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Technical Paper

Optimizing Performance and Fuel Efficiency for a Formula SAE Car

2019-04-02
2019-01-1127
This paper presents a system intended to optimize the balance between performance and efficiency of a vehicle completing a course. For example, the Formula SAE competition includes an endurance event where 100 points are based on fuel efficiency, and 275 points are based on performance. While lap simulation programs are typically used to decrease lap times by modifying the car’s design parameters, our goal is a lap simulation tool that can also be used to maximize the fuel efficiency while maintaining a prescribed performance level. In the FSAE event, if the fuel consumption can be reduced enough while maintaining a comparable lap time, the overall score can increase dramatically. The simulation presented will optimize gear shifts points, maximum throttle position, fuel mixture, and perform a lift and coast procedure to achieve the highest score for endurance and efficiency combined.
Technical Paper

Mechanical Performance of Friction Stir Linear Welds of Al to Mg Alloys

2017-03-28
2017-01-0467
Lightweight metals such as Al and Mg alloys have been increasingly used for reducing mass in both structural and non-structural applications in transportation industries. Joining these lightweight materials using traditional fusion welding techniques is a critical challenge for achieving optimum mechanical performance, due to degradation of the constituent materials properties during the process. Friction stir welding (FSW), a solid-state joining technique, has emerged as a promising method for joining these lightweight materials. In particular, high joining efficiency has been achieved for FSW of various Al alloys and Mg alloys separately. Recent work on FSW of dissimilar lightweight materials also show encouraging results based on quasi-static shear performance. However, coach-peel performance of such joints has not been sufficiently examined.
Technical Paper

Innovative Design - Route to Functionally Graded Structures

2017-01-10
2017-26-0157
Functionally graded materials enable structures to have distribution of different properties (physical, thermal, electrical, mechanical, etc.) across its volume; achievable via material/ design/ process engineering. These functionally graded materials can find an application in systems which demand localized variation or enhancement in properties in different regions of the same component. In this paper, we focus on the potential ways of designing functionally graded polymer composite structure by injection molding process. Advanced mold designs for injection molding process can be effectively used to manufacture the functionally graded structures. Innovative design approach has been explored to control the distribution of the filler content /orientation to impart distinctive properties across the cross section / geometry without affecting the bulk properties.
Technical Paper

Light Weight Structures - Structural Analysis for Weight Optimization and Joining Techniques of Dissimilar Materials

2016-04-05
2016-01-1394
Light weight structures give significant advantages to products in the Industrial sector. Component weight-saving plays a major role in improving the efficiency and performance of assembled systems. The introduction of lighter materials into products using dissimilar material joining techniques can create more weight savings and leads to lighter structures. Structural optimization is another method to optimize the material layout without affecting overall performance of the product. This paper discusses the methods to create lighter structures by the introduction of lighter materials in structures and structural optimization methods. Lighter materials are introduced in the structure using dissimilar material joining techniques. Joining processes such as thermal shrink-fit and mechanical press-fit are useful for metal to metal components. Similarly, adhesively bonded joints are useful for both metal and non-metal (plastics and composites) components.
Journal Article

A Central Differential Gear Ratio Optimization of a 6×6 Articulated Dump Truck

2015-09-29
2015-01-2787
This paper starts with an analysis of design configurations of the drivelines with different power-dividing units (PDUs) of main dump truck manufacturing companies. As it follows from the analysis, improvements of articulated truck energy efficiency and reduction of fuel consumption by optimizing the power distribution to the drive wheels are still open issues. The problem is that a variety of operating and terrain conditions of dump trucks requires different wheel power distributions that cannot be provided by one set of PDUs employed in a truck. The central PDU in the transfer case was identified as the most important PDU among the five PDUs, which plays a crucial role in the power distribution between the front axle and the rear tandem of a 6×6 articulated dump truck. The paper formulates a constraint optimization problem to minimize the tire slippage power losses by optimizing the power distribution between the drive wheels.
Technical Paper

