scholarly journals Optimisation of bitumen emulsion properties for ballast stabilisation

2017 ◽  
Vol 7 (080) ◽  
pp. 124 ◽  
Author(s):  
G. D’Angelo ◽  
D. Lo Presti ◽  
N. Thom
Keyword(s):  
Permanent Deformation ◽  
Field Performance ◽  
Field Conditions ◽  
Damping Properties ◽  
Material Consumption ◽  
Bitumen Emulsion ◽  
Ballasted Track ◽  
Stiffness And Damping ◽  
Specific Part ◽  
Ballast Resistance

Ballasted track, while providing economical and practical advantages, is associated with high costs and material consumption due to frequent maintenance. More sustainable alternatives to conventional ballasted trackbeds should therefore aim at extending its durability, particularly considering ongoing increases in traffic speed and loads. In this regard, the authors have investigated a solution consisting of bitumen stabilised ballast (BSB), designed to be used for new trackbeds as well as in reinforcing existing ones. This study presents the idea behind the technology and then focuses on a specific part of its development: the optimisation of bitumen emulsion properties and dosage in relation to ballast field conditions. Results showed that overall bitumen stabilisation improved ballast resistance to permanent deformation by enhancing stiffness and damping properties. Scenarios with higher dosage of bitumen emulsion, higher viscosity, quicker setting behaviour, and harder base bitumen seem to represent the most desirable conditions to achieve enhanced in-field performance.

Porous Wall Gas Lubricated Journal Bearings: Theoretical Investigation

1979 ◽  
Vol 101 (4) ◽  
pp. 458-465 ◽  
Author(s):  
E. P. Gargiulo
Keyword(s):  
Experimental Investigation ◽  
Dynamic Stiffness ◽  
Porous Wall ◽  
Companion Paper ◽  
Journal Bearings ◽  
Damping Properties ◽  
Governing Equations ◽  
Performance Curves ◽  
Unsteady Characteristics ◽  
Stiffness And Damping

A model has been developed to compute the dynamic stiffness and damping properties of externally pressurized, porous-wall, gas journal bearings which includes the effects of journal rotation and eccentricity. This paper presents the derivation of the governing equations and the perturbation analysis used to find the unsteady characteristics. Typical nondimensional performance curves are found and the influences of seven governing parameters are discussed. A companion paper describes an experimental investigation of porous journal bearings.

Dynamics of a Rotating Flexible Multi-Link With Viscoelastic Constraining Layers

1993 ◽  
Author(s):  
H. S. Tzou ◽  
G. C. Wan
Keyword(s):  
Vibration Control ◽  
High Precision ◽  
Structural Systems ◽  
Damping Properties ◽  
Passive Vibration Control ◽  
Viscoelastic Dampers ◽  
Viscoelastic Layers ◽  
Stiffness And Damping ◽  
Dynamics And Vibration

Abstract Due to an increased flexibility of modern mechanical and structural systems, effective vibration control becomes essential to their high-precision operations. In this paper, dynamics and vibration control of a rotating multi-link are studied. Passive vibration control of the link with distributed viscoelastic layers is studied. Effectiveness of the distributed viscoelastic dampers with various stiffness and damping properties is investigated.

Broadband Vibration Suppression Assessment of Negative Impedance Shunts

2008 ◽  
Author(s):  
Benjamin Beck ◽  
Kenneth A. Cunefare ◽  
Massimo Ruzzene
Keyword(s):  
Active Control ◽  
Vibration Suppression ◽  
Piezoelectric Materials ◽  
Input Power ◽  
Experimental Results ◽  
Spatial Average ◽  
Negative Capacitance ◽  
Damping Properties ◽  
Control Solution ◽  
Stiffness And Damping

Piezoelectric materials allow for the manipulation of stiffness and damping properties of host structures by the application of electrical shunting networks. The use of piezoelectric patches for broadband control of vibration using a negative impedance shunt has been shown to be an effective active control solution. The wave-tuning and minimization of reactive input power shunt selection methodologies require the use a negative capacitance. This paper shows that the two theories are comparative and obtain the same shunt parameters. The results of the theoretical shunt selection and simulation are compared to experimental results of tip vibration suppression, spatial average vibration, and reactive input power minimization.

Study on Nonlinear Damping Properties of Hydro-Pneumatic Suspension System for XP302-Pneumatic Tyred Roller

2014 ◽  
Vol 945-949 ◽  
pp. 987-991
Author(s):  
Bang Sheng Xing ◽  
Ning Ning Wang ◽  
Le Xu
Keyword(s):  
Dynamic Performance ◽  
Nonlinear Damping ◽  
Suspension System ◽  
Nonlinear Stiffness ◽  
Damping Properties ◽  
Vehicle Dynamic ◽  
Nonlinear Mathematical Model ◽  
Computer Simulation Program ◽  
Pneumatic Suspension ◽  
Stiffness And Damping

The nonlinear stiffness and damping properties of the hydro-pneumatic suspension system are introduced, and the nonlinear mathematical model of it is established. Using MATLAB 2009b to establish the computer simulation program and draw out the nonlinear stiffness curve and damping properties curve of the hydro-pneumatic suspension system. Then, researching the influences of related parameters' changes on the nonlinear stiffness and damping properties of the hydro-pneumatic suspension system. The simulation of vehicle dynamic performance research's foundation is provided.

