Simulation of landing vehicle dynamic motion in the final stage of landing

2020 ◽  
Author(s):  
V.V. Koryanov
Keyword(s):  
Final Stage ◽  
Initial Conditions ◽  
Space Mission ◽  
Stick Slip ◽  
Dynamic Motion ◽  
Numerical Studies ◽  
Descent Vehicle ◽  
Vehicle Motion ◽  
The Moment ◽  
Motion Dynamics

When designing promising spacecrafts and missions to explore the planets of the Solar system, preliminary testing of all the important systems affecting the success of the space mission is necessary. Among the other systems responsible for the functioning of the spacecraft, it is necessary to distinguish the landing system. The landing stage is important and complex, since this stage is accompanied by large overloads and forces of the stick-slip nature acting on the spacecraft, their effect can be critical for the spacecraft structure. When landing the descent vehicle, it is necessary to study separately the moment of approach to the surface and the movement in the ground. The purpose of this article is to describe the methodology for modeling the motion dynamics at the final stage of movement and perform numerical studies of the descent vehicle motion dynamics at the final stage of movement in the case of a hard landing. Studies were conducted for different initial conditions of approach to the surface. As a result, the values of the arising overloads acting on the descent vehicle were obtained. The data provided by the simulation allow making conclusions about the most dangerous landing options that should be considered for the successful completion of future missions.

scholarly journals Use of Modern Digital Software to Model the Motion Dynamics of Spacecraft during Landing

2020 ◽  
Vol 35 ◽  
pp. 04012
Author(s):  
Vsevolod V. Koryanov ◽  
Maria Hermosilla Heras
Keyword(s):  
Environmental Conditions ◽  
Initial Conditions ◽  
Dynamic Simulations ◽  
Dynamic Motion ◽  
Matlab Code ◽  
Descent Vehicle ◽  
Future Space ◽  
Entry Velocity ◽  
Universal Mechanism ◽  
Efficient Software

Landing systems for future space missions in Earth and Mars require trustable technologies capable of achieving their aim in the most accurate way possible. For this purpose, systems should go through rigorous dynamic simulations run by precise and efficient software. This study aims to approximately determine the dynamic motion of a landing vehicle using the modern digital software of Universal Mechanism and MATLAB. Universal Mechanism applies the classic mechanics theory on a model based on the geometry of the spacecraft, taking into account the environmental conditions that affect its motion and the properties of the ground to resist its impact [1]. The forces implied in the vehicle phase of descent are also included in MATLAB code to calculate the landing area of the vehicle according to its re-entry velocity [2-4]. Studies were conducted for different initial conditions and approaches to the surface. As a result, the values of the arising overloads and forces acting on the descent vehicle were obtained [1]. The data provided by the simulations conclude the safest landing options that should be taken into account for the success of future missions.

Numerical Study of an Impact Oscillator

1995 ◽  
Author(s):  
Kannan Marudachalam ◽  
Faruk H. Bursal
Keyword(s):  
Dynamical Systems ◽  
Numerical Algorithm ◽  
Initial Conditions ◽  
Numerical Study ◽  
Harmonic Excitation ◽  
General Purpose ◽  
Constrained Systems ◽  
Global Dynamics ◽  
Impact Oscillator ◽  
Stick Slip

Abstract Systems with discontinuous dynamics can be found in diverse disciplines. Meshing gears with backlash, impact dampers, relative motion of components that exhibit stick-slip phenomena axe but a few examples from mechanical systems. These form a class of dynamical systems where the nonlinearity is so severe that analysis becomes formidable, especially when global behavior needs to be known. Only recently have researchers attempted to investigate such systems in terms of modern dynamical systems theory. In this work, an impact oscillator with two-sided rigid constraints is used as a paradigm for studying the characteristics of discontinuous dynamical systems. The oscillator has zero stiffness and is subjected to harmonic excitation. The system is linear without impacts. However, the impacts introduce nonlinearity and dissipation (assuming inelastic impacts). A numerical algorithm is developed for studying the global dynamics of the system. A peculiar type of solution in which the trajectories in phase space from a certain set of initial conditions merge in finite time, making the dynamics non-invertible, is investigated. Also, the effect of “grazing,” a behavior common to constrained systems, on the dynamics of the system is studied. Based on the experience gained in studying this system, the need for an efficient general-purpose numerical algorithm for solving discontinuous dynamical systems is motivated. Investigation of stress, vibration, wear, noise, etc. that are associated with impact phenomena can benefit greatly from such an algorithm.

