Road Load Research Articles

Evaluation of Fatigue Life Reliability of Steering Knuckle Using Pearson Parametric Distribution Model

Steering module is a part of automotive suspension system which provides a means for an accurate vehicle placement and stability control. Components such as steering knuckle are subjected to fatigue failures due to cyclic loads arising from various driving conditions. This paper intends to give a description of a method used in the fatigue life reliability evaluation of the knuckle used in a passenger car steering system. An accurate representation of Belgian pave service loads in terms of response-time history signal was obtained from accredited test track using road load data acquisition. The acquired service load data was replicated on durability test rig and the SN method was used to estimate the fatigue life. A Pearson system was developed to evaluate the predicted fatigue life reliability by considering the variations in material properties. Considering random loads experiences by the steering knuckle, it is found that shortest life appears to be in the vertical load direction with the lowest fatigue life reliability between 14000–16000 cycles. Taking into account the inconsistency of the material properties, the proposed method is capable of providing the probability of failure of mass-produced parts.

UTILIZAÇÃO DA PROGRAMAÇÃO LINEAR NA OTIMIZAÇÃO DE RESULTADOS DE UMA EMPRESA DO RAMO DE TRANSPORTE RODOVIÁRIO DE CARGAS

Trata o presente artigo de um estudo sobre a otimização de resultado de uma empresa de transporte rodoviário de cargas, que apresenta capacidade de carga ociosa. Essa empresa faz parte de um setor altamente competitivo no Brasil, que necessita de ferramentas gerenciais que possam auxiliar seus gestores no processo de tomada de decisão. O objetivo do artigo é aplicar a programação linear para otimizar o resultado dessa empresa, estabelecida na Região do Vale do Itajaí, Estado de Santa Catarina. O estudo é de caráter exploratório com abordagem quantitativa, e os dados foram obtidos por meio de pesquisa documental, com consulta a documentos primários e secundários da empresa. Os resultados apontam que a empresa necessita incrementar o volume transportado por sua matriz e pelas duas filiais estabelecidas no Estado de Santa Catarina. Dadas as restrições na demanda de cada filial, bem como à restrição de veículos possuídos pela empresa para esse serviço, a matriz da empresa deve aumentar o seu volume transportado em aproximadamente 17%, a Filial SC 1 em 60% e a Filial SC 2 em 50%. Conclui-se que a programação linear pode ser bastante útil para resolução de problemas empresariais que envolvam limitações ou restrições de recursos. No caso das empresas de transporte rodoviário de cargas, essa ferramenta pode ser interessante na distribuição de metas de volume transportado entre os estabelecimentos da empresa, auxiliando na distribuição dos veículos para cada estabelecimento, como apresentado nesse estudo.

Research and Verification of the Logic Threshold Self-adjusting Control Method for ABS

Independently developing anti-lock braking system(ABS) is the basis of mastering the active dynamic control technology of vehicle chassis.According to the experimental data and the logic threshold control method widely used in the industrial ABS,the impact on ABS control of every logic threshold is analyzed and the basic rules of calibrating the logic thresholds is established.By borrowing the idea from the self-tuning regulator in adaptive control,a logic threshold self-adjusting algorithm is presented.The algorithm identifies the optimal brake slip ratio of the road and calculates the reference speed on-line.The main logic thresholds are adjusted automatically according to the error between the wheel slip ratio and the optimal slip ratio in order to improve the control performance.The control parameters are calibrated and the control performance of the self-adjusting algorithm is verified by road tests under various conditions.The test results indicate that the presented logic threshold self-adjusting algorithm overcomes the influence of different factors,such as road adhesion coefficient,speed and load,on the ABS,thereby the optimal ABS control under every condition is realized.The developed ABS has good control effect and meets the development requirement.It provides a foundation for ABS industrialization.

DESIGN AND ANALYSIS OF A MAGNETIC-GEARED ELECTRONIC-CONTINUOUSLY VARIABLE TRANSMISSION SYSTEM USING FINITE ELEMENT METHOD

This paper proposes a new electronic-continuously variable transmission (E-CVT) system for power-split hybrid electric vehicles (HEVs). The key is to integrate two permanent magnet motor/generators (M/Gs) together with a coaxial magnetic gear (CMG). By designing the modulating ring of the CMG to be rotatable, this integrated machine can achieve both power splitting and mixing, and therefore, can seamlessly match the vehicle road load to the engine optimal operating region. With the one-side-in and one- side-out structure and the non-contact transmission of the CMG, all the drawbacks aroused by the mechanical gears and chain existing in the traditional E-CVT system can be overcome. Moreover, the proposed E-CVT system possesses the merits of small size and light weight, which are vitally important for extending the full-electric drive range of HEVs. The working principle and the design details are elaborated. By using the flnite element method (FEM), the electromagnetic characteristics are analyzed.

