The Climate chamber system is an essential facility for aerodynamic performance development of commercial vehicles to investigate air flow field characteristics in different climatic conditions. In particular, the analysis of airflow fields within the chamber system is an essential consideration for optimal design. In this study, the pressure characteristics and velocity uniformity in the test section area were predicted with blower impeller rotational speed using CFD. The velocity uniformity is affected by the distance from the blower nozzle outlet, reaching up to 72.7% at 695 RPM. The pressure differential between 300 RPM and 740 RPM shows an approximate difference of 2651 Pa, with a high-pressure distribution observed along the right side wall of the blower. These results are expected to be used as design data applicable for improving the performance of environmental chamber systems.

In this study, the thermal behavior of adaptor housing was analyzed by the numerical method. The boundary conditions used to die casting process were the temperature of molten metal and injection time. As the temperature of the molten metal increased, the tensile strength of the product decreased by the blow hole generated in the molten metal, and the decreasing tendency was gradually decreased. As the injection time of the molten metal increased, the heat flux rose, but the degree of the increase was very small. So, the injection time of the molten metal had little effect on the thermal behavior and diffusion of the adapter housing. As a result, the heat of the molten metal was transferred into the housing and the thermal behavior spread widely.

There are many different causes of air drum brake judder noise in commercial vehicles. This study set out to identify those causes from the perspective of brake structure, not taking the environment into account. For that purpose, the investigator measured vibrations and noises in case of brake judder noise and analyzed their causes. The structural vibrations of the brake were analyzed to identify the causes with an experimental method involving O.D.S. (Operational Deflection Shape) analysis and model testing. In an effort to find directions for improvement with an analytical method, the investigator modeled the brake system in an analytical manner, correlated it with the experiment results, and tested directions for improvement in an analytical fashion. The structural rigidity of the brake that had been tested analytically was increased so that the generation frequency and structural vibration frequency of brake judder noises would not be contiguous. The parts of high structural rigidity were tested for brake judder noises with a model test and vehicle test.

Abnormal cab vibrations in the Y direction in commercial vehicles during driving(70~90kph) are not common vibrations that happen to vehicles during driving and can be an obstacle to normal driving. This study conducted Operation Deflection Shape(ODS) testing to identify the causes of those abnormal cab vibrations and find solutions for them and also a sine sweep test to find resonance and frequency in the cab suspension system and set directions for improvement. The study also altered the shape of the bush inner part for changes to the rigidity features of the cab bush in the Y direction and revised the design with optimal rigidity in the Y direction, thus improving abnormal cab vibrations in the Y direction during driving.