Energy exchanges during indentation tests in fresh-water ice

1991 ◽  
Vol 15 ◽  
pp. 247-253
Author(s):  
Devinder S. Sodhi
Keyword(s):  
Experimental Data ◽  
Heat Dissipation ◽  
Graphical Form ◽  
Small Scale ◽  
Water Ice ◽  
Structure Interaction ◽  
First Law Of Thermodynamics ◽  
Indentation Tests ◽  
Energy Exchanges ◽  
Work Done

The data from a small-scale experimental study on ice-structure interaction are used to compute the energy exchanges that take place during creep deformation and intermittent and continuous crushing of ice. The energy supplied by the carriage is partly stored in the structural spring, partly converted to kinetic energy, partly dissipated in deforming and extruding the ice and partly dissipated as heat in the damping mechanisms of the structure. Except for the heat dissipation, all other forms of energy were computed from the experimental data, and the heat dissipation was computed from the energy balance using the first law of thermodynamics. Plots of all forms of energy are shown in graphical form, in which their relative magnitudes, times of occurrence and interplay can be seen. The main result of this study is the thesis that intermittent crushing or ice-induced vibration takes place whenever there is an imbalance between the rates of work done by the carriage and the indentor and that there are no vibrations when these rates of work are equal.

scholarly journals Energy exchanges during indentation tests in fresh-water ice

1991 ◽  
Vol 15 ◽  
pp. 247-253 ◽  
Author(s):  
Devinder S. Sodhi
Keyword(s):  
Experimental Data ◽  
Heat Dissipation ◽  
Graphical Form ◽  
Small Scale ◽  
Water Ice ◽  
Structure Interaction ◽  
First Law Of Thermodynamics ◽  
Indentation Tests ◽  
Energy Exchanges ◽  
Work Done

The data from a small-scale experimental study on ice-structure interaction are used to compute the energy exchanges that take place during creep deformation and intermittent and continuous crushing of ice. The energy supplied by the carriage is partly stored in the structural spring, partly converted to kinetic energy, partly dissipated in deforming and extruding the ice and partly dissipated as heat in the damping mechanisms of the structure. Except for the heat dissipation, all other forms of energy were computed from the experimental data, and the heat dissipation was computed from the energy balance using the first law of thermodynamics. Plots of all forms of energy are shown in graphical form, in which their relative magnitudes, times of occurrence and interplay can be seen. The main result of this study is the thesis that intermittent crushing or ice-induced vibration takes place whenever there is an imbalance between the rates of work done by the carriage and the indentor and that there are no vibrations when these rates of work are equal.

Elastic and Plastic Mechanical Properties Determined by Nanoindentation and Numerical Simulation at Mesoscale

2006 ◽  
Vol 326-328 ◽  
pp. 203-206 ◽  
Author(s):  
Feng Yuan Chen ◽  
Rwei Ching Chang
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Numerical Simulation ◽  
Small Scale ◽  
Finite Element Code ◽  
Scale Analysis ◽  
Plastic Properties ◽  
Nanoindentation Testing ◽  
Indentation Tests ◽  
Simulation And Experiment

This work presents a comparison of numerical simulation and experiment of nanoindentation testing. A commercial finite element code ANSYS is adopted in the numerical simulation, in which elastic-plastic properties are considered. A PMMA specimen and a three side pyramidal Berkovich probe tip is used in the indentation tests. While the elastic-linear workhardening properties are adopted, the numerical results agree well with the experimental data for different indentation loads. It proves the numerical simulation can be used in the small scale analysis.

scholarly journals Dynamics of the Ice-Crushing Process

1988 ◽  
Vol 34 (118) ◽  
pp. 318-326 ◽  
Author(s):  
Ian J. Jordaan ◽  
Garry W. Timco
Keyword(s):  
Ice Sheet ◽  
Load Cycle ◽  
Stored Energy ◽  
Indentation Process ◽  
Ice Particles ◽  
Mode Of Failure ◽  
Indentation Tests ◽  
Energy Exchanges ◽  
The Mean ◽  
Crushed Ice

Abstract During fast indentation tests on ice sheets at constant rates, crushing is commonly observed at appropriate combinations of speed and aspect ratio. An analysis is made of this mode of failure, using as a basis a recently conducted test on an ice sheet under controlled conditions. The variation of load with time is given special attention, and cyclic variation of load is associated with periodic crushing (pulverization) events, followed by clearing of the crushed ice particles. An analysis of the clearing process is summarized in the paper, treating the crushed ice as a viscous material. A detailed analysis of the energy exchanges during the indentation process is given. Elastic variations of stored energy in the indenter and in the ice sheet are calculated; these are relatively minor. The dissipation of energy during a typical load cycle (3 mm movement during 0.05 s) is about 8 J. The energy required to create surfaces of the crushed ice particles is small (0.006 J), as is the work of crushing based on mechanical testing (0.09 J). It is concluded that the process of viscous extrusion of crushed ice is the main seat of energy dissipation, basically as a frictional process. A relationship for the mean thickness of the crushed ice layer is developed, based on energy-balance considerations.

