Plate subjected to an out-of-plane follower force

The stability of bending-torsional equilibrium of a uniform plate subjected to an out-of-plane follower force is studied in this paper. The resulting system approximates to a wing subjected to the thrust of a jet engine. Attention is focused on the determination of the dynamic stability of the wing as a function of engine thrust. Criteria are established for the determination of the maximum allowable value of the engine thrust.

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Use of a “green” propellant in low-thrust control jet engine systems

Technical mechanics ◽

10.15407/itm2021.04.029 ◽

2021 ◽

Vol 2021 (4) ◽

pp. 29-43

Author(s):

V.I. Timoshenko ◽

◽

L.K. Patryliak ◽

Yu.V. Knyshenko ◽

V.M. Durachenko ◽

...

Keyword(s):

The State ◽

Low Thrust ◽

Fuel Component ◽

Jet Engine ◽

Engine Thrust ◽

Thrust Characteristics ◽

Green Propellants ◽

Green Propellant ◽

Engine Systems

The aim of this work is to analyze the state of the art in the development and use of pollution-free (“green”) propellants in low-thrust jet engines used as actuators of spacecraft stabilization and flight control systems and to adapt computational methods to the determination of “green”-propellant engine thrust characteristics. The monopropellant that is now widely used in the above-mentioned engines is hydrazine, whose decomposition produces a jet thrust due to the gaseous reaction products flowing out of a supersonic nozzle. Because of the high toxicity of hydrazine and the complex technology of hydrazine filling, it is important to search for its less toxic substitutes that would compare well with it in energy and mass characteristics. A promising line of this substitution is the use of ion liquids classed with “green” ones. The main components of these propellants are a water solution of an ion liquid and a fuel component. The exothermic thermocatalytic decomposition of a “green” propellant is combined with the combustion of its fuel component and increases the combustion chamber pressure due to the formation of gaseous products, which produces an engine thrust. It is well known that a “green” propellant itself and the products of its decomposition and combustion are far less toxic that hydrazine and the products of its decomposition, The paper presents data on foreign developments of “green” propellants of different types, which are under test in ground (bench) conditions and on a number of spacecraft. The key parameter that governs the efficiency of the jet propulsion system thrust characteristics is the performance of the decomposition and combustion products, which depends on their temperature and chemical composition. The use of equilibrium high-temperature process calculation methods for this purpose is too idealized and calls for experimental verification. Besides, a substantial contribution to the end effect is made by the design features of propellant feed and flow through a fine-dispersed catalyst layer aimed at maximizing the monopropellant-catalyst contact area. As a result, in addition to the computational determination of the thrust characteristics of a propulsion system under design, its experimental tryout is mandatory. The literature gives information on the performance data of “green”-propellant propulsion systems for single engines. However, in spacecraft control engine systems their number may amount to 8–16; in addition, they operate in different regimes and may differ in thrust/throttling characteristics, which leads to unstable propellant feed to operating engines. To predict these processes, the paper suggests a mathematical model developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine and adapted to “green”-propellant engine systems. The model serves to calculate the operation of low-thrust jet engine systems and describes the propellant flow in propellant feed lines, propellant valves, and combustion chambers. To implement the model, use was made of the results of experimental studies on a prototype “green”-propellant engine developed at Yuzhnoye State Design Office. The analysis of the experimental results made it possible to refine the performance parameters of the monopropellant employed and obtain computational data that may be used in analyzing the operation of a single engine or an engine system on this propellant type in ground and flight conditions

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Nonlinear Response of an Inextensible, Cantilevered Beam Subjected to a Nonconservative Follower Force

Journal of Computational and Nonlinear Dynamics ◽

10.1115/1.4042324 ◽

2019 ◽

Vol 14 (3) ◽

Cited By ~ 4

Author(s):

Kevin A. McHugh ◽

Earl H. Dowell

Keyword(s):

