scholarly journals A Novel Approach to the Analysis of Under Sleeper Pads (USP) Applied in the Ballasted Track Structures

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2438 ◽  
Author(s):  
Artur Zbiciak ◽  
Cezary Kraśkiewicz ◽  
Anna Al Sabouni-Zawadzka ◽  
Jan Pełczyński ◽  
Sławomir Dudziak
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Mechanical Model ◽  
Rheological Model ◽  
Laboratory Tests ◽  
Vibration Isolation ◽  
Special Focus ◽  
Vibration Isolators ◽  
Novel Approach ◽  
Ballasted Track

The present paper is dedicated to the analysis of under sleeper pads (USP), which are resilient elements used in ballasted track systems as vibration isolators. Four types of USP are considered. The authors present the results of laboratory tests, which are then used as input values for the finite element (FE) and mechanical model of the structure. A special focus is put on the description of an original four-degree-of-freedom (4DoF) mechanical model of the system that includes a fractional rheological model of USP. Using the proposed approaches, the dynamic characteristics of under sleeper pads are determined, and conclusions on vibration isolation effectiveness are drawn.

scholarly journals Laboratory Tests and Analyses of the Level of Vibration Suppression of Prototype under Ballast Mats (UBM) in the Ballasted Track Systems

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 313
Author(s):  
Cezary Kraśkiewicz ◽  
Artur Zbiciak ◽  
Kacper Wasilewski ◽  
Anna Al Sabouni-Zawadzka
Keyword(s):  
Mechanical Model ◽  
Laboratory Tests ◽  
Vibration Suppression ◽  
Track Structure ◽  
European Standard ◽  
Static And Dynamic Characteristics ◽  
Vibration Isolators ◽  
Testing Procedures ◽  
Ballasted Track ◽  
German Standard

The present paper is aimed at the analysis of under ballast mats (UBM) which are used in ballasted track structures as vibration isolators and to protect the ballast layer against fast degradation. The mats were tested in the laboratory and afterwards a novel 4-DoF mechanical model of the track structure with UBM was developed. The novelty of this study consists in the comparison of two testing procedures: a procedure based on the popular German standard DIN 45673-5 and a new European standard EN 17282, released in October 2020. Major discrepancies were demonstrated in the determined values of the static and dynamic characteristics using both approaches—especially in reference to the mats with higher stiffness.

Influence of Fractional Damping and Time Delay on Maxwell-Voigt Model for Vibration Isolation

2016 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Time Delay ◽  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Model Parameters ◽  
Fractional Damping ◽  
Vibration Isolators ◽  
Multiple Parameters ◽  
Realistic Representation ◽  
Voigt Model ◽  
Isolation Systems

Models of vibration isolators are very commonly used for the design and analysis of isolation systems. Accurate isolator modeling is critical for a successful prediction of the dynamic characteristics of isolated systems. Isolators exhibit a complex behavior that depends on multiple parameters such as frequency, displacement amplitude, temperature and loading conditions. Therefore, it is important to choose a model that is accurate while adequately representing the relationships with relevant parameters. Recent literature has indicated some inherent advantages of fractional derivatives that can be exploited in the modeling of elastomeric isolators. Furthermore, time delay of damping is also seen to provide a realistic representation of damping. This paper examines the Maxwell-Voigt model with fractional damping and a time delay. This model is compared with the conventional Maxwell-Voigt model (without time delay or fractional damping) and the Voigt model in order to comprehend the influence of fractional damping and time delay on dynamic characteristics. Multiple simulations are performed after identifying model parameters from the data collected for a passive elastomeric isolator. The analysis results are compared and it is observed that the Voigt model is highly sensitive to fractional damping as well as time delay.

scholarly journals Study on Vertical Dynamic Characteristics of Composite Sleeper Ballasted Track in Tunnels

2019 ◽  
Vol 275 ◽  
pp. 02015
Author(s):  
Zhenhang ZHAO ◽  
Yuting SHEN ◽  
Xue YAN ◽  
Qiankun SU
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Response ◽  
Dynamic Characteristics ◽  
Vibration Damping ◽  
The Finite Element Method ◽  
Type Iii ◽  
Damping Characteristics ◽  
Rail Systems ◽  
Ballasted Track

In order to study the vertical dynamic characteristics of the composite sleeper ballasted track in tunnels, this paper establishes a dynamic model based on the finite element method, and compares the dynamic response of vehicle, wheel and rail systems, track systems and backfill layer with the type-III concrete sleeper. The research results show that the composite sleeper ballasted tracks’ acceleration of the car body and the wheel-rail force are smaller than that of the type-III sleeper. It can meet the safety of the train and passenger comfort. Because the composite sleeper has good elasticity, The rail displacement and acceleration, the sleeper displacement and acceleration of the composite sleeper are slightly larger than the type-III sleeper ballasted track, but the effect is not great. The composite sleeper has good elasticity and large damping, so that the acceleration of the track bed and the backfill layer is less than that of the type-III sleeper ballasted track. This shows that the composite sleeper has vibration damping characteristics for the track bed and the backfill layer.

