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SAE International Journal of Passenger Cars Mechanical Systems
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Development of a New Multi-link Rear Suspension

SAE International Journal of Passenger Cars - Mechanical Systems

Nissan Motor Company Ltd.-Reo Koide, Yoshihiro Kawabe, Keiichi Nakajima, Kiriyama Kazuhiro
  • Journal Article
  • 2012-01-0978
Published 2012-04-16 by SAE International in United States
The requirements of suspension systems have become increasingly complex in recent years due to the expansion of global markets and diversification of the conditions under which vehicles are used in different parts of the world. It is also becoming increasingly important to ensure that vehicles offer the secure handling stability which are expected by drivers, but can also provide an adequate level of ride comfort when driving on a wide diversity of road surfaces in all parts of the world. From an environmental viewpoint, it is also essential to achieve weight reductions for better fuel economy.To meet these wide-ranging requirements, we have developed a new multi-link rear suspension that has a simple link configuration and a lower link that features a connecting bushing mechanism developed by Nissan. This innovative new connecting bushing mechanism not only helps to provide better handling stability by ensuring high stiffness and an adequate level of compliance steer, but also helps to improve the ride comfort by suitably controlling the behavior of tires when they encounter irregularities in the road surface,…
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Sensitivity of Collision Simulation Results to Initial Assumptions

SAE International Journal of Passenger Cars - Mechanical Systems

MEA Forensic Engineers & Scientists-Bradley Heinrichs, Brian Mac Giolla Ri, Ross Hunter
  • Journal Article
  • 2012-01-0604
Published 2012-04-16 by SAE International in United States
PC-Crash simulations of staged collisions require dozens of parameters describing vehicle and impact parameters. The Collision Optimizer will vary initial speeds and impact parameters to obtain a best fit to a desired end state, but vehicle parameters are left unchanged. The present paper allows these other parameters to vary in thousands of combinations, re-optimizing the solution in each to find the relationships between the previously fixed parameters and the resulting impact speeds. The results show that tire friction and vehicle inertial properties have the most influence on impact speeds. Other parameters have little influence on the results.
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Method of Vehicle Dynamics Analysis by Means of Equivalent Cornering Stiffness for Aerodynamic Forces and Moments

SAE International Journal of Passenger Cars - Mechanical Systems

Honda R&D Co., Ltd.-Hideaki Shibue, Atsushi Ogawa, Susumu Mashio
  • Journal Article
  • 2012-01-0213
Published 2012-04-16 by SAE International in United States
The dynamic performance of a vehicle traveling at high speeds is affected by the aerodynamic characteristics consisting of lift on front and rear axles, side force, and yawing moment. In order to enable consideration of these aerodynamic characteristics from the early stages of the vehicle development process, it is required that the characteristics are replaced by simple development indices. The study discussed in this paper introduced the concept of equivalent cornering stiffness to analyze these aerodynamic characteristics from the viewpoint of vehicle dynamics. Using this method, it is possible to integrate four aerodynamic characteristics into two variables which are very important to vehicle dynamics. As a result, the interaction between each aerodynamic characteristic is simply expressed in the equations of motion. Moreover the aerodynamic characteristics are dealt with as the same variables which are commonly used in other chassis systems such as suspensions and tires. It can hereby simplify to allocate the various chassis characteristics including aerodynamics to fulfill the high requirements for the vehicle dynamics performance, such as minimizing running resistance in keeping with…
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Reduction of Exhaust Noise by Means of Thermal Acoustics