Linear Model ◽

Critical Force ◽

Follower Force ◽

System Of Nonlinear Equations ◽

Constraint Force ◽

New Energy ◽

Out Of Plane ◽

Engineering Designs ◽

Cantilevered Beam

The dynamic stability of a cantilevered beam actuated by a nonconservative follower force has previously been studied for its interesting dynamical properties and its applications to engineering designs such as thrusters. However, most of the literature considers a linear model. A modest number of papers consider a nonlinear model. Here, a system of nonlinear equations is derived from a new energy approach for an inextensible cantilevered beam with a follower force acting upon it. The equations are solved in time, and the agreement is shown with published results for the critical force including the effects of damping (as determined by a linear model). This model readily allows the determination of both in-plane and out-of-plane deflections as well as the constraint force. With this novel transparency into the system dynamics, the nonlinear postcritical limit cycle oscillations (LCO) are studied including a concentration on the force which enforces the inextensibility constraint.

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ДИНАМІЧНА РЕАКЦІЯ ТА СТІЙКІСТЬ ПОШКОДЖЕНОЇ КОНСТРУКЦІЇ ТРАНСПОРТНОГО ЛІТАКА

Open Information and Computer Integrated Technologies ◽

10.32620/oikit.2020.87.10 ◽

2020 ◽

pp. 173-180

Author(s):

Є. Ю. Іленко ◽

В. М. Онищенко

Keyword(s):

Dynamic Stability ◽

Equations Of Motion ◽

Initial Perturbation ◽

Aerodynamic Characteristics ◽

Operating Conditions ◽

Ultimate State ◽

Main Method ◽

Operating Load ◽

The Stability

In the process of designing and operating the aircraft, it is important to determine the ultimate state of the structure, taking into account the dynamic load of the structure and its stability. The ultimate state of the structure is characterized by damage, in which the structure still retains the ability to withstand without catastrophic destruction of the maximum operating load. The main method of studying the stability of the structure is the dynamic method. It allows us to investigate the perturbed motion of a structure as a nonconservative system for some initial perturbation. The monotonic departure of the system from the equilibrium position or its oscillations with increasing amplitudes indicate the instability of the structure. The paper analyzes the effect of damage to the aircraft structure on its dynamic stability based on the determination of the dynamic response of the aircraft to some non-stationary perturbation, for example, on the action of a turbulent atmosphere. The method of computational analysis is used to study the dynamic stability of the structure. The basis of this method is mathematical modeling (MM) of the operation of the aircraft in the form of a system of equations of motion and deformation of the structure. The problem of dynamic aeroelasticity is considered - the behavior of the elastic damaged structure of the aircraft in the air flow to the initial perturbation. On the basis of computer simulation, the dynamic stability of the elastic structure, its oscillating or quasi-static (aperiodic) deformation motion within the flight range of the aircraft is estimated. On the basis of parametric researches the limits of instability of a design at the set damages for typical operating conditions are estimated. The relevance of the direction focused on the creation and advanced operation of MM aircraft - their mathematical backups in the process of design and operation of aircraft due to the complexity and limited capabilities of ground experimental installations and flight experiment. It is noted that the condition for the application of this method is the formed MM operation of the aircraft and the availability of information on the mass-inertial, stiffness and aerodynamic characteristics of the aircraft.

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METHODS OF SOLVING THE STABILITY QUARTIC AND DETERMINATION OF DYNAMIC STABILITY CRITERIA

Aircraft Dynamic Stability and Response ◽

10.1016/b978-0-08-024768-7.50022-3 ◽

1980 ◽

pp. 207-215

Keyword(s):

Dynamic Stability ◽

Stability Criteria ◽

The Stability

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DETERMINATION OF THE TYPE OF A SINGLE-USE GRENADE LAUNCHER BASED ON ITS COMPOSITE PARTS AND FRAGMENTS OF REACTIVE GRENADE FOUND AT THE PLACE OF ACCIDENT