scholarly journals Mass determination of the 1:3:5 near-resonant planets transiting GJ 9827 (K2-135)

2018 ◽  
Vol 618 ◽  
pp. A116 ◽  
Author(s):  
J. Prieto-Arranz ◽  
E. Palle ◽  
D. Gandolfi ◽  
O. Barragán ◽  
E. W. Guenther ◽  
...  
Keyword(s):  
Planetary System ◽  
Initial Conditions ◽  
Dynamical Evolution ◽  
Space Mission ◽  
Mass Determination ◽  
Velocity Measurements ◽  
Orbital Periods ◽  
The Masses ◽  
Better Than

Context. Multiplanet systems are excellent laboratories to test planet formation models as all planets are formed under the same initial conditions. In this context, systems transiting bright stars can play a key role, since planetary masses, radii, and bulk densities can be measured. Aims. GJ 9827 (K2-135) has recently been found to host a tightly packed system consisting of three transiting small planets whose orbital periods of 1.2, 3.6, and 6.2 days are near the 1:3:5 ratio. GJ 9827 hosts the nearest planetary system (~30 pc) detected by NASA’s Kepler or K2 space mission. Its brightness (V = 10.35 mag) makes the star an ideal target for detailed studies of the properties of its planets. Methods. Combining the K2 photometry with high-precision radial-velocity measurements gathered with the FIES, HARPS, and HARPS-N spectrographs we revised the system parameters and derive the masses of the three planets. Results. We find that GJ 9827 b has a mass of Mb = 3.69−0.46+0.48 M⊕ and a radius of Rb = 1.58−0.13+0.14 R⊕, yielding a mean density of ρb = 5.11−1.27+1.74 g cm−3. GJ 9827 c has a mass of Mc = 1.45−0.57+0.58 M⊕, radius of Rc = 1.24−0.11+0.11 R⊕, and a mean density of ρc = 4.13−1.77+2.31 g cm−3. For GJ 9827 d, we derive Md = 1.45−0.57+0.58 M⊕, Rd = 1.24−0.11+0.11 R⊕, and ρd = 1.51−0.53+0.71 g cm−3. Conclusions. GJ 9827 is one of the few known transiting planetary systems for which the masses of all planets have been determined with a precision better than 30%. This system is particularly interesting because all three planets are close to the limit between super-Earths and sub-Neptunes. The planetary bulk compositions are compatible with a scenario where all three planets formed with similar core and atmosphere compositions, and we speculate that while GJ 9827 b and GJ 9827 c lost their atmospheric envelopes, GJ 9827 d maintained its primordial atmosphere, owing to the much lower stellarirradiation. This makes GJ 9827 one of the very few systems where the dynamical evolution and the atmosphericescape can be studied in detail for all planets, helping us to understand how compact systems form and evolve.

scholarly journals The analysis of thermodynamic indicators of the VCR engine made with AVL Fire program

2019 ◽  
Vol 24 (6) ◽  
pp. 212-217
Author(s):  
Jerzy Merkisz ◽  
Maciej Bajerlein ◽  
Paweł Daszkiewicz ◽  
Patryk Urbański
Keyword(s):  
Dynamic Simulation ◽  
Compression Ratio ◽  
Initial Conditions ◽  
Combustion Process ◽  
The Moment

As part of the work, the piston path generated in the dynamic simulation in the Solidworks program was used to study the processes occurring during the combustion process. The simulation was carried out in the AVL Fire program for the same initial conditions. Different variants of the motor cam control were compared at the same compression ratio. In the analyzed article, the moment and period of time that the piston remains in the Upper Dead Location (TDC) were analyzed.

scholarly journals A Transient Dynamic Model of Brake Corner and Subsystems for Brake Creep Groan Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-18 ◽  
Author(s):  
Dejian Meng ◽  
Lijun Zhang ◽  
Jie Xu ◽  
Zhuoping Yu
Keyword(s):  
Dynamic Model ◽  
Vehicle Body ◽  
Flexible Body ◽  
Stick Slip ◽  
Transient Dynamic ◽  
Numerical Studies ◽  
Slipping Friction ◽  
Frequency Domains ◽  
Rigid Body Simulation ◽  
Stick Slip Motion

To improve the understanding of brake creep groan, both experimental and numerical studies are conducted in this paper. Based on a vehicle road test under the condition of downhill, complicated stick-slip type motion of caliper and its correlation with the interior noise were analyzed. In order to duplicate these brake creep groan phenomena, a transient dynamic model including brake corner and subsystems was established using finite element method. In the model, brake components were considered to be flexible body, and the subsystems including driveline, suspension, tire, and vehicle body were considered to be rigid body. Simulation and experimental results of caliper vibration in time and frequency domains were compared. It was demonstrated that the new model is effective for the prediction and analysis of brake creep groan, and it has higher accuracy compared to the previous model without the subsystems. It is also found that the lining and caliper not only have stick-slip motion in each coordinate direction but also have translational and torsional movements in plane, which relate to the microscopic sticking and slipping, friction coefficient, and forces, as well as the contact status at the friction interface.

