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SAE International Journal of Passenger Cars Mechanical Systems
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Clarification of Transient Characteristics by Coupled Analysis of Powertrains and Vehicles

SAE International Journal of Passenger Cars - Mechanical Systems

Toyota Central R&D Labs., Inc.-Ryoichi Hibino, Tomohiko Jimbo, Hiroyuki Yamaguchi, Yasuaki Tsurumi
Toyota Motor Corporation-Hideaki Otsubo, Shinji Kato
  • Journal Article
  • 2016-01-1314
Published 2016-04-05 by SAE International in United States
With the goal of improving drivability, this research aimed to clarify the mechanism of vehicle longitudinal acceleration, focusing on tip-in acceleration. Conventional typical analysis methods include experimental modal and model-based analysis. However, since the former requires the measurement of impulses and other input forces while the vehicle is stopped, measurement under actual driving conditions is difficult. The latter requires characteristic values such as the stiffness and damping coefficients to be identified in advance, which cannot be achieved either easily or precisely. Therefore, this paper proposes a new experiment-based analysis method. This method enables the acquisition of engine torque and transmission torque/force by measuring only the acceleration values of some components under driving conditions. The key to realizing this method is the measurement of motions with the necessary and sufficient degrees of freedom (e.g., pitch motion) since these greatly affect vehicle behavior. Another aspect of this method is the adoption of appropriate equations to express the relationship between action and reaction forces and the measured acceleration (inertial force). Once the torque and force are obtained, a…
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Climate Control Load Reduction Strategies for Electric Drive Vehicles in Cold Weather

SAE International Journal of Passenger Cars - Mechanical Systems

National Renewable Energy Laboratory-Matthew A. Jeffers, Larry Chaney, John P. Rugh
  • Journal Article
  • 2016-01-0262
Published 2016-04-05 by SAE International in United States
When operated, the cabin climate control system is the largest auxiliary load on a vehicle. This load has significant impact on fuel economy for conventional and hybrid vehicles, and it drastically reduces the driving range of all-electric vehicles (EVs). Heating is even more detrimental to EV range than cooling because no engine waste heat is available. Reducing the thermal loads on the vehicle climate control system will extend driving range and increase the market penetration of EVs.Researchers at the National Renewable Energy Laboratory have evaluated strategies for vehicle climate control load reduction with special attention toward grid-connected electric vehicles. Outdoor vehicle thermal testing and computational modeling were used to assess potential strategies for improved thermal management and to evaluate the effectiveness of thermal load reduction technologies. A human physiology model was also used to evaluate the impact on occupant thermal comfort. Experimental evaluations of zonal heating strategies demonstrated a 5.5% to 28.5% reduction in cabin heating energy over a 20-minute warm-up. Vehicle simulations over various drive cycles show a 6.9% to 18.7% improvement in EV…
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Vehicle Wind Noise Measurements in a Wind Tunnel with a Contoured Top Profile

SAE International Journal of Passenger Cars - Mechanical Systems

Calvin College-Vincent Rovedatti, Jacob Milhorn
Calvin Engineering-Richard DeJong
  • Journal Article
  • 2016-01-1316
Published 2016-04-05 by SAE International in United States
A 1/4 scale model vehicle profile has been tested in a wind tunnel with speeds up to 360 km/h. In order to simulate the free field flow over the vehicle, the top surface of the wind tunnel is contoured. A CFD simulation of the free field flow at various speeds is used to identify the desired top streamline. Then the boundary layer growth on the top surface is calculated and the top contour is adjusted accordingly. Since this contour changes very little with flow speeds of interest, an average contour is used for a fixed top surface of the wind tunnel. Pressure drop measurements are used to verify the flow similarity to the CFD model. Wind noise measurements using surface mounted pressure transducer arrays are used to determine the acoustic loads on the vehicle surfaces.
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On the Effect of Friction Law in Closed-Loop Coupling Disc Brake Model

