Testing and Modelling of an Advanced Motorcycle Shock Absorber

2010 ◽  
Author(s):  
Vittore Cossalter ◽  
Alberto Doria ◽  
Roberto Pegoraro ◽  
Luca Trombetta
Keyword(s):  
Hysteresis Loop ◽  
Shock Absorber ◽  
Oil And Gas ◽  
Hysteresis Loops ◽  
Experimental Results ◽  
Total Force ◽  
Complete Model ◽  
Specific Test ◽  
Wide Range ◽  
Physical Phenomena

In shock absorbers damper-rod force not only depends on damper-rod velocity, but also on position and acceleration. Since hydraulic losses are responsible for velocity-dependent forces, other phenomena are responsible for the dependence of force on position and acceleration, they are: compliances of the chambers and of the seals, compressibility of oil and gas and inertia of oil. The presence of position and/or acceleration-dependent terms in the force causes a hysteresis loop in the force-velocity diagram and a delay between force and velocity in the force-time diagram, which affect the performance of the shock absorber. Usually test benches measure only the damper-rod force, hence, it is difficult to recognize the physical phenomena that generate the hysteresis loop. This paper deals with a research program in which a high performance motorcycle shock absorber was tested by means of a specific test bench which includes the measurement of pressures inside the cambers during harmonic tests (frequency range 1–7 Hz). The experimental results with proper mathematical models made it possible to analyze the hysteresis loops of the pressures in the various chambers and the generation of the hysteresis loop and time delay of damper-rod force. First some experimental results dealing with pressures inside compression, rebound and compensation chambers are shown. Then a simplified mathematical model is presented, it is able to capture the most relevant physical phenomena that generate the hysteresis loop of the total force. Finally a complete model of the shock absorber is described, it takes into account details of oil motion inside the valves and it is able to predict the behavior of the shock absorber for a wide range of working conditions. Some numerical results obtained with the complete model are presented and compared with experimental results.

scholarly journals CMOS Realization of All-Positive Pinched Hysteresis Loops

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-15 ◽  
Author(s):  
B. J. Maundy ◽  
A. S. Elwakil ◽  
C. Psychalinos
Keyword(s):  
Hysteresis Loop ◽  
Detailed Analysis ◽  
Hysteresis Loops ◽  
Nonlinear Circuits ◽  
Experimental Results ◽  
First Order ◽  
Pinched Hysteresis Loop ◽  
A Charge ◽  
Pinched Hysteresis ◽  
Nmos Transistors

Two novel nonlinear circuits that exhibit an all-positive pinched hysteresis loop are proposed. These circuits employ two NMOS transistors, one of which operates in its triode region, in addition to two first-order filter sections. We show the equivalency to a charge-controlled resistance (memristance) in a decremental state via detailed analysis. Simulation and experimental results verify the proposed theory.

Characteristic properties of embedding strength for the nailing of the gonfolo rose (Qualea rosea Aubl.)

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 86-90 ◽  
Author(s):  
Laurent Bleron ◽  
Gilles Duchanois ◽  
Bernard Thiebaut
Keyword(s):  
Computer Program ◽  
Experimental Results ◽  
Test Apparatus ◽  
Research Project ◽  
Specific Test ◽  
Wide Range ◽  
Strength Tests ◽  
Loading And Unloading ◽  
Steel Joints ◽  
Unloading Stiffness

Abstract Experimental results are presented with single nail joints of gonfolo rose which were loaded at different grain angles and compared to results obtained by Eurocode V. A wide range of embedding strength tests was conducted. The embedding behaviour across the grain was also investigated with a specific test apparatus. The results were analysed and modelled in terms of strength. Initial loading and unloading stiffness of the timber have been taken into account. The embedment strength of the nails varied according to the angle between the direction of loading and that to the grain. This work is part of a larger research project to establish a computer program for the prediction of stiffness and limit strengths of all timber-to-timber and timber-to-steel joints.