Influence of number of cycles on strain

1978 ◽  
Vol 15 (4) ◽  
pp. 584-592 ◽  
Author(s):  
Vijay K. Khosla ◽  
Ram D. Singh
Keyword(s):  
Stress Level ◽  
Permanent Deformation ◽  
Field Performance ◽  
Complete Spectrum ◽  
Ottawa Sand ◽  
The Past ◽  
Stress Cycles ◽  
Number Of Cycles ◽  
Made In

In the past, tests conducted on sand to evaluate the field performance of machine foundations have utilized only a limited number of load cycles. Results of these tests were extrapolated to determine the permanent deformation experienced by the foundation materials over the life of the machines. An attempt has been made in this presentation to develop a complete spectrum of the variation of strain with stress level and number of loading cycles for anisotropically consolidated Ottawa sand. Up to 10 million stress cycles were applied. The axial strains show three distinct stages of strain with number of cycles.

Design and Analysis of a Magnetorheological Fluid Mount Featuring Uni-Directional Squeeze Mode

2015 ◽  
Author(s):  
Xian-Xu Bai ◽  
Peng Chen ◽  
Li-Jun Qian ◽  
Ping Kan
Keyword(s):  
Dynamic Stiffness ◽  
Magnetorheological Fluid ◽  
Relative Displacement ◽  
Bottom Surface ◽  
Damping Properties ◽  
Damping Force ◽  
Equivalent Damping ◽  
Engine Vibration ◽  
Coil Winding ◽  
Stiffness And Damping

A magnetorheological fluid (MRF) mount featuring unidirectional squeeze mode for vehicle engine mounting system is proposed and designed to attenuate the engine vibration with characteristics of broadband and small amplitude. The MRF mount is comprised of upper and lower bases for installation, a main rubber for static load, a bobbin for electromagnetic coil winding and a squeeze plate. The bottom surface of the bobbin and the top surface of the squeeze plate form the polar plates, between which the MRF is squeezed during the rebound of the MRF mount. Combining dynamic stiffness property of passive hydraulic mounts without fluid and adjustable damping force of MRF at squeeze mode, the MRF mount could provide a unique variable dynamic stiffness and damping properties, by adjusting the exciting current. To evaluate the performance of the MRF mount, a mathematical model considering the behavior of MRF at squeeze mode is derived to theoretically analyze and numerically simulate the dynamic stiffness and equivalent damping properties of the MRF mount. Further, the MRF mount based quarter vehicle mounting system model considering suspension system is constructed to analyze the force transmissibility of engine mounting system in frequency domain and simulate the relative displacement response in time domain.

Dynamic Properties of Tilting-Pad Journal Bearings: Experimental and Theoretical Investigation of Frequency Effects due to Pivot Flexibility

2006 ◽  
Vol 129 (3) ◽  
pp. 865-869 ◽  
Author(s):  
Waldemar Dmochowski
Keyword(s):  
High Speed ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Journal Bearings ◽  
Operating Conditions ◽  
Damping Properties ◽  
Frequency Effects ◽  
Tilting Pad ◽  
Stiffness And Damping ◽  
Tilting Pad Journal Bearings

Tilting-pad journal bearings (TPJBs) dominate as rotor supports in high-speed rotating machinery. The paper analyzes frequency effects on the TPJB’s stiffness and damping characteristics based on experimental and theoretical investigations. The experimental investigation has been carried out on a five pad tilting-pad journal bearing of 98mm in diameter. Time domain and multifrequency excitation has been used to evaluate the dynamic coefficients. The calculated results have been obtained from a three-dimensional computer model of TPJB, which accounts for thermal effects, turbulent oil flow, and elastic effects, including that of pad flexibility. The analyzes of the TPJB’s stiffness and damping properties showed that the frequency effects on the bearing dynamic properties depend on the operating conditions and bearing design. It has been concluded that the pad inertia and pivot flexibility are behind the variations of the stiffness and damping properties with frequency of excitation.

scholarly journals Field Performance of Backcross (BC1) Blueberry Hybrids of Vaccinium padifolium (Section Hemimyrtillus) with V. corymbosum/V. angustifolium

HortScience ◽  
2020 ◽  
Vol 55 (11) ◽  
pp. 1788-1793
Author(s):  
Mark K. Ehlenfeldt ◽  
Joseph Kawash ◽  
James Polashock
Keyword(s):  
Cluster Structure ◽  
Field Performance ◽  
Field Conditions ◽  
Plant Structure ◽  
Strong Growth

There is ongoing interest in transferring new characteristics into commercial blueberry from other blueberry species. Vaccinium padifolium is a species distantly related to commercial blueberry that has traits of notable value to conventional blueberry development. Among these traits are upright structure, strong growth, abundant flowering and fruiting, superior self-fertility, fruit-cluster structure suited to mechanical harvesting, and repeat/continuous flowering. Previously produced F1 hybrids of V. padifolium × V. corymbosum were used in crosses with a variety of conventional blueberry selections to generate 13 backcross (BC1) families. The backcross families were evaluated under field conditions to determine their performance and to guide further use of this germplasm. The offspring varied considerably, but most families produced several individuals of acceptable commercial quality. The recovery of V. padifolium characteristics varied. Many plants bore evidence of V. padifolium plant structure, but none showed indications thus far of continuous or repeat flowering. The best selections from these families have been saved and will be intermated to generate the next cycle of this material. These clones will also be crossed to hybrid combinations of V. arctostaphylos and V. cylindraceum to further diversify and recombine this germplasm.

Sign in / Sign up

Export Citation Format

Share Document