SAE International Journal of Passenger Cars - Mechanical Systems

Magneti Marelli-Emanuele Milani, Costanza Paze, Massimo Ambrosino, Pierangelo Pagliano
  • Journal Article
  • 2012-01-0804
Published 2012-04-16 by SAE International in United States
It is well known that mufflers attenuate the engine noise essentially through dissipative and reflective effects. There is however another alternative technique for noise attenuation that has not been deeply explored, i.e. thermal acoustics. In fact the temperature of the gas influences the acoustic behaviour of the exhaust system; reducing the exhaust gas temperature, the sound pressure of the acoustic waves is reduced. This phenomenum could be used to improve the sound attenuation.We propose an experimental study of this phenomenum and of how it could be used to reduce the exhaust noise. We measured that, using in underfloor position passive heat exchangers like corrugated pipes, the exhaust gas quickly exchanges heat with the external environment and arrives to the rear muffler significantly colder. We observe about 2 dB decrease of the OA dB value when the gas temperature decreases of about 100°C. With colder exhaust gas the noise can be heavily reduced; in particular the flow noise improves the sound attenuation at high engine speed.
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Assessing Dirlik's Fatigue Damage Estimation Method for Automotive Applications

SAE International Journal of Passenger Cars - Mechanical Systems

Chrysler Group LLC-Yung-Li Lee
General Dynamics Land Systems-John P. Quigley
  • Journal Article
  • 2012-01-0757
Published 2012-04-16 by SAE International in United States
Fatigue analysis in the time domain using the rainflow cycle counting algorithm is considered the most accurate method for estimating damage. Dirlik's method has been found to be very accurate for damage estimation in the frequency domain. Previous studies have demonstrated the usefulness of Dirlik's method for ocean engineering and wind turbines but few have shown how well Dirlik performs in automotive applications. This study compares Dirlik's method with the rainflow cycle counting and with other frequency domain methods. The study analyzes measured data for an automotive component subjected to five test track load conditions. In addition, fourteen of Dirlik's original spectra and seven additional spectra which combine sine and random spectra are studied. It was found that Dirlik's method predicts more damage than the rainflow cycle counting method when applied to the original data used in creating the method. At the same time Dirlik's method underestimates damage for the automotive component by up to 30%. Still, when compared against other frequency domain methods, the Dirlik method is found to be the most accurate when…
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Indoor/Outdoor Testing of a Passenger Car Suspension for Vibration and Harshness Analysis

SAE International Journal of Passenger Cars - Mechanical Systems

Honda R&D Americas Inc.-Charles J. Gagliano
Politecnico di Milano-Massimiliano Gobbi, Giampiero Mastinu, Mario Pennati
  • Journal Article
  • 2012-01-0765
Published 2012-04-16 by SAE International in United States
This paper presents a validation method for indoor testing of a passenger car suspension. A study was done to design a supporting modular structure with comparable inertances with respect to a vehicle's actual suspension and body connection points. For the indoor test, the rear axle is positioned on a rotating drum. The suspension system is excited as the wheel passes over cleats fixed on the drum and transient wheel motions are recorded. The indoor test rig outputs (i.e., wheel and chassis accelerations) were compared with experimental data measured on an actual vehicle running at different speeds on the same set of cleats along a flat road. The comparison results validate the indoor testing method. The forces and moments acting at each suspension and chassis connection point were measured with a set of patented six-axis load cells. The forces, moments, wheel and subframe accelerations were measured up to 120 Hz. This study yielded a set of performance indexes by analyzing the forces and acceleration measured on the suspension system (the force measure is possible only on…
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Life Prediction Approach for Stainless Steel Exhaust Manifold

