The camshafts are responsible for controlling the timing of the intake and exhaust valves at the right time in internal combustion engines. In this study, failure analysis was performed on two camshafts in a six-cylinder CAR made of gray cast iron. One camshaft failure occurred after about 177, 000 kilometers and the other after about 208, 000 kilometers between cam 1 and 2. In order to investigate the cause of cam failure, first, a series of tests including determination of chemical composition, microstructure, hardness measurement, and fractography were performed. The morphology of the fracture surface showed that the growth of intergranular crack was from the zone of stress concentration and accompanied by ratchet marks. The hardness measurement results of the camshaft cross-section measured a maximum of 155 HB, while the average surface hardness values of the heat-treated surfaces are suggested to be at least 480 HB. The results of the investigation showed that the phenomenon of crack initiation and eventual failure of the cam can be caused by factors such as excessive load, low hardness, and the presence of impurities in the stress concentration zone of the camshaft.

The This research was defined with the aim of analyzing combustion and development of fire in a PASSENGER CAR with Pyrosim software, and it is intended to be a complete study on the optimization of the interior design material structure of the PASSENGER CAR against fire, which will reduce the amount of casualties in the event of an accident. This work was done by simulating fire development by Pyrosim software and using experimental data. A reference model that has been subjected to fire testing in real scale was modeled in Pyrosim software. After validating the existing model and then changing the insulating materials used in the wagon body and seats, new insulations of compressed polystyrene, expanded polystyrene , stone wool and glass wool were used.The results showed that glass wool and stone wool insulation had a good performance against fire, that is, they showed a lower heat emission rate and recorded a lower development rate, and the internal temperature of the wagon and the amount of smoke reached the critical range over a longer period of time. Foams had a very poor performance and in addition to increasing the rate of heat release and internal temperature, they had a higher amount of soot production. It was concluded that from the point of view of optimal control of fire development, it is better to use glass wool or stone wool insulation in the CAR body and to use phenolic foam insulation in the interior design of the seat for PASSENGER comfort.

The objective of this paper is to optimize defrost/demist performance in a vehicle. However, to initiate the problem, it is necessary to have a thorough understanding of flow behavior within the compartment. So a full-scale model of PASSENGER compartment has been modeled and the air stream from very near to the windshield up to back of the compartment has been analyzed applying computational fluid dynamics. A computational C++ code is developed to calculate vapor film thickness glass temperature and some other parameters in different time steps. The code inputs are the air flow parameters resulted from the CFD simulation. Some different flow arrangements are prepared by changing locations of demist panels and outlet pores to evaluate defrost and demist performance. Ultimately, between 6 different cases suggested, the optimum location of demist panels and exit vents is determined. For the case in which warm air enters through left A-Pillar in addition to the bottom panel, and exits through right A-Pillar, the windshield clearance time is minimum for the same initial conditions

BACKGROUND AND OBJECTIVES: For air quality management, appropriate emission inventories are required to be categorized on-road mobile sources such as CARs, depending on their use, vehicle technology, and local environmental conditions. This study aims to estimate atmospheric pollutant emissions generated by PASSENGER CARs using the international vehicle emission model for the year 2023.METHODS: To implement the international vehicle emission model and develop a baseline for an emissions inventory, vehicle technology in the study area was identified through surveys at filling fuel stations in the two districts with the highest traffic. The fleet was categorized based on parameters such as emission control technology, fuel type, and engine displacement. Additionally, the study considered geographic and environmental variables, including travel patterns on urban roads, fuel specifications, and elevation.FINDINGS: 53 vehicle categories were identified across the province and classified within the international vehicle emission model. After setting the fleet file with the distribution of vehicle categories and the location file with environmental conditions and representative characteristics, the model estimated atmospheric pollutant emissions for 2023 in metric tons. PASSENGER CARs contributed the most to pollutant emissions, with CARbon dioxide reaching 1.78 million tons per year and CARbon monoxide 234.16 kiloton per year. Regarding emission factors, gasoline vehicles showed a proportional increase in CARbon dioxide, nitrous oxide, nitrogen oxides, and sulfur oxides emissions per kilometer as vehicle size increased. A notable case was CARbon monoxide emissions, where a medium-sized vehicle emitted approximately 41 grams per kilometer—twice the amount of a heavy CAR as 23 grams per kilometer, according to international vehicle emission model estimation. Particulate matter emissions were primarily generated by heavy PASSENGER vehicles, compared with light and medium CARs, whose emissions were 90 percent and 83 percent, respectively.CONCLUSION: This study developed an on-road mobile source emission inventory for 2023, focusing on PASSENGER CARs in Panama. A survey of 409 vehicles characterized a fleet of 534,322 CARs, identifying 53 categories, with 94.8 percent running on gasoline and 5.12 percent on diesel. More than 45 percent of the vehicles exceed 160,000 kilometers, increasing their emissions. Medium-sized CARs (1.5–3 liters) account for 61.1 percent of the fleet and are the largest emitters of CARbon dioxide and nitrogen oxide. Although fewer in number, diesel vehicles produce nearly half of the particulate matter-10 emissions. Comparisons with national and international inventories validate the contribution of these vehicles to air pollution and the impact of each pollutant. 

