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Technical Paper

Transfer Function Analysis of Rear Multi-Link Suspension to Improve Ride Vibration and Road Noise

2011-05-17
2011-01-1571
The expectation of customers on ride comfort is very high and vehicle engineers also have keen interesting to improve ride vibration and road noise. As the conventional tuning parameters for the ride vibration and road noise, vibration characteristics of tire, body structure, bushing, suspension members etc. are mainly considered. But these conventional tuning parameters are sometimes not enough due to the side effects such like handling performances and durability. Therefore, instead of these conventional design and tuning parameters, suspension geometry and alignment characteristics of suspension system are selected as the alternative parameters to compromise ride vibration, road noise and vehicle dynamic performance. In this research, multi-link type rear suspension is selected for the integrated analysis of ride vibration, road impact noise and handling performance.
Technical Paper

Noise Contribution Analysis at Suspension Interfaces Using Different Force Identification Techniques

2011-05-17
2011-01-1600
Road-tire induced vibrations are in many vehicles determining the interior noise levels in (semi-) constant speed driving. The understanding of the noise contributions of different connections of the suspension systems to the vehicle is essential in improvement of the isolation capabilities of the suspension- and body-structure. To identify these noise contributions, both the forces acting at the suspension-to-body connections points and the vibro-acoustic transfers from the connection points to the interior microphones are required. In this paper different approaches to identify the forces are compared for their applicability to road noise analysis. First step for the force identification is the full vehicle operational measurement in which target responses (interior noise) and indicator responses (accelerations or other) are measured.
Journal Article

Determining Isolator Damping for Minimized Response from Impulse: A Theoretical Approach

2011-09-13
2011-01-2239
Several recent product developments for vibration and motion control have needed passive viscous damping, in addition to traditional elastomer-based hysteretic damping, to be successful in their respective applications. In addition to attenuating steady-state vibration, an important function of these recent product developments is to control motion from impulsive or mechanical shock input. Examples are the cab mounts of off-highway vehicles that need damping in the vertical direction to control cab motion from ground input through the vehicle and some torsionally flexible couplings that need damping to control torque spikes from shift shocks or other transient events. In this work, the theoretical damped impulse response quantities of displacement, velocity, acceleration, force, jerk, yank, and jounce are investigated. This work shows that, for certain response quantities, there is a specific magnitude of damping that minimizes response from impulsive or mechanical shock input.
Technical Paper

Study on Natural Torsional Vibration Characteristics of Dual Mass - Flywheel Radial Spring Type Torsional Vibration Damper

2009-05-19
2009-01-2062
The working principle of dual mass flywheel - radial spring (DMF-RS) type torsional vibration damper was analyzed, and the design method of natural torsional vibration characteristics control of DMF-RS type torsional damper for automotive powertrains was studied herein. Based on the multi-freedom lumped mass - torsional vibration spring analysis model of powertrain, the natural torsional vibration characteristics of the system with DMF-RS type torsional damper were analyzed, and compared with the clutch type torsional vibration damper, the effectiveness of DMF-RS type torsional damper on the torsional vibration control was verified.
Technical Paper

Noise Path Analysis Process Evaluation of Automotive Shock Absorber Transient Noise

2009-05-19
2009-01-2091
Shock absorber transient noise, often referred to as “chuckle” or “loose lumber”, has been a vehicle level noise and vibration concern for many years. The noise often occurs with lightly damped shock tuning under small road inputs at low speed. This transient type noise is of particular concern to the operator because it can sound like mechanical looseness in the chassis. This noise concern is generally addressed late in the design cycle and the options of a fix are limited to a change in damper tuning or added mass. A need for a wider design envelope exists to address this concern which must include noise paths into the structure and body sensitivity. The study documented in this paper walks through the process of acquiring this noise on the road and reproducing it in the lab on a 4-post hydraulic test rig.
Technical Paper

Improving Vehicle Vibration Behavior via Structural Modification with Random Road Input