SAE International Journal of Passenger Cars - Mechanical Systems

Beijing Institute of Technology-Pu Gao
Tsinghua Univ.-Yongchang Du, Yingping Lv, Yujian Wang
  • Journal Article
  • 2016-01-0476
Published 2016-04-05 by SAE International in United States
Brake squeal is a complex dynamics instability issue for automobile industry. Closed-loop coupling model deals with brake squeal from a perspective of structural instability. Friction characteristics between pads and disc rotor play important roles. In this paper, a closed-loop coupling model which incorporates negative friction-velocity slope is presented. Different from other existing models where the interface nodes are coupled through assumed springs, they are connected directly in the presented model. Negative friction slope is taken into account. Relationship between nodes’ frictional forces, relative speeds and brake pressure under equilibrant sliding and vibrating states is analysed. Then repeated nodal coordinate elimination and substructures’ modal coordinate space transformation of system dynamic equation are performed. It shows that the negative friction slope leads to negative damping items in dynamic equation of system. Then the complex eigenvalue analysis is applied to find out the unstable modes of the system. Finally, the presented method is applied on a disc brake system to study the effect of friction character on the stability of the system. Prediction results from models with/without considering…
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Development of New Electronically Controlled Hydraulic Unit for Various Applications

SAE International Journal of Passenger Cars - Mechanical Systems

ADVICS Co., Ltd.-Yusuke Kamiya, Yoshio Masuda, Tomoyuki Yamaguchi
Toyota Motor Corporation-Takahiro Okano, Akira Sakai
  • Journal Article
  • 2016-01-1660
Published 2016-04-05 by SAE International in United States
The use of hybrid, fuel cell electric, and pure electric vehicles is on the increase as part of measures to help reduce exhaust gas emissions and to help resolve energy issues. These vehicles use regenerative-friction brake coordination technology, which requires a braking system that can accurately control the hydraulic brakes in response to small changes in regenerative braking. At the same time, the spread of collision avoidance support technology is progressing at a rapid pace along with a growing awareness of vehicle safety. This technology requires braking systems that can apply a large braking force in a short time. Although brake systems that have both accurate hydraulic control and large braking force have been developed in the past, simplification is required to promote further adoption. This paper describes the following three items: (1) an examination of the brake system functions that realize the regenerative-friction brake coordination and collision avoidance support functions, (2) considerations and a proposal for a brake system that achieves the functions described in item (1) with a simple structure, and (3) development…
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An Improved Reanalysis Method Using Parametric Reduced Order Modeling for Linear Dynamic Systems

SAE International Journal of Passenger Cars - Mechanical Systems

Oakland University-Syed F. Haider, Zissimos Mourelatos
  • Journal Article
  • 2016-01-1318
Published 2016-04-05 by SAE International in United States
Finite element analysis is a standard tool for deterministic or probabilistic design optimization of dynamic systems. The optimization process requires repeated eigenvalue analyses which can be computationally expensive. Several reanalysis techniques have been proposed to reduce the computational cost including Parametric Reduced Order Modeling (PROM), Combined Approximations (CA), and the Modified Combined Approximations (MCA) method. Although the cost of reanalysis is substantially reduced, it can still be high for models with a large number of degrees of freedom and a large number of design variables. Reanalysis methods use a basis composed of eigenvectors from both the baseline and the modified designs which are in general linearly dependent. To eliminate the linear dependency and improve accuracy, Gram Schmidt orthonormalization is employed which is costly itself. In this paper, we propose a method to reduce the orthonormalization cost and improve the computational efficiency of the PROM reanalysis method. Our method eliminates non-important design variables and/or reduces the basis size by eliminating redundant modes. A vibratory analysis of an automotive door demonstrates the efficiency and accuracy of the…
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Real-World Thermal Effects on Wheel Assembly Efficiency of Conventional and Electric Vehicles

SAE International Journal of Passenger Cars - Mechanical Systems

Argonne National Laboratory-Forrest Jehlik, Eric Rask, Michael Duoba
  • Journal Article
  • 2016-01-0236
Published 2016-04-05 by SAE International in United States
It is widely understood that cold ambient temperatures negatively impact vehicle system efficiency. This is due to a combination of factors: increased friction (engine oil, transmission, and driveline viscous effects), cold start enrichment, heat transfer, and air density variations. Although the science of quantifying steady-state vehicle component efficiency is mature, transient component efficiencies over dynamic ambient real-world conditions is less understood and quantified.This work characterizes wheel assembly efficiencies of a conventional and electric vehicle over a wide range of ambient conditions. For this work, the wheel assembly is defined as the tire side axle spline, spline housing, bearings, brakes, and tires. Dynamometer testing over hot and cold ambient temperatures was conducted with a conventional and electric vehicle instrumented to determine the output energy losses of the wheel assembly in proportion to the input energy of the half-shafts. Additionally, response surface methodology (RSM) techniques were applied to the conventional vehicle serving as predictive models of the wheel assembly efficiency as a function of its thermal state. For the conventional vehicle, data showed that under -17°C ambient…
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A Reduced-Order Model for Evaluating the Dynamic Response of Multilayer Plates to Impulsive Loads

