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Clamping Force Relaxation-Based Bolted joint Design to Prevent Failure

diagram of Clamping Force Relaxation-Based Bolted joint DesignBolted joints are extensively used in various engineering applications across industries such as aerospace, automotive, transportation, and energy. These joints are often subjected to dynamic loads across a wide frequency range that can cause vibration in the connected substructures. However, under dynamic loading, bolted joints may experience a loss in clamping pressure, known as relaxation, which can result in vibrational loosening. If left undetected, this loosening can cause serious consequences, such as train derailments. For instance, the 2002 London (Potters Bar) WAGN train derailment and the 2007 Grayrigg (Cumbria) WCR train derailment were caused by loose bolts, leading to fatalities and injuries.

Moreover, bolt loosening can have economic and environmental implications, such as rail lines being closed for months for maintenance after a derailment, or environmental damage caused by fuel spills in freight train derailments. Despite the significant risks, bolted joints are not designed to prevent loosening. The current state-of-the-art practices for bolted joint design are based on static and fatigue requirements, which do not take into account conditions that can trigger loosening after installation. Although some techniques are used to reduce loosening after installation, they are not always effective. An alternative approach used in rail tracks is continuous welded rail (CWR), which is a permanent joint strategy but lacks the advantages of bolted joint connections.

This project seeks to revolutionize bolted joint design for railway applications by proposing a novel approach that accounts for the dominant factors of loosening dynamics and the conditions triggering it. To achieve this goal, an in-depth understanding of the bolt loosening phenomenon and a sophisticated model formulating its inherent dynamics are required. The accuracy of the developed strategy will be validated through a combination of numerical simulations and experimental investigations. The proposed approach has the potential to create a significant impact on bolted joint design, benefiting rail companies in the improvement of rail line reliability and enhancing safety, thereby saving human lives and preserving the environment.

Faculty: Engineering and Environment

Department: Mechanical and Construction Engineering

Principal Supervisor: Dr Hassan Jalali

Recent publications by supervisors relevant to this project

[1] Jalali, Jamia, Friswell, Khodaparast, Taghipour, Mech Syst Signal Process., 179 (2022) 109339.

[2] Jamia, Jalali, Taghipour, Friswell, Khodaparast, Mech Syst Signal Process. 153 (2021) 107507.

[3] Jalali, Khodaparast, Madinei, Friswell, Mech Syst Signal Process. 129 (2019) 645-658.

[4] Jalali, Khodaparast, Friswell, J Sound Vib. 447 (2019) 186-204.


Eligibility and How to Apply


Applications are invited from exceptional candidates who have a good first or upper second class degree (or equivalent) in Mechanical Engineering. Students who are not UK/EU residents are eligible to apply, provided they hold the relevant academic qualifications, together with an IELTS score of at least 6.5. This project is well suited to motivated and hard-working candidates with a keen interest in vibration analysis and structural dynamics. The applicant should have excellent communication skills including proven ability to write in English.

For more information and informal enquiries please contact Dr Hassan Jalali

Further details of the application process and entry requirements can be found here:

Deadline for applications: 1st December for March (following year) start; 1st July for October (same year) start.

Start Dates: March and October of each year

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