Performance prediction of transonic axial multistage compressor based on one-dimensional meanline method

2021 ◽  
pp. 095765092199881
Author(s):  
Yingying Zhang ◽  
Shijie Zhang
Keyword(s):  
Experimental Data ◽  
Mass Flow ◽  
Flow Separation ◽  
Performance Prediction ◽  
Factor Model ◽  
Separation Method ◽  
Prediction Program ◽  
Blockage Factor ◽  
Reliability And Robustness ◽  
Work Done

This study proposes a 1D meanline program for the modeling of modern transonic axial multistage compressors. In this method, an improved blockage factor model is proposed. Work-done factor that varies with the compressor performance conditions is added in this program, and at the same time a notional blockage factor is kept. The coefficient of deviation angle model is tuned according to experimental data. In addition, two surge methods that originated from different sources are chosen to add in and compare with the new method called mass flow separation method. The salient issues presented here deal first with the construction of the compressor program. Three well-documented National Aerodynamics and Space Administration (NASA) axial transonic compressors are calculated, and the speedlines and aerodynamic parameters are compared with the experimental data to verify the reliability and robustness of the proposed method. Results show that consistent agreement can be obtained with such a performance prediction program. It was also apparent that the two common methods of surge prediction, which rely upon either stage or overall characteristic gradients, gave less agreement than the method called mass flow separation method.

An Investigation of the Aerodynamic and Vibration Behavior of a Helicopter Rotor Blade

2020 ◽  
Author(s):  
Mohammad Khairul Habib Pulok ◽  
Uttam K. Chakravarty
Keyword(s):  
Rotor Blade ◽  
Fluid Structure Interaction ◽  
Interaction Model ◽  
Scale Model ◽  
Helicopter Rotor ◽  
Small Scale ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Aerodynamic Analysis ◽  
Helicopter Rotor Blade

Abstract Rotary-wing aircrafts are the best-suited option in many cases for its vertical take-off and landing capacity, especially in any congested area, where a fixed-wing aircraft cannot perform. Rotor aerodynamic loading is the major reason behind helicopter vibration, therefore, determining the aerodynamic loadings are important. Coupling among aerodynamics and structural dynamics is involved in rotor blade design where the unsteady aerodynamic analysis is also imperative. In this study, a Bo 105 helicopter rotor blade is considered for computational aerodynamic analysis. A fluid-structure interaction model of the rotor blade with surrounding air is considered where the finite element model of the blade is coupled with the computational fluid dynamics model of the surrounding air. Aerodynamic coefficients, velocity profiles, and pressure profiles are analyzed from the fluid-structure interaction model. The resonance frequencies and mode shapes are also obtained by the computational method. A small-scale model of the rotor blade is manufactured, and experimental analysis of similar contemplation is conducted for the validation of the numerical results. Wind tunnel and vibration testing arrangements are used for the experimental validation of the aerodynamic and vibration characteristics by the small-scale rotor blade. The computational results show that the aerodynamic properties of the rotor blade vary with the change of angle of attack and natural frequency changes with mode number.

Further analysis of the size effect in indentation hardness tests of some metals

1995 ◽  
Vol 10 (11) ◽  
pp. 2908-2915 ◽  
Author(s):  
M. Atkinson
Keyword(s):  
Size Effect ◽  
Strain Hardening ◽  
Indentation Size Effect ◽  
Plastic Hinge ◽  
Small Scale ◽  
Indentation Hardness ◽  
Vickers Indentation ◽  
Indentation Size ◽  
Hardness Tests ◽  
Indentation Tests

The variation of apparent hardness observed in previously reported Vickers indentation tests of metals is reexamined. Common deseriptions of the effect are shown to be inaccurate: the variation of apparent hardness is monotonic but not simple. The effect is consistent with varying size of a previously postulated “plastic hinge” at the perimeter of the indent. This complexity confers uncertainty on the estimation of characteristic macrohardness from small scale tests. Association of the indentation size effect with friction and with strain hardening is confirmed.

