Mechanism is a subject that focuses on the structure and motion of mechanisms in machinery, and is the main branch of mechanical principles.A subject that studies the common problems of the structure, motion and force of the relevant mechanisms in various machines.
The research content is divided into two aspects: the first is the research of existing mechanisms, namely mechanism analysis (structural analysis, kinematic analysis and dynamic analysis);The second is to design new mechanisms according to requirements, namely mechanism synthesis (structure synthesis, motion synthesis and dynamic synthesis).
Mechanical extension has strengthened the function of human limbs, while computer has greatly extended and strengthened the function of human brain.Modern machinery is an integrated system composed of machinery and computer. It consists of five subsystems: mechanism, drive, control, sensing and information processing. The mechanism system is the skeleton and actuator of modern machinery.Mechanism is a subject that focuses on the structure and motion of mechanisms in machinery, and is the main branch of mechanical principles.A subject that studies the common problems of the structure, motion and force of the relevant mechanisms in various machines.
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Traditional mechanics regards the motion of a mechanism as only related to its geometric constraint mode, but related to the forcequalityandtimeAnd other unrelated subjects.In this way, in the middle of the 19th century, mechanism science was independent from general mechanics and developed increasingly.Mechanism studies the structure and motion of various commonly used mechanisms, such as linkageCam mechanism、Gear unit, differential mechanismIntermittent motion mechanism、Rectilinear motionMechanism, screw mechanism and directional mechanism, as well as the common problems of these mechanisms, are analyzed and synthesized theoretically and methodically.Mechanism analysis includes structure analysis and motion analysis.The former studies the composition of the mechanism and judges its movement possibility and certainty;The latter investigates the variation of displacement, velocity and acceleration during the movement of the mechanism, so as to determine its motion characteristics.
It is essential to master the method of mechanism analysis for how to use the machine rationally and verify whether the mechanical design is perfect. Therefore, mechanism analysis is also the basis of mechanism synthesis.But sometimes there is no unique solution for synthesis, so mechanism analysis and synthesis are often irreversible.
When designing a new machine, two issues should be considered first: first, what kind of movement should be taken to complete a certain process or production, which is a professional issue;The second is what mechanism is used to realize this movement, which is the problem of mechanism synthesis.The so-called mechanism synthesis is to select the structure type of the mechanism, determine the geometric size of the mechanism according to the required motion, that is, carry out the structure synthesis and motion synthesis of the mechanism, and then draw the motion sketch of the mechanism that can achieve the desired motion.For high-speed or high-precision mechanisms, in order to better conform to the actual situation, the dynamic analysis and dynamic synthesis of practical factors such as component elasticity and clearance of kinematic pairs should also be considered.
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In the past, most of the methods of mechanism analysis and synthesis used to use graphical methods, but in modern times, due to thecomputerWith the development of aided design and optimal design, analytical methods have been more and more widely used.
In the second half of the 18th century, the first industrial revolution promoted the rapid development of mechanical engineering discipline, and mechanics developed into an independent discipline on the basis of the original mechanical mechanics.From the end of the 18th century to the beginning of the 19th century, the foundation of mechanism synthesis theory was laid by the works of geometers and mechanics such as Romonosov and Euler.By the second half of the 19th century, the geometric school represented by Palmerster and Lelow, based on the geometry of motion, and represented by Chebyshev, based onFunction approximation theoryAlgebraic school based on.In the 1970s, Japan proposed "mechatronics" to define a new concept of mechatronics, while the United States proposed that it was "coordinated and controlled by computer information networks".Therefore, the formation of the concept of "modern machinery" is a new milestone in the development of mechanism.
2. Analysis and effectiveness of NSFC funding
Like other basic sciences, mechanics is an exploratory discipline with greater depth and difficulty, which needs a solid foundation.Its research is a hard process, which often requires years or even generations of efforts to explore.Its research results run through the whole mechanical engineering.According to statistics, the National Natural Science Foundation of China (NSFC) supported about 400 programs in the discipline of institutional science from 1986 to 2011, including more than 50 programs involving the use of modern mathematical tools to solve institutional problems.With the support of the National Natural Science Foundation of China (NSFC), most of the achievements of Chinese institutional science in various research directions and stages are inseparable from mathematical tools. Most of the high-level academic papers published in recent years use mathematical tools to solve institutional problems[1]。
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(1) Mechanism is the basic subsystem of modern mechanical system. Mechanism and drive, control, information and other disciplines intersect and integrate. The research method is multidisciplinary synthesis, and the research content is significantly expanded compared with traditional mechanisms.
(2) The topology, kinematics and dynamics of the mechanism realize unified modeling, and create a combination of the three. Considering the system theory of driving and control technology, it provides a new method for innovative design.
(3) The combination of mechanism innovative design theory and computer technology provides a technical basis for the development of practical software for mechanism innovative design.
(4) Based on the principle of "natural machinery", new types of mechanisms are developed and bionic mechanisms are developed.The innovative design of mechanism determines the innovation of products.If the design of the mechanism is defective, the product will be a congenitally deficient product or a "disabled machine".For product innovation, the innovative design of mechanism topology has the characteristics of originality, and is the most challenging and inventive core content in mechanical invention.Therefore, the research of modern mechanism is of great significance to improve the independent design, innovation and international competitiveness of China's mechanical products.
