Numerical Prediction of Ride Comfort of Tracked Vehicle Equipped with Novel Flexible Road Wheels

Enhancing ride comfort has always constituted a crucial focus in the design and research of modern tracked vehicles,heavily reliant on the driving system's performance.While the road wheel is a key component of the driving system,traditional road wheels predominantly adopt a solid structure,exhibiting subpar adhesion performance and damping effects,thereby falling short of meeting the demands for high-speed,stable,and long-distance driving in tracked vehicles.Addressing this issue,this paper proposes a novel type of flexible road wheel(FRW)characterized by a catenary construction.The study investigates the ride comfort of tracked vehicles equipped with flexible road wheels by integrating finite element and vehicle dynamic.First,three-dimensional(3D)finite element(FE)models of both flexible and rigid road wheels are established,considering material and contact nonlinearities.These models are validated through a wheel radial loading test.Based on the validated FE model,the paper uncovers the relationship between load and radial deformation of the road wheel,forming the basis for a nonlinear mathematical model.Subsequently,a half-car model of a tracked vehicle with seven degrees of freedom is established using Newton's second law.A random road model,considering the track effect and employing white noise,is constructed.The study concludes by examining the ride comfort of tracked vehicles equipped with flexible and rigid road wheels under various speeds and road grades.The results demonstrate that,in comparison to the rigid road wheel(RRW),the flexible road wheel enhances the ride comfort of tracked vehicles on randomly uneven roads.This research provides a theoretical foundation for the implementation of flexible road wheels in tracked vehicles.

Vehicle Ride Comfort Based on Matching Suspension System

The existing investigations of vehicle ride comfort mainly include motion characteristics analysis based on creating a multi-body dynamic simulation model,and the parameters analysis to improve the suspension control for the target.In the study of creating multi-body dynamics simulation models,there is usually without considering calibration and test verification,which make it difficult to ensure the production of engineering.In the study of improving the suspension control parameters for the target,there is a lack of systematic match about comfortable and human characteristics,so it is difficult to implement in the field of driving and leading the vehicle design.In this paper,based on the different characteristic of suspension system that effects on the vehicle ride comfort, according to the suspension system dynamic mechanism,the research methods of vehicle road test,bench test and CAE simulation is used,at the same time,several sensitivity analysis of vehicle ride comfort related to suspension stiffness and damping and speed is made. As a result,the key suspension systematic parameters are given that have important impact on vehicle ride comfort.Through matching parameters,a calibration analysis of suspension system based on human comfort is obtained.The analysis results show that the analysis methods for the design target of making the vehicle with best comfort are effective.On the basis of the theory study,five suspension parameter matching principles are explored to promise the vehicle with perfect ride comfort,which also provide theoretical basis and design methods for the passenger car best match of suspension system stiffness and damping.The research results have the promotional value of practicability and a wide range of engineering application.

Annoyance Rate Evaluation Method on Ride Comfort of Vehicle Suspension System

The existing researches of the evaluation method of ride comfort of vehicle mainly focus on the level of human feelings to vibration. The level of human feelings to vibration is influenced by many factors, however, the ride comfort according to the common principle of probability and statistics and simple binary logic is tmable to reflect these uncertainties. The random fuzzy evaluation model from people subjective response to vibration is adopted in the paper, these uncertainties are analyzed from the angle of psychological physics. Discussing the traditional evaluation of ride comfort during vehicle vibration, a fuzzily random evaluation model on the basis of annoyance rate is proposed for the human body＇s subjective response to vibration, with relevant fuzzy membership function and probability distribution given. A half-car four degrees of freedom suspension vibration model is described, subject to irregular excitations from the road surface, with the aid of software Matlab/Simulink. A new kind of evaluation method for ride comfort of vehicles is proposed in the paper, i.e., the annoyance rate evaluation method. The genetic algorithm and neural network control theory are used to control the system. Simulation results are obtained, such as the comparison of comfort reaction to vibration environments between before and after control, relationship of annoyance rate to vibration frequency and weighted acceleration, based on ISO 2631 / 1 （1982）, ISO 2631-1 （1997） and annoyance rate evaluation method, respectively. Simulated assessment results indicate that the proposed active suspension systems prove to be effective in the vibration isolation of the suspension system, and the subjective response of human being can be promoted from very uncomfortable to a little uncomfortable. Furthermore, the novel evaluation method based on annoyance rate can further estimate quantitatively the number of passengers who feel discomfort due to vibration. A new analysis method of vehicle comfort is presented.

