Investigation of a Simplified Fatigue Reliability Model for Optimising the Design of Tubular Joints

2002 ◽  
Author(s):  
G. K. Cole ◽  
R. Pinna ◽  
B. F. Ronalds ◽  
P. Romagnolo
Keyword(s):  
Fatigue Failure ◽  
Research Effort ◽  
Fatigue Reliability ◽  
Inspection Planning ◽  
Construction Costs ◽  
Planning Techniques ◽  
Tubular Joints ◽  
Considerable Research ◽  
Target Probability ◽  
Probabilistic Technique

While there has been considerable research effort over the last decade aimed at refining risk based fatigue inspection planning techniques, there has been relatively less effort aimed at using the same techniques to optimise the design of welded joints. This paper discusses the use of a simplified, semi-probabilistic technique for optimising the design of tubular joints on the basis of their total through-life costs. A model is developed which combines the probability of fatigue failure with initial construction costs, inspection costs, and repair and failure costs. An example study of a critical joint in a minimum structure is provided. In this example, where costs associated with joint failure were assumed to be purely financial, an optimum target probability of failure (threshold for inspection) was found to be 10−4 to 10−3. Provided the target probability of fatigue failure used in inspection planning is kept below this level, design in accordance with API RP2A appears to provide a reasonably optimised joint. The sensitivity of the total cost to this target failure probability, and a range of other important cost variables, was also investigated.

Fatigue reliability assessment of tubular joints of existing offshore structures

2001 ◽  
Vol 28 (4) ◽  
pp. 691-698 ◽  
Author(s):  
A A Aghakouchak ◽  
S F Stiemer
Keyword(s):  
Decision Making ◽  
Reliability Assessment ◽  
Offshore Structures ◽  
Fatigue Reliability ◽  
Inspection Planning ◽  
Additional Information ◽  
Linear Elastic ◽  
Tubular Joints ◽  
Elastic Fracture ◽  
Tubular Joint

Tubular joints of offshore structures are prone to fatigue damage. Because of uncertainties involved in quantifying the fatigue process in this type of structure, a reliability approach may be adopted to assess the risks of failure. In-service inspections of structures produce additional information, which may be taken into consideration in order to update the reliability. The paper reviews the methods for carrying out such reliability analyses based on principles of linear elastic fracture mechanics and applies them to a sample tubular joint. The results of this type of analyses may be used for inspection, planning, and (or) decision making regarding repairs or modification of the service life of a structure.Key words: fatigue, reliability, tubular joints, offshore structures, condition assessment.

Integrality Assessment of Tubular Joints in Aging Offshore Platform Based on Reliability Theory

2012 ◽  
Vol 532-533 ◽  
pp. 238-242 ◽  
Author(s):  
Hong Lin ◽  
Guo Ming Chen ◽  
Zheng Fang Wang ◽  
Lei Yang
Keyword(s):  
Computing Methods ◽  
Offshore Platforms ◽  
Fatigue Reliability ◽  
Inspection Planning ◽  
Wave Load ◽  
Reliability Models ◽  
Tubular Joints ◽  
The Difference ◽  
Maintenance Schedules ◽  
Structural Integrality

The paper presents a reliability-based approach to assess the structural integrality of tubular joints with cracks in aging offshore platforms. Two different fatigue failure models are established respectively according to crack propagation size and equivalent fatigue strength, and the corresponding computing methods of fatigue reliability are proposed. The fatigue stress of tubular joint suffering sea wave load is calculated by spectrum analysis. The numerical examples are given to show the difference between the two reliability models. Considered the influence of inspection and repair, the reliability is updated by two different maintenance schedules. The analysis results can help to work out the optimal inspection planning, so as to prolong the service life for aged offshore platforms.

scholarly journals Analgesia for Sheep in Commercial Production: Where to Next?

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1127
Author(s):  
Alison Small ◽  
Andrew David Fisher ◽  
Caroline Lee ◽  
Ian Colditz
Keyword(s):  
Research Effort ◽  
Mitigation Strategies ◽  
Worth Living ◽  
Life Worth Living ◽  
The Past ◽  
Considerable Research ◽  
Husbandry Practices ◽  
Industry Practice ◽  
Successful Launch ◽  
Inflammatory Drugs

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on livestock production industries to alleviate pain associated with husbandry practices, injury and illness. Over the past 15–20 years, there has been considerable research effort to understand and develop mitigation strategies for painful husbandry procedures in sheep, leading to the successful launch of analgesic approaches specific to sheep in a number of countries. However, even with multi-modal approaches to analgesia, using both local anaesthetic and non-steroidal anti-inflammatory drugs (NSAID), pain is not obliterated, and the challenge of pain mitigation and phasing out of painful husbandry practices remains. It is timely to review and reflect on progress to date in order to strategically focus on the most important challenges, and the avenues which offer the greatest potential to be incorporated into industry practice in a process of continuous improvement. A structured, systematic literature search was carried out, incorporating peer-reviewed scientific literature in the period 2000–2019. An enormous volume of research is underway, testament to the fact that we have not solved the pain and analgesia challenge for any species, including our own. This review has highlighted a number of potential areas for further research.

