Accession Number : ADA330035

Title :   Weld Detail Fatigue Life Improvement Techniques

Descriptive Note : Final rept.

Corporate Author : MIL SYSTEMS ENGINEERING OTTAWA (ONTARIO)

Personal Author(s) : Kirkhope, K. J. ; Bell, R. ; Caron, L. ; Basu, R. I.

PDF Url : ADA330035

Report Date : DEC 1996

Pagination or Media Count : 145

Abstract : Fatigue cracks in steel ships often occur at welded joints where stress concentrations due to the joint geometry are relatively high and the fatigue strength of the weld is reduced in comparison to that of the base metal. This becomes more critical in ships built of High Strength Steels (HSS) because the fatigue strength of steel in the a welded condition does not increase in proportion to the yield or tensile strength. In many cases, the fatigue performance of severely loaded details can be improved by employing good detail design practices, for example by upgrading the welded detail class to one having a higher fatigue strength. In some cases, however, there may be no better alternatives to the detail in question and modification of the detail may not be practicable. As an alternative to strengthening the structure at a considerable increase in costs, procedures which reduce the severity of the stress concentration at the weld, remove imperfections, and/or introduce local compressive stresses at the weld can be used for improvement of the fatigue life. Similarly, these fatigue improvement techniques can be applied as remedial measures to extend the fatigue life of critical welds that have failed prematurely and have been repaired. To date, weld fatigue life improvement techniques have been successfully applied in several industries. While there has been increasing interest in the application of fatigue life improvement techniques to ship structures, at present there is a lack of guidance on the use of such techniques for design, construction and repair. Hence the key elements of this project were to compile available data on fatigue life improvement techniques, assess the feasibility and practicality for their application to ship details, identify gaps in the technology, and finally to recommend design, construction and repair requirements.

Descriptors :   *FATIGUE LIFE, *WELDED JOINTS, TENSILE STRENGTH, CRACKING(FRACTURING), CANADA, HIGH STRENGTH ALLOYS, STEEL, REPAIR, FATIGUE(MECHANICS), COMPRESSIVE STRENGTH, STRESS CONCENTRATION, SHIP STRUCTURAL COMPONENTS.

Subject Categories : Couplers, Fasteners, and Joints
      Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE