scholarly journals Analytical method for establishing indentation rolling resistance

2018 ◽  
Vol 29 ◽  
pp. 00001
Author(s):  
Lech Gładysiewicz ◽  
Martyna Konieczna
Keyword(s):  
Rolling Resistance ◽  
Experimental Tests ◽  
Travel Speed ◽  
High Energy ◽  
Operating Conditions ◽  
New Method ◽  
Long Distance ◽  
Indentation Rolling Resistance ◽  
Belt Conveyors ◽  
The Impact

Belt conveyors are highly reliable machines able to work in special operating conditions. Harsh environment, long distance of transporting and great mass of transported martials are cause of high energy usage. That is why research in the field of belt conveyor transportation nowadays focuses on reducing the power consumption without lowering their efficiency. In this paper, previous methods for testing rolling resistance are described, and new method designed by authors was presented. New method of testing rolling resistance is quite simple and inexpensive. Moreover it allows to conduct the experimental tests of the impact of different parameters on the value of indentation rolling resistance such as core design, cover thickness, ambient temperature, idler travel frequency, or load value as well. Finally results of tests of relationship between rolling resistance and idler travel frequency and between rolling resistance and idler travel speed was presented.

scholarly journals Experimental tests of the impact of selected parameters on the indentation rolling resistances

2018 ◽  
Vol 29 ◽  
pp. 00002 ◽  
Author(s):  
Dariusz Woźniak ◽  
Lech Gładysiewicz ◽  
Martyna Konieczna
Keyword(s):  
Main Part ◽  
Rolling Resistance ◽  
Experimental Tests ◽  
Conveyor Belt ◽  
Significant Component ◽  
Different Types ◽  
Indentation Rolling Resistance ◽  
Belt Conveyors ◽  
The Impact

Belt conveyors are main part of transporting systems in mines and in many other branches of industry. During conveyor belt works different types of resistances are generated. Indentation rolling resistance is the most significant component of the resistances from the perspective of energy losses and it cause the biggest costs as well. According to latest state of analyses and measurements it is well known that theoretical rolling resistance were underestimated in comparison with the measured in-situ one. In this paper new method for determination indentation rolling resistance is presented. The authors compared theoretically and experimentally established damping factors. The relation between these two values enabled to obtain more precise equation for damping function. This function is one of the most important component in calculation of the rolling resistance. In new theoretical model value of rolling resistance is nearly twice higher than this used so far.

Experimental Study of the Effect of Water Spray in the Air on Thermal Transfers Along a Plate of an Exchanger

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Nihel Grich ◽  
Walid Foudhil ◽  
Souad Harmand ◽  
Sadok Ben Jabrallah
Keyword(s):  
Salt Water ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Heated Plate ◽  
Environment Effect ◽  
Single Plate ◽  
Salt Layer ◽  
Turbulent Airflow ◽  
Heat Transfers ◽  
The Impact

Abstract This study is an experimental investigation of the oceanic environment effect on a plate heat exchanger performance. Indeed, an experiment was carried out on a single plate of the exchanger to generate a turbulent airflow in which fine water droplets were injected into a horizontal vein where a heated plate was placed. The experimental tests were conducted for different air velocities and various water concentrations of freshwater and saltwater. In fact, two plate forms were considered: The first one is flat while the second is corrugated. Three main facts were observed in this work: (i) the correlations linking the heat transfer rate to the operating conditions, (ii) the effect of fog addition and the plate form on convective heat transfers, and (iii) the impact of the formation of a salt layer on the surface of the plate in the case of salt water.