Comfort and Durability Tire Model Validation

Abstract In this study, a systematic validation of comfort and durability tire models (CDT) using LMS software was performed by focusing on the measured tire data collection, bench test, and full vehicle model predictions. Different road events are considered in the validation process, including deterministic and random type roads, as well as braking/accelerating and cornering events. The study shows that the current version of commercial CDT models is reasonably accurate for durability road loads simulation, but requires simulation time improvement. The seven published SAE J-documents for road load tire model parameterization tests cover the necessary data to parameterize the CDT model for “non-misuse” road loads simulation.

Motorcycle Dynamics Simulation Based on Real Road Load

The motorcycle dynamics simulation method based on the road simulation test and virtual prototype is developed, and a rigid-flexible coupling virtual prototype with test platform of motorcycle is created with CATIA, NASTRAN and ADAMS software. According to two-channel tire-coupled road simulator of MTS Systems Corporation, the simulation model and platform are repetitively refined to fairly high precision by comparing simulation results with experimental results. The iterated excitation signal based on real road load or typical spectrum of different roads is imported into the virtual test platform, the comfort and durability tests of motorcycle can be undertaken to replace road simulator, the test period and cost are greatly reduced, and test security is increased.

Dynamic response analysis of a heavy commercial vehicle subjected to extreme road operating conditions

Wheel excitations measured on a heavy commercial vehicle by driving it through extreme road operating conditions, are considered as inputs to perform dynamic response analysis in a simulated laboratory and computational environment. From initial modal analysis results using finite elements, critical vehicle frame rail locations are identified for dynamic laboratory strain measurements on a six poster road load simulator that employs dynamic wheel excitations as input. Dynamic stresses calculated from measured strain values are then compared with computationally obtained stress results on each of these locations. This study also points out all geometric locations and vibration modes that may affect the design behavior of the frame members under extreme road operating conditions. The results obtained from this work can be considered for further fatigue life prediction and design optimization of chassis frame rail assembly.

FatiRAN – Optimized Generation of Spectra for Random Vibration Testing*

Abstract Random vibration testing with stochastic broad band noise signals is a commonly used procedure in qualification testing of vehicle parts. However, there are no standard procedures for deriving adequate test power spectral densities from road load data; hence test spectra can be defined far too low leading to tests not covering the loads of service life. In this paper, a new method is presented that gives consideration to the aspects of material fatigue during the whole process of windowing, overlapping, amplitude correction, and averaging that all have vital influence on the test spectra obtained. This allows for deriving test spectra with calculated damage equivalent to a defined set of design load histories, and thus helps minimizing the effort for calibration runs of test spectra on a test rig. The theoretic derivation will be shown as well as a comparison with the commonly used procedures using an exemplary case study.

Development of the Inner Spherical CVT for a motorcycle

An Inner Spherical CVT (ISCVT) transfers engine power by utilizing the traction force of the lubricant fluid film on the contact point between concave and convex spherical rolling bodies. Since the concave and the convex contact surfaces of the ISCVT are exactly spherical parts, they have a large circular (not elliptic) contact area, and the ISCVT mechanism has a larger torque capacity, less spin loss, and better stability than other traction drive mechanisms. The IVT (Infinitely Variable Transmission) performances also can easily be embodied in the ISCVT. In this work, we developed a prototype of the ISCVT for a motorcycle with a 125cc single cylinder engine having a maximum torque of 13.73 Nm at 8,000 rpm. The design parameters were determined, and the transmission performances were evaluated by optimal design procedure. The transmission efficiency, the life time, the maximum severe stresses on each part of the ISCVT, and the work needed for varying speed ratio were theoretically investigated, and the efficiency performances were experimentally measured. The manufactured prototype was installed in an actual motorcycle, which was fixed on the test-bench equipped with a dynamometer. The parasitic loss of the prototype and the cross-sectional road load performance were tested. The power efficiency of the simulated prototype was between 87∼92%, and the life span was more than 50,000 hours. The tested overall power efficiency was around 70∼92% under frequent driving conditions, which is an impressive performance in a motorcycle transmission despite the small difference from the simulation.

Performance analysis of a CVT clutch system for a hybrid electric vehicle

In this study, the performance of a CVT clutch system for a hybrid electric vehicle was investigated. To analyzed the vehicle performance at restart, the restart delay and driveshaft torque was investigated by simulations and experiments. It was found from the simulation results that the vehicle restart response depends on the clutch pressure buildup time to the point where the clutch torque begins to overcome the vehicle road load, and driving comfort at restart is directly related to the rate change of the clutch pressure.

