power plants Fundamentals of aircraft powerplants_图文.doc

power plants Fundamentals of aircraft powerplants_图文 导读：就爱阅读网友为您分享以下“Fundamentals of aircraft powerplants_图文”的资讯，希望对您有所帮助，感谢您对92的支持! FM 1-506 Contraction and expansion. contraction andexpansion are reactions produced in metals asthe result of heating or cooling. A high degreeof heat applied to a metal will cause it to expandor become larger. Cooling hot metal will shrinkor contract it. Contraction and expansion affectthe design of welding jigs, castings, andtolerances necessary for hot rolled material.metal to hold loads (or forces) without breakingStrength. Strength refers to the ability of aStrength is a property that sums up many of thedesirable qualities of metals. Strength withtoughness is the most important combination ofproperties a metal can possess. Metalshaving this combination of properties are usedin vital structural members that may becomeshould be mentioned. Stress is a force placed upon aIn a discussion of metal properties, stress and strainoverloaded in service. body and is measured in terms of force per unit area, theforce being expressed in pounds and the unit of area insquare inchs; in other words, pounds per square inch(psi). Stress may be in the form of compression, tension,torsion, bending, shearing loads, or a combination of twoor more of these. All parts of an aircraft are subjected tostresses. When a part fails to return to its original formafter being stressed, it is said to be strained. The variousstresses acting on parts of an aircraft, while in flight, havean importantamp;wing on the metals used: apart or stretching produced by two forces pull-Tension. Tension is the resistance to pullinging in opposite directions along the samestraight line. The cables of a control system areplaced under tension when the controls areoperated.