Human understanding of some basic principles of mechanics can be traced back to prehistoric times. Mechanics has been described in the works of ancient China and ancient Greece. But buildings before the Middle Ages were built by experience.
1638 In March, Galileo's book Dialogue and Mathematical Proof on Two New Sciences was considered as the first book on mechanics of materials in the world, but his research on stress distribution in beams was not mature.
In 18 19, Navi proposed a complete solution for the strength and deflection of beams. 1821May 14, Navid read the article "General Equation of Balance and Motion that All Points on the Surface and Inside of an Object Should Be Established" at the Paris Academy of Sciences, which is considered as the basis of elasticity theory. Later, in 1870, Saint Venan published a paper on plasticity theory. Hydraulics is also an ancient discipline.
As early as the Spring and Autumn Period and the Warring States Period in China (5th-4th century BC), Mo Zhai described the relationship between the buoyancy of an object and the volume of liquid it displaced in the Mohist Classic. Euler put forward the motion equation of ideal fluid. Rheology of objects is a new subject to study generalized mechanical motion. 1929, Bingham, USA initiated the establishment of the Rheology Society, and this discipline received widespread attention.
research method
It is divided into experimental research and theoretical analysis and calculation. However, the two are often used synthetically and promote each other.
experimental research
Including experimental mechanics, structural inspection and structural test analysis. Model tests are divided into local model tests and overall model tests. The field test of the structure includes the test of structural members and the test of the whole structure. Experimental research is the main means to verify and develop theoretical analysis and calculation methods. Field testing of structures has other purposes:
(a) to verify whether the function and safety of the structure meet the requirements of structural planning, design and construction;
(2) identify the integrity of the structure in the use stage and obtain the maintenance and reinforcement data.
Theoretical analysis and calculation
The step of structural theoretical analysis is to determine the calculation model first, and then choose the calculation method.
Soil mechanics was gradually formed at the beginning of the 20th century and developed rapidly after the 1940s. In the early stage of its formation and development, Karl Terzaghi played an important role. Rock mechanics is a young discipline. Since 1950s, it has organized special academic discussions, and since then, it has expanded from studying the properties of hard rocks with discontinuities to studying the properties of soft rocks. Rock mechanics is the combination of engineering mechanics and engineering geology.
From19th century to the first half of 20th century, the characteristic of continuum mechanics is to study the properties of various objects, such as the stiffness and strength of beams, the stability of columns, the relationship between deformation and force, elastic modulus and viscous modulus. Continuous mechanics in this period studied the properties of objects from a macro perspective through experimental analysis and theoretical analysis. It is extended from the law of particle mechanics to the law of continuous mechanics, so there are naturally some contradictions.
So based on the progress of physics and modern mathematics in the first half of the 20th century, a new discipline-rational mechanics appeared. 1945 Lai Na put forward a paper on viscous fluid analysis, 1948 rivlin put forward a paper on elastic solid analysis, which gradually laid a new system of so-called rational continuum mechanics.
With the progress of structural engineering technology, engineers have contributed to the progress of engineering mechanics, as well as mechanics and mathematicians. If there was no analysis method for trusses in the early stage of development, it was not until 1847 that whipple, an American bridge engineer, published the correct analysis method for trusses. The application of computers and modern experimental equipment, the research of new materials and new construction technology and the application of modern mathematics have promoted the rapid development of engineering mechanics.
Particle, particle system and rigid body mechanics are the research objects of theoretical mechanics. The so-called rigid body refers to an idealized solid whose size and shape are fixed and will not change due to external effects, that is, the distance between points in the particle system is absolutely constant. The theoretical basis of theoretical mechanics is Newton's law, which is the mechanical basis for studying engineering technology science.
Solid mechanics includes material mechanics, structural mechanics, elastic mechanics, plastic mechanics, composite mechanics and fracture mechanics. Especially the first three disciplines of mechanics are widely used in civil engineering. Traditionally, these three disciplines are collectively referred to as architectural mechanics to illustrate that this is a discipline that studies the influence of various functions on various forms of civil buildings with the general principles of mechanics.
In the late 1950s, with the appearance of computer and finite element method, an interdisciplinary subject-computational mechanics was gradually formed. Computational mechanics is divided into two branches: basic computational mechanics and engineering computational mechanics. When the latter is applied to architectural mechanics, its four pillars are architectural mechanics, discretization technology, numerical analysis and computer software. Its task is to study the computer programming method, structural optimization method and structural analysis image display by using discretization technology and numerical analysis method.
Many branches of engineering mechanics can be subdivided into statics and dynamics if they are classified according to the nature that makes the structure react. For example, structural statics and structural dynamics, the latter mainly includes structural vibration theory, wave mechanics and structural dynamic stability theory. Because the external force applied to the structure is almost random, and the strength of the material is also uncertain in nature.
With the progress of science and technology, since the 1950s, the application of probability and statistics theory in engineering mechanics has become more and more extensive and in-depth, and new branches and methods have gradually formed, such as reliability mechanics and probabilistic finite element method.