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New Half Shaft Bench Test Methodology for NVH Characterization

Siemens PLM Software-Saeed Siavoshani, Prasad Balkrishna Vesikar
FCA US LLC-Wei Yuan, Ahmad Abbas, Francisco Antonio Sturla
Published 2019-06-05 by SAE International in United States
The main purpose of this paper is to develop a reliable bench test to understand the vibratory behavior of the half shafts under applied torque comparable to an idle condition. In some cases, the half shaft path is a major factor influencing the idle vibration in the vehicle. At idle condition vehicle vibrations are caused by engine excitation and then they pass through different paths to the body structure. Half shaft manufacturers generally characterize shaft joints for their frictional behavior and typically there is no data for vibration characteristics of the half shaft under idle conditions. However, for predictive risk management, the vibratory behavior of the half shaft needs to be identified. This can be achieved from measured frequency response functions under preloaded test conditions.This bench test enables manufacturers to conduct comprehensive design of experiments on the impact of powertrain vibration input while transmitting through the half shaft into the vehicle system. This method enables the study of the half shaft at the component level, because studying the half shaft at vehicle level is difficult…
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Acoustic Optimization of a Muffler through the Sherpa Algorithm

Siemens PLM Software-Edgar Matas
Siemens Software Industry GmbH-Carlo Locci, Karl Oberhumer
Published 2019-04-02 by SAE International in United States
Regulations on noise and gas emissions become more and more stringent resulting in noise abatement devices needing further engineering and optimization. Mufflers are installed at the end of powertrains to reduce the acoustic impact of the sound pressure from the engine. Such acoustic reduction is achieved through internal structures that promote destructive interference within the muffler. However, the muffler increases the backpressure downstream of the aftertreatment line, thus decreasing the engine efficiency. In the following work, an optimization workflow is presented to find the best design for a muffler geometry. The optimization is performed with the Sherpa algorithm that uses several optimization algorithms simultaneously to increase robustness and efficiency. Sherpa is implemented in an optimization tool that manages the workflow of two other software tools. The acoustic transmission loss of the muffler is calculated as a function of the geometrical characteristics of the muffler design. The parametrized muffler CAD is changed at each optimization iteration. For each CAD variation, the transmission loss and the backpressure are calculated. A Pareto front is generated and used to…
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A Study of the Half Order Modulation Control for Diesel Combustion Noise by Using Model Based Controller Design

Siemens PLM Software-Karthikeyan B
Hyundai Motor Company-Ki Hwa Lee, Choonggeun Nam, O Jun Kwon, Jung-Hwan Moon
Published 2019-03-25 by SAE International in United States
This model based investigation is carried out in order to control the half order modulation for diesel engines using by virtual calibration approach and proposes a feedback control strategy to mitigate cylinder to cylinder imbalance from asymmetric cylinders torque production. Combustion heat release analysis is performed on test data to understand the root cause of observed cylinder to cylinder pressure variations. The injected fuel variations are shown to cause the observed pressure variations between cylinders. A feedback control strategy based on measured crank shaft position is devised to control the half order modulation to balance the combustion pressure profile between cylinders. This control strategy is implemented in Simulink and is tested in closed-loop with the diesel engine model in AMESim. The closed-loop performance indicates that the half order modulation is considerably improved while having minimal impact on the fuel consumption.
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Class 8 Truck Investigation Comparing Wind Tunnel Test to Simulated Open Road Performance Using CFD

Siemens PLM Software-Daniel Steen, Frederick J. Ross
Navistar-John Kiedaisch, Craig Czlapinski, Ashraf Farag
Published 2018-04-15 by SAE International in United States
Development of new, competitive vehicles in the context of stricter regulations to reduce greenhouse gas emissions and increase fuel economy is driving OEM of commercial vehicles to further explore options for reducing aerodynamic drag in a real-world setting. To facilitate this in regards to the aerodynamics of a vehicle, virtual design methods such as CFD are often used to compliment experiments to help reduce physical testing time and costs. Once validated against experiments, CFD models can then act as predictive models to help speed development. In this paper, a wind tunnel experiment of a Class 8 truck is compared to a CFD simulation which replicates said experiment, validating the CFD model as a predictive tool in this instance. CFD is then used to evaluate the drag and flow around the vehicle in an open road scenario, and the results between the open road and wind tunnel scenarios are compared. Overall, experimentation is used to validate the CFD model, while the CFD model is then used to explore the differences between flows observed in the wind…
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Development of Traction Fluid Property Tables for a Toroidal CVT Multi-Body Simulation

Siemens PLM Software-Alan Lewis
Honda R & D Americas Inc.-Toshihiro Saito
Published 2018-04-03 by SAE International in United States
A toroidal variator is the core part of an advanced Continuously Variable Transmission (CVT) design. Knowing its behavior and internal forces is key to defining the operational conditions of the transmission. To maintain a steady-state speed ratio, or to accurately and efficiently move between speed ratios, optimal trunnion control force is required. The unique design of the toroidal CVT makes the design very sensitive to trunnion positioning and force transients. Analytical understanding of the mechanism response is critical to toroidal variator controller design. A critical feature of the toroidal CVT simulation is representation of the friction forces in the disk-roller contact. This effect is important to the mechanism torque capacity and efficiency. This article describes a new toroidal CVT multi-body simulation which includes a detailed representation of the disk-roller friction, including contact patch geometry based on Hertzian formulation; subdivision of the contact patch to calculate accurate pressure, slip, and friction force at all locations on the patch; application of table-based traction fluid friction properties at each sub-patch; and summing of the total friction force and…
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Chemistry-Based Laminar Flame Speed Correlations for a Wide Range of Engine Conditions for Iso-Octane, n-Heptane, Toluene and Gasoline Surrogate Fuels

