Prediction of Collapse Load Reduction Due to Non-Aligned Multiple Flaws

2021 ◽  
Author(s):  
Fuminori Iwamatsu ◽  
Katsumasa Miyazaki ◽  
Koichi Saito
Keyword(s):  
Load Reduction ◽  
Collapse Load

Prediction of Collapse Load Reduction due to Non-Aligned Multiple Flaws

2020 ◽  
Author(s):  
Fuminori Iwamatsu ◽  
Katsumasa Miyazaki ◽  
Koichi Saito
Keyword(s):  
Plastic Strain ◽  
Fracture Strain ◽  
Equivalent Plastic Strain ◽  
Plastic Collapse ◽  
Load Reduction ◽  
Test Results ◽  
Collapse Load ◽  
Flat Plates ◽  
Fracture Tests ◽  
Flaw Characterization

Abstract Fitness-for-Service (FFS) codes, such as ASME Boiler and Pressure Vessels Code, Section XI, have flaw characterization rules for evaluation of structural integrity. Since stress corrosion cracking (SCC) and thermal fatigue frequently cause multiple flaws, FFS codes should have proximity rules as a part of flaw characterization rules. The flaw characterization rules should consider fracture modes, such as brittle fracture, ductile fracture, and plastic collapse. Those in the current codes are not divided by the fracture modes. Especially, application of the current proximity rules to plastic collapse of non-aligned multiple flaws should be validated because there are few studies for this issue. Thus, fracture tests of flat plates with through-wall flaws and finite element analysis (FEA) were conducted for predicting collapse loads due to plastic collapse. A series of the fracture tests of flat plates with non-aligned two flaws has been conducted, and a trend between the load reduction and the flaw locations was shown from the results. This trend shows that the defined net-section for non-aligned multiple flaw dominate the collapse load. For the validation the trend shown by the fracture tests, FEA was performed for predicting the measured collapse load. Equivalent plastic strain around a flaw tip dominates a collapse behavior, and an equivalent plastic strain at collapse called as fracture strain was determined for FEA. The collapse loads predicted by the fracture strain are correspond with the test results for any flaw locations. FEA conditions can interpolate and cover a wide range of flaw locations conducted by the tests. The load ratios which represent effect of flaw interaction on a collapse load were estimated by parametric FEA. The ratios were mapped to investigate the trend of the effect on a collapse load. The mapped results show that the load ratio depends on a shorter flaw length of two flaws. This trend shown by the analysis results is corresponds with the fracture test results. These results are fundamental idea to make a flaw characterization rule in the FFS codes, such as ASME BPVC Section XI, for ductile fracture evaluation.

Field Experiment of Demand Responsive Load Control in Office Buildings in Summer and Winter: Analysis of Load Reduction Impact and Customers^|^apos; Acceptance

2014 ◽  
Vol 134 (8) ◽  
pp. 702-715
Author(s):  
Masahito Takahashi ◽  
Tsuyoshi Ueno ◽  
Shigeru Bando ◽  
Atsushi Kurosaki ◽  
Takashi Koyanagi ◽  
...  
Keyword(s):  
Field Experiment ◽  
Office Buildings ◽  
Load Control ◽  
Load Reduction

scholarly journals Mechanical clinching and self-pierce riveting for sheet combination of 780-MPa high-strength steel and aluminium alloy A5052 sheets and durability on salt spray test of joints

2021 ◽  
Vol 113 (1-2) ◽  
pp. 59-72
Author(s):  
Yohei Abe ◽  
Ken-ichiro Mori
Keyword(s):  
Aluminium Alloy ◽  
High Strength Steel ◽  
Salt Spray ◽  
High Strength ◽  
Alloy Sheet ◽  
Galvanized Steel ◽  
Load Reduction ◽  
Minimum Thickness ◽  
Steel Sheets ◽  
Mechanical Clinching