Novel Meminductor Emulators Using Operational Amplifiers and their Applications in Chaotic Oscillators

2021 ◽  
pp. 2150219
Author(s):  
Aneet Singh ◽  
Shireesh Kumar Rai
Keyword(s):  
Hysteresis Loop ◽  
Operational Amplifier ◽  
Experimental Results ◽  
Operational Amplifiers ◽  
Chaotic Oscillator ◽  
Chaotic Oscillators ◽  
Wide Range ◽  
Pinched Hysteresis Loop ◽  
Simulation Results ◽  
Pinched Hysteresis

This paper presents six different meminductor emulator circuits based on operational amplifiers. Five circuits of meminductor emulators have been proposed using two operational amplifiers, one memristor, three resistors and one capacitor, whereas the sixth circuit uses two operational amplifiers, two memristors, one resistor and two capacitors. All circuits of the proposed meminductor emulators are very simple over most of the realizations of meminductor emulators in the literature. The behaviors of meminductor emulators are satisfactory over a wide range of frequencies. The proposed configurations of meminductor emulators have been simulated by the LTspice tool. The SPICE models of both operational amplifier (AD711) and memristor have been used for simulation. The workability of the proposed meminductor emulators has also been verified using the basic and well-known structure of operational amplifier. In addition, the pinched hysteresis loop obtained by the simulation results of meminductor emulator has been achieved by the experimental results as well. Chaotic oscillator has been designed using the proposed meminductor emulator to prove the worthiness of the design.

Numerical Study on Performance of Surface Piercing Propeller using RANS Approach

2015 ◽  
Author(s):  
Kohei Himei ◽  
Hajime Yamaguchi
Keyword(s):  
Standardized Test ◽  
Numerical Study ◽  
High Reliability ◽  
Experimental Studies ◽  
Performance Estimation ◽  
Experimental Results ◽  
Ventilated Cavitation ◽  
Wide Range ◽  
Physical Phenomena ◽  
Surface Piercing Propeller

Surface Piercing Propeller (SPP) can achieve high propulsive efficiency on high-speed vessels planing to reduce the frictional resistance of hull. It has the characteristic blade section and works partially submerged condition. The blades repeat entry to and exit from the water free surface and the suction sides and trailing edge of blades are exposed to ventilated cavitation while they are under the water. And interface near SPP is severely deformed by the high rotating blades. This working condition of SPP, therefore, makes it hard that propeller open characteristics are estimated with high reliability. Because SPP is unusual propeller having above difficulty of the performance estimation, the studies for SPP are few compared with large sized propellers for merchant ships. Although the various model tests had been carried out to understand the physical phenomena around various SPPs and their effects on propeller performances, they were not universal approach with standardized test conditions and propeller shape, as mentioned in 23th ITTC report and recommendation (2002). In applying the conventional calculation based on potential theory to SPP, there are many difficulties to model the physical phenomena theoretically. In calculations by Furuya (1984, 1985), thickness of blade and ventilated cavitation were non-consideration, and it was assumed that the suction side of the blade was fully ventilated in the water. In calculations by Young and Kinnas (2001), the interface deformation near SPP was not modeled theoretically. Therefore, they attributed the difference from experimental results to the effect of incompleteness of numerical modeling. On the other hand, CFD analysis can treat the effects of physical phenomena including thick ventilated cavitation and the sharp deformation of interface around SPP. In addition, the characteristic blade shape is modeled accurately without the geometric limitation in CFD. In this paper, typical SPP with experimental results open to the public is analyzed by CFD-RANS approach using Volume of Fluid (VOF) method based on interface-capturing algorithm at wide range of propeller advance coefficient J. Regarding propeller open characteristics, the 6-component force/moment fluctuations by blade rotations, and ventilation patterns, analyses results are compared with measured values. Moreover, the results of simulations in various Froude numbers and Weber numbers are evaluated whether their effects were negligible when they are sufficiently high, in the same manner as the results found by the other’s experimental studies (Shiba, 1953; Brandt, 1973).