The objective of developing kinetic energy recovery systems for vehicles is to repurpose energy otherwise dissipated during braking. Brake energy recovery and storage are achieved through two broad methods: electrical and mechanical, contingent on the energy storage type and the traction system's operational approach. Utilizing a rotating flywheel emerges as a practical, cost-effective, safe, and environmentally friendly means of storing energy, offering an extended service life. This study, synthesizing insights from various theories, aims to devise a prototype brake energy recovery system compatible with Samand CAR, employing the flywheel tank. Additionally, considerations for the power transmission system and clutch involve designing their type and dimensions, taking many factors into account for the selection. The initial design undergoes simulation and evaluation using MATLAB_SIMULINK and the ADVISOR plugin. The investigation delves into the influence of various design parameters on the efficiency of the system. Subsequently, attempts are undertaken to clarify the factors contributing to varied outcomes. The simulation results indicate a notable decrease in fuel consumption and emissions for a Samand CAR during urban driving cycles characterized by frequent braking. This improvement is realized through the utilization of a steel flywheel with an incomplete cone geometry and a specified radius. Suggestions are put forth for refining the controller to potentially enhance reductions in fuel consumption and pollution.

High-speed PASSENGER CAR requires a lighter weight for improving power performance and reducing fuel consumption; a CAR with higher-speed and lighter weight will lead to the PASSENGER CAR more sensitive to the crosswind, which will affect the stability and drivability of the PASSENGER CAR. This study employs the fully-coupled method to investigate a PASSENGER CAR subjected “ 1-cos” crosswind with consideration of the vehicle motion. Large eddy simulation (LES) and dynamic mesh is adopted to investigate the unsteady aerodynamic, and the vehicle is treated as a three-freedom-system and driver’ s control is considered to investigate the vehicle dynamic. The one-way simulation and quasi-steady simulation are also conducted to compare with the fully-coupled simulation. The results of the three simulation methods show large difference. The peak value of the lateral displacement in fully-coupled simulation is the smallest between the three simulation approaches. While the change of aerodynamic loads and vehicle motion in fully-coupled simulation is more complicated than in one-way and quasi-steady simulation. These results clearly indicate the significance of including of the unsteady aerodynamic loads in PASSENGER CAR moving analysis.

In the present paper, employing a complete model of a PASSENGER CAR, contribution of various components and assemblies in the frontal crash energy absorption is determined. Thickness of components with more remarkable contribution is increased to improve the occupant safety. Furthermore, effects of substituting the metallic bumper with one fabricated from GMT materials on the frontal crash behavior of the vehicle are investigated. Boundary condition and dynamic parameters are defined in PAM-CRASH software. To increase the accuracy of the results, all subassemblies and their joints are precisely modeled. Finally, components with more remarkable contribution in energy absorption are detected and a comparison is made between the crash results of the original design and the crash results obtained after the mentioned modifications.

The handling quality of a PASSENGER CAR is noticeably influenced by the structural and functional characteristics of the individual components of the vehicles various mechanisms, including the steering, suspension and braking systems. This implies that in designing each of these mechanisms, its contribution to the dynamic behavior of the vehicle should be taken into account. In this paper the sensitivity of the vehicles handling quality to the geometry of a rack-and-pinion steering mechanism, specially to the coordinates of its joints, is analytically studied and a new Genetic-based approach the determination of the joint coordinates is proposed. In the proposed approach, the dynamic equations and kinematics constraints of the steering mechanism are derived and incorporated in a dynamic model of the vehicle. The model is then solved for a step-input to the steering wheel, using MATLAB, and the values of the handling parameters are calculated. An Elitist Genetic Algorithm is used to search the hyper-space of the joint coordinates and to find the ones resulting in the best handling quality. The advantages of the proposed method over the classical solution methods are also discussed.

Muffler is one of the main components of an automotive exhaust system, which reduces the noise of the exhaust system. In this paper, modeling and simulation of the acoustic behavior of a muffler is presented with the aid of an engineering software. For this purpose, firstly, an analytical model is presented to evaluate the sound transmission loss in cylindrical shells based on Sander's theory. Then, catalytic converter and muffler are modeled by considering the model's major dimensions in the engineering software. The comparison of the present results with previous studies shows the accuracy of the analytical model as well as the simulation results. In addition, the contour of sound pressure inside the catalytic converter and the muffler, as well as the direction of the exhaust gas flow inside the muffler, indicate that the sound level created by Muffler is in the safe range according to the limitations posed by the standards.