Thickness Variation and non Uniform Plate Behaviour using Modal Test Results

Abstract

This paper presents a proposal to apply model updating to a simple structure, using single measured point to establish dynamic This can be interesting specially for reduced glass thickness because changes of 10% in thickness implies also a 10% on frequencies that could be detected with the proposed procedure. Plates of 1938 x 876 mm, tempered of 10mm and 5mm and nnealed laminates 3+3, are selected to obtain free-free natural frequencies, and more than 15 modes are used to update a finite element model in order to study non uniform stiffness distribution due to the production process. Initially, classical modal test approach is used with the measurement of the force and acceleration response on only one point. Finally the possibility of operational modal test is checked using only the response of the structure for more than 15 modes with a measurement on one point. After the updating the FEM model is possible to analyze the similarity with a reference glass plate. This paper presents a first step for the use of Operational Modal Analysis for line quality control of glass plates, during the production process.