Classification Scheme for Random Longitudinal Road Unevenness Considering Road Waviness and Vehicle Response

A novel approach to the road unevenness classification based on the power spectral density with consideration of vehicle vibration response and broad interval of road waviness (road elevation PSD slope) is presented. This approach enables transformation of two basic parameters of road profile elevation PSD (unevenness index, C, and waviness, w) into a single-number indicator Cw when using a correction factor Kw accounting for w. For the road classification proposal two planar vehicle models (passenger car and truck), ten responses (reflecting ride comfort, dynamic load of road and cargo, ride safety) and three different vehicle velocities have been considered. The minimum of ten estimated vibration response ranges sum for a broad waviness interval typical for real road sections (w = 1.5 to 3.5) has been used for the correction factor estimation. The introduced unevenness indicator, Cw, reflects the vehicle vibration response and seems to be a suitable alternative to the other currently used single-number indicators or as an extension of the road classification according to the ISO 8608: 1995, which is based on constant waviness value, w = 2.

Classification Scheme for Random Longitudinal Road Unevenness Considering Road Waviness and Vehicle Response

A novel approach to the road unevenness classification based on the power spectral density with consideration of vehicle vibration response and broad interval of road waviness (road elevation PSD slope) is presented. This approach enables transformation of two basic parameters of road profile elevation PSD (unevenness index,C, and waviness,w) into a single-number indicatorCwwhen using a correction factorKwaccounting forw. For the road classification proposal two planar vehicle models (passenger car and truck), ten responses (reflecting ride comfort, dynamic load of road and cargo, ride safety) and three different vehicle velocities have been considered. The minimum of ten estimated vibration response ranges sum for a broad waviness interval typical for real road sections (w= 1.5 to 3.5) has been used for the correction factor estimation. The introduced unevenness indicator,Cw, reflects the vehicle vibration response and seems to be a suitable alternative to the other currently used single-number indicators or as an extension of the road classification according to the ISO 8608: 1995, which is based on constant waviness value,w= 2.

Simulation of Battery SOC State of a Hybrid Electric Vehicle (Applying a Proposed Method of Road Inclination Convert to a Data Received by GPS)

This report evaluates a position of SOC (State of Charge) along with a down hill drive on a real world to its simulation on an emission chassis dynamometer with a gradient road load. On a down hill drive, a vehicle kinetic energy regenerates the battery continuously and an amount of charge volume which shifts the battery SOC up. Excessive charge is a negative factor for the battery life which is designed both a long term of life and a long distance of drive. This regenerating driving mode could not be evaluated on a flat road. A gradient drive way or a gradient simulation system forced energy into a vehicle could evaluate the mode. To evaluate, on the one hand some necessary investigation is carried out to a realization of a down hill drive simulation on an emission chassis dynamometer and problems hitting upon the investigation has been clarified. On the other hand the real world data driving down hill is measured by HEV (Hybrid Electric Vehicle). The real world data collected by GPS (Global Positioning System) has fluctuated widely. This report proposes a method of spline interpolation to the data for a chassis simulation test and reviews the results of the test to the real world mode and evaluates the studies. And here the author also reports an applied chassis simulation for the study of this method.

Evaluation of Battery SOC State of a Hybrid Electric Vehicle on an Emission Chassis Dynamometer with Gradient Road Load Simulation of a Real World Descent Drive

Evaluation of Battery SOC State of a Hybrid Electric Vehicle on an Emission Chassis Dynamometer with Gradient Road Load Simulation of a Real World Descent Drive

Battery SOC State of a Hybrid Electric Vehicle (A Study of Up-hill Drive Way with a Number of Start-stop Modes)

This paper studies a tracking line of battery SOC (State of Charge) which indicates battery energy remaining along with an up-hill drive way in Death Valley with a number of start-stop modes to its simulation on an emission chassis dynamometer with a gradient road load. A method of spline interpolation smoothes apply to set a road gradient data for a chassis simulation test. It was found that the SOC in the chassis simulation matches the SOC in a real world test. The paper mentions a quantitative evaluation to the simulation results based on Mahalanobis distance method.

