scholarly journals AGING, FATIGUE AND DURABILITY OF RUBBER VIBRATION ISOLATION ELEMENTS

2017 ◽  
Vol 3 ◽  
pp. 269
Author(s):  
Svetlana Polukoshko ◽  
Andris Martinovs ◽  
Svetlana Sokolova
Keyword(s):  
Vibration Isolation ◽  
Dynamic Properties ◽  
High Stress ◽  
Machine Building ◽  
Thin Layers ◽  
Shock Absorbers ◽  
Elastomeric Materials ◽  
High Fatigue ◽  
Long Time ◽  
Compensating Devices

This paper deal with shock and vibration insulators, which usually are performed from the elastomeric (rubber-like) materials. Elastomeric materials give many engineering advantages due to their capability of absorbing input energy much better than engineering materials, high elasticity, good dynamic properties, low volume compressibility, a linear relationship between stress and strain up to strain of 15% ÷ 20%, resistance to aggressive environmental factors. Elastomeric materials are widely used in machine building, shipbuilding, civil engineering, aviation and aerospace as compensation devices, vibration dampers, shock absorbers. Laminated elastomers, consisting of interleaved thin layers of elastomer and rigid reinforcing layers are also successfully used as bearing, joints, dampers, compensating devices, shock-absorbers. Such structures have many advantages: ability to endure high stress (>200 MPa), ease of maintenance, non- necessity for lubrication, vibration and noise reduction, ability to work in a very dirty, dusty, abrasive environment. The disadvantage of elastomeric material are aging, i.e. changing its properties over time. In this paper the influence of aging of elastomeric materials on the damping properties of shock absorbers is considered based on the mechanical models of elastomers - Maxwell and Burgers modes. Fatigue endurance, i.e. the ability to withstand mechanical actions for a long time is studied based on experiments on dynamic shear with laminated rubber-metal structures. The experiments show that such structures have a very high fatigue life - up to 100 million cycles.

scholarly journals Flow Simulation Using Local Grid Refinements to Model Laminated Reservoirs

2018 ◽  
Vol 73 ◽  
pp. 5 ◽  
Author(s):  
Manuel Gomes Correia ◽  
Célio Maschio ◽  
Denis José Schiozer
Keyword(s):  
Simulation Model ◽  
Dynamic Properties ◽  
Flow Behavior ◽  
Flow Simulation ◽  
Coarse Grid ◽  
Thin Layers ◽  
Static Properties ◽  
Dynamic Representation ◽  
Medium Flow ◽  
Local Grid

Super-giant carbonate fields, such as Ghawar, in Saudi Arabia, and Lula, at the Brazilian pre-salt, show highly heterogeneous behavior that is linked to high permeability intervals in thin layers. This article applies Local Grid Refinements (LGR) integrated with upscaling procedures to improve the representation of highly laminated reservoirs in flow simulation by preserving the static properties and dynamic trends from geological model. This work was developed in five main steps: (1) define a conventional coarse grid, (2) define LGR in the conventional coarse grid according to super-k and well locations, (3) apply an upscaling procedure for all scenarios, (4) define LGR directly in the simulation model, without integrate geological trends in LGR and (5) compare the dynamic response for all cases. To check results and compare upscaling matches, was used the benchmark model UNISIM-II-R, a refined model based on a combination of Brazilian Pre-salt and Ghawar field information. The main results show that the upscaling of geological models for coarse grid with LGR in highly permeable thin layers provides a close dynamic representation of geological characterization compared to conventional coarse grid and LGR only near-wells. Pseudo-relative permeability curves should be considered for (a) conventional coarse grid or (b) LGR scenarios under dual-medium flow simulations as the upscaling of discrete fracture networks and dual-medium flow models presents several limitations. The conventional approach of LGR directly in simulation model, presents worse results than LGR integrated with upscaling procedures as the extrapolation of dynamic properties to the coarse block mismatch the dynamic behavior from geological characterization. This work suggests further improvements for results for upscaling procedures that mask the flow behavior in highly laminated reservoirs.

scholarly journals From a smokehouse to a vacuum dehydrator

2004 ◽  
Vol 49 (1) ◽  
pp. 131-139
Author(s):  
Branislav Zlatkovic ◽  
Todor Vulic
Keyword(s):  
Product Quality ◽  
Food Industry ◽  
Liquid Fuel ◽  
Machine Building ◽  
High Quality ◽  
Great Honor ◽  
Fruit Processing ◽  
Long Time ◽  
Vacuum Condensation ◽  
Vacuum Dehydration

The tradition of fruit dehydration in Serbia has been long and anviable. It seems that Serbian machine-building in the area of fruit processing technology has given its greatest contribution in this field. It has been one 100 years since the smoking house of Mr Stokovic, PhD was announced to be the best and the most promising plum dehydrator at the open competition organized in Topcider by the Ministry of Agriculture. It was the first real almost continual fruit dehydrator where plums were moved at certain intervals closer and closer to the source of heat. Such a concept of plum dehydration from lower to higher temperatures was held on even later in perhaps our most famous dehydrator CER. Even the smoky smell was retained but liquid fuel was used for technical purposes. For a long time, it has been a well- known fact that vacuum dehydration has many advantages. In our country there have been many attempts to make fruit dehydrator of greater capacities in which vacuum would be used. Of course, there have been many problems, both technical and technological, but today a hundred years after accepting Stojkovic?s smokehouse, it is our great honor to present to you the results of plum dehydration in a home-made vacuum condensation dehydrator. We hope that now path is widely open to high quality dehydration, and not only for that plum, but for fruit susceptible to oxidation which is the reason our food industry has not produced it so far. This is probably a farewell to the most dangerous, but for the product quality, the most necessary operation - sulphuration.

