What is the mechanical property of indicator?

In mechanical manufacturing, general machinery parts are in normal temperature, normal pressure and not used in strong corrosive medium, moreover in the process of using all the mechanical parts will be under different load. Mechanical property refers to the metal materials under the action of load resistance damage property. So the mechanical property is metal material commonly used indicator of a collection.

Metal material mechanical property is good or bad, determine its use scope and life. In design and material selection of parts, can in accordance with metal material mechanical property. Of course, plus load nature is different (such as stretch, compression, torsion, impact and cyclic load, etc.), the mechanical property of metal material requirements will also be different.

Often say a kind of metal mechanical property is not good, refers to it easy to fold, break, or if there’s not a good grind ductility. General pure metal mechanical strength will be weak alloy strength, such as the property of the steel is better than aluminum alloy. Commonly used mechanical property includes: strength, hardness, stiffness, elasticity, plasticity, fatigue strength, impact toughness and fracture toughness, etc.

Strength: metal material under external force, has resist plastic deformation and fracture ability.

Hardness: metal material under external force, has resist tougher thing press-in metal material ability.

Stiffness: metal material under stress force can resist to elastic deformation ability.

Elasticity: metal material under external force generated deformation, when the external force after remove to restore its original shape ability.

Plasticity: metal material under the action of external force, produce permanent deformation without causing damage ability.

Fatigue strength: metal material under the action of countless times repeated alternating load without causing the breakage biggest stress.

Impact toughness: metal material under the action of resist to impact load breakage ability.

Fracture toughness: used to reflect the material to resist crack instability expansion ability property indicator.

Mechanical member bar deformation form

Mechanical part under different external force, will produce different forms of deformation. Here mainly introduce mechanical member bar in processing produce deformation.

Stretch and compression, it is cause of equal size, opposite direction, action line and member bar doublication, shown as elongation or shortening the length of the member bar. In engineering often seen under tensile or compression member bar, such as the jack screw rod, when it jacking weight thing, under compression.

Shear, in engineering often seen construction member of under shearing action. This kind member bar common characteristic is: on the both sides of the component suffer equal size, in the opposite direction, active line apart is close and perpendicular to rod shaft external force function. Under the action of external force, member bar main deformation is: cross section between the two force as the interface, construction member two parts along the surface come up relative diastrophism, this kind construction member deformation form is called shear.

Torsion, it is caused of equal size, opposite direction, the acting surface is perpendicular to rod shaft two force couples. Show the member bar arbitrarily two intersecting surfaces occur around the axis of relative rotation. For example automobile drive shaft, motor and water turbine principal axis etc. are stand torsion member bar.

Bending, it is transverse force of perpendicular to member bar axis, or cause by role in containing rod shaft vertical plane a pair of equal size, opposite direction force couple. Show the center line of the bar from straight line to a curve. Engineering, bending member bar is one of the most frequently encountered situation. Such as crossbeam of girder bridge crane, all kinds of mandrel and turning tool etc. deformation, belong to bending deformation.

And some member bars at the same time occur several kinds of basic deformation, such as a lathe spindle work happens bending, torsion and compression three basic deformation; Drilling machine column at the same time happen stretching and bending two kinds of basic deformation. And this happened a variety of deformation condition is called combination deformation.