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Technical Paper

Development of an Out-of-Plane Flexible Ring Tire Model Compared with Commercial FTire® Via Virtual Cleat Tests

2018-04-03
2018-01-1120
Abstract In this paper, based on our previously preliminary out-of-plane tire model, a complete out-of-plane flexible tire model is further developed by considering the variation of dimension and parameter values among different slices of the tire model. This tire model is validated via various MSC ADAMS® FTire virtual cleat tests. Especially, the cleat tests with non-zero tire camber angles and non-symmetric cleat shapes, which can better capture the out-of-plane tire properties, are included. By comparing the predicted results of the proposed tire model with FTire for various cleat tests, it shows that the complete out-of-plane flexible ring tire model is better at fully representing the actual tire properties for some complicated cleat testing scenarios.
Technical Paper

Quantification of Energy Pathways and Gas Exchange of a Small Port Injection SI Two-Stroke Natural Gas Engine Operating on Different Exhaust Configurations

2018-04-03
2018-01-1278
Abstract This paper examines the energy pathways of a 29cc air-cooled two-stroke engine operating on natural gas with different exhaust geometries. The engine was operated at wide-open-throttle at a constant speed of 5400 RPM with ignition adjusted to yield maximum brake torque while the fueling was adjusted to examine both rich and lean combustion. The exhaust configurations examined included an off-the-shelf (OTS) model and two other custom models designed on Helmholtz resonance theory. The custom designs included both single and multi-cone features. Out of the three exhaust systems tested, the model with maximum trapping efficiency showed a higher overall efficiency due to lower fuel short-circuiting and heat transfer. The heat transfer rate was shown to be 10% lower on the new designs relative to OTS model.
Technical Paper

Effects of Fiber Volume Fraction, Fiber Length and Fillers on Fracture Toughness, Impact Toughness and Fracture Energy of Glass Fiber Composite Panels

2018-04-03
2018-01-1122
Abstract Composites are wonderful materials that have revolutionized the field of engineering because they can provide more versatility when compared to other materials and can be tailored to have maximum strength and stiffness. Experimental investigation was carried out to study the influence of fiber volume fraction, fiber length and percentage of fillers on fracture toughness ,fracture energy and impact energy of glass fiber reinforced composite. Panels with different configurations were made using fiber glass chopped strand mat and unidirectional roving with epoxy resin. Wet Hand Layup method was adopted for fabrication of panels with different fiber volume fractions and filler density while Bulk Molding Compound Technique was used for making panels with different fiber lengths. ASTM D-5045-14 was consulted for the development of test specimens to conduct flexural testing of these panels.
Technical Paper

Effects of Motor and Transmission on Noise Level of Electric Bus Powertrain Using Lead Packaging Method

2018-04-03
2018-01-1281
Abstract Because of the advantages of excellent power, fuel economy and zero-emission characteristics, electric buses have been used widely as cities’ short-range commuter vehicles. However, the high-frequency noise becomes more prominent for the powertrain system of the electric bus due to the lack of noise masking effect for the traditional internal combustion engine. To improve the noise characteristic of electric bus powertrain, the identification of the main noise source of the powertrain is well needed. In this paper, the effects of the motor and transmission on the noise level of the electric bus powertrain have been studied using lead packaging method. The variations of acoustical power level of the powertrain according to different rotation speed and torque under the conditions of only motor covered and only transmission covered have been discussed.
Technical Paper

Multi-Objective Optimization of Fuel Injection Pattern for a Light Duty Diesel Engine through Numerical Simulation

2018-04-03
2018-01-1124
Abstract Development trends in modern Common Rail fuel injection systems show dramatically increasing capabilities in terms of optimization of the fuel injection strategy through a constantly increasing number of injection events per engine cycle as well as through the modulation and shaping of the injection rate. In order to fully exploit the potential of the abovementioned fuel injection strategy optimization, numerical simulation can play a fundamental role by allowing the creation of a kind of a virtual test rig, where the input is the fuel injection rate and the optimization targets are the combustion outputs, such as the burn rate, the pollutant emissions and the combustion noise.
Technical Paper

