Material Structure in Viscoplasticity: An Extension of Bodner's Theory.
Abstract
Although Bodner's viscoplastic constitutive equation is useful because it does not require a yield criterion, it also exhibits deficiencies related to hardening behavior. Two new constitutive forms were developed from Bodner's equation to address this problem. The general approach employed scaling relations to define macrostructural response in terms of microstructural evolution. The first new equation expresses strain rate as a function of scaled microstructural models available from the metallurgical literature, and is useful for structural analyses. The second new equation represents a nonlocal model for viscoplasticity. It describes the evolution of internal stress field fluctuations in terms of scaled hardening and damage state variables, and contains the basis for a new material state tensor. The two new equations were verified by comparison to creep data for a steel alloy and aluminum, respectively. Keywords: Bodner's theory, Microstructure; Fractals; Scalings; Nonlocal stress polarizations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 15, 1986
- Accession Number
- ADA174990
Entities
People
- R. E. Williford