The purpose of this study is to create a new combustion concept that offers a high thermal efficiency and very low NOx and soot emissions. To this end, we performed 3D-CFD simulations to identify problems with an actual PCCI that is characterized by in-cylinder mixture non-homogeneity that arises through the direct injection of diesel fuel. We compared the combustion characteristics with an ideal 'HCCI' with homogeneous mixture conditions. Then, to overcome PCCI problems such as difficulties in combustion controllability and the limited operating range, we identified the key parameters impacting the HCCI/PCCI process through experiments with a variety of paraffinic hydrocarbon fuels. Finally, based on the knowledge gained through these steps, we developed a new concept for dual-fuel PCCI combustion using high- and low-RON fuels to achieve extremely low NOx and smoke emissions. In this system, gasoline was supplied from the intake air port and diesel fuel was injected directly into the engine cylinder to act as an ignition trigger at a timing before TDC. It was found that the ignition phasing of this PCCI combustion can be controlled by changing the ratios of the two injected fuels, such that combustion proceeds very mildly, even without EGR, thanks to the spatial stratification of ignitability in the cylinder, which prevents the entire mixture from igniting instantaneously. The operable load range, where the NOx and smoke emissions were less than 10 ppm and 0.1 FSN, respectively, was extended up to an IMEP of 12 bar using an intake air boosting system together with dual fueling.

In sheet metal forming simulations, the widely used shell elements are assumed to be in the plane stress state, as defined by the Mindlin-Reissner theory. Unfortunately, numerical prediction with conventional shell elements is not accurate for bending radiuses that are small relative to the sheet thickness. This is mainly because the stress and strain formulation for a conventional shell element does not actually reflect reality. So, to accurately predict the springback of a sheet with a severe bend, we have proposed a method for measuring the through-thickness strain. The stress and strain are formulated based on measured and calculated values for a solid element, as well as a proposed shell element that is based on a formulation that has been newly incorporated into the FEM code. We have confirmed the accuracy with which this method can predict the springback shape of two bending processes. As a result, we found that we can accurately predict the springback shape even after severe bending. From the viewpoint of computation cost, the proposed shell element is much more effective than a solid element.