Investigating the Impact of Rainfall on Travel Speed

2014 ◽  
Vol 71 (3) ◽  
Author(s):  
Nordiana Mashros ◽  
Johnnie Ben-Edigbe ◽  
Hashim Mohammed Alhassan ◽  
Sitti Asmah Hassan
Keyword(s):  
Empirical Studies ◽  
Heavy Rain ◽  
Weather Conditions ◽  
Travel Speed ◽  
Operating Conditions ◽  
Speed Reduction ◽  
Light Rain ◽  
Rainfall Condition ◽  
Adverse Weather ◽  
The Impact

The road network is particularly susceptible to adverse weather with a range of impacts when different weather conditions are experienced. Adverse weather often leads to decreases in traffic speed and subsequently affects the service levels. The paper is aimed at investigating the impact of rainfall on travel speed and quantifying the extent to which travel speed reduction occurs. Empirical studies were conducted on principle road in Terengganu and Johor, respectively for three months. Traffic data were collected by way of automatic traffic counter and rainfall data from the nearest raingauge station were supplied by the Department of Irrigation and Drainage supplemented by local survey data. These data were filtered to obtain traffic flow information for both dry and wet operating conditions and then were analyzed to see the effect of rainfall on percentile speeds. The results indicated that travel speed at 15th, 50th and 85th percentiles decrease with increasing rainfall intensities. It was observed that allpercentile speeds decreased from a minimum of 1% during light rain to a maximum of 14% during heavy rain. Based on the hypothesis that travel speed differ significantly between dry and rainfall condition; the study found substantial changes in percentile speeds and concluded that rainfalls irrespective of their intensities have significant impact on the travel speed.

scholarly journals Ecophysiology of avian migration in the face of current global hazards

2012 ◽  
Vol 367 (1596) ◽  
pp. 1719-1732 ◽  
Author(s):  
Marcel Klaassen ◽  
Bethany J. Hoye ◽  
Bart A. Nolet ◽  
William A. Buttemer
Keyword(s):  
Global Change ◽  
Migratory Birds ◽  
High Energy ◽  
Change Processes ◽  
Negative Consequences ◽  
Long Distance ◽  
Physiological Limits ◽  
The Face ◽  
Abiotic And Biotic Factors ◽  
The Impact

Long-distance migratory birds are often considered extreme athletes, possessing a range of traits that approach the physiological limits of vertebrate design. In addition, their movements must be carefully timed to ensure that they obtain resources of sufficient quantity and quality to satisfy their high-energy needs. Migratory birds may therefore be particularly vulnerable to global change processes that are projected to alter the quality and quantity of resource availability. Because long-distance flight requires high and sustained aerobic capacity, even minor decreases in vitality can have large negative consequences for migrants. In the light of this, we assess how current global change processes may affect the ability of birds to meet the physiological demands of migration, and suggest areas where avian physiologists may help to identify potential hazards. Predicting the consequences of global change scenarios on migrant species requires (i) reconciliation of empirical and theoretical studies of avian flight physiology; (ii) an understanding of the effects of food quality, toxicants and disease on migrant performance; and (iii) mechanistic models that integrate abiotic and biotic factors to predict migratory behaviour. Critically, a multi-dimensional concept of vitality would greatly facilitate evaluation of the impact of various global change processes on the population dynamics of migratory birds.

scholarly journals The influence of belt cover thickness on conveyor belt indentation rolling resistance

2019 ◽  
Vol 2 (1) ◽  
pp. 242-248
Author(s):  
Dariusz Woźniak
Keyword(s):  
Energy Consumption ◽  
Rolling Resistance ◽  
Conveyor Belt ◽  
Small Scale ◽  
Scale Method ◽  
Number Of Factors ◽  
Indentation Rolling Resistance ◽  
Belt Conveyors ◽  
Bottom Cover ◽  
Cover Thickness

Abstract One of the methods for lowering of energy consumption in the drive mechanisms of long horizontal belt conveyors is to reduce belt indentation rolling resistances. These resistances depend on a number of factors: bottom cover properties, bottom cover thickness, belt design, idler diameter, load, speed and frequency at which the belt passes on the idler (indentation frequency), as well as on temperature. Determining how these factors influence indentation rolling resistances of various conveyor belt types is of great importance. The article describes a small-scale method for testing indentation rolling resistance. The method allows analysis of the influence of various factors on indentation rolling resistances. The article presents the results of tests on how belt indentation rolling resistance is influenced by thickness of the belt bottom cover. The tests were performed on belts with various core types.

scholarly journals Theoretical analysis of the impact of belt speed on indentation rolling resistance

