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MASS OPTIMIZED HOOD DESIGN FOR CONFLICTING PERFORMANCES

GM Technical Center-Santosh Swamy, Gulshan Noorsumar, Shivakumar Chidanandappa
  • Technical Paper
  • 2019-28-2546
To be published on 2019-11-21 by SAE International in United States
MASS OPTIMIZED HOOD DESIGN FOR CONFLICTING PERFORMANCES Santosh Swamy, Gulshan Noorsumar, Shivakumar Chidanandappa General Motors Technical Center, India Keywords Hood; Head Injury Criterion (HIC); Stiffness; Shape optimization; Multi-Disciplinary Optimization (MDO) Research and/or Engineering Questions/ Objective The objective of this work is to obtain a light weight hood which has least possible mass, and at the same time meets all contradicting performances of pedpro (pedestrian protection) and structural stiffness disciplines. Passenger vehicles have stringent safety norms from pedpro perspective to meet child and adult head injury criteria (HIC). These pedestrian safety requirements often conflict with structural stiffness performance criteria which pose a challenge for most automotive OEMs. Therefore, there is a growing need for mass optimization and performance balancing to meet both the requirements simultaneously. Methodology The outlined method uses a CAE based Multi-Disciplinary Optimization (MDO) approach involving shape variables to find an optimum design for stiffness and pedpro performances. Adding slots along the vertical beam walls of the hood inner panel helps soften the area around the head impact location, thereby improving pedpro performance locally.…
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Suspension hard points optimisation

Altair Engineering-AshithKumar Shetty
  • Technical Paper
  • 2019-28-2419
To be published on 2019-11-21 by SAE International in United States
Objective This paper explores the usage of Altair simulation driven optimisation process, Front Suspension hard points of a sedan Car model are optimised for specific target toe curves using MotionView, MotionSolve and HyperStudy This process gives the optimal hard point values to match the target curves without much iterations. Methodology Parametric Multibody model of the front end of sedan is built in MotionView. To Carry out optimisation HyperStudy is used where few of the suspension hard points which affect the toe curves are chosen as design variable. For the chosen Design variables upper and lower bound limits are specified. Ride, Roll and lateral force tests are performed. Optimisation is performed using HyperStudy where it iterates the suspension hard points to match the target toe curves. Each iteration response can be visualized in HyperStudy and can be compared with the target toe curve. Hyperstudy points the iteration which is closest to the Target curve Advantage • Quick model setup and run time • Parametric model allows quick change in design • Insight at early design stage…
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Design of Lightweight Composites for Vehicle Front End Energy Management of Bumper Beam

Indian Institute of Technology-Balasubramanian Muthiah, Velmurugan Ramachandran
Mahindra & Mahindra, Ltd.-Praveen Kumar, Sarma Sr Akella, Ayan Chakraborty, Shankar M Venugopal
  • Technical Paper
  • 2019-28-0085
To be published on 2019-10-11 by SAE International in United States
Application of advance composites in place of the various conventional materials such as steel can give significant weight and performance advantages. The application of composites is now finding it’s way in the automotive industry due to the growing requirement of the lightweight solutions and high strength to weight ratio. However, their low mechanical properties have limited their application in automotive structural components. The study presented here is focused on the explicit dynamic analysis of a bumper beam and advance composites are used for the study. Different configurations and designs of the bumper are considered to be able to make a comparative study of the stress and deformation levels. The analysis was done in coherence to the Euro NCAP tests and the offset frontal impact analysis was done. The boundary conditions were aligned with the real time impact conditions for proper prediction of the results. Based on stress, deformation, specific strength and weight, the replacing materials for existing steel bumper are considered and the corresponding energy absorption are calculated. Laminated composites such as Glass, Carbon and…
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Developing a Theory for Active Grille Shutter Aerodynamics—Part 1: Base Theory

Porsche AG-Thomas Wolf
Published 2019-06-07 by SAE International in United States
The aim is to develop a theory to describe the aerodynamic behavior of active grille shutters (AGS). The theory correlates the cooling air mass flow and drag of a vehicle with the angle and number of air flaps on the AGS. The relatively simple mathematical formulation of this theory provides an insight into the aerodynamic behavior and characteristic curve shape of AGS. It illustrates how the number of air flaps changes and influences the shape of the AGS characteristic curve. The theory is validated by experiments using wind tunnel measurements on real vehicles with AGS. The comparisons show good agreement between theory and experiment.
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Modeling and Validation for the Hysteretic Behavior of an Automatic Belt Tensioner

BYD Auto Industry Company Limited-Pu Xu
South China University of Technology-Shangbin Long, Xuezhi Zhao, Wen-Bin Shangguan
Published 2019-06-05 by SAE International in United States
An automatic tensioner used in an engine front end accessory drive system (EFEADS) is taken as a study example in this paper. The working torque of the tensioner, which consists of the spring torque caused by a torsional spring and the frictional torques caused by the contact pairs, is analyzed by a mathematic analysis method and a finite element method. And the calculation and simulation are validated by a torque measurement versus angular displacement of a tensioner arm. The working torques of the tensioner under a loading and an unloading process are described by a bilinear hysteretic model, and are written as a function with a damping ratio. The rule of the action for the damping devices is investigated based on the simulation and a durability test of the tensioner. A finite element method for the tensioner without damping device is established. Then the radial deformation for the torsional spring under an unconstrained state is obtained. The analysis results have a good correlation with the measurements. The method presented in this paper is beneficial for…
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EDITORIAL: The unforgettable pyramid on the hood

Automotive Engineering: June 2019

Editor-in-Chief-Lindsay Brooke
  • Magazine Article
  • 19AUTP06_08
Published 2019-06-01 by SAE International in United States

If you're old enough to remember 1990, you may recall the best television ad of the year. It showed the front end of the all-new Lexus LS400 sedan against a black background. A multi-level pyramid of champagne glasses glistened in the center of the car's hood.