Fish Habitat: Essential Fish Habitat and Rehabilitation

1999 ◽  
Keyword(s):  
Research Effort ◽  
Fish Habitat ◽  
Economic Value ◽  
Consumer Surplus ◽  
Travel Cost ◽  
Cost Models ◽  
Conservative Estimate ◽  
Construction Costs ◽  
Cost Study ◽  
One Year

<em>Abstract.—</em> Ohio constructed two artificial reefs beginning in 1986 in Lorain and Cuyahoga counties. The reefs were a demonstration project to evaluate the effects of reefs on fishing satisfaction and the feasibility of reef construction in other areas. Evaluation of the effects of reefs on recreational activity was viewed as essential for further reef development in Ohio and other Great Lakes states. A two-pronged research effort was undertaken: an underwater video investigation and a travel cost study. The travel cost study estimated the economic value derived from use of the Lorain County reef by sport anglers and divers. The results of this research were critical in supporting construction of a large artificial reef off the coast in Cleveland (Cuyahoga County) using rubble from the old Cleveland Stadium. From April to October 1992, 850 individuals who were willing to participate were contacted at Lorain County marinas and launch ramps. In early February 1993, these individuals were mailed questionnaires, with a second questionnaire mailed to nonrespondents in late February. Fifty-five percent responded. We estimated three alternative single-equation travel cost models. The most conservative estimate of consumer surplus (economic value) showed that the typical angler who used the reef in 1991 made nearly 10 more fishing trips during 1992 than the typical angler who did not use the reef in 1991, that is, nearly 26 trips in 1992 compared to 16 trips in 1992 by those who did not use the reef in 1991. The most conservative estimate of consumer surplus also showed that anglers who used the reef before 1992 valued total angling activity at US$302 more for the year 1992 than anglers who did not use the reef before 1992. When aggregated across all Lorain County anglers using the reef during 1991, the total value of the reef was $276,000 in 1992 compared to total construction costs of less than $100,000. Thus, the consumer surplus generated by the reef in one year exceeded construction costs by a wide margin.

Influence of Processing on Nutrients in Foods1

1982 ◽  
Vol 45 (4) ◽  
pp. 367-373 ◽  
Author(s):  
DARYL B. LUND
Keyword(s):  
Environmental Factors ◽  
Systematic Approach ◽  
Research Effort ◽  
Nutrient Retention ◽  
Temperature Treatment ◽  
Process Models ◽  
Toxic Substances ◽  
Considerable Research ◽  
Canned Foods ◽  
The Stability

Considerable research effort has been devoted to the effect of processing on nutrients in foods. Yet only recently has a systematic approach been used to identify changes in processes which result in improved nutritional content of the product. The catalyst for this systematic approach has been the generation of kinetic data on the influence of environmental factors on the stability of nutrients which can then be used in process models. The effort to quantify reactions important in foods must continue for both nutrients and toxic constituents, but because of limited resources, we should conscientiously choose which environmental factors and which nutrients or toxic substances will be studied. The example of improving nutrient retention in canned foods by choice of time/temperature treatment and by changing geometry is used to illustrate the application of modeling. Additional research effort is warranted on the effect of water activity on nutrient stability, the generation of toxic substances during processing and the bioavailability of nutrients as influenced by processing.

Plants and processes in wetlands: A background

1994 ◽  
Vol 45 (8) ◽  
pp. 1369 ◽  
Author(s):  
PI Boon ◽  
MA Brock
Keyword(s):  
Research Effort ◽  
Grey Literature ◽  
Wetland Ecology ◽  
Scientific Journals ◽  
Special Issue ◽  
Inland Wetlands ◽  
Considerable Research ◽  
History Of ◽  
Research Findings ◽  
The Subject

It is easy to gain an impression from the recent contents of Australian scientific journals dealing with ecological research that little attention is paid to the botanical ecology of Australia's inland wetlands. Less than 1% of the papers published in key Australian ecological journals over 1987-93 dealt with some aspect of the vegetation ecology of these environments. Yet over the period 1982-94 research on this topic accounted for up to 23% of the papers presented at annual conferences of the two major Australian scientific societies to which Australian limnologists are likely to belong. This discrepancy indicates that wetland vegetation is the subject of a considerable research effort by Australian limnologists, but that few of their research findings are published in refereed Australian journals. Analyses of the references cited in key review articles suggests that refereed journals outside Australia cannot account fully for the 'missing' publications: we demonstrate that much research is placed in the largely inaccessible 'grey literature' published by government departments and the like. It is also possible that some research is destined never to be published. This imbalance between the intensity of the research effort and the history of publication in Australian refereed journals prompted local scientists involved in wetland research to participate in a Special Issue dedicated to the botanical and process-oriented aspects of wetland ecology.

