Risk assessment of cold side components using quick modal analysis correlation technique.

Abstract: Modal analysis is performed to determine the natural frequencies and mode shapes of a structure or system. It helps engineers understand how a system vibrates and how external forces, such as mechanical loads, might excite unwanted resonances. To check the stresses due to vibration inputs, certain G levels are assumed, and stresses are scaled to those vibration levels. This gives an understanding of the stresses of component with respect to its EFR limit and design margins are calculated. But, assumed acceleration levels in pre-prototype stage level can over predict or under predict the design margins. A quick modal analysis corelation technique can be used by using test measured accelerations conducted at prototype stage of the program. In this work, a modal analysis corelation technique is used to perform risk assessment of intake manifold. The intake manifold failed due to high vibration levels which were not captured from high cycle fatigue analysis with assumed G-level. In the modal analysis correlation technique, an effort is made to align the mode shape and frequency of the intake system and then with measured accelerations high cycle fatigue design margins are calculated. This gave accurate high stress location where in actual intake manifold was failed. Further design recommendations were suggested based on stress nature and location. This technique can be a quick risk assessment solution as only modal analysis with few peripheral components are required to be modelled in FEA analysis. This paper explores modal analysis correlation techniques, detailing the steps for aligning the mode shape and frequency of a system, while also addressing the limitations of the method.