Automotive Science and Engineering
Volume:1 Issue: 4, Autumn 2011

In this study, the effect of Methanol (M5, M7.5, M10, M12.5, M15) on the performance and combustion characteristics of a spark ignition engine (SI) were investigated. In the experiment, an engine with four-cylinder, four stroke, multipoint injection system (Ford, Zetec-E) was used. Performance tests were conducted for brake torque, brake power, brake thermal efficiency, volumetric efficiency, equivalence air-fuel ratio, and brake specific fuel consumption and exhaust emissions (CO, CO2, HC, NOx) were analyzed under wide open throttle operating conditions and variable engine speed ranging from 1500 to 5000 rpm. The experimental results showed that the performance of engine was improved with the use of methanol. It was also shown that CO and HC emissions were reduced with the increase of methanol content while CO2 and NOx were increased.

Flexible manufacturing and customization is a considerable topic in modern manufacturing automobile industry. However, challenges still remain on the responsiveness of production system to the fluctuation of production demand. In this paper we developed a flexible machine layout that is not restricted to equal size machines. The layout optimizes the trade-offs between increased material handling costs as requirements change and machine rearrangement costs needed to adapt the layout to these changes. The proposed flexible machine layout design procedure formulates a robust machine layout design problem over a rolling horizon planning time window.

Moving vehicle dynamics is studied while travelling on a curved bridge in this paper. The vehicle including the driver and the passenger is simulated as a half-car planner model having six degrees of freedom, travelling on the bridge with constant velocity. The bridge is modeled as a curved beam that obeys the Timoshenko beam theory. Finite element method is employed to solve the combinational problem. The obtained numerical results are compared with those reported in the literature in a number of special cases. A parametric study is then carried out and effects of different parameters on both the vehicle and bridge dynamic behavior are investigated.

In this paper, multi-objective uniform-diversity genetic algorithm (MUGA) with a diversity preserving mechanism called the ε-elimination algorithm is used for Pareto optimization of 5-degree of freedom vehicle vibration model considering the five conflicting functions simultaneously. The important conflicting objective functions that have been considered in this work are, namely, vertical acceleration of seat, vertical velocity of forward tire, vertical velocity of rear tire, relative displacement between sprung mass and forward tire and relative displacement between sprung mass and rear tire. Further, different pairs of these objective functions have also been selected for 2-objective optimization processes. The comparison of the obtained results with those in literature demonstrates the superiority of the results of this work. It is shown that the results of 5-objective optimization include those of 2-objective optimization and, therefore, provide more choices for optimal design of vehicle vibration model.

In this study, a precise finite element analysis has been carried out on a diesel engine piston, in order to attain its high cycle fatigue (HCF) safety factor and low cycle fatigue (LCF) life. In order to calculate the HCF safety factor, a macro has been developed using ANSYS Parametric Design Language (APDL). The relative stress gradient parameter is used in order to perceive stress concentration and notch effect. In high cycle fatigue assessment, the effect of mean stress is considered using Haigh diagram. Different LCF life assessment methods have been used to investigate LCF life of piston and their results are compared to each other. The diesel engine piston is subjected to non-proportional multiaxial loading. The non-proportional loading leads to an additional cyclic hardening in the material. Critical plane LCF theories are appropriate for consideration of the additional cyclic hardening effect on the LCF life reduction of the piston.

In the design of vehicle structures for crashworthiness there is a need for rigid subsystems that guarantee an undeformable survival cell for the passengers and deformable subsystems able to efficiently dissipate the kinetic energy. The front rails are the main deformable components dissipating energy in a frontal impact, which is the most dangerous crash situation. In frontal impact these rails have the greatest influence on vehicle crash performance. In this work study of different cross sections of the front rails under full frontal crash with different inclination angle of barrier considering two connected or two separated rails is carried out. The present paper deals with the collapse simulation of two extruded polygonal section columns made of aluminum alloy which are separated or are connected with a nearly rigid bumper and, are subjected to oblique loads. Oblique load conditions in numerical simulations are applied by means of impacting a declined rigid wall on the tubes with no friction. The explicit finite element code LS-DYNA is used to simulate the crash behavior of polygonal section columns which are undergoing both axial and bending collapses situations. In order to validate LS-DYNA results the collapse procedure of square columns is successfully simulated and the obtained numerical results are compared with actual available experimental data. Mean crush loads and permanent displacements correspond to load angles have been investigated considering columns with square, hexagonal and, octagonal cross sections. It is shown that a pair of octagonal cross section connected columns has better characteristics from the point of view of crashworthiness under oblique load condition and connection between two rails dominates bending mode of deformation and reduces crashworthiness capability of front end of vehicle.

This article describes the design and manufacturing of a subscale model of a multipurpose simulator which enables the user to perform costly road tests in lab. The simulator comprises of two AC servo machines, one acting as internal combustion engine and the other acting for road loads. The engine side drive can be programmed to simulate the exact performance curves of any desired engine and to even exert negative load similar to an engine during vehicle coasting with no gas input. The road side drive can also be programmed to simulate car inertia as well as road resistances such as positive or negative slopes, air drag and wind in different directions, tire resistances, and climatic road condition changes. The gear box to be tested, manual or automatic, can be installed between the two drives to complete the drive train. The system has the power saver feature, returning the brake power of the road side drive to electrical grid. A user friendly HMI enables the operator to do the adjustments and programming prior to the test and to customize the engine and the road according to the desired test. The used programming functions are very powerful and easy to use. During the test the operator can apply gas, brake and if necessary clutch manually or through the test program. All the test data is recorded during the test by the simulator data acquisition system for further analysis. This simulator can perform long term road tests bearing heavy cost and manpower on car companies. It is also capable of measuring drive train efficiency, observing speed and load related actions of automatic transmission, pre evaluation of development ideas and road testing engine and gearbox replacements for existing platforms. A 1:50 scale, but full feature, of the system was built and successfully tested for design assessment and evaluation.