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Root Cause Analysis and Structural Optimization of E-Drive Transmission

AVL LIST GmbH-Thomas Resch
AVL-AST d.o.o.-Borislav Klarin, Ivan Grozdanovic, Denis Pevec
  • Technical Paper
  • 2020-01-1578
To be published on 2020-06-03 by SAE International in United States
We face a growing demand for so-called eAxles (electric axle drive) in vehicle development. An eAxle is a compact electric drive solution for full electric vehicles (and P4 hybrids) with integrated electric machine and transmission. The transmission can be rather simple using fixed gear with cylindrical gear steps but increasing demands on power and speed range as well as efficiency increase its complexity with planetary stages or switchable gear steps. Such an electro-mechanic system has different behavior than the classical ICE-driven powertrains, for example regarding NVH, where high frequency and tonal noise from gear whining and electro-magnetic excitation is an important comfort issue that needs to be understood and controlled. As knowledge base for such drives is currently low, development needs to be supported by methodologies, which are not only on high predictive level for NVH responses, but also allow a detailed understanding and insight into the causes and reasons of a certain behavior to identify noise effects and to accelerate learning for such systems. In addition, such methods should lead to the possibility to…
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Asian Consumers Challenging the NVH Performance of European Cars – Implications on the Product Development in the 2020ies

MAGNA STEYR Automotive Technologies-Paulo Padilha
NVH Experts-Christoph Fankhauser
  • Technical Paper
  • 2020-01-1552
To be published on 2020-06-03 by SAE International in United States
Sales of SUV and luxury cars on the largest market of the world – China – are growing at a high rate. The highways in large cities like Beijing or Shanghai are increasingly populated with cars from all over the world like Japan, USA, Europe and Korea and even some refined domestic brands. More than 10 million rich people can afford those cars and are skilled drivers. This huge group of potential consumers is targeted by luxury brand OEMs and by startup companies. It has been understood, that these people have a strong attitude towards comfort. The twistbeam rear axle was replaced by multilink, double clutch transmissions were improved by comfort-mode drive programs, interior trims raised to Western standard performance levels, tyres specially developed for comfort in China, localized insulation materials and packages engineered to a one vehicle class higher level. The European avant-garde is capable of such high levels of complete vehicle NVH performance, whereas premium brands often compromise NVH with respect to high vehicle dynamics performance and passive safety requirements. At the same…
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Measurement Location Optimization of Component TPA Method for Road Noise

Applus + Idiada Spain-Onno de Boer, Javier Iturbe
Applus Idiada-Beatriz Bragado Pérez
  • Technical Paper
  • 2020-01-1581
To be published on 2020-06-03 by SAE International in United States
In this paper, an investigation on the application of a non-intrusive on-site component Transfer Path Analysis (TPA) method is presented together with the comparison with a previously performed direct blocked forces method. The latter is the more common method to determine interface forces between active and passive parts of an assembly. Force transducers are placed between the investigated structure and a rigid measurement rig. The presented comparison shows an investigated whether the faster and cheaper TPA method was able to produce relevant results. The TPA method used in this work calculated the force component contributions, without disassembly of the interfaces, through the local stiffness of multiple indicator positions per interface combined with operational measurement. The method is based on the application of an inverse-matrix model. This approach was applied to a vehicle road noise investigation carried out on a roller bench at three different roller speeds. A rough surface single axle roller bench in the same conditions as for the blocked forces method was used. The matrix inversion was carried out by using an overdetermined…
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Light Duty Truck Rear Axle Thermal Modeling

FCA-Mohammad Nahid
FCA US LLC-Joydip Saha, Sadek Rahman
  • Technical Paper
  • 2020-01-1388
To be published on 2020-04-14 by SAE International in United States
More stringent Federal emission regulations and fuel economy requirements have driven the automotive industry toward more sophisticated vehicle thermal management systems to best utilize the waste heat and improve driveline efficiency. The final drive unit in light and heavy duty trucks usually consists of geared transmission and differential housed in a lubricated axle. The automotive rear axles is one of the major sources of power loss in the driveline due to gear friction, churning and bearing loss and have a significant effect on overall vehicle fuel economy. These losses vary significantly with the viscosity of the lubricant. Also the temperatures of the lubricant are critical to the overall axle performance in terms of power losses, fatigue life and wear. In this paper, a methodology for modeling thermal behavior of automotive rear axle with heat exchanger is presented to predict the axle lubricant temperature rise and study the effect of coolant temperature on the axle warm-up and efficiency for a typical EPA fuel economy driving cycle. Thermal axle consists of automotive rear axle with a heat…
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Ultralight axle development-fracture mechanics life predictions (40% weight reduction).

