材料力学总结

材料力学名词解释及填空

名词解释

1、Stress(应力)

the force per unit area , or intensity of the force distributed over a given section, is called stress.

σ=F/A

2、normal stress(正应力)

The internal force is therefore normal to the plane of the section and the corresponding stress is described as the normal stress.

3、Shearing stress(剪应力)

The internal force is the shear on the plane of the section and the corresponding stress is described as the shearing stress.

4、Linear Strain(应变)

The normal strainεin a member can be defined as the deformation of the meter of the per unit length.

5、The main objective of the study the mechanics of materials（材料力学的任务）is to provide the future engineer with the means of analyzing and designing various machines and loading-bearing structures.

6、Saint-venant’s principle（圣维南原理）

For two sets of statically equivalent forces,except in the immediate vicinity of the points of application of the loads, the stress distribution may be assumed independent of the actual mode of application of the loads (this statement is not only to axial load, but to practically any type of load)

7、Work-energy principle(功能原理)

The Work-energy Principle: In the process of the deformation of a elastomer, the strain energy which is stored in elastomer is equal to the work of the external force in number. This is the Work-energy Principle and it can be represented as Vε=W.

8、effective length （有效长度）is defined as real length multiplied by factor of length

9、principle plane(主平面)

is the plane in which the shearing stress equals zero, and normal stresses achieve maximum or minimum.

Principle stress(主应力)

The normal stress which is exerted on the principle plane is called the principle stress.

10、Radius of radius of gyration【revolution】（惯性半径）of an area can be calculated by the

following formula i=I/A

Where i =the moment of inertia of an area

A=the area of an cross section

11、isotropic materials （各向同性材料）are the materials whose elastic constants are independent of direction.

12、homogeneous materials（均匀性材料）are the materials whose elastic properties are the same everywhere.

13、The strain energy density(应变能密度)

The strain energy in the unit volume can be defined as the strain energy density.

14、Hooke’s law （胡克定律）may be expressed more fully by saying that

1】when the stress increases,the measured strain increases in the same ratio

2】when the stress diminishes, the measured strain diminishes in the same ratio

3】when the stress is removed, no strain can be measured

For a small deformation,the stress is directly proportional to the strain.

15、Hooke’s law for shearing stress(剪切胡克定律)

The relation τ=Gγis known as Hooke’s law for shearing stress. Strain and constant Gis called the modulus of rigidity or shear modulus of material.

16、Generalized Hooke’s law（广义胡可定律）

17、Poisson ratio(泊松比)is defined as the ratio of lateral contraction (strain) to longitudinal extension (strain) of a bar under terminal tension.

18、factor of safety （安全因数）ultimate load over allowable load

19、stress-concentration factor k（应力集中因数K）=maximum stress over average stress

20、statically indeterminate problem（静不定问题）is the problem in which the reactions and internal forces can not be determined by static only , analysis of deformation is needed.

21、neutral surface（中性层）is defined as the surface between the top and bottom of a beam in which longitudinal line do not change.

22、Neutral axis （中性轴）

①The neutral surface intersects a transverse section along a straight line called the neutral axis of the section.

②The intersection of the neutral surface with a transverse section is called the neutral axis of the section.