World trends and prospects of development of technological equipment complexes are considered. The applied stages and phases of machining equipment design are analyzed by means of constructing design ...schemes traditional for machine mechanics. It is proposed to create technological machine tool complexes by layout synthesis with the help of element base, which should contain functional technological and service modules, and the service purpose of the machine tool should include the nomenclature of manufactured surface modules. It is shown that the prospects of application of energy flows for intensification of machining processes should be analyzed at the early stages of design, using thermal and electrophysical criteria to study the emerging relations in the system. It is suggested to start designing mechatronic systems of machine tool complexes from the analysis of structural relations of information technologies in hybrid production including traditional and additive technologies.
An approach to the experimental and computational study of the shear properties of honeycomb cores (HC) produced using Fused Deposition Modeling (FDM) technology is proposed. The experimental ...approach is based on a new sample type for testing HCs for shear. This sample contains two HCs and three steel plates. Shear tests are carried out in the TiraTest 2300 universal tensile testing machine. The HCs are made of ULTEM 9085 and PLA with FDM technology, which is implemented in the 3D Fortus 900 system. The tests resulted in obtaining the shear properties of the HCs by averaging the stress-strain curves of five samples. As follows from the analysis of the experimental results, brittle destruction of an HC is observed. Before its destruction, the value of shear deformation for samples made of PLA was 0.0134, and for samples made of ULTEM, 0.0257. The experimental analysis was accompanied by numerical finite element (FE) modeling of shear experiments, taking into account the deformation of the equipment. With the FE modeling of the experiments, to describe the behavior of the samples, it is necessary to take into account the influence, on the measurements of the shear properties, of the equipment and the deformation of each honeycomb cell. The deformation of three plates was taken into account; the elastic properties of the adhesive joint were not taken into account. A computer model of the deformation of the HCs with equipment was built using ANSYS Design Modeler. With FE modeling, only the elastic behavior of the HCs was considered.
The authors derived a mathematical model of geometrically nonlinear vibrations of three-layer shells, which describes the vibrations of the structure with amplitudes comparable to its thickness. The ...high-order shear theory is used in the derivation of this model. Rotational inertia is also taken into account. At the same time, the middle layer is a honeycomb structure made thanks to additive FDM technologies. In addition, each shell layer is described by five variables (three displacement projections and two rotation angles of the normal to the middle surface). The total number of unknown variables is fifteen. To obtain a model of nonlinear vibrations of the structure, the method of given forms is used. The potential energy, which takes into account the quadratic, cubic, and fourth powers of the generalized displacements of the structure, is derived. All generalized displacements are decomposed by generalized coordinates and eigenforms, which are recognized as basic functions. It is proved that the mathematical model of shell vibrations is a system of nonlinear non-autonomous ordinary differential equations. A numerical procedure is used to study nonlinear periodic vibrations and their bifurcations, which is a combination of the continuation method and the shooting method. The shooting method takes into account periodicity conditions expressed by a system of nonlinear algebraic equations with respect to the initial conditions of periodic vibrations. These equations are solved using Newton's method. The properties of nonlinear periodic vibrations and their bifurcations in the area of subharmonic resonances are numerically studied. Stable subharmonic vibrations of the second order, which undergo a saddle-node bifurcation, are revealed. An infinite sequence of bifurcations leading to chaotic vibrations is not detected.
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•A new approach allows to evaluate the suitability of recycled carbon fibers as a reinforcing filler of plastics for additive technologies.•Recycled carbon fibers with clean surface ...from CFRP waste.•Suitability evaluation of reclaimed short carbon fibers for additive technologies.
This article presents a new approach to suitability assessment of short reclaimed carbon fiber (rCF) for additive technologies via commonly used analytical methods. Acrylonitrile butadiene styrene (ABS) based plastics reinforced with virgin or recycled CF samples were received, their mechanical properties and morphology of tensile fractured surface were determined by SEM (Scanning Electron Microscopy) and tensile strength test. As long as operating characteristics of CFRP are affected by single fiber strength as well as adhesion (interfacial interaction) between matrix and CF, this research also includes investigation of fiber surface with Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and X-ray diffraction (XRD). Correlation between suggested complex parameters of investigated CF and strength of plastics (CFRP) samples was shown. It was also established that contribution of each investigated parameter is additive.
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