Siemens PLM Software-Jens Prager
Universita di Modena e Reggio Emilia-Alessandro D'Adamo, Marco Del Pecchia, Sebastiano Breda, Fabio Berni, Stefano Fontanesi
Published 2017-10-08 by SAE International in United States
CFD simulations of reacting flows are fundamental investigation tools used to predict combustion behaviour and pollutants formation in modern internal combustion engines. Focusing on spark-ignited units, most of the flamelet-based combustion models adopted in current simulations use the fuel/air/residual laminar flame propagation speed as a background to predict the turbulent flame speed. This, in turn, is a fundamental requirement to model the effective burn rate.A consolidated approach in engine combustion simulations relies on the adoption of empirical correlations for laminar flame speed, which are derived from fitting of combustion experiments. However, these last are conducted at pressure and temperature ranges largely different from those encountered in engines: for this reason, correlation extrapolation at engine conditions is inevitably accepted. As a consequence, relevant differences between proposed correlations emerge even for the same fuel and conditions. The lack of predictive chemistry-grounded correlations leads to a wide modelling uncertainty, often requiring an extensive model tuning when validating combustion simulations against engine experiments.In this paper a fitting form based on fifth order logarithmic polynomials is applied to reconstruct correlations…
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Separation of Combustion and Mechanical Noise Using Wiener Filter

Siemens PLM Software-Saeed Siavoshani, Prasad Balkrishna Vesikar, Rajani Ippili
Siemens PLM Solutions-Daniel Pentis
Published 2017-06-05 by SAE International in United States
The objective of this paper is to develop a robust methodology to study internal combustion (IC) engine block vibrations and to quantify the contribution of combustion pressure loads and inertial loads (mechanical loads) in overall vibration levels. An established technique for noise separation that, until recently, has not been applied to engine noise is Wiener filtering. In this paper, the harmonic part of the overall vibration response of the IC engine block is removed, resulting in a residual broadband response which is uncorrelated to the source signal. This residue of the response signal and the similarly calculated residue of the combustion pressure represent the dynamic portion of their respective raw signals for that specific operating condition (engine speed and load). The dynamic portion of the combustion pressure is assumed to be correlated only to the combustion event. A relation (frequency response function) between the source signal and residual broadband response of the block is developed for each cylinder pressure source signal. This relation is defined as the Wiener filter. The Wiener filter is then multiplied…
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Fan Noise Prediction for Off-Highway Vehicle

Siemens PLM Software-Prasanna Chaduvula
Bobcat Company-Patrick Stahl, Michael Jordan, Jamison Huber
Published 2017-06-05 by SAE International in United States
Fan noise can form a significant part of the vehicle noise signature and needs hence to be optimized in view of exterior noise and operator exposure. Putting together unsteady CFD simulation with acoustic FEM modeling, tonal and broadband fan noise can be accurately predicted, accounting for the sound propagation through engine compartment and vehicle frame structure. This paper focuses on method development and validation in view of the practical vehicle design process. In a step by-step approach, the model has been validated against a dedicated test-set-up, so that good accuracy of operational fan noise prediction could be achieved. Main focus was on the acoustic transfer through the engine compartment. The equivalent acoustic transfer through radiators/heat exchangers is modeled based on separate detailed acoustic models. The updating process revealed the sensitivity of various components in the engine compartment. Unsteady CFD included the build-up of a sliding mesh model which was analyzed using the DDES method. After convergence, time data of blade surface pressure were exported in CGNS format. These pressure data were used to generate rotating…
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Multi-Body Model of a Fixed-Wing Large Passenger Aircraft for Nonlinear State Estimation

Siemens PLM Software-Tuur Benoit, Yves Lemmens
KU Leuven-Wim Desmet PhD
Published 2015-09-15 by SAE International in United States
This paper proposes a solution for utilizing multi-body models in nonlinear state observers, to directly estimate the loads acting on the aircraft structure from measurement data of sensors that are commonly available on modern aircraft, such as accelerometers on the wing, rate gyros and strain gages.A high-fidelity aeroelastic multi-body model of a fixed-wing large passenger aircraft is presented, suitable for the monitoring of landing maneuvers. The model contains a modally reduced flexible airframe and aerodynamic forces modeled with a doublet-lattice method. In addition, detailed multi-body models of the nose and main landing gear are attached to the flexible structure, allowing to accurately capture the loads during a hard landing event.It is expected that this approach will make way for embedding non-linear multi-body models, with a high number of degrees of freedom, in state estimation algorithms, and hence improve health monitoring applications.
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Reduced Order Model Approach for Efficient Aircraft Loads Prediction

SAE International Journal of Aerospace

Siemens PLM Software-Yves Lemmens
Siemens PLM Software-University of Bristol-Michele Castellani
  • Journal Article
  • 2015-01-2568
Published 2015-09-15 by SAE International in United States
Flight loads calculations play a fundamental role in the development and certification of an aircraft and have an impact on the structural sizing and weight. The number of load cases required by the airworthiness regulations is in the order of tens of thousands and the analysis must be repeated for each design iteration. On large aircraft, CS-25 explicitly requires taking into account for loads prediction, airframe flexibility, unsteady aerodynamics and interaction of systems and structure, leading to computationally expensive numerical models. Thus there is a clear benefit in speeding-up this calculation process. This paper presents a methodology aiming to significantly reduce the computational time to predict loads due to gust and maneuvers. The procedure is based on Model Order Reduction, whose goal is the generation of a Reduced Order Model (ROM) able to limit the computational cost compared to a full analysis whilst retaining accuracy. The method is applied to a commercial transport aircraft modeled with beam elements, unsteady aerodynamics based on Doublet Lattice Method and servo-hydraulic actuators for the control surfaces. The aeroelastic equations…
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