Date of Award
11-2023
Document Type
Dissertation
Degree Name
Ph.D.
Organizational Unit
Daniel Felix Ritchie School of Engineering and Computer Science, Mechanical and Materials Engineering
First Advisor
Yun-Bo Yi
Second Advisor
Mohammad Abdul Matin
Third Advisor
Matt Howard Gordon
Fourth Advisor
Chadd W. Clary
Keywords
Friction materials, Thermo-mechanical instabilities (TMI), High-speed sliding systems
Abstract
For centuries, the manufacturing industry has incorporated metals like copper into friction materials to enhance thermal properties and minimize thermo-mechanical instabilities (TMI) in high-speed sliding systems. Unfortunately, these metals have adverse environmental effects due to the emission of hazardous particulate matter. As a result, there is a growing movement towards adopting next-generation friction materials as an alternative solution.
The study begins by conducting experimental and numerical investigations to examine the instabilities found in metal-based friction materials. The primary objective is to utilize the insights gained from the investigations to computationally explore effective strategies for mitigating various instabilities that may arise in next-generation friction materials when used in high-speed systems.
To study the instabilities in metallic-based friction materials, a Cu-based friction material was developed. The study analyzed the friction properties and wear rate of this friction material while sliding against 65Mn steel using a Universal Mechanical Tester-5, and investigated the effects of sliding speed and temperature on the engagement process. The results offer valuable information on the relationship between the friction coefficient and wear rate; instabilities and critical sliding speed, as well as the growth rate of hotspots in metallic friction materials.
To assess the ability of a carbon fiber-reinforced hybrid composite friction material, which is free of copper, to withstand thermo-mechanical instabilities in sliding materials, a nonlinear transient thermo-mechanical model using Finite Element Code was used. The model was used to identify material properties that significantly affect the onset of TMI and which properties need enhancement for efficient use of the friction material in brakes and clutches.
Furthermore, to tackle instabilities like vibration and noise in automotive disc brakes and clutches, a viscoelastic friction material was proposed as another alternative. A mathematical model was developed to examine the instability of this material, by considering three physical material parameters: relaxation time, elasticity, and thermal conductivity. The study provides an intuitive means of predicting the onset of thermo-mechanical instabilities in viscoelastic friction materials and a better understanding of the influence of viscoelastic parameters in sliding systems.
Copyright Date
11-2023
Copyright Statement / License for Reuse
All Rights Reserved.
Publication Statement
Copyright is held by the author. User is responsible for all copyright compliance.
Rights Holder
Kingsford Koranteng
Provenance
Received from ProQuest
File Format
application/pdf
Language
English (eng)
Extent
152 pgs
File Size
45.8 MB
Recommended Citation
Koranteng, Kingsford, "Thermo-Mechanical Instabilities in Next-Generation Friction Materials in High-Speed Sliding Systems" (2023). Electronic Theses and Dissertations. 2355.
https://digitalcommons.du.edu/etd/2355
Discipline
Mechanical engineering
Included in
Other Materials Science and Engineering Commons, Other Mechanical Engineering Commons, Structural Materials Commons