SAE International Journal of Passenger Cars - Mechanical Systems

US Army TARDEC-Matthew Castanier, Ravi Thyagarajan
University of Michigan-Weiran Jiang, Alyssa Bennett, Nickolas Vlahopoulos
  • Journal Article
  • 2016-01-0307
Published 2016-04-05 by SAE International in United States
Assessing the dynamic performance of multilayer plates subjected to impulsive loading is of interest for identifying configurations that either absorb energy or transmit the energy in the transverse directions, thereby mitigating the through-thickness energy propagation. A reduced-order modeling approach is presented in this paper for rapidly evaluating the structural dynamic performance of various multilayer plate designs. The new approach is based on the reverberation matrix method (RMM) with the theory of generalized rays for fast analysis of the structural dynamic characteristics of multilayer plates. In the RMM model, the waves radiated from the dynamic load are reflected and refracted at each interface between layers, and the waves within each layer are transmitted with a phase lag. These two phenomena are represented by the global scattering matrix and the global phase matrix, respectively. The product of these two matrices after some mathematical manipulations provides a reverberation matrix that represents the waves within the entire plate. The dynamic response of the plate is calculated by employing the generalized ray theory and an inverse Fourier Transformation. Free response…
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Reliability Evaluation of Thin, Lightweight Laminates for Windshield Applications

SAE International Journal of Passenger Cars - Mechanical Systems

Corning Inc.-Thomas M. Cleary, Timothy Huten, Daniel Strong
Ford Motor Company-Chester S. Walawender
  • Journal Article
  • 2016-01-1401
Published 2016-04-05 by SAE International in United States
The use of lightweight materials to produce automotive glazing is being pursued by vehicle manufacturers in an effort to improve fuel economy. As glazing’s become thinner, reduced rigidity means that the critical flaw size needed to create fracture becomes much smaller due to increased strain under load or impact. This paper documents experiments focused on the impact performance of several alternative thin laminate constructions under consideration for windshield applications (including conventional annealed soda-lime glass as well as laminates utilizing chemically strengthened glass), for the purpose of identifying new and unique failure modes that result from thickness reduction. Regulatory impact tests and experiments that focused on functional performance of laminates were conducted. Given the increased sensitivity to flaw size for thin laminates, controlled surface damage was introduced to parts prior to conducting the functional performance tests. Damage levels were selected based on teardown characterization of real world windshield parts that had been in-service.Regulatory impact testing showed that even very thin (< 2.3 mm total glass thickness) laminates could comply with requirements, as long as parts were…
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Effect of Three Controls (Camber Angle Control, Derivative Steering Assistance Control, and Inside-Outside Wheel Braking Force and Driving Force Control in Body Slip Angle Area

SAE International Journal of Passenger Cars - Mechanical Systems

Kogakuin Univ.-Ryo Yamaguchi, Hiromichi Nozaki
  • Journal Article
  • 2016-01-1666
Published 2016-04-05 by SAE International in United States
In this research, we examine the three controls inside-outside wheel braking force and driving force, camber angle, and the derivative steering assistance to determine how angle differences affect cornering performance and controllability. This is accomplished by comparing body slip angle area differences in a closed loop examination of the grip to drift area using a driving simulator. The results show that inside-outside wheel braking force and driving force control in the area just before critical cornering occurs has a significant effect on vehicle stability. We also clarified that controlling the camber angle enhances grip-cornering force, and confirmed that the sideslip limit could be improved in the vicinity of the critical cornering area. Additionally, when the counter steer response was improved by the use of derivative steering assistance control in the drift area exceeding the critical cornering limit, corrective steering became easier. Moreover, the effect could be achieved by using camber angle and derivative steering assistance controls in combination over a wide area. Based on the above, we conclude that it is possible to control wide-ranging…
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