transition Matrices

Methods and approaches to tests under random loading are considered, their role is characterized. To ensure the random nature of loading, a modeling method based on Markov transition matrices and real processes recorded in operation is proposed. Keywords: random loading process, Markov repetition matrices, resource estimation, corrected linear hypothesis, parameter of completeness of the loading spectrum. [email protected]

scholarly journals Large-Scale Analysis of the Spatiotemporal Changes of Net Ecosystem Production in Hindu Kush Himalayan Region

2021 ◽  
Vol 13 (6) ◽  
pp. 1180
Author(s):  
Da Guo ◽  
Xiaoning Song ◽  
Ronghai Hu ◽  
Xinming Zhu ◽  
Yazhen Jiang ◽  
...  
Keyword(s):  
Large Scale ◽  
Net Primary Production ◽  
Carbon Sink ◽  
Carbon Sources ◽  
Spatial Dynamics ◽  
Tibet Plateau ◽  
Geostatistical Model ◽  
Hindu Kush ◽  
Temporal And Spatial ◽  
The Difference

The Hindu Kush Himalayan (HKH) region is one of the most ecologically vulnerable regions in the world. Several studies have been conducted on the dynamic changes of grassland in the HKH region, but few have considered grassland net ecosystem productivity (NEP). In this study, we quantitatively analyzed the temporal and spatial changes of NEP magnitude and the influence of climate factors on the HKH region from 2001 to 2018. The NEP magnitude was obtained by calculating the difference between the net primary production (NPP) estimated by the Carnegie–Ames Stanford Approach (CASA) model and the heterotrophic respiration (Rh) estimated by the geostatistical model. The results showed that the grassland ecosystem in the HKH region exhibited weak net carbon uptake with NEP values of 42.03 gC∙m−2∙yr−1, and the total net carbon sequestration was 0.077 Pg C. The distribution of NEP gradually increased from west to east, and in the Qinghai–Tibet Plateau, it gradually increased from northwest to southeast. The grassland carbon sources and sinks differed at different altitudes. The grassland was a carbon sink at 3000–5000 m, while grasslands below 3000 m and above 5000 m were carbon sources. Grassland NEP exhibited the strongest correlation with precipitation, and it had a lagging effect on precipitation. The correlation between NEP and the precipitation of the previous year was stronger than that of the current year. NEP was negatively correlated with temperature but not with solar radiation. The study of the temporal and spatial dynamics of NEP in the HKH region can provide a theoretical basis to help herders balance grazing and forage.

scholarly journals Can Mandatory Disclosure Policies Promote Corporate Environmental Responsibility?—Quasi-Natural Experimental Research on China

2021 ◽  
Vol 18 (11) ◽  
pp. 6033
Author(s):  
Yue Liu ◽  
Pierre Failler ◽  
Liming Chen
Keyword(s):  
Property Rights ◽  
Large Scale ◽  
Environmental Responsibility ◽  
Mandatory Disclosure ◽  
Corporate Environmental Responsibility ◽  
Disclosure Policy ◽  
Protection Information ◽  
The Difference ◽  
Csr Disclosure ◽  
Corporate Social

Corporate environmental responsibility (CER) is an important component of the corporate social responsibility (CSR) report, and an important carrier for enterprises to disclose environmental protection information. Based on the corporate micro data, this paper evaluates the effect of a mandatory CSR disclosure policy on the fulfillment of corporate environmental responsibility by adopting the difference-in-differences model (DID) with the release of a mandatory disclosure policy of China in 2008 as a quasi-natural experiment. The study draws the following conclusions: First, a mandatory CSR disclosure policy can promote the fulfillment of CER. Second, after the implementation of a mandatory CSR disclosure policy, enterprises can improve their CER level through two channels: improving the quality of environmental management disclosure and increasing the number of patents. Third, the heterogeneity of the impacts of mandatory CSR disclosure on CER is reflected in three aspects: different CER levels, different corporate scales and a different property rights structure. In terms of the CER level, there is an inverted U-shaped relationship between the CER level and mandatory CSR disclosure effect. In terms of the corporate scale, mandatory disclosure of CSR plays a greater role in large-scale enterprises. In terms of the structure of property rights, mandatory CSR disclosure has a greater effect on non-state-owned enterprises.

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