Tools
Tools
Welch, MA, 2024. The classical analysis of structural integrity and fatigue safe-life of preloaded bolted joints. PhD, Nottingham Trent University.
Preview |
Text
Michael Welch 2024.pdf - Published version Download (20MB) | Preview |
Abstract
The purpose of the published works presented was to contribute to the understanding of preloaded bolted joints. Emphasis was on considering bolted joints as systems. Areas of interest included both static and fatigue analysis of preloaded bolted joints.
Classical methods of analysis were applied throughout each of the papers being presented. Each paper develops new methods of detail analysis and provides guidance on how the methods can be applied to bolted joint designs.
In-plane loads on the joint produce bending stresses in the bolts that have an effect on the fatigue life. Existing methods of calculating these bending stresses are not satisfactory. They are based on an oversimplified, and unrealistic, model which assumes bolt bearing at the holes in the flanges. This would only occur if there were slip at the faying surface or the joint had been assembled with misalignment. The work presented here proposes an improved method for calculating bolt shear and bending stresses.
It was found that the shear strain produced by in-plane external loads and moments results in a transverse displacement of the bolt head/nut which generates shear, bending and axial loads on the bolt. Under high flange shear stress conditions, the individual bolt tensile loads produced by the in-plane external loads can be of a similar order of magnitude to the bolt tensile load component produced by the out-of-plane external loads and moments.
A new damage-equivalent stress function, suited to high mean stress situations, has also been developed. It is suitable for a wide range of stress concentrations and tensile strengths, typical of those found in preloaded bolts. This new function has an accuracy to within 16% with a root mean square error of 8%, a significant improvement on existing methods.
A series of S-N curve specific to high strength bolts and screws, property-class 8.8 to 12.9 have also been produced.
A holistic approach to the analysis of preloaded bolted joints has been adopted throughout the presented works. This has been achieved by considering multi-bolt preloaded bolted joints and as consisting of multiple elements that interact with each other to produce a complex system. The purpose of conducting an analysis is to show a bolted joint has structural integrity and is durable. Structural integrity can be demonstrated by static stress analysis of each element of the joint. Durability is demonstrated by assessment against appropriate safety factors or by a detailed fatigue analysis.
The presented published works have made a contribution to the understanding of preloaded bolted joints. The first two of the published works being presented identified a knowledge gap in the understanding of how in-plane loads are supported within a bolted joint. It was understood that friction at the faying surface would transmit in-plane loads between the flanges. However, the effect that the in-plane loads would have on individual bolts within a multi-bolt joint was an unknown. This lack of knowledge was the research challenge for the subsequent published works. Each making its own contribution, while combining to make a whole body of work.
| Item Type: | Thesis |
|---|---|
| Description: | PhD by Published Works |
| Creators: | Welch, M.A. |
| Contributors: | Name Role NTU ID ORCID Causton, E. Thesis supervisor EGI3CAUSTE UNSPECIFIED |
| Date: | July 2024 |
| Rights: | The copyright in this work is held by the author. You may copy up to 5% of this work for private study, or personal, non-commercial research. Any re-use of the information contained within this document should be fully referenced, quoting the author, title, university, degree level and pagination. Queries or requests for any other use, or if a more substantial copy is required, should be directed to the author. The copyright of the published papers that are incorporated as part of this thesis remain unchanged by this copyright statement. |
| Divisions: | Schools > School of Science and Technology |
| Record created by: | Jeremy Silvester |
| Date Added: | 27 Jun 2025 08:36 |
| Last Modified: | 27 Jun 2025 08:36 |
| URI: | https://irep.ntu.ac.uk/id/eprint/53830 |
https://orcid.org/0000-0001-5346-1933Actions (login required)
 |
Edit View |
Statistics
Views
Views per month over past year
Downloads
Downloads per month over past year
