Applied Mechanics and Materials Vol. 165

Abstract: The present paper reports a simulation study of the fluid flow and thermal phenomena in the passenger vehicle underhood compartment by analysing velocity magnitude, temperature, radiator heat transfer rate and heat transfer efficiency. Analyses are carried out on a half cut passenger vehicle sample model by using commercial computational fluid dynamics (CFD) software, Star CCM+. Total volume meshes of the model are 24 451 759 cells, and the speed of the car is 0.036, 40, 70, 110, 130 and 213 km/h. Investigation are performed for three dimensional conditions, steady state gas with segregated flow, constant density, turbulence flow, with the use of the Reynolds-Averaged Navier-Stokes model and the K-Epsilon turbulence model. In the thermal analysis, particular attention is given to find hot spot locations under the hood. . High temperature region is observed at the right side of the hood (from the top of view) due primary heat sources from the engine. An air intake at hood is introduced in order to facilitate the airflow to engine room and to remove hot spot to the atmosphere. It is shown that the underhood average temperature decreases by 26.2% and the average airflow velocity at section plane of the centreline increases by 14.5% by adding this air intake.

Abstract: The knowledge of the wheel forces is fundamental to the development of Advanced Driver Assistance Systems (ADAS) such as Electronic Stability Control (ESC) and Anti-Roll Control (ARC). However the direct measurement of the wheel forces has been very difficult. To overcome this drawback, it has been a common practice in the industry to estimate the forces at the tire-road contact using mathematical vehicle models and estimators, especially the Extended Kalman Filter (EKF). In this contribution, the performance of the EKF is evaluated using a complete spatial model with 14 degrees of freedom.

Abstract: Liquid sloshing is any motion of free liquid surface inside its container. Sloshing may generate hydrodynamics loads that can be dangerous to structural integrity and stability of moving container. In this study, liquid sloshing in cubical and cylindrical containers with similar characteristic length were investigated. The containers with liquid inside were excited sinusoidally by using an electrodynamics shaker while the free liquid surface level change was captured by using high speed camera. The highest free liquid surface level difference obtained for cylindrical and cubical containers were compared. Results show that cylindrical containers produce less liquid sloshing and thus more suitable to be used for liquid transportation.

Abstract: Noise, Vibration and Harshness (NVH) is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks. NVH parameters which consist of noise (unwanted sound), vibration (mechanical oscillation) and harshness (severity or discomfort of noise or vibration) need to be evaluated in order to improve comfort and safety levels for vehicle occupants. In this paper, NVH study was conducted on Malaysian Armed Forces (MAF) tactical vehicles in order to ensure that the vehicles meet the requirements of the Occupational Safety and Health Administration (OSHA) and Directive 2002/44/EC. The project aim was to identify the preferable solution that can improve the NVH parameters of the vehicles in accordance to the standard and test protocols. A 4x4 Troop Transporter vehicle which carried 8 persons at the rear cabin was used in the NVH testing. The vibration parameters studied are hand arm vibration (HAV), focussing on vibration on the steering wheels of the vehicle, and whole body vibration (WBV), focussing on vibration on the seats. For noise, it was measured at the driver cabin and rear cabin of the vehicles. From the results, the HAV value for driver during idle speed was found to be higher than the others velocity. For WBV, vibration value for passenger 1 in rear cabin was highest compared to the other WBV test points.

Abstract: This paper presents a control strategy for controlling speed of a vehicle experiencing the disturbance from road gradient using simulation method. A non-linear vehicle longitudinal model is used for modeling the vehicle behavior in longitudinal direction and the vehicle is subjected to several positive (uphill) road gradient disturbances. The gain scheduling Proportional-Integral-Derivative (PID) controller is proposed to achieve the control objective. MATLAB-SIMULINK is chosen as a simulation tool to simulate the vehicle dynamics behavior and evaluate the performance of the control structure. The result shows that the proposed controller is effective in controlling the vehicle speed with relatively lower speed drop. The controller performance is far better than the fixed gain PID controller.

Abstract: The problem statement consisted of designing a Wet Sump Lubrication system for Formula Manipal, Manipal Institute of Technology's FSAE racing team. The team uses a 2003 specification Honda CBR 600RR motorcycle engine to power the rear wheels by means of a chain drive and a limited slip differential. Packaging and performance constraints meant that the stock oil pan could not be retained. It was thus proposed to design and manufacture a custom wet sump oil pan and validate it by testing. The goal was to build a lubrication system which worked flawlessly in a racing environment including acceleration, braking and cornering. This was realized by innovatively placing baffles and a windage tray in the oil pan. At the same time, it was important to reduce the height of the oil pan so as to allow the engine to be mounted lower in the chassis, facilitate better packaging and improve the dynamic performance of the car.

Abstract: This paper presents the analysis of energy absorbed that produced from an instrumented charpy impact in order to evaluate the toughness of materials. Alloy rims made from aluminium 6061-T6 are easily damage, fracture and can even destroy after impact loading compared to the steel rim. For this reason, an idea was initiated to determine the strain signal pattern and strain energy for evaluting the toughness of materials. Strain gauges were experimentally connected to the data acquisition system and it was then attached to the charpy striker for the impact signal collection. Specimens of aluminium alloy of 6061-T6 and carbon steel 1050 were used and its were designed according to the ASTM E23 standard. In this work, the signal was converted from the time domain to the frequency domain using the power spectrum density (PSD) method and the area under its graph was then used to calculate strain energy. The comparison between absorbed energy and strain energy was performed based on different materials and thicknesses. It was found the effect of the strain signal pattern with different materials and thicknesses to be influnced the strain energy.

Abstract: The aim of this paper is to examine the modeling sensitivity of the three-point bending test by using finite element method (FEM). Three-point bending test has been frequently used to determine the material hardening parameters of sheet metal. As a part of the parameter identification, three-point bending has been simulated and analyzed using FEM. To minimize the computation time, shell element was used to model the sheet metal. The analysis includes implicit and explicit procedures. In particular, this study examines the effect of FEM results by varying the element type, mesh density, and number of integration point. It is shown that the implicit procedure analyze the simulation with very less computation time compared to the explicit procedure. The results also show that only the number of integration point has significant effect on the simulation in both implicit and explicit procedures.

Abstract: Autonomous vehicle have recently arouse great interest and attention in the academic worldwide because of their great potential. As the new features for driver assistance and active safety systems are growing rapidly in vehicles, the simulation within a virtual environment has become a necessity. A vehicle model is required to represent the vehicle behaviour as close as real vehicle in simulation software. This paper presents 9 DOF vehicle models which consist of handling and Calspan tire model develop in Matlab Simulink environment to study the vehicle behaviour for double lane change (DLC) and step steer input test. Those criteria will be compared with validated vehicle software namely CarsimEd to evaluated the performance of the vehicle model involving lateral acceleration, yaw angle and yaw rate from both output. Results show the 9 DOF vehicle closely follows the CarsimEd trends with acceptable error at both conditions.

Abstract: Pipes are found in almost all buildings and constructions where they are used to convey fluid to a desired location. Liquid containing foreign objects and impurities will sometimes creates unintentional built up or clog obstruction along the interior surface of the pipeline. This phenomenon may affect the fluid flow within the pipe. This work analyzed the impact of different blockage sizes inside a clear Polyvinyl Chloride (PVC) circular pipe using vibration measurement. Observations were made on the fluid flow patterns during the flow. This work encompasses the correlation between blockage thickness inside a circular pipe and vibration parameters.