DYNAMIC PERFORMANCE OF EXHAUST STACK MOUNTING BRACKET OF MINING EQUIPMENT

Nandeesh M N, Shivaprakash S

Abstract: Engine exhaust stack mounting plays a vital role in reducing noise, vibration and ruggedness caused due to excitation and thus providing efficient role in enhancing vehicle performance and durability. Fatigue of exhaust bracket has been endlessly a concern which may susceptible to structural failure if the follow-on stress or strain are excessive than allowable. Hence vibration should be dissolute by installing a bracket for structural integrity. Engine assembly is subjected to vibration which is described by the harmonics of the engine operating frequency known as orders of the engine. In the present study, the exhaust stack mounting bracket is designed by considering the appropriate thickness, stiffeness and space provided to install the bracket. A novel design has been performed to withstand the stable vibration loads due to engine excitation. Modal frequency response analysis is performed on exhaust stack assembly to observe the stable vibration behavior of engine exhaust mounting components. In the current study, six direction of excitation is applied with respect to different orders of engine. Here the excitation refers to acceleration with respect to time domain and with the help of Fast Fourier transformation (FFT) the time domain is converted to frequency domain. The vibration loads are subjected to very high cycle and low amplitude loading. Frequencies are obtained with low idle rpm, high idle rpm and rated rpm and with the help of interference diagram critical frequency is determined. Frequency and mode shape is obtained for axial and fore-aft direction. Stresses were evaluated at different excitation frequency and these stresses were compared with maximum allowable alternating stress limit or endurance limit of material used in this study. The fatigue factor of parent material is evaluated and found to be within the permissible limit. MSC Nastran is found to be useful tool for solving dynamic analysis and interpret the results.

Keywords: Exhaust Bracket, Dynamics, Engine Excitation and Modal Analysis

DOI: https://doi.org/10.15623/ijret.2017.0604003