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The monolithic DPF made of cordierite ceramic has unsatisfactory on his fatigue or long-term strength. A new design of configuration of plugs combined with the hexagonal channels shows a transversally isotropic property, and can remove the anisotropy of monoliths with square channels. This anisotropy is assumed to be one of main reasons for the failure of monoliths with square channels regarding the experimental results. Considering the honeycomb structure as a homogeneous material based on the Boltzmann continuum can't give the correct behaviour of this structure in a FEM simulation. Another homogenization procedure using the Cosserat theory has been discussed. The FEM stress analyses with structural detail-models show that the maximal tensile stresses in the monolith with square channels exist in the diagonal (i.e. 45°-) direction, or on the edges of channels. This feature is identical with what the theory has predicted and the experimental results have shown.

This paper deals with a passenger-car direct-injection-diesel-engine with electronically controlled unit-injector. It is being investigated how far emissions and fuel-consumption can be influenced by exhaust-gas-recirculation (EGR) and pilot-injection especially when they are in combination with each other. The results reveal that the NOx-emission can be decreased much more by EGR than by pilot-injection. The lowest NOx-emissions however can only be reached by combination of EGR and pilot injection.. In the investigated area of the engine map a decrease in soot-emission can be obtained with rising EGR-rates by pilot-injection. On the other hand pilot-injection results in an increase of soot emission at high EGR-rates at the engine operating point N=2000 rpm, bmep=2 bar. Pilot-injection in combination with EGR effects no deterioration of fuel-consumption and HC-emission.