A quest for error factors in predicting heavy weight floor impact sound levels using measured data in existing residential buildings

A number of datasets regarding the heavy weighted floor impact sound level and the driving point impedance level, i.e., twenty times the common logarithm of driving point impedance at an exciting point, were measured in existing residential buildings before the floor finishing of the excitation room and the ceiling finishing of the receiving room were installed. These data were compared to the calculated values by the impedance method, i.e., a practical method that estimates vibration energy of an excited slab using the driving point impedance at the exciting point as a major factor, as well as those using the Finite Element Method (FEM) models of slabs. Furthermore, correlations between the residual errors and the major dimensions of the receiving rooms were investigated. Two major error factors were found to influence the calculated values by the impedance method. The spectral characteristic of the tire impact source within the 63 Hz band effectively decreased the prediction errors when it was included in the calculation and combined with the FEM models of slabs. The length of the shorter side of the receiving room plan correlated to the residual errors of the receiving rooms having a pair of flat parallel walls. These errors arise from the fact that the receiving points were placed at the central and quarter positions within the wall distance, where the nodes of the horizontal mode exist. It was not possible to identify another dimension of the receiving room that significantly correlates to the residual errors of the prediction.     

Passive Stabilization Conditions for a Rectilinearly Moving Wheelset

Nonlinear stability conditions for a wheelset are established in analytical form for some design restrictions. They permits assessing the influence of the parameters of the curvilinear wheel tread on the nature of self-oscillations     

Soil vehicle relationship: The peripheral force

During the past decades the author has continually worked on and perfected his conception of the interaction between the soil and the wheel. First, this work is summarized in this paper. The author then describes his conception of the mechanical interaction between them and clarifies the connection between the kinematic and dynamic processes that take place when a tractor is exerting pull. He shows by means of his kinematic model how the peripheral force is developed. Finally, he derives the appropriate equations for the computation of the peripheral force and the drawbar pull for both two-wheel-drive and four-wheel-drive tractors. Practical experience has proven that the concept is correct and the method is practical.     

Structure-propery relationship of low molecular weight ‘liquid’ polymers in blends of sulfur cured SSBR-rich compounds

In recent years, many patents have been published that are claiming the use of low molecular weight ‘liquid’ polymers in tire tread applications. Herein, tire producers generally introduce improved balances of the tire performances such as wet grip, abrasion resistance and rolling resistance. To understand the influence of the low molecular weight ‘liquid’ polymers in detail, an investigation was carried out to create more clarity about the influence of the structure of these polymers on in-rubber properties and about their interaction with the base polymers and fillers. One basic formulation was selected: A silica filled compound with styrene butadiene copolymer (SSBR), polybutadiene (BR) and natural rubber (NR) that is representing a winter tire tread formulation. Different structures of the low molecular weight ‘liquid’ polymer were added to this compound and compared. Results are discussed for the curing torques and crosslink densities to evaluate the influence on the crosslinking. Payne effect and bound rubber content was measured to evaluate the filler-filler interactions and filler-polymer interactions, respectively. The mechanical properties and dynamic mechanical analysis results deliver finally indications for the expected tire performance.     

Identification of winter tires using vibration signals generated on the road surface

During the winter, traffic regulations state that automobile drivers must use winter tires on unsafe roads such as snowy expressways. The present report is concerned with the development of an automatic tire identification system that can discriminate winter tires from summer tires with high accuracy. The system detects the impact vibration signal that is specifically generated by winter tires when tread blocks with wide grooves strike the road surface during rolling. The signal is picked up by a commercially available vibration sensor. If the signal contains specified impact frequency components, the tire is judged to be a winter tire. Compared with the previous identification system, which used airborne tire/road noise, the proposed system has two advantages. First, it is unaffected by meteorological factors such as wind noise. Second, the proposed system performs well even when the target vehicle is traveling at low speed. We evaluate the performance of the system outdoors using a number of vehicles with various tires and demonstrate an overall improvement in identification accuracy for vehicles traveling at low or moderate speeds.     

Updated Standards of the International Society for Terrain-Vehicle Systems

The last version of the ISTVS standards was published in the Journal of Terramechanics in 1977. Since then, the document has not been updated, although new concepts, techniques, testing procedures, and technology have been developed in the last 40 years, which renders some content of the 1977 ISTVS standards outdated and in-complete. The ISTVS identified as a priority the need to develop a set of standards for terminology and testing for modern day research on off-road mobility. This paper, for which the work has been funded in part by ISTVS, is an updated version of the 1977 ISTVS standards and covers a range of aspects in off-road mobility for: vehicles, tires, tracks, soil, wheels, modelling approaches, test methods, and equipment.     

