up_ixf

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up_ixf

Purpose

Iterative FE model update based on the comparison of measured and predicted FRFs.

Syntax

[jump]=up_ixf('basic',b,c,IIw,IIxf,indw)

Description

up_ixf seeks the values coef of the currently declared Up parameters (see the upcom ParStack command) such that the difference Log least-squares difference (4.4) between the desired and actual FRF is minimized. Input arguments are

method	Currently 'basic' is the only Method implemented.
range	a matrix with three columns where each row gives the minimum, maximum and initial values associated the corresponding alternate matrix coefficient
b,c	input and output shape matrices characterizing the FRF given using the full order model DOFs. See section 2.1.
IIw	selected frequency points given using units characterized by Up.copt(1,3)
IIxf	reference transfer function at frequency points IIw
indw	indices of frequency points where the comparison is made. If empty all points are retained.

Currently 'basic' is the only Method implemented. It uses the maximum MAC (see ii_mac) to match test and analysis modes. To allow the MAC comparison modeshapes. You are expected to provide test modeshapes modeID and a sensor configuration matrix (initialized with fe_sens).

up_ixf uses any available optimization algorithm (see upcom opt) to minimize the cost. Depending on the algorithm, the optimum found may or may not be within the constraints set in the range given in the upcom ParStack command.

This algorithm is very simple and should be taken as an example rather than an truly working solution. Better solutions are currently only provided through consulting services (ask for details at info@sdtools.com).

See also

up_freq, upcom, fe_mk

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