Pyrlyk M. Substantiation of Parameters of an Inertia-Free Load Applicator with an Autonomous Vibration Exciter for Additional Compaction of Concrete Mixtures

The dissertation is devoted to solving an urgent scientific and technical problem of increasing the efficiency of concrete mixture compaction in the forming of concrete and reinforced concrete products by developing and substantiating the parameters of an inertia-free load applicator with an autonomous vibration exciter. The relevance of the study is обусловված by the need to improve the quality and homogeneity of concrete products, reduce the duration of the forming cycle, decrease energy consumption, and improve vibration equipment used for product manufacturing, in particular reinforced concrete rings for engineering networks. The scientific novelty of the obtained results lies in the following: – the design solutions of load applicators for additional compaction of concrete mixtures have been further developed through the use of an autonomous vibration exciter, which provides a local additional dynamic effect on the upper part of the product during vibration forming; – a mathematical model of the system “vibrating mold – concrete mixture – inertia-free load applicator” has been developed, which takes into account the combined action of the main vibrating mold and the autonomous load applicator on the concrete medium; – the regularities of the influence of the load applicator mass, the stiffness of elastic elements, the frequency of the autonomous vibration exciter, and the parameters of the main vibration system on the intensity of additional compaction of the concrete mixture have been established; – analytical dependences have been obtained for determining the oscillation amplitudes, accelerations, and dynamic pressure of the inertia-free load applicator on the concrete mixture, which made it possible to substantiate rational operating modes of the applicator; – the approach to evaluating the efficiency of combined compaction of the concrete mixture has been improved by taking into account the non-uniform transmission of vibration impact along the product height and the additional dynamic loading in its upper zone; – methods for the technical calculation of vibration installations for forming concrete products using additional working bodies for local additional compaction have been further developed. The practical significance of the obtained results lies in the fact that, on the basis of the performed theoretical and experimental studies, a design of an inertia-free load applicator with an autonomous vibration exciter has been developed, which can be used as part of vibration installations for forming concrete and reinforced concrete products. A method for the technical calculation of such installations has been proposed, which makes it possible to determine their main design and operating parameters already at the design stage. The developed technical solution provides improved uniformity of concrete mixture compaction, reduced defects in the upper zone of the product, shortened forming cycle duration, and improved quality of finished products. The results of the dissertation research have been implemented in the form of a prototype inertia-free load applicator with an autonomous vibration exciter, tested under industrial conditions at the limited partnership «Manufacturing enterprise Budmekhanizatsia» (Poltava). Certain results have also been used in the educational process at the National University “Yuri Kondratyuk Poltava Polytechnic” in teaching disciplines related to the theory and design of machines for the construction industry.