Continued Development of a High-Fidelity 1D Physics-Based Engine Simulation model in MATLAB/Simulink

2015-04-14
2015-01-1619
Engine and drivetrain simulation has become an integral part of the automotive industry. By creating a virtual representation of a physical system, engineers can design controllers and optimize components without producing a prototype, thus reducing design costs. Among the numerous simulation approaches, 1D physics-based models are frequently implemented due to balanced performance between accuracy and computational speed. Several 1D physics-based simulation software packages currently exist but cannot be directly implemented in MALAB/Simulink. To leverage MATLAB/Simulink's powerful controller design and simulation capabilities, a 1D physics-based engine simulation tool is currently being developed at The University of Alabama. Previously presented work allowed the user to connect engine components in a physically representative manner within the Simulink environment using a standard block connection scheme and embedded MATLAB functions.
Technical Paper

Development of a High-Fidelity 1D Physics-Based Engine Simulation model in MATLAB/Simulink

2014-04-01
2014-01-1102
Currently, several 1D physics-based high-fidelity engine simulation software packages exist and provide reasonably accurate predictions of engine performance. However, most of the current high-fidelity engine simulation packages are developed in conventional programming languages and cannot be directly implemented in today's predominant MATLAB/Simulink simulation environment. In an effort to develop a MATLAB/Simulink-based engine simulation package, a high-fidelity 1D physics-based engine simulation model is currently being developed at The University of Alabama. The proposed model library includes various functional blocks capable of being connected in a logical manner to form a full engine system. Some of the functional blocks include a 1D unsteady flow section, cylinder valve, throttle, flow junction, cylinder, and engine dynamics. In this paper, preliminary simulation results are presented as well as descriptions of the functional blocks.
Technical Paper

Microstructure-Sensitive Fatigue Modeling of an Extruded AM30 Magnesium Alloy

2013-04-08
2013-01-0980
We characterize the cyclic behavior of an AM30 extruded magnesium alloy. The micromechanisms of cyclic damage were studied by means of strain controlled experiments in both the extruded and transverse directions. A scanning electron microscope (SEM) analysis of the microstructure revealed that second phase particles were present in the Mg alloy that nucleated the cracks. However, crack initiation sites were observed to occur due to profuse twinning. Low cycle fatigue parameters were determined, and a microstructure-sensitive MultiStage Fatigue (MSF) model, which is able to capture mechanical and microstructure properties, was implemented to predict fatigue behavior and failure.
Technical Paper

Downspeeding and Supercharging a Diesel Passenger Car for Increased Fuel Economy

2012-04-16
2012-01-0704
The effects of downspeeding and supercharging a passenger car diesel engine were studied through laboratory investigation and vehicle simulation. Changes in the engine operating range, transmission gearing, and shift schedule resulted in improved fuel consumption relative to the baseline turbocharged vehicle while maintaining performance and drivability metrics. A shift schedule optimization technique resulted in fuel economy gains of up to 12% along with a corresponding reduction in transmission shift frequency of up to 55% relative to the baseline turbocharged configuration. First gear acceleration, top gear passing, and 0-60 mph acceleration of the baseline turbocharged vehicle were retained for the downsped supercharged configuration.
Video

Model-Based Approach to Estimate Fuel Savings from Series Hydraulic Hybrid Vehicle: Model Development and Validation

2011-12-05
A simulation framework with a validated system model capable of estimating fuel consumption is a valuable tool in analysis and design of the hybrid vehicles. In particular, the framework can be used for (1) benchmarking the fuel economy achievable from alternate hybrid powertrain technologies, (2) investigating sensitivity of fuel savings with respect to design parameters (for example, component sizing), and (3) evaluating the performance of various supervisory control algorithms for energy management. Presenter Chinmaya Patil, Eaton Corporation
Technical Paper

Model-Based Approach to Estimate Fuel Savings from Series Hydraulic Hybrid Vehicle: Model Development and Validation