Fuel Consumption Test Method for 4WD HEVs – On a Necessity of Double Axis Chassis Dynamometer Test –

Concerns regarding global climate change have caused the transportation sector to look for alternatives to petroleum as a fuel for vehicles of all types. Hybrid electric vehicles (HEVs) have been recognized as being particularly efficient for urban traffic use. In the last few years, Four wheel drive (4WD) transmissions have been developed for heavy passenger vehicles. As these vehicles become more popular, there is a need for accurate fuel consumptions test methods. Clearly the most accurate fuel consumption measurements would be obtained by using dual axis dynamometers, but these systems are not always available. Single axis dynamometers are commonly used for evaluating fuel consumption, but these are inadequate for 4WD vehicles without adjustments to account for the uncertainty that will result from disabling one of the drive axles.This paper describes a method for extrapolating fuel consumption results from single axle chassis dynamometer testing to estimate the fuel consumption of 4WD vehicles. A simple method is proposed that will allow reasonable estimates of fuel consumption for 4WD vehicles to be made from single axle dynamometer testing.This paper also describes methods to reduce the uncertainty in 4WD chassis dynamometer testing by paying particular attention to road load, tire conditions and restraint characteristics.

적정 포장설계를 위한 과실의 유통 중 진동의 계측 및 분석

The freight vehicle is mostly used to transport the fruit. Shock and impact generated by the freight vehicle may give serious damage to fruits hence to reduce the fruits damage, the optimum packaging design during transportation by vehicle is required. In order to design the packaging system for fruit transportation optimally, the comprehension of characteristic for vibration and shock acting on vehicles under various road conditions and loading methods is required. This research was performed to analyze the shock characteristics, acceleration level and power spectral density (PSD) of the fruit transportation vehicles under several travel roads and positions. The vibration signal was measured and analyzed at the transportation vehicle operating on the road of three different surface conditions. The maximum acceleration was measured at the rear-end of the vehicle, and the acceleration in the direction of up-and-down (z-axis) was much greater than those in the directions of back-and-forth (x-axis) or right-and-left (y-axis). The peak acceleration in the direction of up-and-down (z-axis) at the vehicle driving on the expressway, the local road paved with concrete, and unpaved local road were 5.3621 G, 8.232 G, and 14.162 G respectively. PSD at 2.44 Hz showed maximum value at all road conditions. The maximum values of PSD on the expressway, a local road paved with concrete, and unpaved local road were 0.0075222 <TEX>$G^2/Hz$</TEX>, 0.058655 <TEX>$G^2/Hz$</TEX>, and 0.24598 <TEX>$G^2/Hz$</TEX> respectively. The value of PSD decreased with an increase of the vibration frequency of the transportation vehicle. In most cases, the vibration frequency was below 20 Hz during transportation.

Review of multi-regime hybrid vehicle powertrain architecture

In this paper, we present a review of the recent advances in hybrid vehicle powertrain architectural design. The paper begins with a discussion and categorisation of the various types of hybrid vehicles. The current leading technology is the one-mode design of the Toyota Hybrid System, and the intent of the state-of-the-art architectures is to improve upon the perceived weaknesses of the one-mode design. The proposed designs employ multi-regime architectures that allow for the transmission to operate in any one of series, parallel, or power-split configurations, depending upon the road load, driver demand, and control strategy. These new designs found in the literature are discussed and compared. The work allows further study and detailed modelling of the promising multi-regime architectures to be carried out.

Simulation of Battery SOC State of a Hybrid Electric Vehicle (Applying a Proposed Method of Road Inclination Convert to a Data Received by GPS)

This report evaluates a position of SOC (State of Charge) along with a down hill drive on a real world to its simulation on an emission chassis dynamometer with a gradient road load. On a down hill drive, a vehicle kinetic energy regenerates the battery continuously and an amount of charge volume which shifts the battery SOC up. Excessive charge is a negative factor for the battery life which is designed both a long term of life and a long distance of drive. This regenerating driving mode could not be evaluated on a flat road. A gradient drive way or a system forced energy into vehicle could evaluate the mode. To evaluate, on the one hand some necessary investigation is carried out to a realization of a down hill drive simulation on an emission chassis dynamometer and problems hitting upon the investigation has been clarified. On the other hand the real world data driving down hill is measured by HEV (Hybrid Electric Vehicle). The real world data collected by GPS (Global Positioning System) has fluctuated widely. This report proposes a method of spline compensation to the data for a chassis simulation test and reviews the results of the test to the real world mode and evaluates the studies. And further more study is carried out an applied chassis simulation.

A closed-form method to determine vehicle speed and its maximum value

Two non-linear differential equations representing road load and power consumption are used to determine the maximum vehicle speed and speed-time history. These equations are expressed in terms of velocity by expanding the inertia force, air drag, rolling resistance, gravitational force and tyre tractive force. For simulation purpose, the parameters of Wright State's electric car are used. The results for Front-Wheel Drive (FWD), Rear-Wheel Drive (RWD), Four-Wheel Drive (4WD), high power and low power cases are presented.