A Comparison of Two Sub-structuring Techniques for Representing the Modal Properties of Tires

2001 ◽  
Vol 29 (1) ◽  
pp. 23-43 ◽  
Author(s):  
D. Tsihlas ◽  
T. Lacroix ◽  
B. Clayton
Keyword(s):  
Automobile Industry ◽  
Dynamic Models ◽  
Transfer Functions ◽  
Component Mode Synthesis ◽  
Numerical Techniques ◽  
The Past ◽  
Custom Made ◽  
Modal Behavior ◽  
Noise Vibration ◽  
Reduced Dynamic

Abstract Different numerical sub-structuring techniques for the representation of tire modal behavior have been developed in the past 20 years. By using these numerical techniques reduced dynamic models are obtained which can not only be used for internal studies but also be provided to the automobile industry and linked to reduced dynamic vehicle models in order to optimize the coupled vehicle-tire response for noise vibration and harshness purposes. Two techniques that have been developed in a custom-made finite element code are presented: 1) the component mode synthesis type models for which the wheel center interface is free and 2) the Craig and Bampton type models for which the wheel center interface is fixed. For both techniques the interface between the tire and the ground is fixed. The choice of fixed or free wheel center boundary condition is arbitrary. In this paper we will compare the formulation of these two numerical methods, and we will show the equivalency of both methods by showing the results obtained in terms of frequency and transfer functions. We will show that the two methods are equivalent in principle and the reduced dynamic models can be converted from one to the other. The advantages-disadvantages of each method will be discussed along with a comparison with experimentally obtained results.

Light-Weight Tire Concept

1996 ◽  
Vol 24 (2) ◽  
pp. 119-131
Author(s):  
F. Lux ◽  
H. Stumpf
Keyword(s):  
Fuel Consumption ◽  
Automobile Industry ◽  
Rolling Resistance ◽  
Performance Standards ◽  
Light Weight ◽  
Production Methods ◽  
Lower Fuel Consumption ◽  
Material Resources ◽  
The Past ◽  
Tire Production

Abstract Current demands by the consumer, the automobile industry, and the environment have determined the basis of this investigation. In the past, the requirements—ever faster, ever sportier—were accepted as decisive parameters for the development of our study. In the future, rational and safety-related tire characteristics as well as environmental consciousness will increase, whereas purely performance-related parameters will diminish in their importance. Through our light-weight tire project, we have paved the way for future tire generations. The first priority is the minimal use of material resources; this means a reduction of materials and energy in tire production by using advanced design and production methods without sacrificing performance standards. This benefits the consumer—the final judge of all of our activities—by considerably reducing the rolling resistance, leading to lower fuel consumption. Further design targets include the improvement of rolling behavior and increased comfort by reducing tire weight, and therefore a reduction in unsprung masses on the vehicle.

scholarly journals A Second-Order Time-Difference Position Constrained Reduced-Dynamic Technique for the Precise Orbit Determination of LEOs Using GPS

2021 ◽  
Vol 13 (15) ◽  
pp. 3033
Author(s):  
Hui Wei ◽  
Jiancheng Li ◽  
Xinyu Xu ◽  
Shoujian Zhang ◽  
Kaifa Kuang
Keyword(s):  
Orbit Determination ◽  
Dynamic Models ◽  
Precise Orbit Determination ◽  
Second Order ◽  
Time Difference ◽  
Error Sources ◽  
Precise Orbit ◽  
Unmodeled Dynamic ◽  
Reduced Dynamic

In this paper, we propose a new reduced-dynamic (RD) method by introducing the second-order time-difference position (STP) as additional pseudo-observations (named the RD_STP method) for the precise orbit determination (POD) of low Earth orbiters (LEOs) from GPS observations. Theoretical and numerical analyses show that the accuracies of integrating the STPs of LEOs at 30 s intervals are better than 0.01 m when the forces (<10−5 ms−2) acting on the LEOs are ignored. Therefore, only using the Earth’s gravity model is good enough for the proposed RD_STP method. All unmodeled dynamic models (e.g., luni-solar gravitation, tide forces) are treated as the error sources of the STP pseudo-observation. In addition, there are no pseudo-stochastic orbit parameters to be estimated in the RD_STP method. Finally, we use the RD_STP method to process 15 days of GPS data from the GOCE mission. The results show that the accuracy of the RD_STP solution is more accurate and smoother than the kinematic solution in nearly polar and equatorial regions, and consistent with the RD solution. The 3D RMS of the differences between the RD_STP and RD solutions is 1.93 cm for 1 s sampling. This indicates that the proposed method has a performance comparable to the RD method, and could be an alternative for the POD of LEOs.

