Bolt Thread Stress Optimization

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearch


Designs of threaded fasteners are controlled by different standards, and the number of different thread definitions is large.
The most commonly used thread is probably the metric ISO thread, and this design is therefore used in this paper. Thread root design
controls the stress concentration factor of threads and therefore indirectly the bolt fatigue life. The root shape is circular, and from
shape optimization for minimum stress concentration it is well known that the circular shape is seldom optimal.
An axisymmetric Finite Element (FE) formulation is used to analyze the bolted connection, and a study is performed to establish
the need for contact modeling with regard to finding the correct stress concentration factor. Optimization is performed with a simple
parameterization with two design variables. Stress reduction of up to 9% is found in the optimization process, and some similarities
are found in the optimized designs leading to the proposal of a new standard. The reductions in the stress are achieved by rather simple
changes made to the cutting tool.
Original languageEnglish
Title of host publicationProceedings of the 23rd International Congress of Theoretical and Applied Mechanics
Number of pages2
Publication date2012
Publication statusPublished - 2012
Event23rd International Congress of Theoretical and Applied Mechanics - Beijing, China
Duration: 19 Aug 201224 Aug 2012


Conference23rd International Congress of Theoretical and Applied Mechanics

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