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Advanced substrate design, efficient washcoat/catalyst formulation and robust packaging are critical elements to assure performance and durability of catalytic converters and diesel particulate filters. Radial seals, axial seals and L-seals made of knitted wiremesh are used with conventional mounting systems to provide compressible and durable support cushions for catalyst and filter substrates. Axial and radial mounting forces of the seals are optimized by material type, seal density, wiremesh strand, wiremesh surface profile (flat or round), wiremesh surface characteristics, wiremesh temper, thermal impacts, and wiremesh geometry. Compression characteristics of stainless steel alloy A286 tremendously increase (>20%) during heat treatment as precipitation and hardening occurs. Compression force tends to stabilize during cycling, retaining a residual force. Radial seals provide radial mounting pressure and mat erosion protection.

Knitted wiremesh along with radial gas tight seals provide reliable mounting system for low temperature underbody converters. The compression characteristics of the wiremesh is modified by wire material, wire diameter, wire geometry, mesh crimp heights; wire density, wiremesh courses per inch, needle count, number of strands, wiremesh temper, wiremesh surface profile and surface characteristics. The radial mounting pressure provided by the wiremesh is matched with the mounting pressure requirement. Wiremesh systems can be tailored to any required radial mounting pressure from conventional to ultra thin-wall substrates. The wiremesh mounting system is proven durable, without any failure on more than 25 million underbody converters in light duty vehicles. Cp and Cpk show the capability of the manufacturing process. Thus the wiremesh mounting support is a viable alternate for low temperature gasoline and diesel applications.

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.

The primary function of exhaust muffler is to reduce noise from the internal combustion engine without affecting its performance due to the impact of higher back pressure. The exhaust system back pressure is directly related to the engine fuel efficiency. The consumption of back pressure by the emission control system in BS IV regulation is about 30% from the total permissible engine limit, whereas in BS VI consumption is about 70%. The combination technologies used in BSVI and forthcoming RDE regulations such as TWC, GPF, DOC, DPF and SCR increases significant back pressure in exhaust system, hence the engine performance decreases. This demand robust method to control the exhaust back pressure for better fuel efficiency. Emission, noise and back pressure are the non-complimentary parameters in exhaust system development. The variable valve technology introduction in muffler is one method to optimize the above parameters.