2009-05-19
2009-01-2093
The aim of this research is the modification of frequency response of transmitted vibration to vehicle body via alternating the geometry of vehicle structural components. For this purpose after transmitting the FE model of vehicle body into ADAMS software and building full vehicle model, mode shapes, natural frequencies and transmitted vibration to the vehicle cabin in sensitive points were obtained. It has been shown that changing the engine ram geometry and adding strengthening components, not only affect the natural frequencies of vehicle body but also could modify the natural frequencies of full vehicle model. The result of using random road input demonstrates that the amplitude of the vibration transmitted to the vehicle cabin in modified model is decreased.
Technical Paper

Prediction of Spindle Force Using Measured Road Forces on Rolling Tire

2009-05-19
2009-01-2107
Improvement of vehicle interior noise is desired in recent years in the modern world of the demand of low weight, good fuel economy and offering technical advantages strongly. The dynamic force transmission of rolling tires from the road surface to the spindles is a critical factor in vehicle interior noise. We focus on structure-borne noise transferred through the spindle. It is necessary for effort of the effective tire/road noise reduction to predict spindle force excited by tire/road contact. The major issues in predicting spindle forces are to clarify the distribution of road forces and how to input on the simulation model. Therefore, it is important that road forces are measured accurately on the rolling tire. First, the dynamic road forces on the rolling tire are measured by using the tri-axial force sensor directly. In efforts to reduce interior noise due to structure-borne noise, it is necessary to predict spindle forces excited by the tire/road contact.
Technical Paper

Application of Tuned Mass Damper to Address Discrete Excitation Away From Primary Resonance Frequency of a Structure

2009-05-19
2009-01-2125
Tuned mass dampers (TMDs) or vibration absorbers are widely used in the industry to address various NVH issues, wherein, tactile-vibration or noise mitigation is desired. TMDs can be classified into two categories, namely, tuned-to-resonance and tuned-to-discrete-excitation. An overwhelming majority of TMD applications found in the industry belong to the tuned-to-resonance category, so much of information is available on design considerations of such dampers; however, little is published regarding design considerations of dampers tuned-to-discrete-excitation. During this study, a problem was solved that occurred at a discrete excitation frequency away from the primary resonance frequency of a steering column-wheel assembly. A solution was developed in multiple stages. First the effects of various factors such as mass and damping were analyzed by using a closed-form solution.
Technical Paper

Application of NVH Countermeasures for Interior Booming Noise using Elastomeric Tuned Mass Damper

2009-05-19
2009-01-2124
Tuned mass dampers (TMD) are frequently used in vehicles to resolve vibration and interior booming noise issues arising from powertrain's vibration and road excitation. This paper describes a driveshaft NVH case study in which analysis and test were used to solve the NVH problem. A TMD simulation package that utilizes a database of measured elastomeric material propertied. This facilitates the designing of optimized damper systems for a wide variety of vehicle applications. The simulation software takes into account frequency effects on elastomer properties while designing dampers. And the approach has proven to accurately predict performance in vehicles prior to manufacture. Rules of thumb for TMD design are discussed including locations for placement of dampers in automotive structures, determining the needed mass, and measurements and simulations that can greatly improve the success and reducing time-cost for TMD design.
Technical Paper

Development of High Fatigue Strength Valve Spring Using Control of White Layer by Nitriding

2009-11-03
2009-32-0082
For the requirements of high power output, lightweight and improved fuel consumption of motorcycles to respond to global environmental needs, high fatigue strength to cope with high stress is becoming more important than ever for valve springs. To satisfy such needs, a new alloy steel that softens less in tempering (1),(2) and nitriding that increases surface hardness of valve springs has been developed using oil-tempered silicone-chrome steel wire as the base material. Also, with regards to shot-peening to create compression residual stress on the surface, studies are being performed for multi-stage and high-hardness peening. The research reported in this paper is aimed at an increase of internal hardness after nitriding while maintaining the cold-coiling-ability by adding elements that reduce softening from tempering while reducing non-dissolved carbide in the material.
Journal Article

