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Countering the Destabilizing Effects of Shifted Loads through Pneumatic Suspension Design

SAE International Journal of Vehicle Dynamics, Stability, and NVH

Virginia Tech, USA-Yang Chen, Mehdi Ahmadian
  • Journal Article
  • 10-04-01-0001
Published 2019-11-08 by SAE International in United States
This article proposes a novel approach to reduce the destabilizing impacts of the shifted loads of heavy trucks (due to improper loading or liquid slosh) by pneumatic suspension design. In this regard, the pneumatically balanced suspension with dual leveling valves is introduced, and its potential for the improvement of the body imbalance due to the shifted load is determined. The analysis is based on a multi-domain model that couples the suspension fluid dynamics, shifted-load impacts, and tractor-semitrailer dynamics. Truck dynamics is simulated using TruckSim, which is integrated with the pneumatic suspension model developed in AMESim. This yields a reasonable prediction of the effect of the suspension airflow dynamics on vehicle dynamics. Moreover, the ability of the pneumatic suspension to counteract the effects of two general shifted loads - static (rigid cargo) and dynamic (liquid) - is studied. The simulation results indicate that the dual-leveling-valve suspension results in a reduction in roll angle and roll rate of the vehicle body for both static and dynamic load-shifting cases, as compared to the conventional single-leveling-valve suspension. Suppression of…
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A Simulation-Based Study on the Improvement of Semi-Truck Roll Stability in Roundabouts

Virginia Tech-Yunbo Hou, Yang Chen, Mehdi Ahmadian
Published 2016-09-27 by SAE International in United States
This paper studies the effect of different longitudinal load conditions, roundabout cross-sectional geometry, and different semi-truck pneumatic suspension systems on roll stability in roundabouts, which have become more and more popular in urban settings. Roundabouts are commonly designed in their size and form to accommodate articulated heavy vehicles (AHVs) by evaluating such affects as off-tracking. However, the effect of the roadway geometry in roundabouts on the roll dynamics of semi-tractors and trailers are equally important, along with their entry and exit configuration. , Because the effect of the roundabout on the dynamics of trucks is further removed from the immediate issues considered by roadway planner, at times they are not given as much consideration as other roadway design factors. In this study, the cross-sectional geometry of circulatory roadway, a key roundabout segment, is studied to evaluate its effect on roll stability of a WB-67 semi-truck with three longitudinal load conditions, when the truck is equipped with conventional OE suspensions and a balanced pneumatic system. TruckSim is used to develop various configurations of roundabout models, as…
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Pneumatically Balanced Heavy Truck Air Suspensions for Improved Roll Stability

CVeSS, Virginia Tech.-Yang Chen, Mehdi Ahmadian, Andrew Peterson
Published 2015-09-29 by SAE International in United States
This study provides a simulation evaluation of the effect of maintaining balanced airflow, both statically and dynamically, in heavy truck air suspensions on vehicle roll stability. The model includes a multi-domain evaluation of the truck multi-body dynamics combined with detailed pneumatic dynamics of drive-axle air suspensions. The analysis is performed based on a detailed model of the suspension's pneumatics, from the main reservoir to the airsprings, of a new generation of air suspensions with two leveling valves and air hoses and fittings that are intended to increase the dynamic bandwidth of the pneumatic suspensions. The suspension pneumatics are designed such that they are able to better respond to body motion in real time. Specifically, this study aims to better understand the airflow dynamics and how they couple with the vehicle dynamics. The pneumatic model is coupled with a roll-plane model of the truck to evaluate the effect of the suspension pneumatic dynamics on the body roll, as well as the force transmission to the sprung mass. The results of the study show that maintaining a…
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The Effect of Cylinder Clearance on Output Work of ORC-FP used in Waste Energy Recovery

Jilin Univ.-Yongqiang Han, Jianjian Kang, Xianfeng Wang, Yang Chen, Zhichao Hu
Published 2014-10-13 by SAE International in United States
In the internal combustion engine (ICE), about 40% of fuel energy is released into the atmosphere through waste gas. To recovery the energy, the Organic Rankine Cycle (ORC) has been widely used, and lots of previous studies have selected the rotating turbine as the expander of ORC. However, the rotating turbine has disadvantages of high manufacturing cost and narrow applicable range. For the above reasons, a free piston with constant force output which functions as expander in ORC is proposed to recover the waste energy of exhaust gas from internal combustion engine (ICE). In the system, the free piston with constant force output operates reciprocally to output work under the driving of working fluid R245ca, which absorbs heat from waste gas and provides vapor power. As there is approximately 20% of work is wasted to overcome friction between power piston and cylinder in traditional free piston structure, setting clearance between power piston and cylinder can eliminate friction loss in theory, but results in a negative impact of increasing the extent of working fluid's leakage. Therefore,…
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Performance Evaluation of the Scalable-CAN Integrated In-Vehicle Network

