Final Report: Modeling the Mechanics of Multiaxial Ratcheting
Abstract
Ratcheting is the accumulation of plastic strain due to cyclic loading. This phenomenon is known to reduce the life and lead to unexpected failure of piping components in nuclear power and chemical plants, off shore structures, machinery components, buildings, bridges, and any other structure subject to earthquakes, extreme weather, and/or cyclic mechanical and thermal service conditions. Predictions of ratcheting strains are needed to avoid, foresee, and understand structural failure. The largest challenge associated with finding a realistic constitutive model to accurately predict ratcheting is that any acceptable small error in a single cycle, accumulates over many cycles to an unacceptable level, so it is imperative that the material response is described with a high degree of accuracy. Multiaxial ratcheting has proven to be particularly difficult to predict because in addition to the norm, the direction in strain space towards which the plastic strain tensor accumulates may be unknown and yet it must be predicted with high accuracy in order to capture the overall deformation of the structure and assess its integrity. Our research objective is to use the principles of continuum mechanics and thermodynamics to investigate the mechanics of ratcheting and derive a rigorous, simple, and accurate constitutive model for uniaxial and multiaxial ratcheting that is applicable to a wide array of ductile metals. In other words, we aim to answer the scientific questions: Under repetitive plastic loading paths, what are the changes in the material state at the continuum level and how can these changes of the material state be modeled by means of a constitutive model in order to allow successful simulation of ratcheting?
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 19, 2023
- Accession Number
- AD1225061
Entities
People
- Heidi Feigenbaum
- Yannis Dafalias
Organizations
- Northern Arizona University