Dynamic Experimental Analysis of a Steel Bridge

2014 ◽  
Vol 1020 ◽  
pp. 215-220 ◽  
Author(s):  
Roman Fojtík ◽  
Tomáš Novotný ◽  
Iveta Skotnicova ◽  
Martin Stolárik ◽  
Naďa Zdražilová ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Dynamic Properties ◽  
Traffic Noise ◽  
Practical Experience ◽  
Terrorist Attacks ◽  
Steel Bridge ◽  
Bridge Structure ◽  
Long Time ◽  
Wind Storms ◽  
The Moment

The paper deals with both the theoretical aspects and the practical experience with temporary steel bridge dynamic analysis. Since the moment people built the first bridge it became necessary to replace it in case of natural disasters like wind storms, floods, earthquakes, tsunami or wars and terrorist attacks. As a construction of a stable bridge lasts for a long time, the solution is a temporary bridge - a steel bridge structure designed especially for fast and repeated assembly and disassembly. The paper presents experimental analysis of steel bridge dynamic properties. The experimentally measured results are compared to theoretically calculated ones. Besides frequency analysis of supporting structure, the noise of the bridge during car passes is also measured and analyzed as nowadays traffic noise becomes a more and more important aspect, especially in case of temporary bridges. The bridge measurements are repeated for a clear bridge and for a bridge with anti-vibration mats attached to compare the arrangement results in decrease of traffic noise and the dynamic load of the bridge.

Dynamics and Traffic for Transfecting Exogenous MicroRNA as Studied by Live-Cell Microscopy

2021 ◽  
Vol 17 (8) ◽  
pp. 1647-1653
Author(s):  
Ke Yang ◽  
Yuanyuan Wang ◽  
Bo Sun ◽  
Tian Tian ◽  
Zhu Dai ◽  
...  
Keyword(s):  
Dynamic Properties ◽  
Mean Square Displacement ◽  
Small Region ◽  
Single Particle Tracking ◽  
Live Cell ◽  
Calculation Results ◽  
Long Time ◽  
Live Cell Microscopy ◽  
Cell Microscopy

MicroRNA (miRNA) has emerged as an important gene-regulator that shows great potential in gene therapy because of its unique roles in gene-regulation. However, the knowledge on their function and transportation in vivo is still lacking, and there are limited obvious evidences to define intracellular transportation of miRNA. In this study, the dynamics of exogenous miR-21 transfected into HeLa cells was traced by live-cell microscopy. Their transportation at key time points was recorded and dynamic properties were analyzed by single particle tracking (SPT) and mean square displacement (MSD) calculation. Results showed that the exogenous miRNAs bounded to cells quickly and went through lysosome into cytosol, where they were subsequently recruited into p-body. They finally were degraded, otherwise went back to cytosol in some way. Long time observation and analysis of motion mode showed that the miRNAs were confined in a small region and their motion modes were flexible in different intracellular microenvironment after entering the cells.

Evaluation on Stress Relaxation Properties of Geomembrane

2010 ◽  
Vol 168-170 ◽  
pp. 1572-1576
Author(s):  
Si Fa Xu ◽  
Yong Zhang ◽  
Zhe Wang
Keyword(s):  
Stress Relaxation ◽  
Tensile Force ◽  
High Stress ◽  
Elastic Model ◽  
Design Strength ◽  
Elapsed Time ◽  
Side Slope ◽  
Design Life ◽  
Liner System ◽  
Long Time

Geomembrane installed on the bottom and the side slope of a waste landfill as liner system is made of high density polyethylene or thermo plastic elastmer polyplopylene. Stress in the geotextile is caused by friction between the waste and the geotextile which is a result of the compression of the disposed waste, and the tensile force is transferred into the liner system by friction. With elapsed time, the stress relaxation will occur under certain strain conditions. If the stress of geomembrane is at high stress for a long period of time, the long time design strength of the geomembrane may be controlled by the creep at the end of the design life. So it is very important for design to determine the stress induced in the geomembrane. In this paper, the authors present a formula based three element visco-elastic model to evaluate the relation between the stress and elapsed time. Then the authors present some results of modeled tests conducted, it is shown that the relation between the material characteristic and temperature by indoor experiment.

scholarly journals The Longitudinal Superdiffusive Motion of Block Copolymer in a Tight Nanopore

