Research on Dynamic Modelling and Simulation of Erection System of Mobile Equipment in Absolute Coordinates

2011 ◽  
Vol 66-68 ◽  
pp. 2034-2040
Author(s):  
Qin He Gao ◽  
Xiang Yang Li
Keyword(s):  
Rigid Body ◽  
Dynamic Models ◽  
Dynamic Modelling ◽  
Hydraulic Cylinder ◽  
Correction Method ◽  
Integration Time ◽  
Multi Stage ◽  
Rigid Body Model ◽  
Absolute Coordinates ◽  
The Impact

This paper employed the theories of multibody system dynamics to analyze the multi-rigid-body model of erection system and build the general dynamic models in absolute coordinates. The impact theory of contact mechanics and nonlinear spring-damper force function were used to model the impact problems between rods of multi-stage hydraulic cylinder of erection system and educe the dynamic models of multi-rigid-body erection system with impact. An automatic violation correction method according to the step of integration time was given to solve the violation which is an incident problem in numerical integration of dynamic models in absolute coordinates. Simulation results show that these dynamic models are effective.

scholarly journals Impact of nuclear inertia momenta on fission observables

2018 ◽  
Vol 193 ◽  
pp. 01004
Author(s):  
P. Tamagno ◽  
O. Litaize
Keyword(s):  
Rigid Body ◽  
Excitation Energy ◽  
Nuclear Fission ◽  
Particle Model ◽  
Rotational Inertia ◽  
Neutron Fission ◽  
Fission Fragments ◽  
Rigid Body Model ◽  
Two Parameters ◽  
The Impact

Fission is probably the nuclear process the less accurately described with current models because it involves dynamics of nuclear matter with strongly coupled manybody interactions. It is thus diffcult to find models that are strongly rooted in good physics, accurate enough to reproduce target observables and that can describe many of the nuclear fission observables in a consistent way. One of the most comprehensive current modeling of the fission process relies on the fission sampling and Monte-Carlo de-excitation of the fission fragments. This model is implemented for instance in the FIFRELIN code. In this model fission fragments and their state are first sampled from pre-neutron fission yields, angular momentum distribution and excitation energy repartition law then the decay of both initial fragments is simulated. This modeling provides many observables: prompt neutron and gamma fission spectra, multiplicities and also fine decompositions: number of neutrons emitted as a function of the fragment mass, spectra per fragments, etc. This model relies on nuclear structure databases and on several basic nuclear models describing for instance gamma strength functions or level densities. Additionally some free parameters are still to be determined, namely two parameters describing the excitation energy repartition law, the spin cutoff of the heavy and light fragments and a rescaling parameter for the rotational inertia momentum of the fragments with respect of the rigid-body model. In the present work we investigate the impact of this latter parameter. For this we mainly substitute the corrected rigid-body value by a quantity obtained from a microscopic description of the fission fragment. The independent-particle model recently implemented in the CONRAD code is used to provide nucleonic wave functions that are required to compute inertia momenta with an Inglis-Belyaev cranking model. The impact of this substitution is analyzed on different fission observables provided by the FIFRELIN code.

Three-Dimensional Frictional Rigid-Body Impact

1995 ◽  
Vol 62 (4) ◽  
pp. 893-898 ◽  
Author(s):  
V. Bhatt ◽  
Jeff Koechling
Keyword(s):  
Differential Equations ◽  
Rigid Body ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Local Analysis ◽  
Integration Scheme ◽  
Numerical Integration Scheme ◽  
Rigid Body Model ◽  
Global Nature ◽  
The Impact

We present an analysis of the rigid-body model for frictional three-dimensional impacts, which was originally studied by Routh. Using Coulomb’s law for friction, a set of differential equations describing the progress and outcome of the impact process for general bodies can be obtained. The differential equations induce a flow in the tangent velocity space for which the trajectories cannot be solved for in a closed form, and a numerical integration scheme is required. At the point of sticking, the numerical problem becomes ill-conditioned and we have to analyze the flow at the singularity to determine the rest of the process. A local analysis at the point of sticking provides enough information about the global nature of the flow to let us enumerate all the possible dynamic scenarios for the sliding behavior during impact. The friction coefficient, and the mass parameters at the point of contact, determine the particular sliding behavior that would occur for a given problem. Once the initial conditions are specified, the possible outcome of the impact can then be easily determined.