SAE International Journal of Passenger Cars - Mechanical Systems

Aperam-Antoine Acher
Arcelormittal-Pierre-Olivier Santacreu, Laurent Faivre
  • Journal Article
  • 2012-01-0732
Published 2012-04-16 by SAE International in United States
Stainless steel grades are now widely used for automotive exhaust systems, driven by the need to increase their durability and to reduce their weight. Exhaust Manifolds are subjected to more severe conditions and peak gas temperatures of 1000°C could be reached in new downsized gasoline engines. Also, longer guaranties are now required. This evolution is a direct consequence of the effort to decrease automotive pollutant emissions with new environmental regulations throughout the world. The paper will deal with the thermal-mechanical fatigue (TMF) damage prediction of fabricated automotive exhaust manifold fixed to the engine. A dedicated lifespan prediction approach was created based on elasto-viscoplastic behavior and damage models identification from different thermal-mechanical tests. The experimental procedure will be presented, especially the high temperature cyclic plasticity tests developed on thin sheet specimens and the V-shape thermal fatigue test that simulates the TMF process observed on manifolds subjected to engine bench tests. The Chaboche model was chosen for the elasto-viscoplastic model including a kinematic hardening plastic law coupled with the Norton viscous law. Our damage model is based…
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Experimental Characterization of the Lateral Response of a Tire under Hydroplaning Condition

SAE International Journal of Passenger Cars - Mechanical Systems

Politecnico di Milano-Stefano Melzi, Marco Sbrosi, Edoardo Sabbioni, Vincenzo d'alessandro
  • Journal Article
  • 2012-01-0769
Published 2012-04-16 by SAE International in United States
Hydroplaning represents a threat for riding safety since a wedge of water generated at the tire-road interface can lift tires from the ground thus preventing the development of tangential contact forces. Under this condition directionality and stability of the vehicle can be seriously compromised. The paper aims at characterizing the tire lateral response while approaching the hydroplaning speed: several experimental tests were carried out on a special test track covered with a 8-mm high water layer using a vehicle equipped with a dynamometric hub on the front left wheel. A series of swept sine steer maneuvers were performed increasing the vehicle speed in order to reach a full hydroplaning condition. Variations of tire cornering stiffness and relaxation length were investigated while the vehicle approaches the hydroplaning speed. Experimental tests stated that a residual capability of generating lateral forces is still present also close to the full hydroplaning condition.
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Sway Stability of 5TH Wheel RV Trailers

SAE International Journal of Passenger Cars - Mechanical Systems

Dynamic Research Inc-Peter Broen
Keystone RV Company-Tim Schlabach
  • Journal Article
  • 2012-01-0237
Published 2012-04-16 by SAE International in United States
This paper presents trailer sway testing results of a 5th wheel RV toy-hauler being towed by a conventional “dually” pick-up. Tests were performed at various speeds, trailer gross weights, king pin weights, and tire pressures. Results validate the understanding that 5th wheel trailers, at 20% pin weight generally have substantially better sway damping than conventional trailers. Tests at 10% pin weight show trailer sway damping is substantially reduced, but still is well above minimum industry accepted standards. Much of the improved sway damping for 5th wheel trailers can be attributed to the forward hitch location and not just the higher hitch loads that are typically used. What this means is that, although the recommended hitch load for a fifth wheel trailer is typically 20% or more, the sway response of the combination may be acceptable with substantially lower hitch loads, and they may maintain acceptable stability when the tow vehicle to trailer weight ratio is substantially less than 1:1, which does not generally occur with conventional travel trailers.
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An Investigation of Injury Factors Concerning Drivers in Vehicles Involved in Small-Overlap Frontal Crashes

SAE International Journal of Passenger Cars - Mechanical Systems

Nissan Motor Company Ltd.-Takahiro Kikuchi, Tomoyuki Nakao, Taisuke Watanabe, Hidetsugu Saeki, Tomosaburo Okabe
  • Journal Article
  • 2012-01-0599
Published 2012-04-16 by SAE International in United States
The causes of injuries suffered by drivers in “small-overlap frontal crashes” (SOFC) were examined. These crashes were defined as ones in which vehicles are loaded outside their longitudinal side members. SOFC accident data sets stored in the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) database were investigated. Percentages of cases sustaining injury to each body region of drivers were calculated, and the differences between the percentages of injury by body region were examined. To investigate the injury mechanisms, SOFC tests with two types of rigid barrier were then conducted. Injury values in each body region were analyzed to validate the reproducibility of SOFC test as a relevant test.
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