工程力学英文版课件 Introduction.pptVIP

1 * * Why Engineering Mechanics Suspension bridge Steel cables Bridge pier Finite element modelling of car crash Gears Artificial bone Introduction Mechanics can be defined as that branch of the physical sciences concerned with the state of rest or motion of bodies that are subjected to the action of forces. This semester, two very important branches of mechanics, namely, statics and mechanics of materials will be studied. Statics: The subject deals with the equilibrium of rigid bodies, that is, it is used to determine the forces acting either external to the body or within it necessary to keep the body either at rest or moving with a constant velocity. The general problem of statics consists in reducing a given system of forces to its simplest equivalent, i.e., to its resultant. Mechanics of materials: The subject studies the relationships between the external loads and the intensity of internal forces acting within the body. This subject is also concerned with computing the deformations of the body, and it provides a study of the body’s stability when the body is subjected to external forces. Strength： Capacity of a component or a structural element to resist failure. Rigidity (Stiffness)： Capacity of a component or a structural element to resist deformation. Stability: Capacity of a component or a structural element to retain the original state of equilibrium. Under the requirement that the strength, rigidity, stability criteria are satisfied, provide the necessary fundamental theory and method of calculation for determining reasonable shape and dimension, choosing proper materials for the components with the most economic price. Idealizations: Models or idealizations are used in mechanics in order to simplify the application of the theory. Particle: A particle has a mass, but a size that can be neglected. When a body is idealized as a particle, the principles of mechanics reduce to a rather simplified for