Finite element modeling of tire/terrain interaction: Application to predicting soil compaction and tire mobility

Tire/terrain interaction has been an important research topic in terramechanics. For off-road vehicle design, good tire mobility and little compaction on terrain are always strongly desired. These two issues were always investigated based on empirical approaches or testing methods. Finite element modeling of tire/terrain interaction seems a good approach, but the capability of the finite element has not well demonstrated. In this paper, the fundamental formulations on modeling soil compaction and tire mobility issues are further introduced. The Drucker-Prager/Cap model implemented in ABAQUS is used to model the soil compaction. A user subroutine for finite strain hyperelasticity model is developed to model nearly incompressible rubber material for tire. In order to predict transient spatial density, large deformation finite element formulation is used to capture the configuration change, which combines with soil elastoplastic model to calculate the transient spatial density due to tire compaction on terrain. Representative simulations are provided to demonstrate how the tire/terrain interaction model can be used to predict soil compaction and tire mobility in the field of terramechanics.     

钢轨踏面的空气耦合超声检测方法*

该文针对钢轨踏面浅表面裂纹提出非接触空气耦合超声类瑞利波的检测方法。首先利用半有限元法求解了CHN60型钢轨的振动模式,抽出了钢轨轨头踏面的振动模态结构和频散曲线,并搭建实验系统,根据Snell法则和声源在空气中的声场分布确定了检测参数,最后从理论和实验两方面着手对钢轨踏面浅表面裂纹的有无及裂纹大小进行了实验分析和数值计算,其结果非常吻合,证明了空气耦合超声导波检测方法的可行性和可靠性。     

Estimation of dry road braking distance considering frictional energy of patterned tires

This paper is concerned with the braking distance estimation of tire controlled by anti-lock brake system (ABS) according to a numerical–analytical method. While the frictional heat dissipation at disc pad is derived analytically, the tire frictional energy loss is computed by the 3D dynamic rolling analysis of patterned tire. Since the tire rolling analysis to obtain the time history of the frictional energy rate for the entire braking period is impractical, we alternatively seek the tire frictional energy rate curve versus the lapse of time by interpolating the discretized frictional energy rates computed at intervals of 10 km/h. The effect of ABS is numerically implemented by specifying the corresponding tire angular velocity to the dynamic rolling analysis. Applying the energy conservation law to each speed interval determines the interval-wise braking times and distances from which the total braking time and distance are predicted. Illustrative numerical experiment is presented together with the comparison with the experimental estimation.     

Comparison of Structure,Morphology, and Properties of Miktoarms Star Styrene-Butadiene Rubber and Star-Shaped Styrene-Butadiene Rubbe/Polybutadiene Rubber Blends

Four miktoarms star-shaped polybutadiene-Sn-poly(styrene-butadiene) rubber (MSS-PB-PSBR) with 1,1-diphenylhexyl at the ends of the arms were prepared by two different coupling techniques. One technique was a one-step technology, from which two miktoarms star styrene-butadiene rubbers, called AMSS-PB-PSBR, were obtained in which the four arm stars had varying ratios of PB:PSBR arms; another was a two-step technology, from which another two miktoarms star styrene-butadiene rubbers, called BMSS-PB-PSBR, were obtained in which all consisted of PB-Sn-(PSBR)₃ stars. The molecular structure parameters and morphology-properties of the four MSS-PB-PSBR were determined and studied, and compared with that of a star-shaped styrene-butadiene rubber (S-SSBR)/poly butadiene rubber (PBR) blend. The results showed that the total coupling efficiency (the ratio of the total number of polymer chains (arms) coupled by SnCl₄ to that of the total number of polymer chains) of the MSS-PB-PSBR was higher than 60%. However, the coupling efficiency of the polybutadiene arms of BMSS-PB-PSBR was obviously higher than that of the AMSS-PB-PSBR. Compared with the S-SSBR/PBR blend, MSS-PB-PSBR had a more uniform distribution of the PB phase and a smaller phase size of PB. It was found that MSS-PB-PSBR composites filled with carbon black (CB) had a lower Payne effect than the S-SSBR/PBR/CB composite, with the BMSS-PB-PSBR/CB composites being especially lower. The BMSS-PB-PSBR/CB composites had higher mechanical properties and lower rolling resistance than the AMSS-PB-PSBR/CB composites due to the high coupling efficiency of the polybutadiene arms; the results indicated that the two-step technology was better than the one-step technology for preparing the tread material of “green” tires.