Showing papers in "International Journal of Vehicle Structures & Systems in 2021"
TL;DR: In this paper, a simple and effective method for the determination of Rayleigh co-efficients α and β for the system with multiple degrees of freedom is presented, where an unrealistic constant damping ratio for all modes is assumed to get rational value of α and α, which leads to determination of progressively varying damping matrix of all modes.
Abstract: Rayleigh damping co-efficients are the essential parameters to determine the damping matrix of a system in dynamic analysis. For the systems with multiple degrees of freedom, it is difficult to arrive for suitable Rayleigh damping co-efficients. This paper represents a simple and effective method for the determination of Rayleigh co-efficients α and β for the system with multiple degrees of freedom. An unrealistic constant damping ratio for all modes is assumed to get rational value of α and β, which leads the determination of progressively varying damping ratio for all modes. By comparing the damping ratio arrived from assumed α and β with assumed unrealistic damping ratio, the suitable and most precise values are determined. This method is implemented for different materials with different boundary conditions by considering different significant modes and the effect of above parameters on α and β values are also discussed.
3 citations
TL;DR: A linear two degrees of freedom linear bicycle model is proposed to investigate the vehicle handling criterion and it is found that changing the vehicle center of gravity (CG) position, vehicle mass, tire cornering stiffness and vehicle speed all have a significant influence on the vehicle dynamic stability.
Abstract: In this paper, a linear two degrees of freedom linear bicycle model is proposed to investigate the vehicle handling criterion. The study is based on simulation developed using MATLAB / Simulink to predict the vehicle dynamic stability. Steering angle is given as an input to the mathematical model for various vehicular manoeuvres. This model is validated using a step input which is adjusted to give 0.3g lateral acceleration. The system model is simulated under a typical front wheel steering to examine the highway vehicle prediction output within its manoeuvre. This input is also adjusted to keep lateral acceleration value in steady state region. It is found that changing the vehicle center of gravity (CG) position, vehicle mass, tire cornering stiffness and vehicle speed all have a significant influence on the vehicle dynamic stability.
TL;DR: A drive cycle analysis of the BEV vehicle using the EPA Urban Dynamometer Driving Schedule (UDDS) and Highway Fuel Economy Test (HWFET) drive cycles by means of dynamic modeling and simulation is presented.
Abstract: The “Car of the Future” project converted a 2015 rear-wheel drive (RWD) Subaru BRZ into a hybrid electric vehicle (HEV) with an intermediate milestone of a battery electric vehicle (BEV). BEV architecture required removal of the conventional powertrain components, such as internal combustion engine, transmission and differential, introduced an electric axle and battery. This intermediate BEV step provided a point at which the vehicle could be evaluated in its all electric operation with the absence of what was once critical components including its original powertrain and powertrain electronics. This step also ensures the electric components are working properly before more complexity is added to the system in building HEV. In our previous work, BEV Vehicle Technical Specifications (VTS) or requirements were developed and an electric axle was appropriately sized and selected to meet these requirements. After selecting the electrical axle with independent rear motors that will meet BEV performance requirements, Environmental Protection Agency (EPA) fuel economy rating of the BEV should be assessed. This paper presents a drive cycle analysis of the BEV vehicle using the EPA Urban Dynamometer Driving Schedule (UDDS) and Highway Fuel Economy Test (HWFET) drive cycles by means of dynamic modeling and simulation. In this study, the power required at the wheels, the efficiency of each motor and the energy required at the selected electrical axle were determined. In addition, the city, highway and combined miles per gallon equivalent (MPGe) fuel economy were determined.
TL;DR: In this article, the aerodynamic characteristics of adjustable multi-slotted adjustable airfoil with unmorphed unsymmetrical airfoils at varied speeds and Angle of Attack (AoA) were investigated.
Abstract: Aviation has wide aspects to challenge and discover, the ability to land and take off at slow speed, sudden increase in drag for short runway landings. This paper puts forth the solution by the use of adjustable multi slots configuration of an airfoil. In this case, the slots extend from the wing leading edge to trailing edge. This causes change in the chord, thereby changing the camber of unsymmetrical airfoil. An investigation was made to determine and compare the aerodynamic characteristics of multi slotted adjustable airfoil with unmorphed unsymmetrical airfoil at varied speeds and Angle of Attack (AoA). There are three slots distanced equally along the airfoil. The extension of these slots increases the chord length by 10% of total chord. The slotted and unslotted airfoil profile are then studied using computational fluid dynamics of external flow over a body. The flow simulation is done at 10m/s, 20m/s, 30m/s, 40m/s and 50 m/s flow velocity and at 0, 3, 6, 9 ,12, 15 AoA. The results were obtained for each case and the values for base and slotted model were compared. It was found that lift of slotted model is slightly higher than base model at low flow velocity. It was also seen that the use of slots at high speed causes a large amount of drag. This increased drag factor can be used in UAV’s as spoilers during landing or for landing at shorter runways at lower speed, allowing a sudden decrease in aircraft speed and also to glide at a steeper angle over obstruction.