AbstractTo increase the usage of high-strength steel and aluminium alloy sheets for lightweight automobile body panels, the joinability of sheet combinations including a 780-MPa high-strength steel and an aluminium alloy A5052 sheets by mechanical clinching and self-pierce riveting was investigated for different tool shapes in an experiment. All the sheet combinations except for the two steel sheets by self-pierce riveting, i.e., the two steel sheets, the two aluminium alloy sheets, and the steel-aluminium alloy sheets, were successfully joined by both the joining methods without the gaps among the rivet and the sheets. Then, to show the durability of the joined sheets, the corrosion behaviour and the joint strength of the aged sheets by a salt spray test were measured. The corrosion and the load reduction of the clinched and the riveted two aluminium alloy sheets were little. The corrosion of the clinched two steel sheets without the galvanized layer progressed, and then the load after 1176 h decreased by 85%. In the clinched two galvanized steel sheets, the corrosion progress slowed down by 24%. In the clinched steel and aluminium alloy sheets, the thickness reduction occurred near the minimum thickness of the upper sheet and in the upper surface on the edge of the lower aluminium alloy sheet, whereas the top surface of the upper sheet and the upper surface of the lower sheet were mainly corroded in the riveted joint. The load reduction was caused by the two thickness reductions, i.e., the reduction in the minimum thickness of the upper sheet and the reduction in the flange of the aluminium alloy sheet. Although the load of the clinched steel without the galvanized coating layer and aluminium alloy sheets decreased by about 20%, the use of the galvanized steel sheet brought the decrease by about 11%. It was found that the use of the galvanized steel sheets is effective for the decrease of strength reduction due to corrosion.

Tsunami wave run-up load reduction inside a building array

2021 ◽  
pp. 103910
Author(s):  
Joaquin P. Moris ◽  
Andrew B. Kennedy ◽  
Joannes J. Westerink
Keyword(s):  
Tsunami Wave ◽  
Load Reduction ◽  
Building Array ◽  
Run Up

Experimental Study of Ductile Fracture for Non-Aligned Multiple Flaws in a Plate

2009 ◽  
Author(s):  
Katsumasa Miyazaki ◽  
Kunio Hasegawa ◽  
Koichi Saito ◽  
Bostjan Bezensek
Keyword(s):  
Experimental Study ◽  
Ductile Fracture ◽  
Estimation Procedure ◽  
Maximum Load ◽  
Experimental Results ◽  
Collapse Load ◽  
Plate Specimen ◽  
Fracture Tests ◽  
Almost All

The fitness-for-service code requires the characterization of non-aligned multiple flaws for the flaw evaluation, which is performed using a flaw proximity rule. Worldwide almost all codes provide own proximity rule, often with unclear technical bases of the application of proximity rule to ductile fracture. To clarify the appropriate proximity rule for non-aligned multiple flaws in fully plastic fracture, fracture tests on flat plate specimen with non-aligned multiple through wall flaws were conducted at ambient temperature. The emphasis of this study was put on the flaw alignment rule, which determines whether non-aligned flaws are treated as independent or aligned onto the same plane for the purpose of flaw evaluations. The effects of the flaw separation and flaw size on the maximum load were investigated. The experimental results were compared with the estimations of the collapse load using the alignment rules in the ASME Section XI, BS7910 and API 579-1 codes. A new estimation procedure specific to the fully plastic fracture was proposed and compared with the comparison with the experimental results.

scholarly journals Cognitive load reduction strategies in questionnaire design

2021 ◽  
pp. 147078532098679
Author(s):  
Kylie Brosnan ◽  
Bettina Grün ◽  
Sara Dolnicar
Keyword(s):  
Cognitive Load ◽  
Data Quality ◽  
Survey Data ◽  
Task Difficulty ◽  
Questionnaire Design ◽  
Load Reduction ◽  
The Past ◽  
Load Theory ◽  
Learning Tasks ◽  
Reduction Strategies

Survey data quality suffers when respondents have difficulty completing complex tasks in questionnaires. Cognitive load theory informed the development of strategies for educators to reduce the cognitive load of learning tasks. We investigate whether these cognitive load reduction strategies can be used in questionnaire design to reduce task difficulty and, in so doing, improve survey data quality. We find that this is not the case and conclude that some of the traditional survey answer formats, such as grid questions, which have been criticized in the past lead to equally good data and do not frustrate respondents more than alternative formats.

scholarly journals Environmental Load Reduction Due to Modal Shift Resulting from Improvements to Railway Freight Stations

2007 ◽  
Vol 48 (4) ◽  
pp. 207-214 ◽  
Author(s):  
Guoquan LI ◽  
Masai MUTO ◽  
Naoki AIHARA ◽  
Taro TSUJIMURA
Keyword(s):  
Load Reduction ◽  
Environmental Load ◽  
Modal Shift ◽  
Railway Freight
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