Ride comfort evaluation for road vehicle based on rigid-flexible coupling multibody dynamics

In the present research two different whole vehicle multibody models are established respectively, including rigid and rigid-flexible coupling multibody vehicle models. The former is all composed by rigid bodies while in the later model, the flexible rear suspension is built based on the finite element method （FEM） and mode superposition method, in which the deformations of the components are considered. The ride simulations with different speeds are carried out on a 3D digitalized road, and the weighted root mean square （RMS） of accelerations on the seat surface,backrest and at the feet are calculated. The comparison between the responses of the rigid and rigid-flexible coupling multibody models shows that the flexibility of the vehicle parts significantly affects the accelerations at each position, and it is necessary to take the flexibility effects into account for the assessment of ride comfort. C 2013 The Chinese Society of Theoretical and Applied Mechanics. [doi： 10.1063/2.1301304]

Experimental Study on the Ride Comfort of a Crawler Power Chassis Scale Model Based on the Similitude Theory

The ride comfort experimental assessment of crawler off-road vehicle is relatively overlooked, and is expensive and difficult to execute with higher and higher ride comfort performance requirements. To trade off between precise and cost, an experimental method based on the similitude theory is proposed. Under the guidance of the similitude theory, a 1：5 crawler power chassis scale model equipped with a kind of variable stiffness suspension system is used. The power spectrum density（PSD）, the root mean square（RMS） of weighed acceleration, peak factor, average absorbed power（AAP） and vibration dose value（VDV） are selected as ride comfort evaluation indexes, and tests results are transformed via similarity indexes to predict the performance of full-scale power chassis. PSD shows that the low-order natural frequency of the vertical natural frequency（z axis） is 1.1 Hz, and the RMS, AAP and VDV values indicate the ride comfort performance of this kind of power chassis is between the ＂A little uncomfortable＂ and ＂Rather uncomfortable＂. From the results, low-order vertical natural frequency, obtained by PSD, validates that the similarity relationship between two models is satisfied, and 1：5 scale model used in experiment meets the similarity relationship with the full-scale model; consequently, the ride comfort prophase evaluation with the 1：5 scale model is feasible. The attempt of applying the similitude theory to crawler vehicle ride comfort test study decreases the cost and improves the test feasibility with sufficient test precise.

Frequency Weighting Filter Design for Automotive Ride Comfort Evaluation

Few study gives guidance to design weighting filters according to the frequency weighting factors,and the additional evaluation method of automotive ride comfort is not made good use of in some countries.Based on the regularities of the weighting factors,a method is proposed and the vertical and horizontal weighting filters are developed.The whole frequency range is divided several times into two parts with respective regularity.For each division,a parallel filter constituted by a low-and a high-pass filter with the same cutoff frequency and the quality factor is utilized to achieve section factors.The cascading of these parallel filters obtains entire factors.These filters own a high order.But,low order filters are preferred in some applications.The bilinear transformation method and the least P-norm optimal infinite impulse response（IIR） filter design method are employed to develop low order filters to approximate the weightings in the standard.In addition,with the window method,the linear phase finite impulse response（FIR） filter is designed to keep the signal from distorting and to obtain the staircase weighting.For the same case,the traditional method produces 0.330 7 m · s^–2 weighted root mean square（r.m.s.） acceleration and the filtering method gives 0.311 9 m · s^–2 r.m.s.The fourth order filter for approximation of vertical weighting obtains 0.313 9 m · s^–2 r.m.s.Crest factors of the acceleration signal weighted by the weighting filter and the fourth order filter are 3.002 7 and 3.011 1,respectively.This paper proposes several methods to design frequency weighting filters for automotive ride comfort evaluation,and these developed weighting filters are effective.

Effect of the off-road terrains on the ride comfort of construction vehicles

In order to evaluate the impact of off-road terrains on the ride comfort of construction vehicles,a nonlinear dynamic model of the construction vehicles interacting with the terrain deformations is established based on Matlab/Simulink software.The weighted root mean square(RMS)acceleration responses and the power spectral density(PSD)acceleration responses of the driver s seat heave,the pitch and roll angle of the cab in the low-frequency region are chosen as objective functions under different operation conditions of the vehicle.The results show that the impact of off-road terrains on the driver s ride comfort and health is clear under various conditions of deformable terrains and range of vehicle velocities.In particular,the driver s ride comfort is greatly affected by a soil terrain while the comfortable shake of the driver is strongly affected by a sand terrain.In addition,when the vehicle travels on a poor soil terrain in the frequency range below 4 Hz,more resonance peaks of acceleration PSD responses occurred than that on a rigid road of ISO 2631-1 level C.Thus,the driver s health is significantly affected by the deformable terrain in a low-frequency range.

