Topology Optimization Of Muffler Internal Configuration For Acoustical Performance

Noise will have effect on people's health and behavior. Usually noise is the sound that we don't want or need, which can damage the physiological and psychological health. In the city the main noise pollution sources come from traffic noise. Usually we use mufflers to reduce exhaust noise.At present, it is used to analyze the acoustic performance of exhaust muffler system which are transfer matrix method based on one-dimensional, the boundary element and the finite element method. Among them, the finite element method has its superiority, so to calculate acoustic performance usually chooses the finite element method.The structure optimization design is emerging in recent decades. Mechanical structure optimization design is achieved with transplant and application of the optimum technology to the mechanical design field. Topology optimization is a kind of mechanical structure optimization. The main method of the optimization makes the response function of structure do Taylor expansion of reciprocal first-order variables by introducing MMA method. So the original problem is separated into a series of more simple strictly convex optimization problems. Then sub-problems constantly approach approximation solution.Numerical solutions of the transmission loss of insertion tube muffler with the two-dimensional and three-dimensional finite element analysis have the errors, but they have the trend correlation. Errors are mainly caused by mufflers which are actually three-dimensional entity. Two-dimensional finite element can not considered volume factor, so it causes the calculation errors.MATLAB can seamlessly connect COMSOL with the finite element analysis of acoustics. It is studied in detail how to use MATLAB computing the first order sensitivity.It is used to a simple expansion chamber muffler on the internal structure for topology optimization by using two-dimensional finite element and combined with a gradient-based optimization algorithm, the method of moving asymptotes. Then, on the basis of the topology optimization, the size optimization is further studied .While Expansion chamber on the internal structure changed, transmission loss will be changed. United COMSOL with MATLAB programming, numerical results show that on the target wave number the acoustical performance of the optimized muffler is much better than a simple expansion chamber muffler considerably.