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A system approach is taken for the design of catalytic converters. An axisymmetric stuffing method is considered as a module for canning procedure in this investigation. The major aspects considered in this paper entail; three dimensional parametric modeling, parametric studies on the stuffing procedure, thermo-coupled stress analysis, modal analysis, thermal flow analysis, fatigue analysis for the steel parts, and parametric studies for optimizing the design of the total converter system. Popular commercial software are utilized to form the core of analysis modules. Developed in-house codes provide smooth interfaces between analysis modules by setting detailed analysis techniques and input decks. The system approach integrates established analysis procedures and parametric modeling.

The main objective of this paper is to simulate the springback using combined kinematic/isotropic hardening model. Material parameters in the hardening model are identified by an inverse method. Three-point bending test is conducted on 6022-T4 aluminum sheet. Punch stroke, punch load, bending strain and bending angle are measured directly during the tests. Bending moments are then computed from these measured data. Bending moments are also calculated based on a constitutive model. Material parameters are identified by minimizing the normalized error between two bending moments. Micro genetic algorithm is used in the optimization procedure. Stress-strain curves is generated with the material parameters found in this way, which can be used with other plastic models. ABAQUS/Standard 5.8, which has the combined isotropic/kinematic hardening model, is used to simulate draw-bend of 6022-T4 series aluminum sheet. Absolute springback angles are predicted very accurately.

The motivation of this paper is inverse estimation of the material properties for sheet metals subjected to cyclic loading. Cyclic three-point bending tests are performed. Bending moments are computed from the measured data, namely, punch stroke, punch load, bending strain and bending angle. Bending moments are also calculated based on the selected material model in which normal anisotropy and combined hardening are considered. Material parameters are identified by minimizing the difference between these two bending moments. Modified Levenberg-Marquardt method is used in the optimization procedure. Stress-strain curves are generated with the optimized material parameters.

Catalytic converters are typically constrained and cushioned by an intumescent mat material that is critical to the durability of the ceramic and metallic substrates. In an effort to reduce costs and improve designs, this work attempts to develop and verify a material model for the mat that can be utilized in predictive analysis. Test data are used in conjunction with the finite element program ABAQUS™ to create both a hyperfoam and a user-defined material model. These models will be verified and compared by modelling with ABAQUS the specimens and test conditions used to generate the data.

Non-linear FEA models are applied to three different catalytic converters, with the objective of predicting structural parameters such as shell deformation, push-out force, and mounting-system contact pressure under various conditions. The FEA modeling technique uses a novel constitutive model of the intumescent mat material typically found in ceramic-monolith converter designs. The mat constitutive model accounts for reversible and irreversible thermal expansion, allowing for the prediction of the one-way converter deflection observed in hot durability tests. In addition to this mat material model, the FEA methodology accounts for elastic and plastic shell deformation, contact between materials, and a three-dimensional temperature field in the shell and mat. For each of three designs, predictions are presented for converter canning, heat-up, and cool-down (i.e., post-heating) conditions.