WSEAS Transactions on Applied and Theoretical Mechanics
Print ISSN: 1991-8747, E-ISSN: 2224-3429
Volume 9, 2014
Structural Dynamic Finite Element Model Updating Using Derringer’s Function: A Novel Technique
Authors: ,
Abstract: Aim of this research paper is to develop a new structural dynamic finite element model updating (FEMU) technique using Derringer’s desirability function. Proposed FEMU technique allows formation of subobjectives of model updating problem in a detailed and flexible but in a simplified and user friendly manner. Beauty of the proposed technique is that user can set target value, lower limit, upper limit, weightage on lower limit, weightage on upper limit and relative importance of each sub-objective of model updating problem. Two updating parameters (Elastic modulus and moment of inertia) of a beam structure are varied to develop experimental design matrix. This design matrix is further used to generate response surfaces for first five natural frequencies using response surface methodology. Derringer’s function approach is used for formulating individual desirability function for each sub-objective by considering corresponding natural frequency predicted by response surface model, simulated experimental natural frequency (target value), desired upper and lower limits on predicted frequency, weights on upper and lower limits, and, importance of the related mode (sub-objective). Individual desirability functions are then combined to produce a single overall desirability function, thereby reducing the complex multi-objective FEMU problem to single objective FEMU problem. Optimum (maximum) value of overall desirability function is then used to find out the value of updating parameters. Updating parameters are then used to produce an updated FE model. Dynamic results of updated FE model are then compared with their simulated experimental counterparts and it is found that absolute average error between FE and simulated experimental results is reduced from 14.6% (before updating) to just 0.02% (after updating), thereby suggesting successful implementation of proposed FEMU technique.
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Keywords: Structural dynamics, Finite Element, Model updating, Response surface methodology, Derringer’s function
Pages: 11-26
WSEAS Transactions on Applied and Theoretical Mechanics, ISSN / E-ISSN: 1991-8747 / 2224-3429, Volume 9, 2014, Art. #2