Tire Longitudinal Mechanics Properties under Various Braking Conditions

2014 ◽  
Vol 654 ◽  
pp. 82-86
Author(s):  
Hai Dong Wu ◽  
Kong Hui Guo
Keyword(s):  
Dynamic Properties ◽  
Tire Model ◽  
In Series ◽  
Mass Spring

A dynamical tire model under uneven road is reviewed and the model is adapted to carry out simulation of various braking conditions. The damped characters of the tire at low rotated speed are improved through the study on the system of mass-spring-damper in series. A simple and effective brake model is designed and several extreme braking conditions are simulated. The results of simulation show obvious dynamic properties of the tire at various braking excitation.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

Modeling of Mass-Spring-Damper System by Complex Stiffness Method

2014 ◽  
Vol 983 ◽  
pp. 420-423
Author(s):  
Sheng Guo Zhang ◽  
Xiao Ping Dang
Keyword(s):  
Transfer Functions ◽  
Mechanical Systems ◽  
Stiffness Method ◽  
In Series ◽  
Equivalent Complex ◽  
Mass Spring

This paper aims at directly modeling the transfer functions of mass-spring-damper systems. Using complex stiffness of mass, spring, and damper elements and equivalent complex stiffness of these elements in series and/or in parallel, the transfer functions of the mass-spring-damper systems are modeled quickly. This is very convenient to the modeling of the complicated mechanical systems.

scholarly journals Characterization and Modelling of Various Sized Mountain Bike Tires and the Effects of Tire Tread Knobs and Inflation Pressure

2020 ◽  
Vol 10 (9) ◽  
pp. 3156 ◽  
Author(s):  
Andrew Dressel ◽  
James Sadauckas
Keyword(s):  
Simple Model ◽  
Lateral Stiffness ◽  
Tire Model ◽  
Laboratory Measurements ◽  
Inflation Pressure ◽  
Mountain Bike ◽  
Basic Model ◽  
Radial Stiffness ◽  
In Series ◽  
Distinguishing Features

Mountain bikes continue to be the largest segment of U.S. bicycle sales, totaling some USD 577.5 million in 2017 alone. One of the distinguishing features of the mountain bike is relatively wide tires with thick, knobby treads. Although some work has been done on characterizing street and commuter bicycle tires, little or no data have been published on off-road bicycle tires. This work presents laboratory measurements of inflated tire profiles, tire contact patch footprints, and force and moment data, as well as static lateral and radial stiffness for various modern mountain bike tire sizes including plus size and fat bike tires. Pacejka’s Motorcycle Magic Formula tire model was applied and used to compare results. A basic model of tire lateral stiffness incorporating individual tread knobs as springs in parallel with the overall tread and the inflated carcass as springs in series was derived. Finally, the influence of inflation pressure was also examined. Results demonstrated appreciable differences in tire performance between 29 × 2.3”, 27.5 × 2.8”, 29 × 3”, and 26 × 4” knobby tires. The proposed simple model to combine tread knob and carcass stiffness offered a good approximation, whereas inflation pressure had a strong effect on mountain bike tire behavior.

Effect of Carbon-Black Loading and Crosslink Density on the Heat Build-Up in Elastomers

1991 ◽  
Vol 64 (2) ◽  
pp. 269-284 ◽  
Author(s):  
Eberhard Meinecke
Keyword(s):  
Carbon Black ◽  
Energy Loss ◽  
Heat Generation ◽  
Amplification Factor ◽  
Position Control ◽  
Dynamic Properties ◽  
Filler Loading ◽  
Load Control ◽  
Local Overheating ◽  
In Series

Abstract It has been shown that it is possible to predict the viscoelastic response of elastomers and elastomeric engineering components under both load- and position-control conditions if one assumes: a) that the modulus of the materials increases with the strain amplification factor as given by the Guth and Gold equation, b) that the occluded rubber is taken into account when using this equation, and c) that the energy loss per cycle and unit volume of material is increasing with the square of the strain-amplification factor. These calculations were applied to an assembly where one unfilled section is in series with a filled one. The overall filler loading was kept constant, and it was found that the equations derived show completely different heat-generation rates for load- and position-control conditions. While the losses are the same in both sections and equal to that of the assembly as a whole under position-control conditions, they are quite different under load-control conditions. They increase with both filler loading and values of α and abnormally high local overheating in the unfilled section occurs. These considerations indicate that a uniform mixing quality is important for compounds which will be used in dynamically deformed engineering components. Under position-control conditions, poor filler dispersion will give rise to a decrease in the dynamic modulus and the energy loss per cycle, i.e., variations in the quality of the mix will cause variability of the dynamic properties. Under load-control conditions, the situation is even worse, since the energy dissipation increases with poor mixing, and local overheating of the sections containing less than the average amount of carbon black takes place. The model is obviously too oversimplified for qualitative predictions. But it still gives good qualitative indications regarding the heat-generation rate in structures made from two elastomers having different filler loadings or for imperfectly mixed compounds.