2011-09-13
2011-01-2274
A simulation framework with a validated system model capable of estimating fuel consumption is a valuable tool in analysis and design of the hybrid vehicles. In particular, the framework can be used for (1) benchmarking the fuel economy achievable from alternate hybrid powertrain technologies, (2) investigating sensitivity of fuel savings with respect to design parameters (for example, component sizing), and (3) evaluating the performance of various supervisory control algorithms for energy management. This paper describes such a simulation framework that can be used to predict fuel economy of series hydraulic hybrid vehicle for any specified driver demand schedule (drive cycle), developed in MATLAB/Simulink. The key components of the series hydraulic hybrid vehicle are modeled using a combination of first principles and empirical data. A simplified driver model is included to follow the specified drive cycle.
Technical Paper

Simulation and Experimental Study of Torque Vectoring on Vehicle Handling and Stability

2009-12-13
2009-28-0062
This paper discusses the effect of torque vectoring differential on improving vehicle handling and stability performance. The torque vectoring concept has been analyzed. The vehicle discussed in this paper is an AWD vehicle with torque vectoring differential in the rear and a torque biasing center differential. First, simulation results with vehicle model in CarSim® and torque vectoring control algorithm in Matlab®/Simulink® is discussed. Then, experimental results for vehicle tested at winter and summer test facility is presented. Both simulation and experimental results demonstrate the effectiveness of torque vectoring differential on vehicle handling & stability.
Technical Paper

Hardware-In-the-Loop (HIL) Modeling and Simulation for Diesel Aftertreatment Controls Devlopment

2009-10-06
2009-01-2928
This paper addresses Hardware-In-the-Loop modeling and simulation for Diesel aftertreatment controls system development. Lean NOx Trap (LNT) based aftertreatment system is an efficient way to reduce NOx emission from diesel engines. From control system perspective, the main challenge in aftertreatment system is to predict temperature at various locations and estimate the stored NOx in LNT. Accurate estimation of temperatures and NOx stored in the LNT will result in an efficient system control with less fuel penalty while still maintaining the emission requirements. The optimization of the controls will prolong the lifespan of the system by avoiding overheating the catalysts, and slow the progressive process of component aging. Under real world conditions, it is quite difficult and costly to test the performance of a such complex controller by using only vehicle tests and engine cells.
Technical Paper

Multi-Objective Design Optimization Using a Damage Material Model Applied to Light Weighting a Formula SAE Car Suspension Component

2009-04-20
2009-01-0348
The Mississippi State University Formula SAE race car upright was optimized using radial basis function metamodels and an internal state variable (ISV) plasticity damage material model. The weight reduction of the upright was part of a goal to reduce the weight of the vehicle by 25 percent. Using an optimization routine provided an upright design that is lighter that helps to improve vehicle fuel economy, acceleration, and handling. Finite element (FE) models of the upright were produced using quadratic tetrahedral elements. Using tetrahedral elements provided a quick way to produce the multiple FE models of the upright required for the multi-objective optimization. A design of experiments was used to determine how many simulations were required for the optimization. The loads for the simulations included braking, acceleration, and corning loads seen by the car under track conditions.
Technical Paper

Minimizing Dynamic Rollover Propensity with Electronic Limited Slip Differentials

2006-04-03
2006-01-1279
Vehicle rollover has the highest fatality rate among non-collision vehicle crashes. This paper introduces a control scheme with electronically controlled limited slip differential (ELSD) to prevent vehicle rollover. Although the analysis focuses on only an un-tripped and on-road scenario which is a small portion of vehicle rollover accidents, it intends to minimize the dynamic rollover propensity by meeting the National Highway Traffic Safety Administration's (NHTSA) fishhook test. A nonlinear model of planar vehicle dynamics with roll motion is analyzed, and the general characteristics of ELSD are presented. Based on that, a rollover mitigation algorithm is proposed. Finally, a computer simulation demonstrates the effectiveness of the rollover mitigation algorithm.
Technical Paper