2018 ◽  
Vol 71 ◽  
pp. 00004
Author(s):  
Lech Gładysiewicz ◽  
Martyna Konieczna
Keyword(s):  
High Reliability ◽  
Rolling Resistance ◽  
Theoretical Models ◽  
Phase Lag ◽  
Belt Conveyor ◽  
Unit Load ◽  
Belt Speed ◽  
Open Cast Mining ◽  
Belt Conveyors ◽  
The Impact

Belt conveyors, having high reliability and efficiency, are the main means of continuous transportation both in underground and in open-cast mining. Despite their numerous advantages, however, belt conveyors are expensive in maintenance. Therefore, improvements in the field of belt conveyor transportation largely focus on methods for lowering their power consumption. The energy consumption level of a belt conveyor depends on the motion resistances which occur during its operation. In the case of conveyors having lengths greater than 80 m, main resistances are the dominant component of motion resistances, and up to 60% of main resistances may be accounted for by the rolling resistances of the belt on idlers. Motion resistances, including rolling resistances, have long remained an object of research. Extensive laboratory tests and increasingly detailed theoretical models allow a better insight into the phenomena involved in the movement of the belt on the conveyor. Different research results place different weight on the influence of individual parameters (such as unit load or phase lag angle) on belt rolling resistance. The greatest inconsistencies, however, are observed in the analyses of belt speed impact, which is occasionally not even included in some models. This paper discusses the known and commonly used methods for determining the rolling resistances of the belt on idlers. It also proposes a new solution, which employs the analysis of strain variation in the belt for successive load cycles to determine whether belt speed has a direct influence on the value of rolling resistance.

Relationship between mechanical behavior and microstructure evolution of sintered metallic brake pad under impact of thermomechanical stress

2021 ◽  
pp. 1-18
Author(s):  
Hoang-Long Le Tran ◽  
Anne-Lise Cristol ◽  
Jérôme Hosdez ◽  
Vincent Magnier
Keyword(s):  
Temperature Gradient ◽  
Thermal Gradient ◽  
Experimental Approach ◽  
Compressive Load ◽  
Experimental Tests ◽  
High Energy ◽  
Brake Pad ◽  
Thermomechanical Stress ◽  
The Impact ◽  
Graphite Inclusions

Abstract It is well known that on the brake pad material, the triptych microstructure-properties-solicitations is the key to better understand the phenomena caused by braking stress. The challenging issues are the evolution of this triptych, i.e., the impact of thermal stress and mechanical stress on the microstructure which undoubtedly induces changes in properties. In order to solve the issues without tackling them in all their complexity, this study proposes an experimental approach where physics is decoupled but inspired by the braking sequence in terms of applied temperature gradient and braking loads. Two experimental tests were carried out. The first one is the thermal solicitation test where a temperature gradient from 400°C to 540°C was applied to the material. The second one is the thermomechanical test where a compressive load at 20 MPa was applied under the same thermal gradient. The experiment time is fixed for two minutes, equivalent to the time of one braking stroke. The referred material is sintered metallic composite, which is widely used as brake pad material for high-energy railways. As result, it shows that coupled thermomechanical stress has a greater impact on the material properties than decoupled one. This impact is related to the microstructure where graphite inclusions play an important role.

Investigation on influence of speed on rolling resistance of belt conveyor based on viscoelastic property of rubber

2017 ◽  
Vol 15 (2) ◽  
pp. 254-267
Author(s):  
Lu Yan ◽  
Lin Fu-Yan
Keyword(s):  
Operating Parameter ◽  
Rolling Resistance ◽  
Conveyor Belt ◽  
Winkler Foundation ◽  
Belt Conveyor ◽  
Content Type ◽  
Backing Material ◽  
Experimental Apparatus ◽  
Indentation Rolling Resistance ◽  
Belt Conveyors