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Interior Sound Quality Refinement Base on Mechanism Study of Crankshaft Impact Noise

GAC Automotive Engineering Institute-Zhangming Su, Hanshuang Chen, Qi Yang, Dandan Kong, Weizhe Xing, Yanghui Xu
South China University of Technology-Xuelu Cao
Published 2019-04-02 by SAE International in United States
A rumbling noise is audible in a vehicle passenger compartment during acceleration. Mechanism detail of the rumbling noise is studied. A series of preliminary transfer path experiments investigation on chassis dynamometer shows that the interior rumbling noise is mainly induced by abnormal crankshaft impact at particular crank angle. Spectrum analysis indicates that high level half order harmonic components significantly affects the rumbling noise. Multi-body dynamics model of the powertrain is developed to further investigate the root cause of the abnormal crankshaft impact. Experiment results are used to verify the numeric model. High deviation of main bearing forces at the crank angle 0° to 180° after the Fire Top Dead Center of the no.l cylinder is considered to fundamentally induces the high level half order components. The force ripple coupled with the crankshaft resonance induces the crankshaft rumbling. Sensitivities analysis of various bearing seat structure, crankshaft structural parameters were carried out. The ladder frame, a stiffened crankshaft with bigger overlap and shortened the front end offset distance seem effectively reduce the rumbling impact and improve interior…
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Styling and Packaging Approach to Meet Pedestrian Upper Leg Requirements as per Euro NCAP Protocol

Tata Motors Limited-Dnyaneshwar Mhaskar, Ashish Kumar Mahapatre, Milind Bhagat
Published 2019-01-09 by SAE International in United States
In most of the countries all over the world, thousands of pedestrians and vulnerable road users are struck by motor vehicles and getting killed or get severe injuries. Accident research data shows that pedestrians are a significant proportion of all road user casualties [1]. In pedestrian impact with vehicle front end, several organ forms impact directly to front end of the vehicles and get severe injuries in head, lower leg and pelvis region. Pelvis region of pedestrian get severe injuries due to hit by Bonnet Leading Edge. Impact force is major injury driving parameter in case of pelvis region. In earlier Euro NCAP Pedestrian Protocol -v7.1.1 [2], upper leg impact energy calculation was based on BLE (Bonnet Leading Edge) height and bumper lead. Vehicle front end styling was not playing any role in deciding upper leg impact energy. Upper leg impact performance was purely dependent on BLE height and package space available. Whereas in current Euro NCAP Pedestrian Protocol -v8.4 [3], upper leg impact energy calculation is estimated based on vehicle front end styling and…
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Design, Simulation and Validation of Front End Auxiliary Drive (FEAD) Mounting Bracket for Electric Powertrain Application

VE Commercial Vehicles Ltd-Kamal Rohilla, Suresh Kumar Kandreegula, Saurabh Agrawal, Jasvir Bisht, Pungaraj Muthaiah
Published 2019-01-09 by SAE International in United States
The main driving force behind recent innovations in automotive sector is the need to decrease the dependability on fossil fuels and move towards alternative sources for energy. While there is still substantial scope for improvement in conventional diesel and petrol engine based powertrains, the inherent dependency on limited and rapidly depleting carbon based fuels make their long term usage impractical highlighting the need for alternative non-conventional powertrain setups.In the recent past, electric powertrains have come out as favorable alternative as they are extremely flexible in adopting to scenarios where energy for use might be drawn from multiple sources such as solar power, hydroelectric, nuclear reaction, etc. The advantages can further be magnified by adopting the electric power based powertrains in mass transportation application such as bus application. However, the adoption of electric power based powertrains requires a complete redesign of powertrain mounting architecture.This study is specifically focused on redesigning the Front End Accessory Drive (FEAD) mounting bracket for bus application. The new design will also include the provision for the mounting of prime mover (electric…
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Design and Performance Specifications for a Generic Buck Representing a Small Family Car Used in the Assessment of Pedestrian Dummy Whole Body Impact Response

Human Biomechanics and Simulations Standards Committee
  • Ground Vehicle Standard
  • J3093_201901
  • Current
Published 2019-01-08 by SAE International in United States
This Information Report addresses the design and performance specifications for a generic buck to be used in full-scale vehicle to pedestrian tests conducted to evaluate pedestrian dummy performance. Specifically, the buck is designed to mimic the impact response of the front end of a sedan within the small family car class during a collision with a pedestrian. The goal is to develop a generic buck with simplified geometry and a limited number of components made of clearly defined and readily available engineering materials to facilitate fabrication and reproducibility. To ensure performance of the buck, it is specified that the buck mimics the maximum crush distance, absorbed energy, and maximum force corresponding to a sedan within the small family car class during a pedestrian impact. The design and performance specifications provided in this document focus on: (1) the design specifications describing the materials and geometry of the generic buck and (2) the specific certification tests that are required to ensure that any fabricated buck meets the necessary design specifications.
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