Functional area: Atlas Copco, Tightening technique
Recruiting Manager: Erik Persson
Supervisors: Erik Persson, Sofia Olsson
Email: firstname.lastname@example.org, email@example.com
Mechanical Engineering/Solid Mechanics
Level of thesis project:
Development of a methodology, material model or similar that is to be implemented in a FEM software (preferably Altair Hyperworks), tested and verified with experimental results. The methodology or similar will take into account the fact that when a material is stressed, there will be a change in the sound velocity in that material.
Research on using ultrasonic as a technique to measure the bolt elongation during tightening has been conducted at Atlas Copco for many years. The ultrasonic transceiver is placed e.g. on the bolt head, sends and receives an ultrasonic wave pulse. The Δ-time between the sent pulse and the echo is used to calculate the bolt elongation. A 1 mm thick rubber membrane is attached between the sensor and the bolt to minimize the impedance difference between the two media. During a tightening, the membrane is subjected to compressive stresses. In a similar fashion the fastener is subjected to tensile stresses. The stress in the material will change the sound velocity of that material. This is called the acoustoelastic effect.
Today, simulations do not take the changing speed of sound through materials as they are stressed into consideration. This phenomenon is important to include to accurately simulate the ultrasonic wave travel time from sensor to membrane, to bolt and back to the sensor. No solution known to us is available on the market.
Develop a methodology, material model or similar which can be implemented in a FEM software and which takes the acoustoelastic effect into account for accurate time of flight simulations. Preferably Altair Hyperworks is to be used. The simulation results are to be verified using experiments on threaded fastener joints.
In order to be able to contribute to this project, you are a highly motivated and creative person. You have:
- Skills within solid mechanics
- Interest and some experience with FEM simulations
- Basic knowledge in programming
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