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Training / Education

Vibration Analysis Using Finite Element Analysis (FEA)

2020-11-09
Finite Element Analysis (FEA) has been used by engineers as a design tool in new product development since the early 1990's. Until recently, most FEA applications have been limited to static analysis due to the cost and complexity of advanced types of analyses. Progress in the commercial FEA software and in computing hardware has now made it practical to use advanced types as an everyday design tool of design engineers. In addition, competitive pressures and quality requirements demand a more in-depth understanding of product behavior under real life loading conditions.
Training / Education

Finite Element Analysis (FEA) for Design Engineers

2020-10-19
The Finite Element Analysis (FEA) has been widely implemented by automotive companies and is used by design engineers as a tool during the product development process. Design engineers analyze their own designs while they are still in the form of easily modifiable CAD models to allow for quick turnaround times and to ensure prompt implementation of analysis results in the design process.
Training / Education

Design and Process Failure Modes and Effects Analysis (FMEA)

2020-10-12
This seminar covers the five types of FMEAs with emphasis on constructing Design and Process FMEAs. Each column of the FMEA document will be clearly explained using an actual FMEA example. The course covers various methods for identifying failure modes, effects and causes with special attention given to severity, occurrence, and detection tables and how to develop effective recommended actions strategies. Throughout the class, participants will be involved in exercises/actual projects that demonstrate and incorporate direct application of learned principles.
Training / Education

Weibull-Log Normal Analysis Workshop

2020-10-06
RMS (Reliability-Maintainability-Safety-Supportability) engineering is emerging as the newest discipline in product development due to new credible, accurate, quantitative methods. Weibull Analysis is foremost among these new tools. New and advanced Weibull techniques are a significant improvement over the original Weibull approach. This workshop, originally developed by Dr. Bob Abernethy, presents special methods developed for these data problems, such as Weibayes, with actual case studies in addition to the latest techniques in SuperSMITH® Weibull for risk forecasts with renewal and optimal component replacement.
Technical Paper

Variability Analysis of FMVSS-121 Air Brake Systems: 60-mi/hr Service Brake System Performance Data for Truck Tractors

2020-10-05
2020-01-1640
In support of the Federal Motor Carrier Safety Administration’s (FMCSA) ongoing interest in truck platooning, this report summarizes analyses conducted to measure variability in stopping distance tests conducted on commercial truck tractors. The data used were retrieved from tests performed under the controlled conditions specified for FMVSS 121 air brake system compliance testing. The report explores factors affecting the variability of the service brake stopping distance as defined by 49 CFR 571.121, S5.3.1 Stopping Distance—trucks and buses stopping distance. Variables examined in this analysis include brake type, weight, wheelbase, and tractor antilock braking system (ABS). This analysis uses existing test data collected between 2010 and 2019. Several of the examined parameters affected both tractor stopping distance and stopping distance variability.
Technical Paper

Development of Friction Materials Regulations for Four Latin American Countries

2020-10-05
2020-01-1615
Brakes are the most important safety device in a vehicle, however there are few barriers to manufacture, import, or sell friction materials in most of the countries, including USA. European countries, with the ECE R90 program, are a big exception. International Transport Forum published in 2016 the “Benchmarking of road safety in Latin America” report, it mentions that worldwide 17.5 people in every 100,000 die in road accidents, however Andean countries mortality rate is 23.4 and South American 21.0, considerably higher than the worldwide average.
Technical Paper

Transient Heat Transfer Simulation and Buckling Analysis of Disc Brakes in In-Wheel Motor Driven Vehicles

2020-10-05
2020-01-1618
High temperature distribution in disc brake mounted within in-wheel motor driven vehicle has several negative effects on braking performance. This is mainly due to the enclosed nature of the braking system. This paper aims to determine the effect of contact geometry on temperature distribution and thermal buckling in such a brake. Numerical analysis is conducted to investigate the variation of temperature field on the brake disc at different cover angles of pads while maintaining the same moment of friction. The effect of different radial positions of the pads is a second consideration in the current work, using a transient modeling approach. To validate the simulation results, an approximate, analytical solution is derived according to energy conservation. The results show that, for the same work done by the pads, the maximum temperature on the disc increases with a decrease in the pad cover angle.
Technical Paper