Optimisation of Climate Robust Buildings under Summer Conditions with ＂Primero-Comfort＂ Simulation Software Including Detailed User Behaviour and Comfort Expectance

In this paper the possibilities for avoiding active air conditioning by all means of the room itself （window size, glazing, shading system, natural ventilation, and furniture）, artificial light and control strategy of these systems are investigated. A very important component of the system is the user with his ability to adapt to changing conditions in his surrounding and with his possibilities to manipulate the window, the shading system, the light switch etc. All these aspects interact together. It is necessary to optimize them simultaneously. But real planning often separates them into single sections. Simulation tools also handle normally only one or a few aspects, we know for example the thermal simulation or the daylight simulation. Primero-Comfort （2009） is a simulation tool based on energy＋, what is able to consider thermal simulation as well as daylight simulation as well as user behaviour in regard to the probability of window openings. The resulting thermal comfort is rated by an adaptive comfort model, the Dutch ISSO 74 （2004）. This allows designing office rooms more realistic. And it shows that an optimized solution has to include the interactions of aU mentioned aspects. Investigations with Primero-Comfort for a moderate European climate （Hamburg） show that a very good comfort can be reached only by passive means of building design also for hot summer weather just like the summer in the year 2003. The keys for such hot-summer-robust-buildings are night ventilation with height difference, heat protection glazing and good shading system, reduced internal heat gains for artificial light by accepting a threshold of 300 lx of daylight as comfortable and a reduced window size oriented on daylighting and the view out of the window.

Prediction Research on Ride Comfort of Special Full Trailer used by Precision Equipment

In order to evaluate a full trailer’s vibration performance,lumped mass model of seven degrees of freedom is set up to predict the ride comfort of whole vehicle.The acceleration history and the transfer function of each measuring point can be got from simulation.The analysis results show that the maximum acceleration RMS value of the vehicle mass center is about 0.3g,which satisfies the requirements of attenuating vibration of precision equipment being transported on particular roads and speeds.So the research provides valuable reference for the optimum selection of the suspension system’s parameters.

Research on Ride Comfort Model of Wheel Motor Driving Vehicle Based on Matlab/Simulink

Simulink is a visual simulation tool in MATLAB;?through Simulink software,?to establish a model can reduce the amount of programming workload,?and?improve the efficiency of the establishment of automotive models.?The ride comfort of the vehicle is a measure of the most basic indicators of a car performance.?By establishing a ride comfort model in Matlab/Simulink, the wheel motor electric vehicle mainly affects the smoothness of the car mainly in the following aspects:?pavement, tire, suspension, motor and so on.?Through the establishment of the above model,?we?can effectively study the wheel motor drive electric vehicle ride comfort research.

Automotive Ride Comfort Control Using MR Fluid Damper

In this paper, the performance of automotive ride comfort using Bouc-Wen type magneto-rheological (MR) fluid damper is studied using a two degree of freedom quarter car model. The sliding mode control is used to force the MR damper to follow the dynamics of ideal sky-hock model. The model is tested on two excitations, the first is a road hump with severe peak amplitude and the second is a statistical random road. The results are generated and presented in time and frequency domains using Matlab/Simulink software. Comparison with the fully active, ideal semi-active and conventional passive suspension systems are given as a root mean square values. Simulation results, for the designed controller, show that with the controllable MR damper has a significant improvement for the vehicle road holding then its lateral stability as well as road damage in comparison with passive, fully active and ideal semi-active suspension systems.

