Search Results

This paper discusses many aspects of the structural analysis of catalytic converters on automotive exhaust systems. The analysis covers a canning process, where a substrate is wrapped with a mat material and canned with a steel shell; and a heating process, where high temperature exhaust gas passes through the substrate. In designing a catalytic converter, the maximum pressure on the substrate should not exceed the minimum isostatic strength of a chosen cell geometry of that substrate. At the same time, sufficient pressure is required to maintain a minimum retention force to hold the substrate in place. Also, lack of compression in the mat material, where the mat is in contact with exhaust gas, will cause mat erosion. Therefore, a careful investigation is needed to have the right amount of pressure on the substrate, both during canning and operation conditions, and at room and elevated temperatures.

Canning is a very important aspect in the catalyst converter design, especially with the current trend of using more thin wall and ultra-thin wall substrates. This paper systematically investigated canning issues at different stages of converter manufacturing processes and operations. Commonly used converter canning processes, which include traditional clamshell style and tourniquet wrap, are included in the studies. Using a previously developed mat material model, visco-elastic behavior, as well as the unique expansion characteristic of the intumescent mat under high temperature, are included in the simulations. Lab testing of the mat material at different loading speeds was conducted to obtain the visco-elastic properties. These will allow the studies of the effect of closing speed on the peak pressures during canning processes, as well as the pressures during heating and cooling.