弹簧设计

S-N curve for steel
三、弹簧材料的强度和的特性 Strength of materials and material properties
3.1 材料的几个强度定义 Definitions of some strength of materials ： 极限抗拉强度 Ultimate tensile strength---Sut（单位unit：MPa） 抗拉强度指材料在拉断前承受最大应力值. 抗拉强度 Ultimate tensile strength is defined as the stress at which a material begins to break. (The maximum stress a material can withstand when subjected to tension, Sut可以通过查询手册得到，也可以通过以下公式计算： The values of Sut can select from some spring handbooks, also can calculate according to the following formulas. Sut=196000/d^0.146 (Unit:psi----单位为英制的) Sut=1351/（d/25.4）^0.146 (Unit:MPa) 其中,d为弹簧材料的线经。d means wire diameter.
torsional stress
对于压簧和拉簧， 它给出的是轴向的力，但是有限元上主要应力为扭转应力。 Tension and compression springs give axial loads, but the wire are loaded in torsional stress.
二、弹簧的设计应力 Some design stress of springs
疲劳强度Fatigue strength 疲劳强度是指材料在无限多次交变载荷作用下而不破坏的最大应力称为疲劳 疲劳强度 强度。 Fatigue strength is the maximum stress level that a material can withstand an infinite number of cycles before damage.
Bending stress
对于扭簧，它给出的是扭力，但是有限元上主要应力为弯曲应力。 Torsion spring give torsional fore, but the wire are loaded in bending stress.
二、弹簧的设计应力 Some design stress of springs
二、弹簧的设计应力 Some design stress of springs
张应力Tension stress 张应力是由于轴向拉升材料所产生的应力。 张应力 Tension stress is the stress state caused by an applied load that tends to elongate the material in the axis of the applied load, in the other words the stress caused by pilling the material.
Tension stress
压应力Compression stress 压应力是由于轴向压缩材料所产生的应力。 压应力 Compression stress is the stress state caused by an applied load that acts to reduce the length of material in the axis of the applied load, in other words the stress state caused by squeezing the material. 张应力和压应力的公式如下 The formulas as following： σ=F/A 其中， F为力(N) / A为面积(m2) where F is force (N) acting on an area A (m2);
一 概述 summary
非金属材料 Nonmetal material 橡胶弹簧rubber springs 流体弹簧fluid springs 合成树脂弹簧synthetic resin springs 其他类弹簧the other springs 根据形状分：According to the appearance. 压缩弹簧compression springs 螺旋弹簧 Helical springs 拉伸弹簧compression springs 扭转弹簧 torsion springs 板（片）弹簧 Leaf springs 特种弹簧 Special springs 其他类弹簧the other springs 常用的三种弹簧 The common springs
三、弹簧材料的强度和的特性 Strength of materials and material properties
以下是一些常用材料的Sut值 Some Sut for the common material as following：
设计弹簧时，初始的计算可以选用上表的数值。 Select values from the above table for initial calculation of spring.
一 概述 summary
常用的三种弹簧的介绍 The introduction of three common springs 压缩弹簧 Compression springs Compression Springs are springs which absorb and store energy by offering resistance to a pushing force. Most compression springs are a straight columniform spring made of round wire. 压缩弹簧是通过推压弹簧来存储能量的，大部分的压簧是直的圆柱型圆钢丝弹簧。 拉伸弹簧 Extension springs Extension Springs are springs which absorb and store energy by offering resistance to a pulling force . Typically, extension springs are made from round wire and are close wound with initial tension. 拉伸弹簧是通过拉弹簧来存储能量的，在初始状态，大部分拉簧是圆钢丝且弹簧 钢丝之间是并紧没有间隙的。
compression stress
二、弹簧的设计应力 Some design stress of springs
弯曲应力 Bending stress 弯曲应力是由于弯曲材料所产生的应力。 弯曲应力
Bending stress is the stress state caused by an applied load that tends to bend the material in the axis of the applied load, in the other words the stress caused by bending the material. 注意！Tip! 注意！
三、弹簧材料的强度和的特性 Strength of materials and material properties
材料的几个强度定义 Definitions of some strength of materials ： 屈服强度 Yield strength---Sy （单位unit：MPa） 屈服强度是材料开始发生永久变形或者塑性变形的应力。 屈服强度 The yield strength is defined as the stress at which a material begins to deform permanently or plastically. 剪切强度 Shear strength---Ssy （单位unit：MPa） 剪切强度是指材料承受剪切力的应力. 剪切强度 Shear strength is defined as the stress at which a material fails in shear. 三者关系见下图（The relationship as following figure)：
扭转应力 Torsional stress 扭转应力是由一对平行的方向相反的力作用材料上所产生的应力。 扭转应力 Torsional stress is state caused by a pair of opposing forces acting along parallel lines of action through the material。 注意！Tip! 注意！
三、弹簧材料的强度和的特性 Strength of materials and material properties
如：对于琴钢丝的材料，有如下关系： For music wire, it has the following Relationship: Sy=0.75Sut Ssy=0.577Sy 对于设计扭簧的时候， 对于设计扭簧的时候，材料主要承受的 为弯曲应力，所以设计应力选用Sy； 应力为弯曲应力，所以设计应力选用 ；但 设计拉伸和压缩弹簧时，设计应力选用 设计拉伸和压缩弹簧时，设计应力选用Ssy. For torsion spring, the wire are loaded in bending stress, so the design stress should be choose Sy, but the compression and Figure of stress-strain curve extension spring should be choose Ssy.