On the nominal transverse shear strain to characterize the severity of creasing

TAPPI Journal ◽  
2018 ◽  
Vol 17 (04) ◽  
pp. 231-240
Author(s):  
Douglas Coffin ◽  
Joel Panek
Keyword(s):  
Shear Strain ◽  
Transverse Shear ◽  
Elastic Limit ◽  
Experimental Results ◽  
Transverse Shear Strain ◽  
Maximum Strain ◽  
Machine Direction ◽  
Engineering Approach ◽  
Wide Range ◽  
Analytic Expression

A transverse shear strain was utilized to characterize the severity of creasing for a wide range of tooling configurations. An analytic expression of transverse shear strain, which accounts for tooling geometry, correlated well with relative crease strength and springback as determined from 90° fold tests. The experimental results show a minimum strain (elastic limit) that needs to be exceeded for the relative crease strength to be reduced. The theory predicts a maximum achievable transverse shear strain, which is further limited if the tooling clearance is negative. The elastic limit and maximum strain thus describe the range of interest for effective creasing. In this range, cross direction (CD)-creased samples were more sensitive to creasing than machine direction (MD)-creased samples, but the differences were reduced as the shear strain approached the maximum. The presented development provides the foundation for a quantitative engineering approach to creasing and folding operations.

Extending the Applicability of the ANI Deep Learning Molecular Potential to Sulfur and Halogens

2020 ◽  
Author(s):  
Christian Devereux ◽  
Justin Smith ◽  
Kate Davis ◽  
Kipton Barros ◽  
Roman Zubatyuk ◽  
...  
Keyword(s):  
Drug Development ◽  
Autonomous Vehicles ◽  
Potential Energy Surfaces ◽  
Organic Molecules ◽  
Chemical Elements ◽  
Molecular Potential ◽  
Wide Range ◽  
Energy Surfaces ◽  
New Applications ◽  
Physical Phenomena

<p>Machine learning (ML) methods have become powerful, predictive tools in a wide range of applications, such as facial recognition and autonomous vehicles. In the sciences, computational chemists and physicists have been using ML for the prediction of physical phenomena, such as atomistic potential energy surfaces and reaction pathways. Transferable ML potentials, such as ANI-1x, have been developed with the goal of accurately simulating organic molecules containing the chemical elements H, C, N, and O. Here we provide an extension of the ANI-1x model. The new model, dubbed ANI-2x, is trained to three additional chemical elements: S, F, and Cl. Additionally, ANI-2x underwent torsional refinement training to better predict molecular torsion profiles. These new features open a wide range of new applications within organic chemistry and drug development. These seven elements (H, C, N, O, F, Cl, S) make up ~90% of drug like molecules. To show that these additions do not sacrifice accuracy, we have tested this model across a range of organic molecules and applications, including the COMP6 benchmark, dihedral rotations, conformer scoring, and non-bonded interactions. ANI-2x is shown to accurately predict molecular energies compared to DFT with a ~10<sup>6</sup> factor speedup and a negligible slowdown compared to ANI-1x. The resulting model is a valuable tool for drug development that can potentially replace both quantum calculations and classical force fields for myriad applications.</p>

scholarly journals Numerical Phase-Field Model Validation for Dissolution of Minerals

2021 ◽  
Vol 11 (6) ◽  
pp. 2464
Author(s):  
Sha Yang ◽  
Neven Ukrainczyk ◽  
Antonio Caggiano ◽  
Eddie Koenders
Keyword(s):  
Phase Field ◽  
Liquid Interface ◽  
Mineral Dissolution ◽  
Experimental Results ◽  
Wide Range ◽  
Congruent Dissolution ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Dissolution Of Minerals ◽  
Meso Scale

Modelling of a mineral dissolution front propagation is of interest in a wide range of scientific and engineering fields. The dissolution of minerals often involves complex physico-chemical processes at the solid–liquid interface (at nano-scale), which at the micro-to-meso-scale can be simplified to the problem of continuously moving boundaries. In this work, we studied the diffusion-controlled congruent dissolution of minerals from a meso-scale phase transition perspective. The dynamic evolution of the solid–liquid interface, during the dissolution process, is numerically simulated by employing the Finite Element Method (FEM) and using the phase–field (PF) approach, the latter implemented in the open-source Multiphysics Object Oriented Simulation Environment (MOOSE). The parameterization of the PF numerical approach is discussed in detail and validated against the experimental results for a congruent dissolution case of NaCl (taken from literature) as well as on analytical models for simple geometries. In addition, the effect of the shape of a dissolving mineral particle was analysed, thus demonstrating that the PF approach is suitable for simulating the mesoscopic morphological evolution of arbitrary geometries. Finally, the comparison of the PF method with experimental results demonstrated the importance of the dissolution rate mechanisms, which can be controlled by the interface reaction rate or by the diffusive transport mechanism.

