Parameter estimation of four-parameter viscoelastic Burger model by inverse analysis: case studies of four oil-refineries (original) (raw)

2012, Interaction and multiscale mechanics

Burger model parameter estimation: An inverse formulation

This paper pertains to the development of a generalized inverse analysis formulation aided by a suitable optimization technique for the parameter estimation of four-parameter Burger model representing the time-dependent behavior of viscoelastic soil. The analysis is carried out as a mathematical programming formulation identifying the design vector, the objective function and the design constraints. Thereafter, it has been solved with the aid of fmincon: an in-built MatLab module to solve constrained optimization. To gain experience and check the effi cacy, the developed methodology is applied to a synthetic case study wherein a deformation-time history has been generated using a known set of parameters. The best result is obtained when design variables are restricted only by lower bounds. No starting-point dependency is observed in the present study. A minimum of four data-points from the deformation-time input is observed to be suffi cient to back-predict the parameters with effi ...

Inverse modelling as a tool for the optimization of steel production processes

Inverse process modelling is exemplified by the prediction of optimum cooling technology for sheet materials. The inverse modelling approach is discussed exemplary for the determination of optimized set values inside a spray cooling section. For steel grades requiring accurate temperature control, cooling section technology has to deliver prescribed cooling rates while fulfilling specific constraints, e.g. on the minimum surface temperature. The heat transfer coefficient (HTC) depending on the parameters water impact density V S and the temperature difference ΔT was measured in the Laboratory while the desired final material properties determine temperature control and cooling rate. This information is used to predict the optimum cooling section set values for a specific cooling task. The inverse modelling calculations use a simple cooling section process model. Illustrative examples for optimum cooling of strip or sheet material using water spray cooling demonstrate the approach. Additionally, the specific problems of inverse modelling procedures (ill posed problems, computational complexity, ...) are addressed. [This paper is based on an article to appear in steel research 80 (2009)].

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