Effect of Wear on Frictionally Excited Thermoelastic Instability

2020-10-05
2020-01-1629
A finite element model for the effect of wear on frictionally excited Thermoelastic Instability (TEI) is developed by combining the equations of thermoelasticity, the classical Reye-Archard-Khrushchov wear law, along with the conforming contact conditions. The method is based on a two-dimensional, frictional sliding model with a bimaterial interface and a simplified geometry of finite thickness. An assumption of the solution in the perturbation form leads to a second-order eigenvalue problem, with the eigenvalue being the exponential growth rate of perturbation. The existing analytical solutions using two infinite half planes are used to validate the numerical solutions in several representative scenarios, including a limiting case in the absence of wear. In general, good agreements between the numerical and analytical approaches have been obtained.
Technical Paper

Innovative Material Characterisation Methodology for Tyre Static and Dynamic Analyses

2020-09-30
2020-01-1519
Tyre structures are based on composite materials that constitute numerous layers, each providing specific properties to the tyre mechanic and dynamic behaviour. In principle, the understanding of the partial contributions of the individual layers requires knowledge of its mechanical properties. In case of non-availability of such critical information, it is difficult to perform tyre FE analyses. In the current work, a methodology is proposed to study the tyre static and dynamic behaviour to estimate its constituents properties based on the measured quasi-static responses of the tyre for certain specific loads. As a first step, a simplified tyre numerical model with standard rubber material properties is modeled that can substantively predict the necessary tyre static responses, i.e. radial, longitudinal and lateral stiffness. These responses are correlated with the physical tyre response that are measured using a kinematic and compliance (K&C) test rig in the laboratory.
Technical Paper

A Generic Testbody for Low-Frequency Aeroacoustic Buffeting

2020-09-30
2020-01-1515
Raising demands towards lightweight design paired with a loss of originally predominant engine noise pose significant challenges for NVH engineers in the automotive industry. From an aeroacoustic point of view, low frequency buffeting ranks among the most frequently encountered issues. The phenomenon typically arises due to structural transmission of aerodynamic wall pressure fluctuations and/or, as indicated in this work, through rear vent excitation. A possible workflow to simulate structure-excited buffeting contains a strongly coupled vibro-acoustic model for structure and interior cavity excited by a spatial pressure distribution obtained from a CFD simulation. In the case of rear vent buffeting no validated workflow has been published yet. While approaches have been made to simulate the problem for a real-car geometry such attempts suffer from tremendous computation costs, meshing effort and lack of flexibility.
Technical Paper

Appropriate Damping Loss Factor of Vehicle Interior Cavity For Valid Application of Statistical Energy Analysis

2020-09-30
2020-01-1524
By using a method of a previous study (SAE 2014-01-2081), sound transmission loss (STL) of vehicle panel structure could be calculated with an FEM model. The FEM model is consisting of the body in white, a hemispehere-shaped exterior cavity, and the interior cavity. The exterior cavity is excited and Statistical Energy Analysis (SEA) principle is applied for the calculation of STL of vehicle panel structure. It is known that SEA is a rapid and simple methodology for analyzing the complex vibroacoustic system. However, SEA principle is not always valid and one has to be careful about the physical conditions at which SEA principle is acceptable. In this study, the appropriate damping loss factor of the vehicle interior cavity is studied in the viewpoint of the modal overlap factor of the cavity and the decay per mean free path (DMFP) of the cavity. It is found that DMFP is appropriate between 0.5 ~ 1 dB for applying SEA principle.
Technical Paper

Using Statistical Energy Analysis to Optimize Sound Package for Realistic Load Cases

2020-09-30
2020-01-1525
The statistical energy analysis (SEA) is widely used to support the development of the sound package of cars. This paper will present a model prepared to investigate the sound package of the new Audi A3 and its correlation against measurements. Special care was given during the creation of the model on the representation of the structure to able the analysis of structure borne energy flow on top of the classical airborne analysis usually done with SEA. The sound package is also detailed in the model to allow further optimization and analysis of its performance. Two real life load cases will be presented to validate the model with measurements. First, the dominating powertrain and second, a case with dominating rolling noise. An analysis of the contribution of the different source components and a way to diagnose the weak paths of the vehicle will be presented. The focus of this investigation is the application of optimally adjusted treatment.
Technical Paper

Numerical Analysis of the Influences of Wear on the Vibrations of Power Units

2020-09-30
2020-01-1506
Numerical Analysis of the Influences of Wear on the Vibrations of Power Units Yashwant Kolluru, Rolando Doelling eBike Department Robert Bosch GmbH Kusterdingen, Germany yashwant.kolluru@de.bosch.com rolando.doelling@de.bosch.com Lars Hedrich Institute of Informatics Goethe University Frankfurt Frankfurt, Germany hedrich@em.informatik.uni-frankfurt.de The prime factor, which influences vibrations of electro-mechanical drives, is wear at the components. This paper discusses the numerical methods developed for abrasion, vibration calculations and the coupling between wear and NVH models of drive unit. Wear is a complex process and understanding it is essential for vibro-acoustics. The paper initially depicts finite element static model used for wear calculations. The special subroutines developed, aids in coupling the wear equations, various contact and friction formulations to the numerical model.
Technical Paper