Research on Extended Expansion General-Purpose Engine - Noise Characteristics Caused by Multiple Linkage System and Reduction of the Noise

2009-11-03
2009-32-0042
Research has been conducted on an extended expansion engine, using a multiple linkage system to increase the thermal efficiency of general-purpose engines. In this research, first, the test engine was subjected to an engine acoustics measurement to clarify its noise characteristics. Then, based on the analysis results of the noise characteristics, we propose the direction to reduce the noise of the multiple linkage system engine. When the test engine was operated under a no-load firing condition, rattle noise was observed. Also it was found that the timing of the occurrence of the rattle noise was near after top dead center (ATDC) 90 degrees in crank angle (degCA). Focusing on the gear for linkage drive as a cause of the rattle noise, the authors formulated the torque acting on the gear.
Technical Paper

An integrated approach to extract basic Suspension Data through Integration of tri-axial spindle coupled road simulator, wheel force transducer and a wheel vector sensor.

2009-12-13
2009-28-0027
In a highly competitive global as well as the domestic market of the passenger car industry, the search for the complete car is on the forefront. With such a situation, carmakers are experimenting with innovative technology on various development programs to cater the needs of the customer. This paper shows one such experimentation to extract the basic suspension Kinematics & Compliance data with the integration of a Tri-axial Spindle Coupled road load simulator, a wheel force transducer and a Wheel Vector Sensor in absence of expensive Suspension Parameters Measuring Machine (SPMM).
Technical Paper

Analysis of Characteristics of Dampers of Hydrogas Suspension and the Effect of Damping Configuration on the Vibration Dynamics of a Light Tracked Vehicle

2009-01-21
2009-26-0068
Damping plays a vital role in design of suspension system for off road, tracked military vehicles. The magnitude of damping provided and the configuration of damping adopted have a significant bearing on the mobility characteristics of tracked vehicle. Two types of dampers have been developed for a hydrostrut suspension intended for a light tracked vehicle. The damper is in built in the hydrogas suspension system. The present paper discusses mainly the experimental determination of damping characteristics, results obtained from vehicle model developed in the software ‘LMS Virtual Lab motion’ with two damping configurations and vibration measurement carried out for validation. Experimental testing and analysis have been carried out to study the characteristics of two types of dampers. The Hydro gas suspension unit has been gradually compressed to obtain its displacement vs force characteristics.
Technical Paper

Design of Rubber Spring for Replacement of Torsion Bar on a Three Wheeler Rear Suspension

2009-01-21
2009-26-0073
The three wheeler vehicle segment in India has an important bearing in both passenger and load carrier segment upto 0.5 tones. Durability requirements under specified loadings and good ride comfort are prime parameters in a competitive segment. This segment is highly sensitive to cost and warranty. To meet the above requirements and add more value to the vehicles, the rear suspension of three wheelers which is traditionally a torsion bar and trailing arm type is redesigned with a multilobe rubber spring. The rubber spring profile to meet the desired stiffness characteristics is designed and evaluated through finite element analysis. The paper presents the study on the design of the Multilobe rubber spring through the simulation of the hyper-elastic and nonlinear contact behavior of rubber. The profile is optimized through analysis and a correlation is obtained on a prototype test.
Technical Paper

Modeling and Simulation of Peak Load Events Using Adams - Driving Over a Curb and Skid Against a Curb

2011-04-12
2011-01-0733
The durability peak load events Driving over a curb and Skid against a curb have been simulated in Adams for a Volvo S80. Simulated responses in the front wheel suspension have been validated by comparison with measurements. Due to the extreme nature of the peak load events, the component modeling is absolutely critical for the accuracy of the simulations. All components have to be described within their full range of excitation. Key components and behaviors to model have been identified as tire with wheel strike-through, contacts between curb and tire and between curb and rim, flexibility of structural components, bump stops, bushings, shock absorbers, and camber stiffness of the suspension. Highly non-linear component responses are captured in Adams. However, since Adams only allows linear material response for flexible bodies, the proposed methods to simulate impact loads are only valid up to small, plastic strains.
Technical Paper

