Full-Field Modal Analysis by Using Digital Image Correlation Technique

Abstract

At the state of art, the design validation of mechanical products in automotive, aerospace, and other advanced manufacturing industries is made by using vibration measurements and experimental modal analysis. The structures’ dynamic behavior is investigated mostly using contact transducers (accelerometers, strain gauges, load cells, …). Optical methods such as Digital Image Correlation (DIC) have recently received special attention in the structural dynamics field because it can be used to obtain full-field measurements. However, DIC can only measure vibrations in the camera field of view, which causes problems for hidden parts or in case the structure is too large to fit into the field of view. Therefore, it is of paramount importance to combine DIC with other traditional sensors such as accelerometers and strain gauges. Complex 3D test articles and structures need to be measured from many different directions. The knowledge gained by developing a heterogeneous sensor measurement system can significantly reduce the time and cost associated with pointwise sensor instrumentation. In this paper, DIC technique is used to get the full-field displacement. The sensor merging, DIC + pointwise sensors, is investigated. This information is then used to derive the modal characteristic of the structure (e.g. natural frequencies, damping ratios, and full-field mode shapes) that can be used for a more reliable FE model validation.