《材料力学》课程PPT教学课件（双语版）第十四章 交变应力

ALTERNATING STRESS 814-2 SOME NOMENCLATURE IN THE ALTERNATING STRESS 1\ Cycle characteristics min max max max max o mx Komin) 2、 Mean stress: R+ min p-----F- [0= max min 2 3、 Amplitude of stres O max n 2

§14–2 SOME NOMENCLATURE IN THE ALTERNATING STRESS 1、Cycle characteristics：          = ;( ) ;( ) max min min max min max max min         r 3、Amplitude of stress： 2  max  min  − a = 2、Mean stress： 2  max  min  + m = m min max a T t  o

交实应力 §142交变应力的几个名词术语 循环特征: min max max max max max min 平均应力: R+ min p-----F- [0= max min 2 三、应力幅: O max n 2

§14–2 交变应力的几个名词术语 一、循环特征：          = ;( ) ;( ) max min min max min max max min         r 三、应力幅： 2  max  min  − a = 二、平均应力： 2  max  min  + m = m min max a T t  o

ALTERNATING STRESS 4 Several special alternating stresses 1)Symmetric cycle mIn max max 0 =0 max O=0 mIn

m t 4、Several special alternating stresses： 1).Symmetric cycle： 1 max min = =−   r  a = max  m =0 min max a T  o

交实应 四、几种特殊的交变应力 1.对称循环: mins max max 0 =0 max =0 mIn

m t 四、几种特殊的交变应力： 1.对称循环： 1 max min = =−   r  a = max  m =0 min max a T  o

ALTERNATING STRESS 2) