Fabrication Fault Diagnosis of Bracket for Air Borne Vehicle Using Experimental and Analytical Modal Analysis

Abstract

This paper presents the experimental and analytical modal analysis of bracket structures made of two different materials. Manual inspection of fabricated components may at-times tend to be much tedious and less economical approach in identifying any geometrical and dimensional flaws when the quantity is more and may also result in failure, particularly when the purpose for which the components are designed or fabricated is very sensitive and crucial. Effective methodology has been investigated and implemented through experimental modal analysis (EMA), in diagnosing mechanical fabrication flaws that might have occurred during machining process with the fabricator. Implemented methodology is very well backed up with the support of analytical modal analysis methods aided by finite element analysis (FEA). This paper not only includes discussion about the advantages of using experimental modal data as a means of detecting structural faults, but also includes demonstrations of how the sensitivity ratio of stiffness and mass parameters aid in easy diagnosis of physical or material oriented changes. Specifically, it is shown with a help of two dimensionally identical brackets (as said by fabricator), one made of aluminium and other made of magnesium material, both of which are part of an airborne vehicle. Initial EMA of aluminum bracket provided a basis for cornering on certain modal values and further performing EMA on magnesium bracket ended up with another set of modal values. Technically, it is to be notified that being identical on dimensions and stiffness-to-mass ratio parameters, the modal results of both the brackets must also remain same which is not so observed in this case. A benefit of doubt was achieved when it was found that there was certain dimensional disparity between aluminium and magnesium brackets. Further FEA carried out on both the brackets provided a strong supportive point for the adopted approach.

Cite this Article

Anil Kumar P, Jagadisan K. Fabrication Fault Diagnosis of Bracket for Air Borne Vehicle Using Experimental and Analytical Modal Analysis. Journal of Experimental & Applied Mechanics. 2016; 7(2): 19–29p.