Magna Drivetrain of America Inc.-Michael Bujold
  • Technical Paper
  • 2020-01-0179
To be published on 2020-04-14 by SAE International in United States
This paper details the light weight developments with the use of fracture mechanics technology. Forty percent weight reduction was achieved in an automotive axle. Novel pinion cartridge, ring gear , and differential designs were incorporated in this project to achieve weight, efficiency, noise and performance targets. A fracture mechanics (crack growth model) was used to determine steel cleanliness levels required as component size was optimized based on processing variables(steel material properties, initial flaw size, residual stress, duty cycle analysis,...). Prototype hypoid gear samples made from two variations of steel cleanliness were used to qualify the crack growth models with and without the addition of shot peening to vary the residual stress profiles for life requirements. Housing material variations of aluminum and magnesium were used for additional weight reduction in this program.
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Virtual Method for Simulating Driveline Launch Shudder for Solid Axle Suspension Architecture Vehicles

FCA Engineering India Pvt., Ltd.-Dhanasekar Venkatesan
FCA US LLC-Abhishek Paul, Kevin Thomson
  • Technical Paper
  • 2020-01-1271
To be published on 2020-04-14 by SAE International in United States
Driveline launch shudder is a second-order vibration phenomenon excited by the driveline system in vehicles. It is experienced as low frequency tactile vibrations at the vehicle seat track and is further deteriorated by a high torque demand from the engine. These vibrations are unwanted and affect the vehicle ride quality. A virtual method has been developed in ADAMS/Car to simulate the driveline launch shudder event for solid axle suspension architecture vehicles. Detailed modeling of the full vehicle system with appropriate boundary conditions has been presented. The simulated driveline launch shudder event has been quantified in the form of axle windup and accelerations at the driveline pinion, center bearing and seat track locations. A physical test correlation case study has been performed to validate the developed virtual method. This virtual method is also successfully applied to provide a driveline launch shudder mitigation enabler to improve vehicle ride performance.
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Predictive Break-In and Rapid Efficiency Characterization of Beam Axles

FCA US LLC-Timothy Schumaier, Siqin Wei, Jasbir Singh
FEV North America, Inc.-Patrick R. Bias, Thomas D'Anna
  • Technical Paper
  • 2020-01-1413
To be published on 2020-04-14 by SAE International in United States
Given continued industry focus on reducing parasitic losses, the ability to accurately measure the magnitude of losses on all driveline components is required. A standardized test procedure enables manufacturers and suppliers to measure component losses consistently, in addition to offering a reliable process to assess enablers for efficiency improvements. This paper reviews the development of SAE draft standard J3218, which is a comprehensive test procedure to break-in and characterize the efficiency of beam axles. Focus areas of the study included ensuring the axle’s efficiency does not change as it is being characterized, building a detailed map of efficiency at a wide range of operating points, and minimizing test time. The resulting break-in procedure uses an asymptotic regression approach to predict fully broken in efficiency of the axle and determine how much the efficiency of the axle changes during the characterization phase. This paper outlines several temperature control methods and approaches to efficiency characterization. The paper goes on to define the proposed break-in and efficiency characterization procedures including results from characterization of several production axles.
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Experimental and Computational Studies of the No-Load Churning Loss of a Truck Axle

Dana Incorporated-Steven Wesolowski
Lubrizol-Farrukh Qureshi
  • Technical Paper
  • 2020-01-1415
To be published on 2020-04-14 by SAE International in United States
This paper summarizes the work performed in predicting and measuring the contribution of oil churning to the no-load losses of a commercial truck axle at typical running speeds. A computational fluid dynamics (CFD) analysis of the churning losses was performed. The CFD modeling accounted for design geometry, operating speed, temperature, and lubricant properties. The model computed the torque loss due to oil churning due to the viscous and inertia effects of the fluid. It also displayed the flow pattern generated and computes the oil volume fraction at any location within the volume. CFD predictions of power losses were then compared with no load measurements made on a specially developed dynamometer driven test stand. The same axle that was used in the CFD model was tested in three different configurations: with axle shafts, with axle shafts removed, and with ring gear and carrier removed. This approach to testing was performed to determine the contribution of each source of loss (bearings, seals, and churning) to the total loss. After bearing and seal loss measurements and predictions were…
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Fast Conception (FastCon) – A tool for concept design and optimization of twist beam axles

University of Siegen - FLB-Jens Olschewski, Xiangfan Fang, Kanlun Tan
  • Technical Paper
  • 2020-01-0920
To be published on 2020-04-14 by SAE International in United States
The common development phase of a TBA usually starts with several concepts, based on benchmarking or empirical values. Based on these concepts the first CAD Models are designed and then converted into FE- and MKS models, so that the stiffness and kinematic characteristics can be evaluated. From these first results, it can be estimated which concept is suitable to fulfill all the requirements. The selected concept will be further optimized via numerous CAD and CAE iterations until it meets all concept targets. Due to this process, the quality and the development time of the final development strongly depends on the chosen concept. The presented algorithm FastCon-TBA (FastConcept Twistbeamaxle) is a development tool, which simplifies the process described above and makes it more efficient. Based on the concept variables FastCon analytically evaluates all relevant kinematic and elastokinematic characteristics. To calculate the properties each part of the TBA is idealized as a beam. Each beam element can have a specific orientation and crossection, which allows to approximate the deformation behavior of the TBA. Considering the boundary conditions…
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Composite Hybrid Automotive Suspension System Innovative Structures (CHASSIS)

Ford Motor Company-Alan Banks
Gestamp-Gareth Bone
  • Technical Paper
  • 2020-01-0777
To be published on 2020-04-14 by SAE International in United States
The Composite Hybrid Automotive Suspension System Innovative Structures (CHASSIS) is a project to develop structural commercial vehicle suspension components in high volume utilising hybrid materials and joining techniques to offer a viable lightweight production alternative to steel. Three components are in scope for the project:-Front SubframeFront Lower Control Arm (FLCA)Rear Deadbeam Axle