Dynamic Behavior of Slab Induced by Pedestrian Traffic

2019 ◽  
Vol 19 (12) ◽  
pp. 1950154
Author(s):  
Yan-An Gao ◽  
Qing-Shan Yang ◽  
Yun Dong ◽  
Chao Chen ◽  
Tao-Ping Ye
Keyword(s):  
Dynamic Behavior ◽  
Body Mass ◽  
Dynamic Properties ◽  
Damping Capacity ◽  
Model Parameters ◽  
Leg Stiffness ◽  
Structural Responses ◽  
Pedestrian Traffic ◽  
Mass Spring ◽  
Pseudo Excitation

This study comprehensively explores the dynamic behavior of a slender slab due to the excitation of pedestrian traffic. Three kinds of excitation models are adopted to describe the vibration of the slab induced by pedestrians. A comparison of the structural responses shows that the bipedal model results in larger vibrations than the mass–spring–damper or pseudo-excitation models. Further research indicates that the pedestrians evidently alter the dynamic properties of the slab by affecting its frequency and damping capacity. The slab tends to be more flexible at a lower frequency as the pedestrian walks across its surface while its damping capacity is improved. In contrast, the slab can increase the frequency, while decreasing the damping of the pedestrian model. Thus, the slab also alters the properties of the pedestrians. In addition, an investigation of the bipedal model parameters indicates that the variations of the leg stiffness, damping, and body mass have distinct effects on the slab characteristics and vibrations. In order to assess the response of the slab to a crowd, a new simplified theory is introduced to describe the dynamic properties of the slab under multi-layout excitations, including human influences resulting from different body properties. The results of this study provide potential ways for understanding the vibratory mechanisms of slender structures such as footbridges, grandstands, or stations under crowd excitations.

The Dynamics of Continuous Control Systems with Delay Elements as Part of Correction Filters

Vestnik MEI ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 76-85
Author(s):  
Mikhail A. Babochkin ◽  
◽  
Oleg S. Kolosov ◽  
Anna A. Kuznetsova ◽  
◽  
...  
Keyword(s):  
Control Systems ◽  
Dynamic Properties ◽  
Tracking System ◽  
Continuous Systems ◽  
Continuous Control ◽  
Simple Method ◽  
Low Pass ◽  
In Series ◽  
Local Feedback ◽  
Delay Elements

Matters concerned with the application of correction devices containing delay elements are addressed. Such filters are proposed as an alternative to the high-pass filters and low-pass first-order filters that are widely used in control systems. It is shown that by using filters containing delay elements, the power of high-frequency interference in the controller output signal can be reduced by up to 30% in comparison with the conventional filters. It should be noted that these results are obtained in using the proposed filters in closed-loop continuous systems. Two filter configuration versions used in control applications were analyzed. In the first version, the filters are connected in series in the control loop (as applied to astatic systems with a proportional-differentiating controller in both linear and relay modes of operation). In the second version, a correction filter connected in the local feedback is used (taking a generalized representation of the instrument-assisted position tracking system as an example). The article proposes a fairly simple method for determining the parameters of filters with a delay element that make it possible to use conventional techniques for synthesizing controllers in the frequency domain and estimating their dynamic properties.

scholarly journals A methodology for identifying optimum vibration absorbers with a reaction mass

2019 ◽  
Vol 475 (2228) ◽  
pp. 20190232 ◽  
Author(s):  
Sara Ying Zhang ◽  
Yi-Yuan Li ◽  
Jason Zheng Jiang ◽  
Simon A. Neild ◽  
John H. G. Macdonald
Keyword(s):  
Vibration Suppression ◽  
Dynamic Properties ◽  
Reaction Mass ◽  
Vibration Absorbers ◽  
Tuned Mass Dampers ◽  
Wide Range ◽  
Mass Damper ◽  
In Series ◽  
Significant Performance ◽  
Full Class