Taguchi Method (DOE) Based Performance Optimization of a Three Link Rigid Axle Passenger Car Suspension Using MBD Simulations

2011-04-12
2011-01-0734
This paper describes dimensional synthesis, analysis and performance optimization of a three-link rigid-axle suspension system. This suspension architecture has two longitudinal links and panhard rod as a transverse link. In case of rigid axle with three links, roll stiffness is primarily governed by springs, anti-roll bar, suspension link dimensions and its orientations. Because of suspension architecture, the bushings connecting the longitudinal link to axle will also contribute to the suspension roll stiffness. Typically, this contribution is comparable to the contribution due to the suspension springs. Hence, this paper explores the process of reducing roll stiffness of three-link rigid-axle suspension by identifying and changing high impact parameters. In the multi-step process, the first step is to evaluate the kinematics and compliance performance. This analysis is performed using "ADAMS®" - the multibody dynamics analysis software.
Technical Paper

Interval Optimization of Uncertain Suspension Kinematics Characteristics

2011-04-12
2011-01-0730
The optimization of vehicle suspension kinematics characteristics is an important part in the chassis development. The current optimization algorithms for suspension kinematics parameters are certain optimization method. But vehicles to manufacture in large quantities are uncertainty in the structural parameters. Therefore, suspension kinematics characteristics are all uncertain parameters on vehicles. The paper explored an interval method to describe the uncertainty suspension kinematics characteristics and used improved interval Newton iteration method to optimize it. As we all know, some suspension kinematics characteristics are the curves. When the structural parameters are uncertain variables, these curves are uncertain variables curves.
Journal Article

Reliability Prediction for the HMMWV Suspension System

2011-04-12
2011-01-0726
This research paper addresses the ground vehicle reliability prediction process based on a new integrated reliability prediction framework. The integrated stochastic framework combines the computational physics-based predictions with experimental testing information for assessing vehicle reliability. The integrated reliability prediction approach incorporates the following computational steps: i) simulation of stochastic operational environment, ii) vehicle multi-body dynamics analysis, iii) stress prediction in subsystems and components, iv) stochastic progressive damage analysis, and v) component life prediction, including the effects of maintenance and, finally, iv) reliability prediction at component and system level. To solve efficiently and accurately the challenges coming from large-size computational mechanics models and high-dimensional stochastic spaces, a HPC simulation-based approach to the reliability problem was implemented.
Technical Paper

A New Methodology for Calculating and Modelling Non-Linear Springs in the Valve Train of Internal Combustion Engines

2011-04-12
2011-01-0780
The valve return springs in the distribution chain of internal combustion engines constitute a fundamental component for the duration, efficiency and performance of the engine itself [1,2,3,4]. This is even more true for high-performance engines whose mechanical and thermal power leads to the premature deterioration of poorly designed components. The elevated forces in such engines necessitate, where the valve springs have not been substituted by alternative kinematic systems, progressive springs, i.e. springs with variable stiffness. Despite this fact, the literature does not contain any univocal methods for defining the geometry of this type of spring.
Technical Paper

Dual Rate Jounce Bumper Design

2011-04-12
2011-01-0791
Jounce bumpers are the primary component by which vertical wheel travel is limited in our suspensions. Typically, the jounce bumper is composed of closed or open cell urethane material, which has relatively low stiffness at initial compression with highly progressive stiffness at full compression. Due to this highly progressive stiffness at high load, peak loads are extremely sensitive to changes in input energy (affected by road surface, tire size, tire pressure, etc.) A “Dual Rate Jounce Bumper” concept is described that reduces this sensitivity. Additionally, various mechanizations of the concept are described as well as the specific program benefits, where applicable.
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