2. In Situ Modal Analysis of Gears

There has been a vast amount of work in the analysis of multistage gearbox housings and the effects vibrations can have on them. This subject is of concern in the aerospace industry and is handled by Finite Element Analysis (FEA). Often experimental verification is required, particularly when a new design or material is introduced. Holographic interferometry and speckle interferometry are optical tools that provide in-situ comprehensive solutions when investigating the modal analysis of gears. Both of these experimental techniques provide an output that determines the dynamic characteristics of the gear being analyzed which can be directly connected to the FEA solution. Experimentally it is possible to obtain the dynamic displacement and strains for all the points of the area of interest and hence can be utilized to modify the FEA in such a way that the results of the FEA agree with experimental values. This type of analysis is particularly critical when it is important to determine the in-plane vibration modes of large gears, known as the “oval modes”. These resonant modes are particularly important in aerospace applications because they can cause serious damage if left unchecked. The analysis of oval resonant modes were carried out on a spur gear to show the effectiveness and accuracy of this in-situ approach.