Ignition Delay in Low Temperature Combustion

2018-04-03
2018-01-1125
Abstract Low temperature combustion (LTC) strategies present a means of reducing soot and oxides of nitrogen (NOx) emissions while simultaneously increasing efficiency relative to conventional combustion modes. By sufficiently premixing fuel and air before combustion, LTC strategies avoid high fuel-to-air equivalence ratios that lead to soot production. Dilution of the mixture lowers the combustion temperatures to reduce NOx production and offers thermodynamic advantages for improved efficiency. However, issues such as high heat release rates (HRRs), incomplete combustion, and difficulty in controlling the timing of combustion arise with low equivalence ratios and combustion temperatures. Ignition delay (the time until the start of combustion) is a way to quantify the time available for fuel and air to mix inside the cylinder before combustion. Previous studies have used ignition delay to explain trends seen in LTC such as combustion stability and HRRs.
Technical Paper

Methods to Mitigate Tail Pipe Noise in Passenger Vehicles

2018-04-03
2018-01-1280
Abstract The cold end of an exhaust system plays an important role in today’s passenger cars by reducing the engine noise and thus keeping a pleasant cabin room for optimum passenger comfort. However, due to vehicle layout constraints, it may be difficult to achieve a Muffler design which fulfills the required noise attenuation requirement. It becomes imperative to have an understanding of the different parameters that affect the overall tail pipe noise. In an automobile exhaust system, Exhaust Mufflers play a major role in noise reduction by helping in the attenuation of undesirable noises from the engine. The overall content of the tail pipe noise of an IC engine can be segregated into two categories - Order noise and Flow noise. Order noises are low frequency pressure pulses generated during the exhaust valve opening and closing in the engine combustion cycle.
Technical Paper

Sound Quality Evaluation Method with Consideration of Perceived Fluctuation for Combustion Noise in Vehicle Interior, Combined with Time Domain Combustion Noise Separation Method

2018-04-03
2018-01-1283
Abstract To increase the efficiency of measures targeting combustion noise in complete vehicle development, we developed a new sound quality evaluation method by combining two known methods: the time domain combustion noise separation method (T-CNSM) and a psychoacoustic metric, fluctuation intensity. The T-CNSM was applied to the vehicle interior noise, allowing for precise extraction of the combustion contribution in the time domain. Furthermore, the T-CNSM has enabled a sound quality check of combustion noise using a headphone-playback system. The procedure of this method is as follows. Firstly, simultaneous measurement of vehicle interior noise and in-cylinder pressure of each cylinder is carried out under acceleration. Afterwards, the application of digital signal processing using Fourier transform and multiple regression analysis to the measured data separates the contribution of combustion noise from the vehicle interior noise in the time domain.
Technical Paper

An Integrated Cooling System for Hybrid Electric Vehicle Motors – Design and Simulation

2018-04-03
2018-01-1108
Abstract Hybrid electric vehicles offer the advantages of reduced emissions and greater travel range in comparison to conventional and electric ground vehicles. Regardless of propulsion strategy, efficient cooling of electric motors remains an open challenge due to the operating cycles and ambient conditions. The on-board thermal management system must remove the generated heat so that the motors and other vehicle components operate within their designed temperature ranges. In this paper, an integrated thermal structure, or cradle, is designed to efficiently transfer heat within the motor housing to the end plates for transmission to an external heat exchanger. A radial array of heat pipes function as an efficient thermal connector between the motor and heat connector, or thermal bus, depending on the conuration. Cooling performance has been evaluated for various driving cycles.
Technical Paper

Simultaneous Design and Control Optimization of a Series Hybrid Military Truck

2018-04-03
2018-01-1109
Abstract This paper investigates the fuel saving potential of a series hybrid military truck using a simultaneous battery pack design and powertrain supervisory control optimization algorithm. The design optimization refers to the sizing of the Lithium-ion battery pack in the hybridized configuration. On the other hand, the powertrain supervisory control optimization finds the most efficient way to split power demands between the battery pack and the engine. Most of the previous literatures implement them separately. In contrast, combining the sizing and energy management problem into a single optimization problem produces the global optimal solution. This study proposes a novel unified framework to couple Genetic Algorithm (GA) with Pontryagin’s Minimum Principle (PMP) to determine the battery pack sizing and the power split control sequence simultaneously.
Technical Paper

Commercial Vehicle Two Cylinder Powertrain Mount Selection Based on Robust Optimization Using MSC/ADAMS and Mode Frontier