Development of a reduced dynamic model for comfort evaluation of rail vehicle systems

2016 ◽  
Vol 230 (4) ◽  
pp. 489-504 ◽  
Author(s):  
Mortadha Graa ◽  
Mohamed Nejlaoui ◽  
Ajmi Houidi ◽  
Zouhaier Affi ◽  
Lotfi Romdhane
Keyword(s):  
Dynamic Model ◽  
Degrees Of Freedom ◽  
Dynamic Models ◽  
Railway Vehicle ◽  
Passenger Comfort ◽  
Rail Vehicle ◽  
Vehicle System ◽  
Comfort Evaluation ◽  
Complex Models ◽  
Reduced Dynamic

In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This model considers only 38 degrees of freedom of the rail vehicle system. This reduced model can predict the dynamic behaviour of the rail vehicle while being simpler than existing dynamic models. The developed model is validated using experimental results found in the bibliography and its results are compared with existing more complex models from the literature. The developed model is used for the passenger comfort evaluation, which is based on the value of the weighted root mean square acceleration according to the ISO 2631 standard. Several parameters of the system, i.e., passenger position, loading of the railway vehicle and its speed, and their effect on the passenger comfort are investigated. It was shown that the level of comfort is mostly affected by the speed of the railway vehicle and the position of the seat. The load, however, did not have a significant effect on the level of comfort of the passenger.

Opportunities and Responsibilities of the Franchised Automobile Dealer

1965 ◽  
Vol 29 (4) ◽  
pp. 29-36
Author(s):  
D. Maynard Phelps
Keyword(s):  
Automobile Industry ◽  
Successful Operation ◽  
The Past ◽  
To Come

This is a sophisticated discussion of the significant changes that have taken place in the automobile industry during the past few years, and the ones that are probably about to take place. If franchised dealers plan well with respect to the changes likely to come, they will have unusual opportunities for successful operation, as this article shows.

scholarly journals Review and Selection Strategy for High-Accuracy Modeling of PWM Converters in DCM

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Yu-Jun Mao ◽  
Chi-Seng Lam ◽  
Sai-Weng Sin ◽  
Man-Chung Wong ◽  
Rui Paulo Martins
Keyword(s):  
Closed Loop ◽  
Transfer Functions ◽  
High Accuracy ◽  
Operating Conditions ◽  
Selection Strategy ◽  
Small Signal ◽  
Pwm Converters ◽  
Modeling Methods ◽  
The Past ◽  
Conduction Mode

Among various modeling methods for DC-DC converters introduced in the past two decades, the state-space averaging (SSA) and the circuit averaging (CA) are the most general and popular exhibiting high accuracy. However, their deduction approaches are not entirely equivalent since they incorporate different averaging processes, thus yielding different small signal transfer functions even under identical operating conditions. Some research studies claimed that the improved SSA can obtain the highest accuracy among all the modeling methods, but this paper discovers and clearly verifies that this is not the case. In this paper, we first review and study these two modeling methods for various DC-DC converters operating in the discontinuous conduction mode (DCM). We also streamline the general model-deriving processes for DC-DC converters, and test and compare the accuracy of these two methods under various conditions. Finally, we provide a selection strategy for a high-accuracy modeling method for different DC-DC converters operating in DCM and verified by simulations, which revealed necessary and beneficial for designing a more accurate DCM closed-loop controller for DC-DC converters, thus achieving better stability and transient response.