Benchmark of a Novel Aero-Elastic Simulation Code for Small Scale VAWT Analysis

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
David Marten ◽  
Matthew Lennie ◽  
George Pechlivanoglou ◽  
Christian Oliver Paschereit ◽  
Alessandro Bianchini ◽  
...  
Keyword(s):  
Experimental Data ◽  
Wind Turbine ◽  
Open Source ◽  
Structural Model ◽  
Element Model ◽  
Small Scale ◽  
Elastic Model ◽  
Element Analysis ◽  
Simulation Code ◽  
Highly Nonlinear

After almost 20 years of absence from research agendas, interest in the vertical axis wind turbine (VAWT) technology is presently increasing again, after the research stalled in the mid 90's in favor of horizontal axis wind turbines (HAWTs). However, due to the lack of research in past years, there are a significantly lower number of design and certification tools available, many of which are underdeveloped if compared to the corresponding tools for HAWTs. To partially fulfill this gap, a structural finite element analysis (FEA) model, based on the Open Source multiphysics library PROJECT::CHRONO, was recently integrated with the lifting line free vortex wake (LLFVW) method inside the Open Source wind turbine simulation code QBlade and validated against numerical and experimental data of the SANDIA 34 m rotor. In this work, some details about the newly implemented nonlinear structural model and its coupling to the aerodynamic solver are first given. Then, in a continuous effort to assess its accuracy, the code capabilities were here tested on a small-scale, fast-spinning (up to 450 rpm) VAWT. The study turbine is a helix shaped, 1 kW Darrieus turbine, for which other numerical analyses were available from a previous study, including the results coming from both a one-dimensional beam element model and a more sophisticated shell element model. The resulting data represented an excellent basis for comparison and validation of the new aero-elastic coupling in QBlade. Based on the structural and aerodynamic data of the study turbine, an aero-elastic model was then constructed. A purely aerodynamic comparison to experimental data and a blade element momentum (BEM) simulation represented the benchmark for QBlade aerodynamic performance. Then, a purely structural analysis was carried out and compared to the numerical results from the former. After the code validation, an aero-elastically coupled simulation of a rotor self-start has been performed to demonstrate the capabilities of the newly developed model to predict the highly nonlinear transient aerodynamic and structural rotor response.

scholarly journals Organoleptic, Sensory and Biochemical Traits of Arabica Coffee and their Arabusta Hybrids

2021 ◽  
Author(s):  
Kahiu Ngugi ◽  
Jane Jerono Cheserek ◽  
Chrispine Ogutu Omondi
Keyword(s):  
Experimental Data ◽  
Genetic Diversity ◽  
Genetic Variation ◽  
Coffea Arabica ◽  
Small Scale ◽  
Arabica Coffee ◽  
Biochemical Compounds ◽  
Small Scale Farmers ◽  
Organoleptic Traits ◽  
Cup Quality

Coffee as a cash crop, reduces food insecurity by providing regular incomes and is a major foreign exchange earner in more than fifty tropical countries where it is grown either as Arabica (Coffea arabica) or Robust (Coffea canepora). In Kenya which grow some Robusta but mostly Arabica coffee, the production has been declining, mainly because world coffee prices have plummeted to about 5 USD for a 650Kg of un-hulled beans per acre. The only way world prices are likely to increase and benefit the small-scale farmers, is by improving the cup quality and enabling these countries to sell their coffee in specialty markets. This review, underscores the importance of analyzing and estimating organoleptic, sensory and biochemical compounds diversity in Arabica coffee, since these are the factors that determine cup quality. In an attempt to do so, the chapter presents experimental data that analyzed various sensory and organoleptic traits of Arabica coffee and their Arabusta hybrids that proves that tremendous genetic diversity exists in coffee genotypes grown in Kenya and it is possible to utilize this genetic variation to improve cup quality.

scholarly journals ICE PROPULSION ABILITY OF VESSELS WITH NONTRADITIONAL FORM

2020 ◽  
pp. 143-156
Author(s):  
Vasily A. Lobanov
Keyword(s):  
Experimental Data ◽  
Statistical Analysis ◽  
Empirical Equation ◽  
Main Attention ◽  
Resistance Level ◽  
Water Ice ◽  
Ship Hulls ◽  
The Impact ◽  
Ice Resistance ◽  
Different Thickness

In article the fact related to the significant increase in structure of the ice category fleet internal and mixed a river sea operation with non-traditional ship hulls forms is stated. With the CAE technologies use such vessels interaction nature with ice cakes and small ice cakes of different thickness and concentration in the ice channel is studied and analyzed. The main attention is paid to a research concerning the influence of different forms bulbous fore ends on change of the vessel ice resistance level. Qualitative features of such bulbous vessels contact with the water ice environment are noted. The statistical analysis concerning the obtained experimental data on the impact assessment related to constructive, dynamic and ice factors on ice propulsion ability of vessels with non-traditional forms is carried out. The quantitative forecast of such influence in the form of the multifactorial regression empirical equation is given.

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