2018-04-03
2018-01-1286
Abstract Ride comfort, drivability and driving stability are important factors defining vehicle performance and customer satisfaction. The IC powertrain is the source for the vibration that adversely affects the vehicle performance. The IC powertrain is composed of reciprocating and rotating components which result in unbalanced forces, moments during operation and produce vibrations at the vehicle supporting members. The vibration reduction is possible by minimizing unbalanced forces and/or by providing anti-vibration mounts at the powertrain-vehicle interface. The power train is suspended on the vehicle frame via several flexible mounts, whose function is to isolate powertrain vibrations from the frame. Total six different modes of powertrain vibration namely - roll, yaw, pitch, vertical, lateral and longitudinal need to be isolated. Powertrain mount stiffness and location is critical in this regard.
Technical Paper

On Simulating Sloshing in Vehicle Dynamics

2018-04-03
2018-01-1110
Abstract We present an approach in which we use simulation to capture the two-way coupling between the dynamics of a vehicle and that of a fluid that sloshes in a tank attached to the vehicle. The simulation is carried out in and builds on support provided by two modules: Chrono::FSI (Fluid-Solid Interaction) and Chrono::Vehicle. The dynamics of the fluid phase is governed by the mass and momentum (Navier-Stokes) equations, which are discretized in space via a Lagrangian approach called Smoothed Particle Hydrodynamics. The vehicle dynamics is the solution of a set of differential algebraic equations of motion. All equations are discretized in time via a half-implicit symplectic Euler method. This solution approach is general - it allows for fully three dimensional (3D) motion and nonlinear transients. We demonstrate the solution in conjunction with the simulation of a vehicle model that performs a constant radius turn and double lane change maneuver.
Technical Paper

A Hybrid Thermal Bus for Ground Vehicles Featuring Parallel Heat Transfer Pathways

2018-04-03
2018-01-1111
Abstract Improved propulsion system cooling remains an important challenge in the transportation industry as heat generating components, embedded in ground vehicles, trend toward higher heat fluxes and power requirements. The further minimization of the thermal management system power consumption necessitates the integration of parallel heat rejection strategies to maintain prescribed temperature limits. When properly designed, the cooling solution will offer lower noise, weight, and total volume while improving system durability, reliability, and power efficiency. This study investigates the integration of high thermal conductivity materials, carbon fibers, and heat pipes with conventional liquid cooling to create a hybrid “thermal bus” to move the thermal energy from the heat source(s) to the ambient surroundings. The innovative design can transfer heat between the separated heat source(s) and heat sink(s) without sensitivity to gravity.
Technical Paper

FEA-Based Simulation of Exhaust Hanger Forces

2018-04-03
2018-01-1288
Abstract Exhaust systems can be a source of vibrations that transmit inside the vehicle through the exhaust hangers. These vibrations are caused by engine excitations under acceleration. During the upfront development stage, it is important to predict accurately the forces of the exhaust hangers in order to drive a robust exhaust system design and prevent objectionable noise and vibrations inside the vehicle. This paper describes an FEA-based simulation method to predict the exhaust hanger forces. It demonstrates the effect of temperature on the exhaust dynamic behavior and its importance for an accurate prediction of the exhaust hanger forces.
Technical Paper

One-Dimensional Modelling and Analysis of Thermal Barrier Coatings for Reduction of Cooling Loads in Military Vehicles

2018-04-03
2018-01-1112
Abstract There is a general interest in the reduction of cooling loads in military vehicles. To that end thermal barrier coatings (TBCs) are being studied for their potential as insulators, particularly for military engines. The effectiveness of TBCs is largely dependent on their thermal properties, however insulating effects can also be modified by applying different coating thickness. Convection from in-cylinder surfaces can also be affected by manipulation of surface structure. Although most prior studies have examined TBCs as a means of increasing efficiency, military vehicle design is primarily concerned with the reduction of cylinder heat transfer to allow downsizing of cooling systems. A 1-D transient conjugate heat transfer model was developed to provide insight into the effects of different TBC designs and material selection on cooling loads. Results identify low thermal conductivity and low thermal capacitance as key parameters in achieving optimal heat loss reduction.
Technical Paper