scholarly journals Is contact angle a cause or an effect? – A cautionary tale

2020 ◽  
Vol 146 ◽  
pp. 03004
Author(s):  
Douglas Ruth
Keyword(s):  
Contact Angle ◽  
Solid Surface ◽  
Contact Angles ◽  
Two Dimensions ◽  
Experimental Results ◽  
Flow In Porous Media ◽  
Two Dimensional ◽  
Wide Range ◽  
Fluid Drop ◽  
Surrounding Fluid

The most influential parameter on the behavior of two-component flow in porous media is “wettability”. When wettability is being characterized, the most frequently used parameter is the “contact angle”. When a fluid-drop is placed on a solid surface, in the presence of a second, surrounding fluid, the fluid-fluid surface contacts the solid-surface at an angle that is typically measured through the fluid-drop. If this angle is less than 90°, the fluid in the drop is said to “wet” the surface. If this angle is greater than 90°, the surrounding fluid is said to “wet” the surface. This definition is universally accepted and appears to be scientifically justifiable, at least for a static situation where the solid surface is horizontal. Recently, this concept has been extended to characterize wettability in non-static situations using high-resolution, two-dimensional digital images of multi-component systems. Using simple thought experiments and published experimental results, many of them decades old, it will be demonstrated that contact angles are not primary parameters – their values depend on many other parameters. Using these arguments, it will be demonstrated that contact angles are not the cause of wettability behavior but the effect of wettability behavior and other parameters. The result of this is that the contact angle cannot be used as a primary indicator of wettability except in very restricted situations. Furthermore, it will be demonstrated that even for the simple case of a capillary interface in a vertical tube, attempting to use simply a two-dimensional image to determine the contact angle can result in a wide range of measured values. This observation is consistent with some published experimental results. It follows that contact angles measured in two-dimensions cannot be trusted to provide accurate values and these values should not be used to characterize the wettability of the system.

Numerical investigation of the propagation of shock waves in rigid porous materials: development of the computer code and comparison with experimental results

1996 ◽  
Vol 324 ◽  
pp. 163-179 ◽  
Author(s):  
A. Levy ◽  
G. Ben-Dor ◽  
S. Sorek
Keyword(s):  
Porous Materials ◽  
Initial Conditions ◽  
Computer Code ◽  
Experimental Results ◽  
Numerical Code ◽  
Materials Development ◽  
Numerical Predictions ◽  
Wide Range ◽  
Dimensional Version ◽  
The One

The governing equations of the flow field which is obtained when a thermoelastic rigid porous medium is struck head-one by a shock wave are developed using the multiphase approach. The one-dimensional version of these equations is solved numerically using a TVD-based numerical code. The numerical predictions are compared to experimental results and good to excellent agreements are obtained for different porous materials and a wide range of initial conditions.

Experimental Studies on Cooling Effectiveness of the Double-Decker Air Jet Impingement With Film Outflow

2007 ◽  
Author(s):  
Junkui Mao ◽  
Wen Guo ◽  
Zhenxiong Liu ◽  
Jun Zeng
Keyword(s):  
Infrared Radiation ◽  
Experimental Studies ◽  
Jet Impingement ◽  
Experimental Results ◽  
Thermal Camera ◽  
Local Cooling ◽  
Cooling Effectiveness ◽  
Air Jet ◽  
Double Decker ◽  
Wide Range

Experiments were carried out to investigate the cooling effectiveness of a lamellar double-decker impingement/effusion structure. Infrared radiation (I.R.) thermal camera was used to measure the temperature on the outside surface of the lamellar double-decker. Experimental results were obtained for a wide range of governing parameters (blowing rate M (0.0017∼0.0066), the ratio of the jet impingement distance to the diameter of film hole H/D (0.5∼1.25), the ratio of the distance between the jet hole and film hole to the diameter of the film hole P/D (0, 3, 4), and the material of double-decker (Steel and Copper)). It was observed that the local cooling effectiveness η varies with all these parameters in a complicated way. All the results show that higher cooling effectiveness η is achieved in larger blowing rate cases. A certain range of H/D and P/D can be designed to result in the maximum cooling effectiveness η. And η is less sensitive to the material type compared with those parameters such as H/D, M and P/D.

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