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3 Journal of Achievements in Materials and Manufacturing Engineering

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Dynamical flexibility of the free-free damped rod in transportation

100%

Żółkiewski S.

2009

tom Vol. 35, nr 1

71-78

Purpose: of this thesis is derivation of dynamical flexibility of the free-free rod system in transportation. The well-known problem of dynamical analysis of systems in rotational transportation was developed in this work to systems with taking into consideration damping forces. Design/methodology/approach: The dynamical flexibility method was used to analysis of the free-free rod’s vibrations. Mathematical models derived in previous articles were used to derivation of the dynamical flexibility. Considerations were done by the Galerkin’s method. Findings: There were considered systems in rotational motion treated in this thesis as main transportation. Dynamical characteristics in form of dynamical flexibility as function of frequency and mathematical models were presented in this work. Research limitations/implications: Analyzed systems were simple linear homogeneous not supported rods. Working motion was limited to plane rotational motion. Future works would consider complex systems and nonlinearity. Practical implications: of derived dynamical characteristics can easily support designing process and can be put to use in stability analysis and assigning stability zones. Thank to derived mathematical models the numerical applications can be implemented and some calculations can be automated. Originality/value: Analyzing models are rotating flexible free-free rods with taking into consideration the damping forces.

Dynamical flexibilities of mechanical rotational systems

100%

Żółkiewski S.

tom Vol. 31, nr 2

602-609

Purpose: of this work is to present dynamical flexibilities of rotational beams and rods systems. The results of mathematical calculations were presented in the form of dynamical flexibility of analyzed systems. In final solution there were took into consideration the interactions between the major motions and local vibrations of subsystems. Design/methodology/approach: The dynamical flexibilities were derived by the Galerkin's method. The dynamical flexibilities for example numerical cases were presented onto charts of attenuation-frequency characteristics. The mathematical models were derived on the basis of known equations of motion derived in previous thesis's. Findings: After analysis of characteristics we can observe the transportation effect. We can notice additional poles on the characteristic of dynamical flexibility characteristics and after increasing angular velocity created modes symmetrically propagate from the origin mode and instead of the original mode there is created a zero's amplitude. Research limitations/implications: Analyzed systems are beams and rods in rotational motion. Motion was limited to plane motion. Future works will be connected with consideration of complex systems. Practical implications: of derived dynamical flexibilities of free-free and fixed beams and rods systems is a possibility of derivation of the stability zones of analyzed systems and derivation of eigenfrequencies and zeros in the function of angular velocity of work motion. Originality/value: Models analyzed in this thesis apply to rotating rod and beam systems with taking into consideration the transportation effect. This new approach of analyzing rod and beam systems can be put to use in modelling, analyzing and designing machines and mechanisms with rotational elements.

Mechanical systems vibrating longitudinally with the transportation effect

80%

Buchacz A. , Żółkiewski S.

tom Vol. 21, nr 1

63-66

Purpose: High work speeds of mechanisms, using materials with high flexibility, high precision of work, etc. are the cause of searching of the new ways of modelling. One of these ways is presented in this thesis. The main purpose of this thesis is the dynamical analysis with taking into consideration the interaction between main motion and local vibrations during the model is loaded by longitudinal forces. Design/methodology/approach: Derived equations of motion were made by classical methods, with generalized coordinates and generalized velocities assumed as orthogonal projections of individual coordinates and velocities of the rod and manipulators to axes of the global inertial frame. Findings: Mathematical model of the longitudinally vibrating systems in terms of plane motion can be put to use to derivation of the dynamical flexibility of these systems, and also those equations are the starting point to the analysis of complex systems, especially we can use those equations to derivation of the substitute dynamical flexibility of n-linked systems in transportation. Research limitations/implications: In the thesis were considered mechanical systems vibrating longitudinally in terms of rotation. Next problem of dynamical analysis is the analysis of systems in non-planar transportation and systems loaded by transversal forces. Practical implications: Results of this thesis can be put to use into machines and mechanisms in transportation such as: wind power plant, high speed turbines, rotors, manipulators and in aerodynamics issues, etc. Originality/value: Up to now there were analyzed beams and rods in a separate way, first main motion of the system and after that the local vibrations. The new approach of modelling were presented by authors of this thesis, a new modelling took into consideration the interaction between those two displacements. There was defined the transportation effect for models vibrating longitudinally in this thesis.