Adaptive Thermal Comfort in Brazilian Schools by Building Performance Simulation (BPS)

Building performance simulation (BPS) is a crucial tool towards the design of projects better adapted its climatic context. In this sense, the objective of this research is to evaluate a method of thermal comfort analysis of schools in three Brazilian cities using BPS. The methodological procedures involved a literature review, in which the simulation tool and analysis method were chosen. Following simulations with the software DesignBuilder were performed using as study case a standard school typology designed by the General Coordination of Educational Infrastructure (CODIN/FNDE). This article evaluates its percentage occupied comfort hours in 3 reference cities: Cuiabá-MT, Brasília-DF, and Curitiba-PR. The results show respectively, for the cities of Curitiba, Brasília and Cuiabá, percentages of comfort hours of 76%, 70%, and 23%. The research states that the project must have different strategies for different climates. Finally, this article recommends this method should be applied to other cities and buildings.

Influences of the tank liquid lateral sloshing and mass time-varying on high clearance self-propelled sprayer ride comfort

To explore the influence of the lateral sloshing and the time-varying mass of the liquid in the tank on the ride comfort of the high-clearance sprayer,a spring-mass-damping equivalent mechanics that can describe the lateral sloshing of the liquid under different filling ratios was constructed based on the equivalent criterion.The Fluent was used to simulate the moment acting on the wall of the tank by the lateral sloshing of the liquid,and then the parameters of the equivalent mechanical model are obtained by fitting and solving.Comparative analysis of Fluent simulation and bench test on lateral sloshing of tank liquid under different filling ratios.The results show that the lateral sloshing trend of the tank liquid level obtained from the Fluent simulation and the bench test was consistent,which proved the accuracy of the Fluent fluid simulation process and the correctness of the required equivalent mechanical model parameters.Incorporating a liquid sloshing equivalent model,a four-degree-of-freedom vertical dynamic model of the sprayer half-car was established.Subsequently,the performance of the sprayer was systematically analyzed and compared under the excitation of a bump road and a random E-level road.This investigation took into account varying liquid filling ratios of 10%,50%,and 90%.The focus lay on evaluating the vertical acceleration of the sprayer body,dynamic deflection of the suspension,and dynamic load on the tires in response to these road conditions.This analysis is conducted independently of the liquid sloshing factor.The results show that the lateral sloshing of the liquid medicine significantly reduces the ride smoothness of the machine,and makes the vibration response of the machine produce a certain hysteresis effect.With the reduction of the quality of the liquid medicine in the spray tank,the vibration amplitude of the sprayer body gradually decreases,the hysteresis effect is also gradually weakened.The results presented in this study offer a theoretical foundation for the analysis of ride comfort and the optimization of chassis structure in high-clearance sprayers.

Optimal Design and Dynamic Simulation of Mountain Bike with Rear Suspension

This paper investigates the dynamic design methodology of mountain bikes with rear suspension. Firstly, a multi-rigid body dynamic model of rider and mountain bike coupled system is constructed. The rider model includes 19 skeletons, 18 joints and 118 main muscles. Secondly, to validate the feasibility of the model, an experiment test is designed to reflect the real cycling status. Finally, aiming at enhancing the performance of the rider vibration comfort, the scale parameters of rear suspension are optimized with computer simulation and uniform design. The mathematical model in the vibration performance and the design variables is constructed with regression analysis. The result shows that when the length of side link is 90 mm, the length of connected rod is 336.115 1 mm and the included angle between absorber and side link is 60°, the mountain bike has better vibration comfort. This study and relevant conclusions are of practical importance to the design of the mountain bike＇s rear suspension system.

Saving Strategy and Simulation Analysis of Green Log Walls in Severe Cold Area

Log house is a traditional type of vernacular dwelling in Chinese cold area. It contains distinct regional characteristics and architectural cultures. In recent years,log house has come into vogue softly with the development of wood techniques. However,log houses expend too much wood materials. There are also many negative aspects of this type of wood building which go against the criteria of energy conservation,and its high prime cost hinders the application as well. To solve these problems, the paper emphasizes using more environmental standardized techniques which save cost at the same time,and put forward technical strategy to improve the log walls. The optimization schemes are mainly divided into two categories: internal insulation and filled insulation. Each type of insulation is respectively derived two schemes through changing the thickness of main structure layers and insulation layer. Firstly,we use Weto software to calculate the timber volume of the four schemes,and it concludes that all the optimizations can save more timber than the prototype log wall with the section of 200 mm × 200 mm. Secondly,thermal comfort of each scheme is insulated in Design Builder.The results show that thermal insulation of filling type represents better than the other schemes. At last,we use thermal calculating formula to calculate thermal resistance of every scheme. Contrast to the energy efficiency standards of Heilongjiang Province, the data show that the four schemes meet the requirements of the specification.

