A brief history of statics development

The term statics was introduced by French mathematician and mechanic Pierre Varinon in 1725. It can be inferred from the existing ancient buildings that the builders at that time had used some mechanical knowledge gained from experience, and in order to lift and carry heavy objects, they had been able to use some simple machinery (such as levers, pulleys and inclined planes). ).

Statics began to develop in the 3rd century BC, and Galileo laid the foundation of dynamics in the 6th century. This period experienced the late slave society, feudal period and early Renaissance in Western Europe. Due to the requirements of agriculture and construction industry, as well as the needs of precision measurement related to trade development, the development of mechanics has been promoted. On the basis of using simple tools and machinery, people gradually sum up the concepts and axioms of mechanics. For example, the concept of torque is derived from pulleys and levers; Parallelogram law of inclined plane stress, etc.

Archimedes was the founder who made statics a real science. In his book about the balance and center of gravity of plane graphics, he founded the lever theory and laid the main principle of statics. Archimedes concluded that the lever balance condition is that if the length of the two arms of the lever is inversely proportional to the weight of the object on it, the two objects must be in balance. Archimedes was the first person to find the center of gravity of parallelogram, triangle and trapezoid with strict reasoning. He also used the approximate method to find the center of gravity of the parabolic segment.

Leonardo da Vinci, a famous Italian artist, physicist and engineer, was one of the first people to jump out of the complex science of the Middle Ages during the Renaissance. He thinks that experiments and solving mechanical problems with mathematics are of great significance. He explained the working principle of pulley by torque method; The concept of virtual displacement principle is applied to analyze the pulley and lever system in lifting mechanism. In one of his drafts, he also analyzed the decomposition of vertical force; The slope motion and sliding friction resistance of objects are studied. Firstly, it is concluded that the sliding friction resistance has nothing to do with the size of the friction contact surface of the object.

Steven is the most successful person who studies the mechanical problems of objects on inclined planes. He drew and demonstrated the parallelogram force law. Statics is not complete until Wallinon puts forward the famous Wallinon theorem. The polygon principle of him and Panso is the basis of graphic statics.

Graphic statics, as a method to solve problems with graphics in statics. Although the accuracy of the obtained results is not as good as the numerical solution, it can get a clear answer quickly, so it is often used in the design of general engineering structures. This method is convenient to adjust the original data at any time and quickly find out the errors in the calculation process, and can be used to compare the advantages and disadvantages of several design schemes.

Analytical statics was put forward by Italian mathematician and mechanic J.L. Lagrange. In his large-scale book Analytical Mechanics, he described the whole mechanical theory with strict analytical methods according to the principle of virtual displacement. The principle of virtual displacement was pointed out by Bernoulli as early as 17 17, but the further development of the method of solving mechanical problems by applying this principle and its mathematical research are the achievements of Lagrange.

Ancient scientists in China made great contributions to statics. Mo Zhai, a great philosopher in the Spring and Autumn Period and the Warring States Period (from 5th century BC to 4th century BC), analyzed the lever, shaft and inclined plane in his masterpiece Mo Jing, clearly pointed out that "balance ... is heavy, while short is light" and put forward the principle of balance of lever.