Exhaust and Muffler Aeroacoustics Predictions using Lattice Boltzmann Method

2018-04-03
2018-01-1287
Abstract Exhaust systems are a necessary solution to reduce combustion engine noise originating from flow fluctuations released at each firing cycle. However, exhaust systems also generate a back pressure detrimental for the engine efficiency. This back pressure must be controlled to guarantee optimal operating conditions for the engine. To satisfy both optimal operating conditions and optimal noise levels, the internal design of exhaust systems has become complex, often leading to the emergence of undesired noise generated by turbulent flow circulating inside a muffler. Associated details needed for the manufacturing process, such as brackets for the connection between parts, can interact with the flow, generating additional flow noise or whistles. To minimize the risks of undesirable noise, multiple exhaust designs must be assessed early to prevent the late detection of issues, when design and manufacturing process are frozen.
Technical Paper

Study on Correlation of Commercial Vehicle Axle Response with Road Profile for ISO Road Class Categorization and Durability Analysis

2018-04-03
2018-01-1114
Abstract Durability analysis is essential for vehicle validation and is carried out with the inputs of different road conditions. The selection of roads for durability analysis is critical and should represent the actual working conditions for the selected vehicle. Generally, the road conditions are subject to change with respect to time. To overcome the above, road profile data is an essential parameter which helps to represent and categorize roads in terms of ISO (International Organization for Standardization) road class. The ISO road classes objectively classify the roads with respect to roughness. This classification holds good by categorizing the signals to the respective road classes rather than different test roads. The road profiles are measured using inertial profiler methodology along with vehicle acceleration and displacement responses, also analyzed and categorized with respect to ISO road class.
Technical Paper

Acceleration of Iterative Vibration Analysis for Form Changes in Large Degrees-of-Freedom Engine Model

2018-04-03
2018-01-1290
Abstract Operational analysis of automotive engines using flexible multi-body dynamics is increasingly important from the viewpoint of multi-objective optimization as it can predict not only vibration, but also stress and friction at the same time. Still, the finite element (FE) models used in this analysis have large degrees-of-freedom, so iterative calculation takes a lot of time when there is form change. This research therefore describes a technique that applies a modal differential substructure method (a technique that reduces the degrees of freedom in a FE model) that can simulate form changes in FE models by changing modal mass and modal stiffness in reduced models. By using this method, non-parametric form change in FE model can be parametrically simulated, so it is possible to speed up repeated vibration calculations. In the proposed method, FE model is finely divided for each form change design area, and a reduced model of that divided structure is created.
Technical Paper

An Innovative Design of In-Tire Energy Harvester for the Power Supply of Tire Sensors

2018-04-03
2018-01-1115
Abstract With the development of intelligent vehicle and active vehicle safety systems, the demand of sensors is increasing, especially in-tire sensors. Tire parameters are essential for vehicle dynamic control, including tire pressure, tire temperature, slip angle, longitudinal force, etc.. The diversification and growth of in-tire sensors require adequate power supply. Traditionally, embedded batteries are used to power sensors in tire, however, they must be replaced periodically because of the limited energy storage. The power limitation of the batteries would reduce the real-time data transmission frequency and deteriorate the vehicle safety. Heightened interest focuses on generating power through energy harvesting systems in replace of the batteries. Current in-tire energy harvesting devices include piezoelectric, electromagnetic, electrostatic and electromechanical mechanism, whose energy sources include tire deformations, vibrations and rotations.
Technical Paper

Gear Tooth Modification of EV Powertrain for Vibration and Noise Reduction

2018-04-03
2018-01-1289
Abstract In order to research the vibration and noise reduction in pure electric vehicle power-train, a comprehensive work is to simulate the power-train incentive of a high-speed pure electric vehicle, and indicates significant impact of gear mesh system on the power-train NVH performance. Therefore, it is necessary to further study the impact of meshing gear system on electric vehicle power-train vibration and noise performance and seek reasonable methods to reduce the vibration and noise. In this paper, a typical pure electric vehicle's powertrain was used to conduct vibration and noise dynamic simulation. Firstly, the power train model was established considering the gear meshing stiffness, transmission errors, bearing factors and shell flexible, then the vibration and sound radiation dynamic response of power-train was simulated. Based on the accuracy of prediction model, a gear tooth modification was carried out for vibration and noise optimization.
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