Modeling of viscoelastic polymers to predict insulation integrity in electric machines
Abstract
This project aims to study the occurrence of catastrophic material failure of composite polymers used as electrically insulating materials around medium-voltage copper coils in electric machinery. The resulting failure is often unexpected and may occur at momentswhere continual operation is of the utmost necessity, usually in industrial and military settings. Thus, having reasonable margins of when this failure might occur is important to prevent economic losses or even mission curtailment, and is therefore of fundamental interest to the US Navy and other military forces, which will be able to modernize their operations and maintenance schedules in line with their strategic goals if this problem is solved.These materials sometimes fail after being subjected to repeated mechanical, thermal and electrical loading in the course of their life cycle, but the underlying mechanisms and, more importantly, the time ittakes for these materials to fail, are not well understood. Most insulationlifetime predictions rely on empirical efforts or on extrapolating models from idealized single-component materials. This project proposes to develop constitutive and damage models that assimilate the #aging# effects due to voltage application and mechanical fatigue on the complex material properties of the insulating polymer matrices, with emphasis on the initiation of irreversible damage, typically in the context of void formation inside these materials. The models are challenging in the sense that they do not simply depend on current conditions (like deformation, temperatureand voltage applied), but on the full past history of these key variables. Thus, this work would lay a path to improve insulation lifetime estimates under diverse machine operating conditions. To attain these goals, key data coming from experiments must be collected first. This will be done by collaborators Dr. Aleta Wilder and Dr. Nancy Frost in the USA in the context of the project ONR N00014#22#1#2556, whichis managed by ONR Program Officer Lynn J. Petersen. With this data in hand, constitutive and damage models of these materials will be developed as a complex function of the different variables involved, and later refined under close collaboration with Dr. Wilder and Dr. Frost. These models, written in the framework of continuum mechanics, will then be incorporated into novelnumerical methods, which will also be developed and perfected as a consequence of this research, which in turn will be used to simulate the experiments and eventually validate the models themselves. Lastly, the resulting software, which solves relevant partial differential equations, will be used to simulate important material configurations in realistic scenarios of machine operation, with the hope of being able to reliably predict areas of potential void formation, in turn leading to conservative estimates for the lifetime of form-wound stator coils in electric machines. This basic research could lead to significant theoretical advances to be published in the scientific literature, and to resulting software of industrial appeal.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 13, 2023
- Source ID
- N629092312098
Entities
People
- Federico Fuentes
Organizations
- Office of Naval Research
- Pontifical Catholic University of Chile
- United States Navy