scholarly journals Rigid Body Motions and Local Compliance Response during Impact of Two Deformable Spheres

2017 ◽  
Vol 8 (1) ◽  
pp. 1 ◽  
Author(s):  
Akuro Big-Alabo
Keyword(s):  
Rigid Body ◽  
Dynamic Models ◽  
Numerical Solutions ◽  
Simple Procedure ◽  
Body Motion ◽  
Impact System ◽  
Rigid Body Motions ◽  
Local Compliance ◽  
Nonlinear Dynamic Models ◽  
The Impact

The impact of two hard deformable spheres is revisited with the aim of investigating the constituent rigid body motions and indentation response of each sphere during collision. The latter are determined theoretically and the theoretical solutions are validated by comparing with numerical solutions of the coupled nonlinear dynamic models for impact of two hard deformable spheres. For elastic impact events, normalized tabulated solutions are derived using the Force Indentation Linearisation Method (FILM) and the tabulated solutions can be used to generate actual rigid body motions and indentation histories for each of the colliding spheres without need for numerical or finite element solutions. The analysis shows that the rigid body motion and local compliance response of each sphere depend on: (a) ratio of mass of sphere to effective mass of impact system, and (b) ratio of initial velocity of sphere to initial relative velocity of impact system. Finally, the 2-D collision problem is discussed and a simple procedure to determine the unique solution of all four unknowns is presented.

scholarly journals An Approach for the Impact Dynamic Modeling and Simulation of Planar Constrained Metamorphic Mechanism

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Yanyan Song ◽  
Boyan Chang ◽  
Guoguang Jin ◽  
Zhan Wei ◽  
Bo Li
Keyword(s):  
Rigid Body ◽  
Modeling And Simulation ◽  
Dynamic Modeling ◽  
Dynamic Models ◽  
Dynamic Theory ◽  
Coefficient Of Restitution ◽  
Body System ◽  
Metamorphic Mechanism ◽  
The Impact ◽  
Impact Motion

This paper studied the impact dynamic modeling of the planar constrained metamorphic mechanism (PCMM) during configuration transformation. Based on the dynamic theory of the multi-rigid-body system and the coefficient of restitution equation, a new method for dynamic modeling of PCMM considering impact motions generated by configuration transformation is presented, which can be treated as a theoretical foundation for performance design and dynamic control. Firstly, the topology theory based on the impact motion can be classified as the stable impact motion and the mobile impact motion, which is the prerequisite for dynamic modeling and simulation. Secondly, the stable and mobile impact dynamic models for PCMM are established according to the dynamic theory of the multi-rigid-body system. Then, using these models, the corresponding impulse solving models are deduced combining with the coefficient of restitution equation. Finally, the examples of the stable impact motion and the mobile impact motion are respectively given, and the configuration-complete dynamic simulations are carried out. By comparing with the dynamic models without considering the impact motion, the dynamic characteristics of PCMM are analyzed. The theory and method proposed in this paper can be also applied in general planar robotic systems to deal with the problem of internal collision dynamics.

scholarly journals Improving the precipitation accumulation analysis using lightning measurements and different integration periods

2017 ◽  
Vol 21 (1) ◽  
pp. 267-279 ◽  
Author(s):  
Erik Gregow ◽  
Antti Pessi ◽  
Antti Mäkelä ◽  
Elena Saltikoff
Keyword(s):  
Positive Impact ◽  
Time Integration ◽  
Radar Data ◽  
Correction Method ◽  
Research Field ◽  
Local Analysis ◽  
Integration Time ◽  
Special Focus ◽  
Finnish Meteorological Institute ◽  
The Impact

Abstract. The focus of this article is to improve the precipitation accumulation analysis, with special focus on the intense precipitation events. Two main objectives are addressed: (i) the assimilation of lightning observations together with radar and gauge measurements, and (ii) the analysis of the impact of different integration periods in the radar–gauge correction method. The article is a continuation of previous work by Gregow et al. (2013) in the same research field. A new lightning data assimilation method has been implemented and validated within the Finnish Meteorological Institute – Local Analysis and Prediction System. Lightning data do improve the analysis when no radars are available, and even with radar data, lightning data have a positive impact on the results. The radar–gauge assimilation method is highly dependent on statistical relationships between radar and gauges, when performing the correction to the precipitation accumulation field. Here, we investigate the usage of different time integration intervals: 1, 6, 12, 24 h and 7 days. This will change the amount of data used and affect the statistical calculation of the radar–gauge relations. Verification shows that the real-time analysis using the 1 h integration time length gives the best results.