Tuned mass dampers (TMDs), in which a reaction mass is attached to a structural system via a spring–parallel–damper connection, are commonly used in a wide range of applications to suppress deleterious vibrations. Recently, a mass-included absorber layout with an inerter element, termed the tuned mass damper inerter (TMDI), was introduced, showing significant performance benefits on vibration suppression. However, there are countless mass-included absorber layouts with springs, dampers and inerters, which could potentially provide more preferred dynamic properties. Currently, because there is no systematic methodology for accessing them, only an extremely limited number of mass-included absorber layouts have been investigated. This paper proposes an approach to identify optimum vibration absorbers with a reaction mass. Using this approach, a full class of absorber layouts with a reaction mass and a pre-determined number of inerters, dampers and springs connected in series and parallel, can be systematically investigated using generic Immittance-Function-Networks. The advan- tages of the proposed approach are demonstrated via a 3 d.f. structure example.

Modeling the Stiffness Characteristics of the Human Body while Running with Various Stride Lengths

2000 ◽  
Vol 16 (1) ◽  
pp. 36-51 ◽  
Author(s):  
Timothy R. Derrick ◽  
Graham E. Caldwell ◽  
Joseph Hamill
Keyword(s):  
Ground Reaction Force ◽  
Stride Length ◽  
Reaction Force ◽  
Model Parameters ◽  
Force Curve ◽  
Active Portion ◽  
In Series ◽  
Stiffness Characteristics ◽  
Mass Spring ◽  
The Impact

A modified mass-spring-damper model was used to simulate the vertical ground reaction forces of a human runner as stride length was altered. Spring stiffness values were selected by an optimizing routine that altered model parameters to match the model ground reaction force curve to a runner’s actual ground reaction force curve. A mass in series with a spring was used to simulate the behavior of body structures that produce the active portion of the ground reaction force. A second mass in series with a spring-damper system was used to simulate the behavior of those components that cause the impact portion of the ground reaction force. The stiffness of the active spring showed a 51% decrease as subjects increased their stride length. The stiffness value of the impact spring showed a trend opposite that of the active spring, increasing by 20% as strides lengthened. It appears that the impact stiffness plays a role in preventing the support leg from collapsing in response to the increased contact velocities seen in the longer strides.

Simulation Model of Tire Vibration

1983 ◽  
Vol 11 (1) ◽  
pp. 38-49 ◽  
Author(s):  
M. Takayama ◽  
K. Yamagishi
Keyword(s):  
Simulation Model ◽  
Degrees Of Freedom ◽  
Experimental Results ◽  
Tire Model ◽  
Rigid Ring ◽  
Axial Forces ◽  
Mass Spring

Abstract A mass-spring tire model having five degrees of freedom is used to analyze the tangential and radial axial forces that result from a tire hitting a cleat. The belt and tread region is modeled by a rigid ring. Deflections from the cleat are absorbed by a line spring and those from the smooth portion of the test wheel (the ground) are absorbed by a plane spring; both are attached to the rigid ring. Calculated results agreed well with experimental results.

Contractile properties of hindlimb muscles in rat during surgical overload

1982 ◽  
Vol 242 (5) ◽  
pp. C259-C264 ◽  
Author(s):  
P. L. Freeman ◽  
A. R. Luff
Keyword(s):  
Dynamic Properties ◽  
Compensatory Hypertrophy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Control Value ◽  
In Series ◽  
Isometric Twitch ◽  
Pentobarbital Sodium Anesthesia ◽  
Tetanic Tension

Structural and dynamic properties of the extensor digitorum longus (EDL) and soleus muscles of the rat under pentobarbital sodium anesthesia have been determined 4, 28, and 400 days after extirpation of the tibialis anterior and compared with the properties of muscles from the contralateral limb of the same animal. At 4 days the mass of the EDL increased by about 17%, but the maximum tetanic tension and tension per unit cross-sectional area decreased. The soleus showed a slight decrease in mass of about 6%. At 28 days the mass of the EDL had increased to 126% of the control value. Maximum isometric twitch and tetanic tensions increased, whereas tetanic tension per unit cross-sectional area returned to normal values; the number of sarcomeres in series increased, which led to an increase in the whole muscle speed of shortening. It is concluded that the synergistic EDL undergoes compensatory hypertrophy by the addition of contractile material in series and in parallel but without any change in the intrinsic properties of the muscle. The fibers of the antagonistic soleus shorten slightly but are otherwise unchanged.

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