Modeling and Sensorless Estimation for Single Spring Solenoids

2006-04-03
2006-01-1678
This paper presents an empirical dynamic model of a single spring electromagnetic solenoid actuator system, including bounce, temperature effects and coil leakage inductance. The model neglects hysteresis and saturation, the aim being to compensate for these uncertainties through estimator robustness. The model is validated for all regions of operation and there is a good agreement between model and experimental data. A nonlinear (sliding mode) estimator is developed to estimate position and speed from current measurements. Since the estimator makes use of only current measurement it is given the name sensorless. The estimator is validated in simulation and experimentally. The novelty in this paper lies in the fact that accurate state estimation can be realized on a simple linear model using a robust observer theory. Also, the formulations for leakage inductance and coil temperature are unique.
Technical Paper

Nonlinear Modeling of an Electromagnetic Valve Actuator

2006-04-03
2006-01-0043
This paper presents the modeling of an Electromagnetic Valve Actuator (EMV). A nonlinear model is formulated and presented that takes into account secondary nonlinearities like hysteresis, saturation, bounce and mutual inductance. The uniqueness of the model is contained in the method used in modeling hysteresis, saturation and mutual inductance. Theoretical and experimental methods for identifying parameters of the model are presented. The nonlinear model is experimentally validated. Simulation and experimental results are presented for an EMV designed and built in our laboratory. The experimental results show that sensorless estimation could be a possible solution for position control.
Technical Paper

Stress Analysis of an Automotive Engine Valve by Finite Element Methods

2006-04-03
2006-01-0017
A detailed study, by finite element method (FEM), was conducted on an automotive engine exhaust valve subject to various loads (i.e. spring load, combustion pressure load, temperature profile and valve impact closing velocity). The 3D nonlinear (contact element and temperature-dependent) thermal-mechanical model was constructed and implicit time integration method was employed in transient dynamics under impact velocity. The predicted temperatures and maximum valve stress under impact velocity via FEM were compared with the measured test data, which were in good agreement. In addition, this study finds that the energy transfer during valve closing in normal engine operation is mainly conservative, and a linear relation exists between valve closing velocity and maximum stem stress, that was also confirmed by both test data and analytical expression presented using elastic wave and vibration theory.
Technical Paper

Timing Gear Whine Noise Reduction Methodology and Application in Superchargers

2005-05-16
2005-01-2450
Extensive experimental and numerical investigations were done to improve the vibration and acoustic performance due to excitation at the timing gears of automotive supercharger. Gear excitation, system response, and covers have been studied to find the most cost efficient method for reducing gear whine noise. Initially, gear excitation was studied where it was found that transmission error due to profile quality was the dominant source parameter for gear whine noise. To investigate the system effects on gear noise, a parametric study was carried using FEM model of the supercharger, with special interests in optimizing dynamic characteristics of internal components and the coupling to supercharger housing. The BEM model of the corresponding supercharger was built to predict the noise improvement after dynamic optimization of the system. Good correlations were observed between experimental and numerical results in both dynamic and acoustic parameters.
Technical Paper

A New Composite Drive Cycle for Heavy-Duty Hybrid Electric Class 4-6 Vehicles

2004-03-08
2004-01-1052
This paper presents a new composite drive cycle used to evaluate and test the performance of Class 4-6 heavy-duty hybrid electric vehicles (HEVs). The new cycle is being used in the ongoing Advanced Heavy Hybrid Propulsion Systems (AHHPS) Program, sponsored by the U.S. Department of Energy. The goal was to select a cycle that is acceptable to all involved parties, has an achievable speed-time trace for target applications, represents the typical driving pattern of these applications, and is practical for testing and state-of-charge correction. These criteria were applied to numerous element and composite cycles. Ultimately, a new composite cycle was developed and selected-the Combined International Local and Commuter Cycle (CILCC). Various activities conducted under the AHHPS Program are based on this cycle, including energy auditing, modeling and simulation, system optimization, and vehicle testing.
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