Advanced Materials in Machine Design

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Authors: Aleksander Banaś, Aleksander Muc
Abstract: The analysis of optoelectromechanical properties of nanostructures in bandstructure engineering is discussed In the paper. It is demonstrated that the design of semiconductors is based on the solution of different forms of the Schrodinger (Helmmholtz) equation, dependant on the form of the Hamiltonian characterizing quantum effects. The formulation can lead to the linear or nonlinear eigenvalue problems. Then, the methods of solutions are also presented.
Authors: Aleksander Banaś, Aleksander Muc, Małgorzata Chwał
Abstract: In the paper the stress-strain of pristine and defective single walled carbon nanotubes are investigated. The defects are in the form of point vacancies. The axial deformations of structures are studied only. A special attention is focused on the effects of material and geometrical properties of nanostructures on the results.
Authors: Marek Barski, Małgorzata Chwał, Piotr Kędziora
Abstract: The present paper is devoted to computational simulations of magneto - rheological fluids behavior subjected to external magnetic fields. In order to perform these simulations the modified molecular dynamic algorithm is adopted. The theoretical model of the magneto - rheological fluid in micro scale as well as the basic interactions between the ferromagnetic particles are discussed. Moreover, the classical molecular dynamic algorithm and its necessary modifications are also described. The proposed approach makes possible to study the process of the internal structure (constructed from the ferromagnetic particles) formation under external magnetic field. The obtained results in the form of the particle distribution in the representative volume can be further used in order to evaluate the mechanical or physical properties of the fluid in macro scale, for example magnetic permeability, heat conduction, etc.
Authors: Małgorzata Chwał, Piotr Kędziora, Marek Barski
Abstract: Efforts in the field of polymeric nanocomposites reinforced by carbon nanotubes are presented in the literature from many years. The discussed problems are connected with the characterization of nanocomposites and the modeling of elastic and fracture behavior at the nanoscale. The experimental investigations and the theoretical modeling are conducted simultaneously. The theoretical approaches try to elucidate the experimental observations. In the present paper a brief overview of the analytical and numerical modeling of polymeric nanocomposites reinforced with carbon nanotubes is presented. The attention is mainly focused on the molecular dynamic models, the continuum mechanics approaches and finally the multi-scale models are discussed. The good and wrong sides of the models are pinpointed. Also a comparison between values of Young's modulus of carbon nanotube/polymer nanocomposites for various methods is presented.
Authors: Stefan Chwastek
Abstract: Design of state-of-the art crane mechanisms involves a multi-stage and multi-criterial optimization. Depending on the specificity and intended use of the machine, the optimal structure and dimensions of its mechanisms are sought as well as optimal algorithms for drive control and regulation, which requires the application of optimization criteria. It appears, however, that the approach relying on the minimum of a specifically formulated quadratic functional enables the selection of optimal geometric parameters of the mechanism and, besides, proves effective as the method of drive control. Furthermore, the geometric parameters of the mechanism can be optimized for its entire working range. Simplicity, universality and efficiency of the method are demonstrated on the example of a slewing one-link jib crane system. The search for the optimal control strategy of drive mechanisms is illustrated in the study that investigates an asymmetrically loaded platform suspended on ropes and people moving with respect to it during the hoisting phase. I. Parametric optimization of slewing mechanisms in one-link crane systems
Authors: Piotr Kędziora
Abstract: In this paper, the various optimization criteria used for optimal placement of piezoelectric actuators on laminated structures are discussed. Piezoelectric materials are used as layers or fibers that are embedded within or bonded to the surfaces of a structure. The present formulation of optimal design introduces also boundaries of piezoelectric patches as new class of design variables.
Authors: Piotr Kędziora, Marek Barski, Małgorzata Chwał
Abstract: Piezoelectric materials are used as layers or fibers that are embedded within or bonded to the surfaces of a structure. Piezoelectric transducers can be made in the different shapes. Piezoelectric elements are mainly made of polymer or ceramic materials.
Authors: Maciej Krasiński, Marek Stodulski, Andrzej Trojnacki
Abstract: The paper deals with a stress modification in thick-walled multi-layer pressure vessels widely used in every field of high pressure technology. The stress modification is obtained by means of initial (residual) stresses which are introduced into the vessel structure during the manufacturing process. Certain technological parameters are determined. Their realization leads to the equivalent stresses being more uniformly distributed across the vessel wall under the operating pressure. As a consequence the load carrying capacity of the multi-layer vessel increases as compared with the solid wall without additional treatment. The analytical approach as well as the finite-element method are used to solve the problem. A special attention is focused on the unconventional original Polish technology in which the internal pressure is applied to form the thick multi-layer cylinder wall through subsequent expansion of thin layers. The advantages of the proposed method are illustrated by the numerical example of the expanded multi-layer high-pressure vessel with modified initial stress distribution.
Authors: Piotr Kucybała
Abstract: The presented paper deals the simulation model of hydro-pneumatic accumulator. Mathematical model of the system uses the motion and flow continuity equations as well as formulas determining hydro-pneumatic piston accumulator behavior. In accumulator model heat transfer phenomena are included and Van der Waals real gas low, to calculate gas parameters during its operation. Modeling and simulation tests are performed for different work cycles to determine the key parameters of hydrostatic system associated with energy saving, such as: piston velocity, working pressure and heat flux. The aim of the research program is to determine the efficiency of energy accumulation in the assumed work cycles and to find which parameters are significant and how they can be changed to increase accumulator efficiency.

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