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Tube bends are critical in an exhaust system. The acceptability of tube bends is based on the induced level of shape imperfections considered. An analysis is presented for the performance tuning of the genetic algorithm including the importance of raw material selection, ovality and elongation property. This study is an attempt to analyze the ovality effect of STAC 60/60 material. CAE tools are essential to exploit the design of experiments and find out the optimum values of the design parameters in comparison with full factorial designs. Especially the effects of materials, dimensions and geometry shape of the ultimate strength were discussed by both CAE and experiments. The ultimate strength of steel tube was evaluated at least 20-30% as a local strain independent of the materials. The dependency of ultimate bending angle on original centre angle of the tube bend was clarified.

A combined Computer Aided Engineering (CAE) simulation and physical fatigue testing of a passenger car exhaust system resonator with wire mesh seal between the inlet and outlet pipe is performed to evaluate the durability and improvise the design. The outlet pipe end cap of the exhaust system resonator deformed and cracked at the fillet region repeatedly upon the application of the maximum load from a pre developed accelerated specification test. However, the system meets the end usage on-road durability target of 5 years / 1,00,000 km. There is a gap between the accelerated bench test and the end usage durability target. The current study correlates CAE simulation and biaxial fatigue testing and improvise possible alternate resonator design. Conventionally, components passing the accelerated test always meets the end usage durability target whereas components meeting the end usage durability target need not necessarily pass the accelerated test.

Computer aided engineering is used to design, develop, optimize and manufacture catalytic converter. Heatcad, a transient heat transfer analysis is used to simulate the temperature response in the exhaust system to locate the catalytic converter to achieve maximum performance. Heatcad analysis provides the easy way to identify thermal management issues and to design and optimize the runner lengths and material thicknesses of the manifold, and downpipes. P-Cat is used to estimate back pressure due to substrates, end cones, and inlet/outlet pipes. Catheat, a one dimentional heat transfer tool is used to identify the converter insulation to maintain the required external skin temperature. Computational Fluid Dynamics (CFD) analysis, a powerful means of simulating complex fluid flow situations in the exhaust system, is used to optimize the converter inlet and outlet cones and the downpipes to obtain uniform exhaust gas flow to achieve maximum converter performance and reduce mat erosion.

Automotive exhaust system components are exposed to many types of vibrations, from simple sinusoidal to maximum random excitations. Computer-Aided engineering (CAE) plays an inevitable role in design and validation of hot vibration shaker assembly. Key Life Test (KLT), an accelerated hot vibration durability test, is established to demonstrate the robustness of a catalytic converter. The conditions are chosen such a way that the parts which passes key life test will always pass in the field, whereas the parts which fail in the key life test need not necessarily fail in the field. The hot end system and the test assembly should survive in these aggressive targeted conditions. The test fixture should be much more robust than the components that it should not fail even if the components fail. This paper reveals the computational methodology adopted to address the design, development and validation of the test assembly.