Some problems of dynamics for tethered and hinged (very short tether) bodies are presented in thi... more Some problems of dynamics for tethered and hinged (very short tether) bodies are presented in this paper. General problem of kinematics of systems is presented in the first part of the paper. For bodies in gravitational field the motion with respect movable references is important to be known (2). Equations of relative motion of the rigid body are used (3)
The principle of virtual work is used to study the motion of a system under the action of externa... more The principle of virtual work is used to study the motion of a system under the action of external and internal forces. General kinematics problem of systems of rigid bodies with constraints are presented in first part of the paper. If an internal force has to be found, a ...
The principle of virtual work or Lagrange equations can be used in order to study the motion of a... more The principle of virtual work or Lagrange equations can be used in order to study the motion of a system under the action of external forces, or to find reactions, as well as various other internal forces. The principle of virtual work is used to study the motion of ...
Due to the permanent extension of space activities, the danger generated by the larger space debr... more Due to the permanent extension of space activities, the danger generated by the larger space debris objects is increasing. Mechanisms and procedures to remove those objects should be developed in the next future. It is to be thought that the objects in LEO would be removed by putting them in into an earth atmosphere entry orbit, while those in GEO could be placed into an orbit 300 km or more higher than the nominal geostationary orbit. This paper deals with the general problem of dynamics for a system formed of a remover vehicle and a removed object. The trajectory and the attitude motion are considered for the remover and the debris. The number of degrees-of-freedom of the system is reduced, considering the joint system. Particular cases of tethered systems can be in correlation with the TERESA (Tethered Remover Satellite) concept, which has been developed by P. Eichler and A. Bode or with TOT (Tumble Orbit Transfer), initially proposed by T. Yasaka. Lagrange’s equations for holono...
This paper is filling an important gap in the scientific literature dealing with the vibrations o... more This paper is filling an important gap in the scientific literature dealing with the vibrations of rotor blades which sustain large deformations during normal operation. Although the occurring phenomena are known, there is no succinct and complete approach in recent literature in order to clarify this aspect. Therefore, it will be shown that the traditional approach to natural vibration calculation is not sufficient in order to obtain accurate results.
Acesta lucrare reprezintă un studiu asupra creşterii acurateţii rezultatelor care privesc stabili... more Acesta lucrare reprezintă un studiu asupra creşterii acurateţii rezultatelor care privesc stabilitatea lateral-directională a unui avion real aflat în stadiul de proiectare, folosind rezultatele obtinute pe un model zburator construit la scară. Sunt propuse criterii coerente privind similitudinea dimensională, masică, inertială şi cinematică între avionul real şi modelul mockup la scară. Rezultatele comparative între avionul real şi modelul la scară arată aceleaşi valori pentru factorul de amortizare în modul „ruliu olandez”. Sunt obţinute valori factorizate cu o constanta, pentru caracteristicile de timp în modurile „ruliu olandez”, „ruliu” şi „spiral”.
By modelling the corresponding direct and inverse problems, it is possible to determine positions... more By modelling the corresponding direct and inverse problems, it is possible to determine positions in terms of the end-effector’s timing and that it may impose different travel paths within a set time so that the final effect should achieve precise tasks. The practical aspect can be inferred by analyzing the kinematics of the serial robot SCORBOT ER-VII at the same time determining velocity and acceleration charts for a characteristic point on the end-effector.
The motion of the center of mass of a spacecraft, considered a rigid body, under the effect of a ... more The motion of the center of mass of a spacecraft, considered a rigid body, under the effect of a gravitational center is analyzed. Newton's equations are used for the variation of the orbital elements, showing the trajectory perturbations of the center of mass. Two particular cases are studied: (1) the rapid rotation, and (2) the gravitational stabilization.
Due to the permanent extension of space activities, the danger generated by the larger space debr... more Due to the permanent extension of space activities, the danger generated by the larger space debris objects is increasing. Mechanisms and procedures to remove those objects should be developed in the next future. It is to be thought that the objects in LEO would be removed by putting them into an Earth atmosphere entry orbit, while those in GEO could
Lagrange formalism and the principle of virtual work are used to study the motion of a system und... more Lagrange formalism and the principle of virtual work are used to study the motion of a system under the action of know external and internal forces. If an internal force has to be found, a supplementary mobility is considered in the system. The corresponding internal force for new mobility is found for zero mobility. General kinematics problem of systems of rigid bodies with constraints are presented in the first part of the paper. Based on a comparative analysis of the Lagrange formalism and the principle of virtual work, the models and the elaborated methods allow solving a large number of problems in multi-bodies systems dynamics.