scholarly journals A Theoretical Rigid Body Model of Vibrating Screen for Spring Failure Diagnosis

Mathematics ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 246 ◽  
Author(s):  
Yue Liu ◽  
Shuangfu Suo ◽  
Guoying Meng ◽  
Deyong Shang ◽  
Long Bai ◽  
...  
Keyword(s):  
Rigid Body ◽  
Dynamic Characteristics ◽  
Dynamic Models ◽  
Separation Efficiency ◽  
Failure Diagnosis ◽  
Amplitude Change ◽  
Vibrating Screen ◽  
Body Model ◽  
Rigid Body Model ◽  
Critical Components

Springs are critical components in mining vibrating screen elastic supports. However, long-term alternating loads are likely to lead to spring failures, likely resulting in structural damages to the vibrating screen and resulting in a lower separation efficiency. Proper dynamic models provide a basis for spring failure diagnosis. In this paper, a six-degree-of-freedom theoretical rigid body model of a mining vibrating screen is proposed, and a dynamic equation is established in order to explore the dynamic characteristics. Numerical simulations, based on the Newmark-β algorithm, are carried out, and the results indicate that the model proposed is suitable for revealing the dynamic characteristics of the mining vibrating screen. Meanwhile, the mining vibrating screen amplitudes change with the spring failures. Therefore, six types of spring failure are selected for simulations, and the results indicate that the spring failures lead to an amplitude change for the four elastic support points in the x, y, and z directions, where the changes depend on certain spring failures. Hence, the key to spring failure diagnosis lies in obtaining the amplitude change rules, which can reveal particular spring failures. The conclusions provide a theoretical basis for further study and experiments in spring failure diagnosis for a mining vibrating screen.

scholarly journals Quantification of the Effect of Water Temperature on the Fall Rate of Expendable Bathythermographs

2016 ◽  
Vol 33 (6) ◽  
pp. 1271-1284 ◽  
Author(s):  
John P. Abraham ◽  
Rebecca Cowley ◽  
Lijing Cheng
Keyword(s):  
Water Temperature ◽  
Dynamic Models ◽  
Fluid Dynamic ◽  
Correction Method ◽  
Rate Coefficients ◽  
Rate Equations ◽  
Measured Temperature ◽  
Fall Rate ◽  
Influence Of Water ◽  
The Impact

AbstractA very large portion of the historical information on ocean temperatures has been measured using expendable bathythermograph (XBT) devices. For decades, these devices provided the majority of global information. It is, therefore, important to quantify their accuracy and identify biases in this important historical dataset. Here, calculations are made of the influence of water temperature on the rate of descent of the XBT devices into the ocean waters. In colder regions, the larger viscosity of the water is expected to cause a greater drag force on the device, which would slow the descent. It was found through computational fluid dynamic models that the impact of temperature and viscosity on the probe descent is approximately 2.2% for water temperatures that range from 0° to 27°C. Probe-specific temperature-dependent fall rate equations were applied to 269 collocated XBT/conductivity–temperature–depth (CTD) measurements from two different research cruises. It was found that the probe-specific descent equations were an improvement over the uncorrected method. Next, in an effort to automate the process, the fall rate coefficients were related to the topmost measured temperature in the water column. With this relationship, comparisons were made between the probe-specific descent calculations and 2937 high-resolution XBT–CTD pairs. It was found that again, the new methodology outperformed the standard fall rate equation. The new method was also compared with an independent correction method that was previously published. It was found that both new methods were improvements upon the industry-standard fall rate calculation. Subsequent calculations using the top-100-m water temperature were performed and were found to be statistically insignificant compared to the proposed simplified method.