Analytical Prediction of Acoustic Emissions From Turbocharger Bearings

2020-09-30
2020-01-1504
Turbochargers are progressively used in modern automotive engines to enhance engine performance and reduce energy loss and adverse emissions. Use of turbochargers along with other modern technologies has enabled development of significantly downsized internal combustion engines. However, turbochargers are major sources of acoustic emissions in modern automobiles. Their acoustics has a distinctive signature, originating from fluid-structure interactions. The bearing systems of turbochargers also constitute an important noise source. In this case, the acoustic emissions can mainly be attributed to hydrodynamic pressure fluctuations of the lubricant film. The developed analytical model determines the lubricant pressure distribution in the floating journal bearings used mainly in the modern turbocharges. This allows for an estimation of acoustic emissions.
Technical Paper

Characterisation of Brake Creep Groan Vibrations

2020-09-30
2020-01-1505
Creep Groan is an impulsive brake noise at very low velocities of the vehicle. Generally, stick-slip between brake disc and brake pads is assumed as the most dominating vibration mechanism of creep groan. This contribution will show by sophisticated measurement techniques, that stick-slip and speed dependent friction is an important trigger of this annoying vehicle noise. However, the overall vibration is much more complex than common stick-slip vibration models. It turns out, that in typical brake systems of passenger vehicles creep groan occurs around 15-20 Hz and 70-90 Hz. The mechanism at 15-20 Hz is an impulsive noise. Transitions between stick and slip phases trigger complex nonlinear vibrations of the complete brake and suspension system. At 70-90 Hz, the vibrations show a more harmonic-like behaviour, caused primarily by speed-dependent friction characteristics.
Technical Paper

Analytical Rotordynamic Study of a High-Speed Gear Transmission System for Race Applications

2020-09-30
2020-01-1502
In motorsport power transmission systems, high-speed operation can be associated with significant rotordynamic effects. Changes in the natural frequencies of lateral (bending) vibrational modes as a function of spin speed are brought about by gyroscopic action linked to flexible shafts and mounted gear components. In the investigation of high-speed systems, it is important that these effects are included in the analysis in order to accurately predict the critical speeds encountered due to the action of the gear mesh and other sources of excitation. The rotordynamic behaviour of the system can interact with crucial physical parameters of the transmission, such as the stiffnesses of the gear mesh and rolling element-to-raceway contact in the bearings. In addition, the presence of the gear mesh acts to couple the lateral and torsional vibration modes of a dual-shaft transmission through which a torque flows.
Technical Paper

Finite Element Model Reduction Applied to Nonlinear Impact Simulation for Squeak and Rattle Prediction

2020-09-30
2020-01-1558
Increasing demand for simulation accuracy often leads to increased model complexity, which in turn, results in higher computational costs. As a provision, Component Mode Synthesis approaches are employed to approximate the system response by using dynamic substructuring and model reduction techniques in linear systems. However, the use of available model reduction techniques in nonlinear problems has not been completely addressed. In this paper, the application of a Component Mode Synthesis method in squeak and rattle nonlinear simulation has been investigated. Critical regions for squeak and rattle of the side door model of a passenger car were modelled by nonlinear contact interfaces in finite element solution. Craig-Bampton model reduction method was employed to substructure the finite element model, while keeping the nonlinear contacts in the model.
Technical Paper

Research on the Subjective Rating Prediction Method for the Ride Comfort with Deep Learning

2020-09-30
2020-01-1566
Suspension is an important chassis part which is vital to ride comfort. However, it is difficult to achieve our targeted comfortability level in a short time. Therefore, improving efficiency of damper development is our primary challenge. We have launched a project which aims to reduce the workload on developing dampers by introducing analytical approaches to the improvement of ride comfort. To be more specific, we have been putting effort into developing subjective rating prediction, vehicle dynamics prediction, the damping force prediction. This paper describes the subjective rating prediction method which output a subjective rating corresponding to the physical value of the vehicle dynamics with Deep Learning. As a result of verifying with the unlearning data, DNN(Deep Neural Network) prediction method could almost predict the subjective rating of the expert driver.
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