Some problems of dynamics for tethered and hinged (very short tether) bodies are presented in thi... more Some problems of dynamics for tethered and hinged (very short tether) bodies are presented in this paper. General problem of kinematics of systems is presented in the first part of the paper. For bodies in gravitational field the motion with respect movable references is important to be known (2). Equations of relative motion of the rigid body are used (3)
The principle of virtual work is used to study the motion of a system under the action of externa... more The principle of virtual work is used to study the motion of a system under the action of external and internal forces. General kinematics problem of systems of rigid bodies with constraints are presented in first part of the paper. If an internal force has to be found, a ...
The principle of virtual work or Lagrange equations can be used in order to study the motion of a... more The principle of virtual work or Lagrange equations can be used in order to study the motion of a system under the action of external forces, or to find reactions, as well as various other internal forces. The principle of virtual work is used to study the motion of ...
Due to the permanent extension of space activities, the danger generated by the larger space debr... more Due to the permanent extension of space activities, the danger generated by the larger space debris objects is increasing. Mechanisms and procedures to remove those objects should be developed in the next future. It is to be thought that the objects in LEO would be removed by putting them in into an earth atmosphere entry orbit, while those in GEO could be placed into an orbit 300 km or more higher than the nominal geostationary orbit. This paper deals with the general problem of dynamics for a system formed of a remover vehicle and a removed object. The trajectory and the attitude motion are considered for the remover and the debris. The number of degrees-of-freedom of the system is reduced, considering the joint system. Particular cases of tethered systems can be in correlation with the TERESA (Tethered Remover Satellite) concept, which has been developed by P. Eichler and A. Bode or with TOT (Tumble Orbit Transfer), initially proposed by T. Yasaka. Lagrange’s equations for holono...
This paper is filling an important gap in the scientific literature dealing with the vibrations o... more This paper is filling an important gap in the scientific literature dealing with the vibrations of rotor blades which sustain large deformations during normal operation. Although the occurring phenomena are known, there is no succinct and complete approach in recent literature in order to clarify this aspect. Therefore, it will be shown that the traditional approach to natural vibration calculation is not sufficient in order to obtain accurate results.
Acesta lucrare reprezintă un studiu asupra creşterii acurateţii rezultatelor care privesc stabili... more Acesta lucrare reprezintă un studiu asupra creşterii acurateţii rezultatelor care privesc stabilitatea lateral-directională a unui avion real aflat în stadiul de proiectare, folosind rezultatele obtinute pe un model zburator construit la scară. Sunt propuse criterii coerente privind similitudinea dimensională, masică, inertială şi cinematică între avionul real şi modelul mockup la scară. Rezultatele comparative între avionul real şi modelul la scară arată aceleaşi valori pentru factorul de amortizare în modul „ruliu olandez”. Sunt obţinute valori factorizate cu o constanta, pentru caracteristicile de timp în modurile „ruliu olandez”, „ruliu” şi „spiral”.
By modelling the corresponding direct and inverse problems, it is possible to determine positions... more By modelling the corresponding direct and inverse problems, it is possible to determine positions in terms of the end-effector’s timing and that it may impose different travel paths within a set time so that the final effect should achieve precise tasks. The practical aspect can be inferred by analyzing the kinematics of the serial robot SCORBOT ER-VII at the same time determining velocity and acceleration charts for a characteristic point on the end-effector.
The motion of the center of mass of a spacecraft, considered a rigid body, under the effect of a ... more The motion of the center of mass of a spacecraft, considered a rigid body, under the effect of a gravitational center is analyzed. Newton's equations are used for the variation of the orbital elements, showing the trajectory perturbations of the center of mass. Two particular cases are studied: (1) the rapid rotation, and (2) the gravitational stabilization.
Due to the permanent extension of space activities, the danger generated by the larger space debr... more Due to the permanent extension of space activities, the danger generated by the larger space debris objects is increasing. Mechanisms and procedures to remove those objects should be developed in the next future. It is to be thought that the objects in LEO would be removed by putting them into an Earth atmosphere entry orbit, while those in GEO could
Lagrange formalism and the principle of virtual work are used to study the motion of a system und... more Lagrange formalism and the principle of virtual work are used to study the motion of a system under the action of know external and internal forces. If an internal force has to be found, a supplementary mobility is considered in the system. The corresponding internal force for new mobility is found for zero mobility. General kinematics problem of systems of rigid bodies with constraints are presented in the first part of the paper. Based on a comparative analysis of the Lagrange formalism and the principle of virtual work, the models and the elaborated methods allow solving a large number of problems in multi-bodies systems dynamics.
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