Dynamic modeling and simulation of impact in hydraulic cylinders

2020 ◽  
pp. 095440622098047
Author(s):  
Osama Gad
Keyword(s):  
Contact Force ◽  
Dynamic Models ◽  
Maxwell Model ◽  
Hydraulic Cylinder ◽  
Rigid Bodies ◽  
Solid Model ◽  
Contact Period ◽  
Suitable Model ◽  
Hydraulic Cylinders ◽  
The Impact

In this paper, modeling impact dynamics of a piston and its cylinder body in a hydraulic cylinder is investigated. The studied system consists of two identical hydraulic cylinders controlled by a pressure sequence valve. The impact is assumed as a linear one dimensional and purely translational viscoelastic impact of rigid bodies. Four impact models, the Kelvin-Voigt, the Maxwell, the standard-solid, and the Hunt-Crossley, are considered. Measurements of the transient variations of the cylinders operating pressures and both pistons strokes, at different loading conditions, are conducted. A comprehensive dynamic model of the studied system, considering the four models, is deduced. The Kelvin-Voigt model produced tensile forces by the end of the contact period and it resulted in discontinuities in the contact force during its steady state period. Both results are physically impossible in rigid bodies impacting. In the Maxwell model, large amount of discontinuities appeared in the contact force, which causes the piston to make an infinite number of rebounds during the contact period. In the standard-solid model, the discontinuities in the contact force were found to be much less than those of the Maxwell model. As a result, when the impact occurs, the cylinder pressure gets an overshoot accompanied with large oscillations when the Maxwell model is applied, however, these oscillations do not approximately appear when the standard-solid model is applied. The simulation results showed also that the Hunt-Crossley nonlinear model presented very high penetration depth, which is certainly unrealistic in rigid bodies impacting. The validation of the proposed dynamic models showed that the standard-solid is the most suitable model that may represent the impact in the studied cylinders.

scholarly journals Improving the precipitation accumulation analysis using radar-, gauge- and lightning measurements

2016 ◽  
Author(s):  
Erik Gregow ◽  
Antti Pessi ◽  
Antti Mäkelä ◽  
Elena Saltikoff
Keyword(s):  
Time Integration ◽  
Correction Method ◽  
Research Field ◽  
Local Analysis ◽  
Integration Time ◽  
Special Focus ◽  
Finnish Meteorological Institute ◽  
Real Time Analysis ◽  
Statistical Relationships ◽  
The Impact

Abstract. The aim of this article is to introduce and compare new methods on how to perform precipitation accumulation analysis, with special focus on the high intensity cases. This includes assimilation of lightning observations, in combination with radar and gauge measurements, and the impact of different integration time intervals on the radar-gauge correction method. The article is a continuation of previous work in the same research field, by Gregow et al. (2011). A new Lightning Data Assimilation (LDA) method has been implemented and validated within the Finnish Meteorological Institute- (FMI) Local Analysis and Prediction System (LAPS). The performed precipitation accumulation analyses show the usefulness of lightning assimilation, together with radar information. The radar-gauge assimilation method is highly dependent on statistical relationships between radar and gauges, when performing the correction to precipitation accumulation field. Here we investigate the usage of different time integration intervals; 1, 6, 12, 24 hours and 7 days. This will change the amount of data used and affect the statistical calculation of the radar-gauge relations. Verification shows that the real-time analysis using the 1 hour integration time length gives the best result.

Monetary policy and the effect of the transfer of oil prices to inflation

2020 ◽  
pp. 41-50
Author(s):  
Ph. S. Kartaev ◽  
I. D. Medvedev
Keyword(s):  
Monetary Policy ◽  
Inflation Targeting ◽  
Dynamic Models ◽  
Oil Prices ◽  
Oil Price ◽  
Oil Price Shocks ◽  
Negative Effects ◽  
Price Shocks ◽  
Policy Regime ◽  
The Impact

The paper examines the impact of oil price shocks on inflation, as well as the impact of the choice of the monetary policy regime on the strength of this influence. We used dynamic models on panel data for the countries of the world for the period from 2000 to 2017. It is shown that mainly the impact of changes in oil prices on inflation is carried out through the channel of exchange rate. The paper demonstrates the influence of the transition to inflation targeting on the nature of the relationship between oil price shocks and inflation. This effect is asymmetrical: during periods of rising oil prices, inflation targeting reduces the effect of the transfer of oil prices, limiting negative effects of shock. During periods of decline in oil prices, this monetary policy regime, in contrast, contributes to a stronger transfer, helping to reduce inflation.

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