Optimization of Heave Motions for a Four Column Semi-Submersible Based on Genetic Algorithm

2018 ◽  
Author(s):  
Suji Zhu
Keyword(s):  
Genetic Algorithm ◽  
Global Optimization ◽  
Computer Aided Design ◽  
Transfer Functions ◽  
Parametric Modelling ◽  
Optimal Solutions ◽  
Global Optimization Algorithm ◽  
The Past ◽  
Computer Aided ◽  
Aided Design

Semi-submersible is designed with low heave motions compared with conventional ships by utilizing the cancelation effects between pontoons and columns. During the past years, continuous efforts have been devoted to reducing the heave amplitudes considering utilizing dry-tree system. Different concepts of semi-submersible have been proposed with favorable heave response. Deep draft semi-submersibles have been proved to be efficient in reducing the heave motions, and the damper structures under the pontoon may also reduce the heave responses significantly. Those concepts are beyond the conventional semi-submersible design, which may bring high costs for fabrication and installations. During computer-aided design and analysis, optimization algorithms are used to search for the optimal hull configuration. However, due to the restrictions of computer capacities, the global optimization algorithm, in some cases, have difficulties in finding out the optimal solutions without the aid from engineering experience. In this paper, the geometry of a ring-pontoon four-column semi-submersible is generated by parametric modelling. The heave transfer functions at center of gravity are calculated using WADAM. Genetic algorithm is used to find the most favorable heave responses. In the end, the parameters that influence the heave motions are summarized and discussed.

Automotive vibration and noise control using smart materials: a state of art and challenges

2013 ◽  
Vol 10 (6) ◽  
pp. 535-542
Author(s):  
S. Kumbhar ◽  
Subhasis Maji ◽  
Bimlesh Kumar
Keyword(s):  
Automotive Industry ◽  
Smart Materials ◽  
Piezoelectric Materials ◽  
New Materials ◽  
Market Place ◽  
The Past ◽  
Noise Vibration ◽  
Damping Materials ◽  
Damping Treatments ◽  
State Of Art

In the past several years, there has been increased market place awareness of noise, vibration, and harshness performance in automobiles. The differentiation between the quality and reliability levels of automobiles has become less pronounced and, as a result, manufacturers have had to demonstrate superiority by focusing on NVH concerns. The automotive industry is currently spending millions of dollars on NVH work to develop new materials and damping techniques so that the damping treatments are lighter, cheaper, and more effective. Some of the methods used to control noise, vibration, and harshness includes the use of different carpeting treatments, the addition of rubber or asphalt material to car panels, gap sealant, and the injection of expandable foam into body panels. The aim of this study is to explore the feasibility of smart damping materials such as magnet orheological elastomers (MRE), piezoelectric materials, with its basic properties, for augmenting and improving the performance benefits of damping materials. This study also evaluates the noise and vibration benefits of smart damping materials as compared to conventional damping treatments.

A Statistical Analysis on Automobile Sales Performance in India

2020 ◽  
Vol 17 (2) ◽  
pp. 778-782
Author(s):  
Kayalvizhi Subramanian ◽  
Mahmod Othman ◽  
Rajalingam Sokkalingam ◽  
Gunasekar Thangarasu
Keyword(s):  
Statistical Analysis ◽  
Automobile Industry ◽  
Sales Performance ◽  
Sales Growth ◽  
Export Markets ◽  
Secondary Sources ◽  
The Past ◽  
The World ◽  
Automobile Sales ◽  
Performance Report

The automobile business is a main drivers of India’s economy and also one of the biggest markets in the world. The automobile business has developed more grounded in deals over all fragments have been record breaking number in the past in both domestic and export markets. The presence of many manufacturers and brands in the country provides many choices to the buyers. This study pursues to examine the sales of the Indian Automobile Industry through statistical methods. The data used in this analysis are from secondary sources. The period of the study spans from 2012–2018. The obtained result shows on positive sales growth in the past five years. The automobile sales performance report will be useful for the current and new participant vehicle fabricating organization in India.

Simplified transfer functions of the dynamic models of convective and radiant tubular heat exchangers

2007 ◽  
Vol 54 (10) ◽  
pp. 786-794
Author(s):  
N. D. Aleksandrova ◽  
N. I. Davydov ◽  
T. G. Tyupina
Keyword(s):  
Heat Exchangers ◽  
Dynamic Models ◽  
Transfer Functions
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