Abstract

High precision structures, as telescope mirrors for space applications, require high thermal stability and structural stiffness combined with low weight. Laminate structures with their special properties can satisfy these stringent requirements.

Model updating and physical parameter identification on the basis of measurements can be applied to optimize such structures or define correction measures w.r.t. manufacturing inaccuracies.

In classic update procedures correction factors are used to improve physical parameters. The definition of correction differences which are suitable for parameters with zero starting values or values changing from positive to negative as it may be the case for the layer orientations of a laminate is presented.

High precision structures require high accurate measuring methods for the test. Thermal deformations can be measured by holographic, interferometric methods with high precision in the μm range. An interferometric contour map can be compared with the nodal point displacements of a Finite Element model by special spline functions called Zernike’s polynomials.

The equations to determine the various design parameters or material properties may not be linear independent, depending on the applied thermal load case. The degree of correlation between the various parameters is investigated. The results are used to optimize the load case selection and to improve error localization methods.

The proposed method is applied to a segment of a high stability spherical mirror plate with real measuring data.

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