Vibration Analysis of Exhaust Gas Silencer

Abstract

This research presents an analysis of the vibration of exhaust gas silencer , assuming that the silencer is mainly consisting of a porous pipe of 0.042 m outer diameter , 0.0006 m thickness and 0.8 m length , surrounded by a cylindrical casing of 0.1325 m outer diameter , 0.001 m thickness and 0.53 m length , and the tail pipe is of 0.13 m length , taking in consideration that the silencer is fixed from one end andfree at the other end . The system is assumed to be made up of two simple beams connected together by number of springs . The rubber fastener (hook) which support the casing is modeled as an elastic spring . Each of the porous pipe and the casing are divided into (30) node and (29) element along the system The method of transfer matrices is adopted to simulate the vibration of the silencer , the dynamic characteristics , i.e. (deflection , slope , shear force , bending moment) as well as velocity , pressure and temperature are post-processed for each node . It is shown that the casing exerts a considerable influence upon the response of the pipe , and system natural frequencies are highly affected by the interaction effectsbetween the casing and the pipe . The results show that the transfer matrices method is a powerful technique to compute the eigen modes in addition to the natural frequencies of vibration systems. The theoretical study is also show that the rubber fastener (hook) has a considerable influence upon the system because some values of the rubber stiffness leads to reduction the amplitude of vibration and also the other values of eigen modes which is make the dynamic behavior of the system much better.