Finite element-based parameter estimations for a characteristic simulation model of a hydraulically damped rubber mount for vehicle engines

2007 ◽  
Vol 221 (10) ◽  
pp. 1273-1286 ◽  
Author(s):  
L-R Wang ◽  
J-C Wang ◽  
Z-H Lu ◽  
I Hagiwara
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Cross Sectional Area ◽  
Response Analysis ◽  
Sectional Area ◽  
Cross Sectional ◽  
Upper Chamber ◽  
Elastic Characteristics ◽  
Hydraulically Damped Rubber Mount

The hydraulically damped rubber mount (HDM) is widely used for vibration isolation in automotive powertrains and other dynamic systems. In predictions of its dynamic characteristics, some key parameters or parametric characteristics in the lumped-parameter dynamic analysis model of an HDM, such as the volumetric elastic characteristics of fluid chambers and the equivalent piston cross-sectional area of the upper chamber, must be especially determined, because they are difficult to measure by experiment owing to fluid-structure interactions (FSIs). In this paper, a numerical simulation approach of volumetric elastic characteristics is developed on the basis of finite element analysis methods relating to rubber material hyperelasticity and hydrostatic FSI using ABAQUS software. Volumetric elastic characteristics of the upper fluid chamber, including the main rubber spring and/or uncoupling rubber membrane, and that of the lower fluid chamber are identified; volumetric stiffness and equivalent piston cross-sectional area are also calculated for further dynamic characteristic simulations of HDM. The contributions of different rubber parts to the volumetric elastic characteristics of the upper chamber are revealed. Predications of dynamic characteristics and frequency response analysis of a typical HDM with fixed decoupler verify the effectiveness of the proposed parameter identification method. The proposed simulation methods of volumetric elastic characteristics can be applied to other FSI systems.

Finite Element Analysis on Medium-Speed Mill-Foundation Coupled System

2012 ◽  
Vol 166-169 ◽  
pp. 510-513
Author(s):  
Man Zhi Yang ◽  
Zhi Feng Peng ◽  
Fang Liu ◽  
Yi Liang Peng ◽  
Xiao Ling Sun
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Vibration Isolation ◽  
Coupled System ◽  
Element Model ◽  
Element Analysis ◽  
Vibration Displacement ◽  
Horizontal Vibration ◽  
Vibration Isolators ◽  
Medium Speed

A medium speed mill-foundation coupled finite element model was established using ANSYS. The modal and harmonic responses of medium-speed mill were analyzed. The influence of the number of vibration isolators and the ratio of foundation bedplate to equipment on the vibration of mill was analyzed. The shock absorption measures of medium-speed mills were discussed. To get good vibration isolation effect, the maximum horizontal vibration displacement of medium-speed mill with spring vibration-isolated foundation is suggested as 50 μm, and the ratio of foundation bedplate to equipment as 3.0±0.2.

Investigations Into the Experimental and Numerical Simulation of a Shaping Machine

1996 ◽  
Author(s):  
Vijay Reddy ◽  
P. T. Rajeev ◽  
V. Ramamurti ◽  
R. Madhusudan
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Finite Element ◽  
Dynamic Characteristics ◽  
Mechanical Model ◽  
Material Removal ◽  
Machining Accuracy ◽  
Acceleration Response ◽  
Shell Elements ◽  
Optimal Machine

Abstract One of the main requirements for efficient and economical material removal is optimal machine tool design. The main objective of this paper is to investigate the dynamic characteristics of a shaping machine using finite element method. In the first part, experimentation and computation are combined to formulate and validate the mechanical model of the shaper. A parametric study is done in the second part. The main housing along with the ram of a typical shaper is analyzed during the process of shaping. This assembly is modeled using triangular shell elements. The eigenvalues and the eigenvectors are obtained. There is an acceptable degree of agreement between analytical results and the experimental observations. The cutting force is determined experimentally and using this the response of the shaping machine is determined. The dynamic acceleration response so obtained is compared with the experimentally obtained response. An exhaustive stress analysis is done. The system is sensitive to changes in certain parameters which are identified and analyzed, with optimization of the structural weight and machining accuracy being the criteria.

A Detailed Mechanical Model of a Double Pumper Fluid Mount

1998 ◽  
Vol 120 (2) ◽  
pp. 361-370 ◽  
Author(s):  
N. Vahdati
Keyword(s):  
Mechanical Model ◽  
Vibration Isolation ◽  
Detailed Model ◽  
Noise And Vibration ◽  
Vibration Isolators ◽  
The Past

Conventional passive elastomenc mounts have been used as noise and vibration isolators in the automotive and aircraft industries for many years. For even better noise and vibration isolation, passive fluid mounts have been replacing elastomeric mounts in both the automotive and aerospace industries during the past few years. With more increase in the popularity of fluid mounts, it is important to characterize the dynamics of the fluid mounts more accurately. Many papers have been published on the modeling of these devices, but mostly on single pumper fluid mounts. In this paper, we focus on double pumper fluid mounts. The intent of this paper is to develop a very detailed model of a double pumper fluid mount including all dampings.