Optimization Design of Open Spaces Based on Wind Tunnel and CFD Simulation： Case Study of a Street Canyon in Northern China

Airflow in open spaces can significantly affect spatial quality. Therefore, according to the type of building structures, the airflow also has different forms. Studies have been conducted on the relation between airflow and pedestrian comfort; however, only few of them have focused on comprehensive urban planning that considers different weather conditions and people＇s ability to adapt. This research focuses on the differences in wind conditions caused by different spatial forms in different seasons. On the basis of a field survey in both summer and winter in a public open space, evaluation standards developed from environmental meteorological data and public feedback were used to evaluate simulation results. Next, several assumptions about canyon orientation and building types were proposed. Wind tunnel and CFD （computational fluid dynamics） simulations were conducted to evaluate the assumptions. The results showed that the canyon orientation significantly affected overall wind conditions and different building structures affected airflow. This research also provides a method to evaluate urban areas that have complicated wind environments.

A Study of IVECO Automobile Suspension System by Simulation

For analyzing the ride comfort performance, a dynamical model of an IVECO vehicle was built in this paper. The simulation study of the IVECO vehicle suspension performance on random uneven road is carried out by means of the dynamical model. The effects of suspension system parameters on the vehicle ride comfort parameter, i. e. , the root mean square （ RMS） of the vibrating acceleration of the vehicle body, are analyzed. The optimal parameters and initial value of the suspension system can be determined by the model and the method of this paper.

Zero-Energy-Buildings in Different Climates： Design Strategies, Simulation and Prognosis METHOD for Energy Demand

The European Directive 2010/31 claims that by 2020 only （nearly-） ZEB （zero-energy-buildings） may be built. To reach this goal, it is pertinent for buildings to be energetically optimized first. The remaining energy demand must then be covered by on-site renewable energies （PV, geothermal, etc.）. With the area of use （energy demand） and the size of the building envelope/estate （renewable energy supply） in competition with each other, the maximum number of building stories will be most likely limited. For 15 different climatic locations worldwide, the energy demand of optimised office rooms has been simulated and compared with the possible renewable energy production on site. For every location, a good correlation has been found between the simulated energy demand and data like heating and cooling degree hours. Correspondent linear equations are given here. As another result, the maximum numbers of possible stories for ZEBS have been derived, being between 3 and 10 depending on the location.

Optimization of the Traditional Method for Creating a Weather Simulation file:The Pelotas.epw Case

The basic assumption of an energy-efficient project is the proper relation with the local climatic context.To analyse a building’s performance before its construction,it is necessary that the object to be designed is recreated in a virtual environment,to evaluate its thermal balance.In order to recreate this virtual environment,it is necessary to use computer programs,and that requires a file composed of a weather database organized hourly in a specific year and defined,in the case of this article,from a TRY(test reference year).The objective of this study is to prepare a weather file for the city of Pelotas,RS,Brazil.This research was structured in five stages.In the first stage,the TRY was determined.In the second stage,the necessary variables for the preparation of the weather file to be used in the programs EnergyPlus?and Design Builder?were created and treated.In the third stage,weather files were prepared in.epw and.try formats.In the fourth stage,the weather file generated was simulated and compared with two other weather files belonging to the same bioclimatic zone.In the fifth and last stage,a typical day was elaborated for the city of Pelotas.As a result,the importance of optimization of the EPW generation process based on algorithms was highlighted.It was also verified that although we have three nearby cities with similar characteristics,it is possible to have differences of simulation results when the appropriate weather file is not used.

Analysis and Simulation of a Crowbar Protection for DFIG Wind Application during Power Systems Disturbances

The performance of a 1.5 MVA wind-power Doubly Fed Induction Generator （DFIG） under network fault is studied using simulator developed in MATLAB-SIMULINK. This paper investigates a new control method able to improve the fault-ride through capability of DFIG. In such generators the appearance of severe voltage sags at the coupling point make highlight important over currents at the rotor/stator windings, making the use of crowbar protection device necessary and inevitable in order to protect the machine as well as the rotor side power converter. The simulator consists of the DFIG analytical model, power transformer model and the detailed frequency converter model including crowbar protection device. Simulation results are carried out to show the transient behavior of the DFIG when a sudden voltage dip is introduced with and without the crowbar implementation.