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2931
Author(s):  
Waldemar Nowicki
Keyword(s):  
Dynamic Properties ◽  
Polymer Chains ◽  
Coarse Grained ◽  
Free Energy Barrier ◽  
Ballistic Motion ◽  
The Monte Carlo Method ◽  
Long Time ◽  
The Mean ◽  
Confined Environment ◽  
Unidirectional Motion

The structure and dynamic properties of polymer chains in a confined environment were studied by means of the Monte Carlo method. The studied chains were represented by coarse-grained models and embedded into a simple 3D cubic lattice. The chains stood for two-block linear copolymers of different energy of bead–bead interactions. Their behavior was studied in a nanotube formed by four impenetrable surfaces. The long-time unidirectional motion of the chain in the tight nanopore was found to be correlated with the orientation of both parts of the copolymer along the length of the nanopore. A possible mechanism of the anomalous diffusion was proposed on the basis of thermodynamics of the system, more precisely on the free energy barrier of the swapping of positions of both parts of the chain and the impulse of temporary forces induced by variation of the chain conformation. The mean bead and the mass center autocorrelation functions were examined. While the former function behaves classically, the latter indicates the period of time of superdiffusive motion similar to the ballistic motion with the autocorrelation function scaling with the exponent t5/3. A distribution of periods of time of chain diffusion between swapping events was found and discussed. The influence of the nanotube width and the chain length on the polymer diffusivity was studied.

Effect of Carbon Black on Dynamic Properties of Rubber Vulcanizates

1978 ◽  
Vol 51 (3) ◽  
pp. 437-523 ◽  
Author(s):  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Vibration Isolation ◽  
Power Transmission ◽  
Dynamic Properties ◽  
Engineering Application ◽  
Mullins Effect ◽  
Rubber Compounds ◽  
Background Material ◽  
Power Transmission Belts ◽  
Transient Forces

Abstract The term dynamic properties as applied to elastomers refers to the response to periodic or transient forces which do not cause failure or appreciable fatigue (permanent change of properties) during the investigation. Generally this is limited to vulcanizates subjected to deformations not exceeding about 25%; and generally the dynamic properties are measured after several cycles or (in a transient experiment such as resilience) after several preconditioning transients, so that the Mullins effect or difference between first and second strain cycles is not of consequence. Thus, dynamic properties represent the viscoelastic properties of vulcanizates at deformations below about 25%, after reaching a pseudo-equilibrium state. The dynamic properties of rubber are altered tremendously by the addition of a filler. The scope of this article is restricted to the dynamic properties of rubber vulcanizates with carbon black as a filler. The effect covered in this article are important in designing rubber compounds to be used under dynamic conditions, such as tires, power transmission belts, vibration isolation mountings, etc. However, the engineering application of dynamic properties, which has been treated in detail elsewhere, is outside the scope of this review. A certain amount of background material is needed. We will first define the terms used in describing dynamic properties. The methods and instruments used for measuring these properties will be described briefly, and the nature of carbon black will be reviewed. Finally, some historical material is given, together with the dynamic behavior of typical compounds, as a preface to the review of more recent work in this field.

scholarly journals Vibration Isolation: Use and Characterization

1980 ◽  
Vol 53 (5) ◽  
pp. 1041-1087 ◽  
Author(s):  
J. C. Snowdon
Keyword(s):  
Vibration Isolation ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Second Order ◽  
Two Stage ◽  
General Terms ◽  
Pole Parameter ◽  
Wave Effects ◽  
Compressive Loads ◽  
Rubberlike Materials

Abstract This article is concerned with vibration isolation, with antivibration mountings (resilient isolators), and with the static and dynamic properties of rubberlike materials that are suited for use in antivibration mountings. The design of practical antivibration mounts incorporating rubber or coiled-steel springs is described in Refs. 1–27; pneumatic isolators (air mounts, etc.) are described in Refs. 5, 28–35. Throughout the literature, as here, attention is focussed predominantly on the translational (vertical) effectiveness of antivibration mountings. However, the two- and three-dimensional vibration of one- or two-stage mounting systems is addressed in Refs. 4, 10, 12, 36–56. Following a description of the static and dynamic properties of rubberlike materials, the performance of the simple or one-stage mounting system is analyzed, account being taken of the occurrence of second-order resonances in the isolator and in the mounted item. In the latter case, as likely in practice, the bulk of the mounted item is assumed to remain masslike, whereas the feet of the item are assumed to be nonrigid (multiresonant). Discussion is then given to the two-stage or compound mounting system, which affords superior vibration isolation at high frequencies. Subsequently, the powerful four-pole parameter technique is employed to analyze, in general terms, the performance of an antivibration mounting with second-order resonances (wave effects) when both the foundation that supports the mounting system and the machine are nonrigid. The universally adopted method of measuring mount transmissibility is then described, followed by an explanation of how transmissibility can also be determined by four-pole parameter techniques based on an apparatus used by Schloss. The four-pole measurement approach has not been exploited hitherto, but it is apparently feasible and valuable because it enables mounts to be tested under compressive loads equal to those routinely encountered in service.

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