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This paper describes the application of CAE tools in the design optimization of a DCT and driveline system of a passenger vehicle, with emphasis on NVH performance. The multi-body dynamics simulation tools are employed for driveline system analysis. The MBD model consists of the engine, transmission, clutch, drive shafts, tires and vehicle. The wheel slip effects are considered in the calculation of shuffle frequencies. In the analysis of gear whine, the transmission housing, gears and shafts are modeled by detailed 3-D finite element models, so that the mesh stiffness of the gears and the housing support stiffness are described more accurately. The calculated velocity spectra of the housing are presented. The prediction of gear rattle in the transmission is carried out. The loose gear acceleration index and the averaged impact power of free gears are calculated to assess the rattle generation potential and the level of rattle severity.

In order to predict more accurately the cracking failure of cylinder head during the durability test of turbocharged engine in the development, a comprehensive evaluation method of cylinder head durability is established. In this method, both high cycle and low cycle fatigue performance are calculated to provide failure assessment. The method is then applied to investigate the root cause of cracking of cylinder head and assess design optimizations. Multidisciplinary approach is adopted to optimize high cycle fatigue and low cycle fatigue performance simultaneously to achieve the best comprehensive performance. In this paper, the details of the method development are described. First, the high cycle and low cycle fatigue properties of cylinder head material were measured at different temperature condition, and the fatigue life and high temperature creep properties of materials under thermo-mechanical fatigue cycle were also tested.

This paper describes the application of CFD tools in the design optimization of intake ports, combustion chamber and injector of SAIC Motor's 2.0L turbo charged direct injection gasoline engine. For a more realistic simulation of spray processes, detailed investigations of mesh dependency, wall impingement models were conducted. The validation of the spray simulation was carried out by comparison between the experimental data and calculation results. To investigate the droplet-wall interactions, a comparison between the results from Bai's model and the instantaneous evaporation model was made. With the Star-CD code, the in-cylinder air motion, fuel injection and air/fuel mixing in the combustion system with central injector were evaluated, at different engine operation conditions and start of injection timings. Several proposed intake port options, with different tumble levels, were numerically investigated and compared.