Effect of Welding Procedure on Main Girder Fatigue Property

2014 ◽  
Vol 496-500 ◽  
pp. 666-672
Author(s):  
Gang Shen ◽  
Dong Xiang ◽  
Nan Liu ◽  
Peng Mou ◽  
Yong Yang ◽  
...  
Keyword(s):  
Fatigue Failure ◽  
Manufacturing Industry ◽  
Fatigue Property ◽  
Vertical Force ◽  
Bridge Crane ◽  
Fatigue Reliability ◽  
Welding Joint ◽  
Welding Procedure ◽  
Main Girder ◽  
Crack Position

Hoisting machinery is an important part of the equipment manufacturing industry, and the general bridge crane is the most widely used hoisting machinery. The main girder of bridge crane is the main load-bearing structure. Further, fatigue failure of main girder usually occurs not on the material itself but in the welding joint. The article has carried out three groups of experiments, which are experiment on fatigue property under vertical force, experiment on fatigue property under the comprehensive function of vertical force and horizontal force and experiment on failure mode of main girder under the prefabricated crack, to further discuss the effect of welding procedure on main girder fatigue property. Finally the following three conclusions are obtained. Firstly, the crack occurs closely to the middle position of welding place of the lower board and the main web, with the trend of scaling up along the main web perpendicular to the welding place. Secondly, the crack occurs on the main web close to the upper board, with the two-way expansion trend. Thirdly, fatigue failure cracks do not occur in the welding joint except the prefabricated crack position close to the square steel rail after the cyclic loading of two million times on main girder, which indicates that the uniformity of welding quality has an importance influence on the fatigue reliability of the whole main girder.

Extrusion of Polymer Melts and Melt Flow Instabilities. I. Experimental Study of Capillary Flow and Extrudate Distortion

1969 ◽  
Vol 42 (3) ◽  
pp. 675-681 ◽  
Author(s):  
Gene A. Bialas ◽  
James L. White
Keyword(s):  
Experimental Data ◽  
Polymer Melts ◽  
Capillary Flow ◽  
Flow Instability ◽  
Research Effort ◽  
Flow Instabilities ◽  
Melt Flow ◽  
Considerable Research ◽  
Extrudate Distortion ◽  
First Descriptions

Abstract The extrusion of molten plastics, elastomers and fibers represent an important industrial operation. The rate of extrusion of melts through dies is limited by the onset of a flow instability. This phenomenon consists of a change in flow from uniform to irregular that results in the production of rough and distorted extradates drastically different from the smooth cylinders obtained at lower rates. Extrusion melt flow instability is observed in the entire spectrum of polymer melts ranging from silicone gums through nylon and polyolefin plastics to raw elastomers. Since the first descriptions of this phenomena in the 1940's considerable research effort has been expended in this area with limited agreement. It is the purpose of part I to: (1) present new experimental data on capillary flow of polymer melts and extrudate distortion, and (2) to review critically the literature on extrudate distortion.

Land Inequality and Political Violence

1989 ◽  
Vol 83 (2) ◽  
pp. 577-596 ◽  
Author(s):  
Edward N. Muller ◽  
Mitchell A. Seligson ◽  
Hung-der Fu ◽  
Manus I. Midlarsky
Keyword(s):  
Latin America ◽  
Political Violence ◽  
Latin American ◽  
Research Effort ◽  
Middle Eastern ◽  
Alternative Measure ◽  
Supporting Evidence ◽  
Land Distribution ◽  
Land Inequality ◽  
Considerable Research

Considerable research effort has been invested in establishing the appropriate relationship between patterns of land distribution and political violence. In an article in the June 1988 issue of the Review, Manus I. Midlarsky proposed and tested a new measure of the distribution of land, which he called “patterned inequality.” He presented supporting evidence with data from Latin American and Middle Eastern countries. In this controversy, Midlarsky's analysis is challenged by Edward N. Mutter, Mitchell A. Seligson, and Hung-der Fu. They advocate an alternative measure of land inequality, test its effect on levels of political violence in Latin America, and find it wanting. In his rejoinder, Midlarsky offers new analytical support for his claims.

Multistack Close Range Photogrammetry for Low Cost Submillimeter Metrology

2013 ◽  
Vol 13 (4) ◽  
Author(s):  
L. M. Galantucci ◽  
F. Lavecchia ◽  
G. Percoco
Keyword(s):  
Surface Topography ◽  
Research Effort ◽  
Low Cost ◽  
Three Dimensional ◽  
Robotic Systems ◽  
Image Composition ◽  
Close Range Photogrammetry ◽  
Considerable Research ◽  
Close Range ◽  
Dimensional Surface

Considerable research effort has been focused on evaluating the accuracy of meso- and macroscale digital close range photogrammetry. However, evaluations of accuracy and applications in the submillimeter scale are rare. In this paper the authors propose the development of a three-dimensional (3D) photogrammetric scanner, based on macrolens cameras, able to reconstruct the three-dimensional surface topography of objects with submillimeter features. The system exploits multifocal image composition and has been designed for installation on all types of Numerical Controlled or Robotic systems. The approach is exploitable for digitizing submillimeter features at mesoscale as well as macroscale objects.

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