Theoretical mechanics is a subject that studies the basic laws of mechanical motion of objects. A branch of mechanics. It is the basis of all branches of general mechanics. Theoretical mechanics is usually divided into three parts: statics, kinematics and dynamics. Statics studies the simplified theory of force system acting on objects and the equilibrium conditions of force system; Kinematics only studies the mechanical motion characteristics of objects from the geometric point of view, and does not involve the force of objects; Dynamics studies the relationship between mechanical motion and force. Dynamics is the core of theoretical mechanics. The research method of theoretical mechanics is based on some basic axioms or laws that reflect objective laws induced by experience or experiments, and the mechanical motion laws of objects in general and the characteristics of specific problems are obtained through mathematical deduction. Objects in theoretical mechanics mainly refer to particles, rigid bodies and rigid body systems. When the deformation of an object can not be ignored, it becomes the object of discussion in deformation mechanics (such as material mechanics and elastic mechanics). Statics and dynamics are the main parts of engineering mechanics.
2. Mechanics of materials
Mechanics of materials is to study the strain, stress, strength, stiffness and stability of materials under various external forces and the limits that lead to the failure of various materials. Generally speaking, it is a compulsory course for college students majoring in mechanical engineering, civil engineering and related majors. Learning material mechanics generally requires students to take advanced mathematics and theoretical mechanics first. Material mechanics, theoretical mechanics and structural mechanics are also called the three major mechanics. The research object of material mechanics is mainly rod-shaped materials, such as rods, beams and shafts. Structural mechanics discusses truss structure, and elastic mechanics discusses plate and shell structure.
3. Structural mechanics
Structural mechanics is a branch of solid mechanics, which mainly studies the law of stress and force transfer of engineering structures and how to optimize structures. It is a compulsory course for students majoring in civil engineering and machinery. The research content of structural mechanics includes the composition law of the structure and the response of the structure under various actions (external force, temperature effect, construction error, bearing deformation, etc.). ), including the calculation of internal force (axial force, shear force, bending moment and torque), displacement (linear displacement and angular displacement) and dynamic response (natural vibration period and mode shape) of the structure under dynamic load. There are usually three analytical methods in structural mechanics: energy method, force method and displacement method. Matrix displacement method derived from displacement method later developed into finite element method, which became the theoretical basis of computer structural calculation.