A new interval finite element formulation with the same accuracy in primary and derived variables. (12th July 2011)

• Record Type: Journal Article
• Authors: Rao, M.V. Rama; Mullen, Robert L.; Muhanna, Rafi L.
• Is Part Of: International journal of reliability and safety. Volume 5:Number 3/4(2011)
• Page Start: 336
• Page End: 357
• Publication Date: 2011-07-12
• Subjects: interval FEM -- IFEM -- uncertainty -- dependent variables -- finite element method -- FEM -- overestimation -- Lagrange multiplier; Reliability (Engineering) -- Periodicals; Industrial safety -- Periodicals; 620.00452
• Languages: English
• ISSNs: 1479-389X

Abstract

This paper addresses the main challenge in interval computations, which is to minimise the overestimation in the target quantities. When sharp enclosures for the primary variables are achievable in a given formulation, such as the displacements in interval finite elements, the calculated enclosures for secondary or derived quantities, such as stresses and strains, are usually obtained with significantly increased overestimation. One should follow special treatment in order to decrease the overestimation in the derived quantities. In this work, we introduce a new formulation for Interval Finite Element Methods (IFEM) where both primary and derived quantities of interest are included in the original uncertain system as primary variables. The formulation is based on the variational approach and the Lagrange multiplier method by imposing certain constraints that allows the Lagrange multipliers themselves to be the derived quantities. Numerical results of this new formulation are illustrated in a number of example problems.