Term paper on the Theory of mechanisms and machines as a basis for future scientific research
DOI:
https://doi.org/10.31734/agroengineering2022.26.037Keywords:
theory of mechanisms and machines, kinematic chain, dynamic synthesis, kinematic and dynamic analysis, mechanical characteristic of an asynchronous electric motorAbstract
The article considers the issue of composing the topic of the term paper in the Тheory of mechanisms and machines, which would correspond to the modern technologies of conducting theoretical research on the use of computer technology. The modern development of computer technology, software and their availability allows modernizing and expanding the tasks for the term paper. It is shown that replacement of the graph-analytical methods with analytical ones will not only free up time for the term paper, but will also allow students to get acquainted with the first two stages of designing mechanisms and machines – tasks of synthesis and analysis.
In the article, a kinematic synthesis of a crank-and-rocker mechanism is carried out according to the extreme positions of the executive link (rocker arm) and the lengths of the links are determined. The scheme of the kinematic chain of an actuator drive and its dynamic model is shown. A dynamic synthesis of the executive lever mechanism is carried out and the combined moments of inertia and forces of resistance to the crank are determined. A mathematical model of movement of the crank is recorded. To simplify mathematical calculations, the combined moment of inertia and resistance forces are assumed as constant. A straight line approximates the stable interval of operation of the electric motor and its coefficients are determined. The formula for the angular speed of the crank is given and its graph is plotted. The brand of the electric motor and the gear ratio of the kinematic chain reducer are determined by the maximum moment of the resistance forces. For the synthesized law of crank motion, the kinematic and force analysis of the lever mechanism was carried out. The kinematic characteristics of the mechanism links and reactions in kinematic pairs were calculated. The results of calculations are shown in the form of graphs and hodographs of forces. To check the correctness of the analytical calculations, the balancing moment is calculated in two ways and the obtained results are compared.
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