AutoNetworks Technologies, Ltd.-Masanobu Nishimura, Satoshi Horihata, Tatsuya Nakajima
Nagoya University-Ryo Kurachi, Yang Chen, Hiroaki Takada
Published 2013-04-08 by SAE International in United States
Today, the Controller Area Network (CAN) is a widely used in-vehicle network. However, due to the constraint of the theoretical upper bound speed of CAN, we proposed Scalable-CAN (SCAN), which employs round-robin scheduling to improve upper bound speed while keeping the compatibility with traditional CAN. Moreover, we proposed the worst-case response time (WCRT) analysis for a single SCAN bus system and showed the real-time performance.In this paper, to apply SCAN to a next-generation in-vehicle network composed of a SCAN bus and a CAN bus, we first propose a schedulability analysis method for the integrated network system. Second, we show its real-time performance and highlight the effects of the bandwidth extension and throughput performance of the SCAN integrated system. Finally, we conclude that SCAN achieves lower latency, high schedulability, and high integrity toward a next-generation in-vehicle network.
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Multi-objective Optimization of a Charge Air Cooler using modeFRONTIER

BEHR America Inc.-Phil Stephenson, Yang Chen
ESTECO North America Inc.-Nader Fateh, Sumeet Parashar
Published 2008-04-14 by SAE International in United States
In order for an automotive charge air cooler (CAC) to function efficiently, the flow of air through the cross tubes should be as uniform as possible. The position of the inlet and outlet, as well as the shape of the header tanks, are generally the most important determinants of the flow uniformity, and therefore of the cooling performance of the system. In an attempt to achieve this goal of flow uniformity, however, the effect on pressure loss in the system must also be considered. Further, the cost of the CAC tanks, which is directly related to the amount of material, should be minimized. Finally, the physical space in which the CAC can be located is limited by other underhood components and vehicle styling features. This presents an optimization problem with four conflicting objectives: to reduce the pressure loss in the system, to increase the uniformity of flow in the tubes, to minimize the tank material and to conform to the package volume. In this work, CATIA v5 was used to define the package volume to…
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Virtual Temperature Cycle Testing of Automotive Heat Exchangers by Coupled Fluid Structure Simulation

SAE International Journal of Materials and Manufacturing

Behr Climate Systems Inc.-Yang Chen
Behr GmbH & Co KG-Friedrich Brotz, Wolfram Kühnel
  • Journal Article
  • 2008-01-1210
Published 2008-04-14 by SAE International in United States
Temperature cycling is a major load for all automotive heat exchangers. A simulation method based on coupled fluid structure simulation was developed to analyze the thermal cycle behavior of the heat exchanger even in an early phase of the development process. The method is based on the modeling of transient heat transfer from the coolant and the air to the solid parts as well as heat conduction in the solid structure. In a first step, the temperature transients are simulated with Computational Fluid Dynamics (CFD). In a second step, the temperature distribution at specified time steps is mapped to a Finite Element Model (FEM) used for structural analysis. Compared with measurements, all relevant physical phenomena are well predicted in the simulations. This method helps to get a better understanding of the basic failure mechanisms. Finally, the calculated local stress values are the basis for subsequent lifetime prediction based on component Wöhler (S-N) curves or fatigue software tools.
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Integrated Development and Validation of HVAC Modules Using a Combined Simulation and Testing Approach

Behr America, Inc.-Yang Chen, Philip Stephenson, Frederic Guilbaud, Mingyang Jia, Stefan Scherer
Published 2008-01-14 by SAE International in United States
Cost saving and short turn-around time are two major challenges for the development of automotive HVAC modules and systems. Traditionally, the development process is test-driven with a typical workflow shown on the left-hand side of Figure 1:Utilizing experimentally validated Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) methodologies, engineers are able to predict the aerodynamic and thermal behavior of the HVAC module and ductwork as well as the structural design robustness prior to physical testing in the laboratory. In addition to providing comparable results to those achieved through testing (e.g. temperature regulation curves and airflow distribution) the CFD results provide unique insight into the complicated airflow and thermal mixing behavior inside the HVAC module and ductwork. The early integration of CFD into the design process allows many more design concepts to be evaluated than would be possible through testing alone. The use of validated CFD/FEA methods improves the agreement with test results, allowing an integrated approach in which the benefits of 3D simulation and testing can both be realized. Such a development and validation…
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Optimization of HVAC Temperature Regulation Curves with modeFrontier and Fluent

Behr America, Inc.-Yang Chen, Philip Stephenson
General Motors Corporation-Kanthasamy Elankumaran
Published 2007-04-16 by SAE International in United States
Simultaneously obtaining a linear temperature control curve along with the correct temperature stratification at module outlets is one of the most difficult tasks in developing an automotive HVAC module. Traditionally, Computational Fluid Dynamics (CFD) development of temperature control linearity has been accomplished by iteratively adjusting the location, size and orientation of baffles which redirect warm and cold airstreams. This approach demands considerable interaction from the engineer in building the computational mesh, defining boundary and operating conditions and post processing the simulation results. The present study was conducted to investigate the optimization of HVAC temperature regulation curves using the multi-objective optimization code modeFrontier (1, 3) in conjunction with CFD code, Fluent (2). An auxiliary HVAC module was selected for the present study. The diffuser of the model was omitted from the computational domain in order to reduce the model size resulting in faster turn around time. The penetration depths into the flow domain of two deflector baffles were the key parameters considered for optimization. The objective of the optimization is to obtain linear temperature control at…
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