Testing exhaust systems’ mechanical resistance to vibration

Exhaust systems, due to being connected to an internal combustion engine, are subjected to constant vibrations. As a consequence, these systems suffer cyclic stresses that lead to fatigue cracks. The catalytic converter assembly, in which the ceramic substrate is housed in a metal casing, is particularly susceptible to damage resulting from vibrations. These systems must be validated in terms of their fatigue strength. Durability tests of a specific catalytic converter unit or particulate filter precede vibration measurements. These measurements are performed using tri-axial accelerometers placed in locations considered to be the most exposed to vibrations. Analysis of the results obtained determines the rotational speed of the engine at which vibrations reach critical resonant frequencies. The speed values thus obtained are the basis for determining the test profile to which the exhaust system will be subjected. The duration of the test depends on the required number of displacement cycles which the element under test should be able to withstand.