Metallic Catalytic Converter Cross Axis Strength Considerations

The catalytic converter has to withstand in addition to high temperatures also mechanical loads due to pressure fluctuations and vibrations. During transients while temperatures may rise over 1000 °C, the mechanical strength and stiffness of the metallic substrate are only a fraction of those at room temperature. Adequate strength, with the catalyst made of precoated foil, in the flow direction has been achieved earlier by using e.g. the multi pin system to fasten the freely rolled straight and corrugated foils of the catalytic converter core to the casing. In this paper lateral strength analysis and structural development work is described. The catalytic converter core is analysed by FEM utilising a homogenisation process to replace the corrugated foil structure by an orthotropic continuum. Thermal expansion stresses and deformations, and natural frequencies are calculated. By proper corrugation shape design, and heat resistant super alloys, it is possible to improve significantly mechanical endurance also in the cross axis directions. Laboratory and in field tests have proved the predicted good performance of the metallic catalytic converter.