Theory and Practice of Forensic Science and Criminalistics ◽

10.32353/khrife.2017.31 ◽

2017 ◽

Vol 17 ◽

pp. 245-252

Author(s):

V. V. Somov

Keyword(s):

Combustion Chamber ◽

Structural Features ◽

Outlet Section ◽

Technical Expertise ◽

Jet Engine ◽

Size Ofthe ◽

Single Use ◽

Nozzle Block ◽

Considerable Damage

In carrying out an investigation into the explosion, among others, the investigative version of the use of a single-use reactive grenade launcher is being considered. The most common for criminal explosions are applied grenade launchers RPG-18, RPG-22, RPG-26. Their use is due to a number of such properties as small size and weight, which makes it possible to transfer them covertly, the range of the shot significantly exceeding the range of the hand grenade throw, the high detonating effect of the rocket grenade explosion. The single-use rocket launchers are generally of the same design. Their differences are in the features of the components construction and dimensional characteristics, which are given in the article. On the basis of expert practice, details ofgrenade launchers that remain at the site of the explosion and have the least damage are determined. These details are the objects of investigation of the explosion technical expertise. These objects include launchers of grenade launchers and rocket parts ofjet grenades. The design features of the launchers, their dimensional characteristics and marking symbols make it possible to determine their belonging to a specific type of jet grenade launchers. Missile parts of jet grenades differ in the form of the combustion chamber of the jet engine, nozzle, in the size ofthe outlet section of the nozzle, in the form and size of the stabilizerfeathers. To determine the belonging of the rocket part of the grenade to a specific type ofjet grenade launcher, it’s necessary to establish a set of structural features and dimensional characteristics. At considerable damage of the combustion chamber of the jet engine, as a rule, the nozzle block remains intact that allows to define diameter of critical section of a nozzle, and on it to establish type of the used single-use grenade launcher.

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Determination of the Stability of Thiamin, Nicotinic Acid and Riboflavin in Whisky over a Six-Month Period

Quarterly Journal of Studies on Alcohol ◽

10.15288/qjsa.1943.3.541 ◽

1943 ◽

Vol 3 (4) ◽

pp. 541-545 ◽

Cited By ~ 3

Author(s):

Arthur F. Novak ◽

Stuart L. Adams

Keyword(s):

Nicotinic Acid ◽

The Stability

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Anisotropy of Nanoindentation – a tool for the determination of nanocrystal orientation ?

MRS Proceedings ◽

10.1557/proc-779-w5.14 ◽

2003 ◽

Vol 779 ◽

Author(s):

David Christopher ◽

Steven Kenny ◽

Roger Smith ◽

Asta Richter ◽

Bodo Wolf ◽

...

Keyword(s):

Crystal Surface ◽

Scanning Force Microscopy ◽

Depth Range ◽

Dislocation Loops ◽

Force Microscopy ◽

Pile Up ◽

Out Of Plane ◽

Scanning Force ◽

Dynamics Simulations

AbstractThe pile up patterns arising in nanoindentation are shown to be indicative of the sample crystal symmetry. To explain and interpret these patterns, complementary molecular dynamics simulations and experiments have been performed to determine the atomistic mechanisms of the nanoindentation process in single crystal Fe{110}. The simulations show that dislocation loops start from the tip and end on the crystal surface propagating outwards along the four in-plane <111> directions. These loops carry material away from the indenter and form bumps on the surface along these directions separated from the piled-up material around the indenter hole. Atoms also move in the two out-of-plane <111> directions causing propagation of subsurface defects and pile-up around the hole. This finding is confirmed by scanning force microscopy mapping of the imprint, the piling-up pattern proving a suitable indicator of the surface crystallography. Experimental force-depth curves over the depth range of a few nanometers do not appear smooth and show distinct pop-ins. On the sub-nanometer scale these pop-ins are also visible in the simulation curves and occur as a result of the initiation of the dislocation loops from the tip.

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