Evolving the Banded Radial Tire

1987 ◽  
Vol 15 (1) ◽  
pp. 30-41 ◽  
Author(s):  
E. G. Markow
Keyword(s):  
Finite Element ◽  
Wear Rate ◽  
Finite Element Modeling ◽  
Laboratory Tests ◽  
Rolling Resistance ◽  
Two Dimensional ◽  
Theoretical Discussion ◽  
Radial Tire ◽  
Puncture Resistance ◽  
Element Modeling

Abstract Development of the banded radial tire is discussed. A major contribution of this tire design is a reliable run-flat capability over distances exceeding 160 km (100 mi). Experimental tire designs and materials are considered; a brief theoretical discussion of the mechanics of operation is given based on initial two-dimensional studies and later on more complete finite element modeling. Results of laboratory tests for cornering, rolling resistance, and braking are presented. Low rolling resistance, good cornering and braking properties, and low tread wear rate along with good puncture resistance are among the advantages of the banded radial tire designs.

scholarly journals A Novel Particle-Based Approach for Modeling a Wet Vertical Stirred Media Mill

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 55
Author(s):  
Simon Larsson ◽  
Juan Manuel Rodríguez Prieto ◽  
Hannu Heiskari ◽  
Pär Jonsén
Keyword(s):  
Finite Element Method ◽  
Reynolds Number ◽  
Finite Element ◽  
Grinding Fluid ◽  
Novel Approach ◽  
Grinding Media ◽  
Interparticle Contacts ◽  
Mineral Slurry ◽  
Stirred Media Mill ◽  
Element Method

Modeling of wet stirred media mill processes is challenging since it requires the simultaneous modeling of the complex multiphysics in the interactions between grinding media, the moving internal agitator elements, and the grinding fluid. In the present study, a multiphysics model of an HIG5 pilot vertical stirred media mill with a nominal power of 7.5 kW is developed. The model is based on a particle-based coupled solver approach, where the grinding fluid is modeled with the particle finite element method (PFEM), the grinding media are modeled with the discrete element method (DEM), and the mill structure is modeled with the finite element method (FEM). The interactions between the different constituents are treated by loose (or weak) two-way couplings between the PFEM, DEM, and FEM models. Both water and a mineral slurry are used as grinding fluids, and they are modeled as Newtonian and non-Newtonian fluids, respectively. In the present work, a novel approach for transferring forces between grinding fluid and grinding media based on the Reynolds number is implemented. This force transfer is realized by specifying the drag coefficient as a function of the Reynolds number. The stirred media mill model is used to predict the mill power consumption, dynamics of both grinding fluid and grinding media, interparticle contacts of the grinding media, and the wear development on the mill structure. The numerical results obtained within the present study show good agreement with experimental measurements.

scholarly journals Finite Element Analysis for Nonlinear Unbonded Circular Fiber-Reinforced Elastomeric Bearings

2021 ◽  
Vol 5 (7) ◽  
pp. 170
Author(s):  
Pablo Castillo Ruano ◽  
Alfred Strauss
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Carbon Fiber ◽  
Seismic Isolation ◽  
Nonlinear Viscoelasticity ◽  
Fiber Reinforcement ◽  
Special Focus ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Elastomeric Bearings

In recent years, interest in low-cost seismic isolation systems has increased. The replacement of the steel reinforcement in conventional elastomeric bearings for a carbon fiber reinforcement is a possible solution and has garnered increasing attention. To investigate the response of fiber-reinforced elastomeric bearings (FREBs) under seismic loads, it is fundamental to understand its mechanical behavior under combined vertical and horizontal loads. An experimental investigation of the components presents complexities due to the high loads and displacements tested. The use of a finite element analysis can save time and resources by avoiding partially expensive experimental campaigns and by extending the number of geometries and topologies to be analyzed. In this work, a numerical model for carbon fiber-reinforced bearings is implemented, calibrated, and validated and a set of virtual experiments is designed to investigate the behavior of the bearings under combined compressive and lateral loading. Special focus is paid to detailed modeling of the constituent materials. The elastomeric matrix is modeled using a phenomenological rheological model based on the hyperelastic formulation developed by Yeoh and nonlinear viscoelasticity. The model aims to account for the hysteretic nonlinear hyper-viscoelastic behavior using a rheological formulation that takes into consideration hyperelasticity and nonlinear viscoelasticity and is calibrated using a series of experiments, including uniaxial tension tests, planar tests, and relaxation tests. Special interest is paid to capturing the energy dissipated in the unbonded fiber-reinforced elastomeric bearing in an accurate manner. The agreement between the numerical results and the experimental data is assessed, and the influence of parameters such as shape factor, aspect ratio, vertical pressure, and fiber reinforcement orientation on stress distribution in the bearings as well as in the mechanical properties is discussed.

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