Purpose As indentation rolling resistance accounts for the major part of the total resistance of belt conveyors, the purpose of this paper is to compute it using a proper method. Design/methodology/approach First, an approximate formula for computing indentation rolling resistance is offered. In this formula, a one-dimensional Winkler foundation and a three-parameter viscoelastic Maxwell solid model of the belt backing material are used to determine the resistance to the motion of a conveyor belt over idlers. The velocity of the belt is an important operating parameter in the working conditions of the belt conveyor. What is more, a set of experimental apparatus which can measure the value of indentation rolling resistance is designed. Findings With the help of the experimental apparatus, the authors obtained a series of measured data under different belt speeds. Finally, a computation example that is provided for a typical rubber compound backing material shows the comparison between measured results and theoretical results which offers the influence of speed on rolling resistance. Originality/value This study provides the design of an apparatus, and finds the relationship between belt speed and indentation rolling resistance.

Cavitation Performance of Constant and Variable Pitch Helical Inducers for Centrifugal Pumps: Effect of Inducer Tip Clearance

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Enver S. Karakas ◽  
Hiroyoshi Watanabe ◽  
Matteo Aureli ◽  
Cahit A. Evrensel
Keyword(s):  
Bubble Dynamics ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Tip Clearance ◽  
Centrifugal Pumps ◽  
Two Phase ◽  
Variable Pitch ◽  
Cavitation Performance ◽  
Constant Pitch ◽  
The Impact

Abstract In this paper, the effect of the inducer tip clearance is studied to understand its impact on the cavitating and noncavitating performance of centrifugal pumps. Helical inducers with constant pitch and with variable (progressive) pitch are considered. Computational fluid dynamics (CFD) simulations of a single stage pump are conducted on each inducer type to determine the cavitating (two-phase) and noncavitating (single-phase) performance for varying inducer tip clearance. The Rayleigh–Plesset cavitation model is used to understand the bubble dynamics under the assumptions of single fluid undergoing no thermal energy transfer between each phase. Experimental tests are conducted on a pump with the variable pitch inducer to determine the true performance in cavitating and noncavitating operating conditions. Experimental results are compared to the simulations to validate the accuracy of the proposed numerical modeling. Net positive suction head (NPSH) with 3% differential head drop is used as a criterion to identify the true cavitation performance of each inducer configuration. It is found that, as the inducer tip clearance increases, excessive back leakage and larger vortex recirculation occur at the tip location. This results in pressure loss within the inducer and, consequently, degrades the cavitation performance. In addition, the change in cavitation performance with the tip clearance is much more evident for variable pitch inducer geometries as compared to the constant pitch case. Furthermore, the impact on the noncavitating performance of inducer tip clearance is found to be minimal.

High-Energy Impact Certification of Aero Structures: Experiments and Numerical Simulations

2015 ◽  
Vol 237 ◽  
pp. 233-238
Author(s):  
Grzegorz Socha ◽  
Sebastian Szałkowski ◽  
Andrzej Zbrowski
Keyword(s):  
Numerical Simulations ◽  
Impact Resistance ◽  
Experimental Tests ◽  
High Energy ◽  
Sustainable Technologies ◽  
Impact Tests ◽  
Energy Impact ◽  
Particle Hydrodynamics ◽  
Real Objects ◽  
The Impact

The article presents the test results obtained from the “Research methods and systems for the investigation on impact resistance of elements of aero structures and land vehicles aimed at the assessment of passenger safety” R&D project that was jointly executed by the Institute of Aviation, the Institute for Sustainable Technologies – National Research Institute, and the PZL Mielec. The main objective of the project was to perform impact tests of the windscreen and the vertical stabilizer of the PZL M28 Skytruck. The experimental tests were conducted for real objects in full scale. The investigations were carried out using an original 250 mm pneumatic gun. Apart from the impact tests, the project was also focused on numerical simulations of impacts employing the Finite Element Method (test object modelling) and the Smoothed Particle Hydrodynamics methods (the model of the gelatine projectile). The authors compare the results of experimental tests and numerical simulations. They present the differences in the results obtained and analyse the reasons behind these discrepancies, and based on the analysis, they conclude that the main cause for them is the simplified mathematical model describing the behaviour of the material subjected to dynamic loads, which was used in numerical simulations.

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