Dewey and Higher Education

2018 ◽  
pp. 392-410
Author(s):  
Leonard J. Waks
Keyword(s):  
Higher Education ◽  
John Dewey ◽  
Final Stage ◽  
Logical Theory ◽  
Close Attention ◽  
The Third ◽  
The Moment ◽  
The University ◽  
Theory Of Inquiry

While John Dewey wrote relatively little about higher education, he had a well-developed and largely unexplored conception of the university, grounded in his three- stage account of thought or inquiry as developed in Studies in Logical Theory and further developed in Logic: Theory of Inquiry. The first stage is antecedent to inquiry proper, residing in the situations of living that evoke thought. The second is inquiry proper, where data or immediate materials are subjected to systematic thought to yield judgment. The third is the moment after thought has considered its data and reached its result and brought it forth in situations of living as transformed by this new element. This final stage, is the “objective of thought” but lies outside of the context of inquiry proper. This chapter, building on the Dewey corpus, explains that conception, with close attention to university-based research, teaching, and service.

scholarly journals Common envelope episodes that lead to double neutron star formation

2020 ◽  
Vol 37 ◽  
Author(s):  
Alejandro Vigna-Gómez ◽  
Morgan MacLeod ◽  
Coenraad J. Neijssel ◽  
Floor S. Broekgaarden ◽  
Stephen Justham ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Initial Conditions ◽  
Large Fraction ◽  
Computational Modelling ◽  
Evolutionary Stage ◽  
Population Synthesis ◽  
Radio Pulsars ◽  
Common Envelope ◽  
The Common ◽  
The Moment

Abstract Close double neutron stars (DNSs) have been observed as Galactic radio pulsars, while their mergers have been detected as gamma-ray bursts and gravitational wave sources. They are believed to have experienced at least one common envelope episode (CEE) during their evolution prior to DNS formation. In the last decades, there have been numerous efforts to understand the details of the common envelope (CE) phase, but its computational modelling remains challenging. We present and discuss the properties of the donor and the binary at the onset of the Roche lobe overflow (RLOF) leading to these CEEs as predicted by rapid binary population synthesis models. These properties can be used as initial conditions for detailed simulations of the CE phase. There are three distinctive populations, classified by the evolutionary stage of the donor at the moment of the onset of the RLOF: giant donors with fully convective envelopes, cool donors with partially convective envelopes, and hot donors with radiative envelopes. We also estimate that, for standard assumptions, tides would not circularise a large fraction of these systems by the onset of RLOF. This makes the study and understanding of eccentric mass-transferring systems relevant for DNS populations.

Thermal Instability of Sliding and Oscillations Due to Frictional Heating Effect

1988 ◽  
Vol 110 (1) ◽  
pp. 69-72 ◽  
Author(s):  
I. L. Maksimov
Keyword(s):  
Thermal Instability ◽  
Initial Conditions ◽  
Frictional Heating ◽  
Interface Temperature ◽  
Heating Effect ◽  
Stick Slip ◽  
Instability Development ◽  
The Stability ◽  
Sliding Dynamics ◽  
Sliding Instability

The stability of sliding has been studied, taking into account frictional heating effect and friction coefficient dependence upon the interface temperature and sliding velocity. The collective—thermal and mechanical—sliding instability has been found to exist; instability emergence conditions and dynamics (both in linear and nonlinear stages) have been determined. It is shown that both the threshold and the dynamics of thermofrictional instability differ qualitatively from the analogous characteristics of “stick-slip” phenomenon. Namely, the oscillational instability behavior due to the energy exchange between thermal and mechanical modes has been found to occur under certain initial conditions; the velocities range has been determined for which collective sliding instability may occur whereas the stick-slips would be not possible. The nonlinear analysis of instability evolution has been carried out for pairs with the negative thermal-frictional sliding characteristics, the final stage of sliding dynamics has been described. It is found that stable thermofrictional oscillations can occur on the nonlinear stage of sliding instability development; the oscillations frequency and amplitude have been determined. The possibility has been discussed of the experimental observation of new dynamical sliding phenomena at low temperatures.

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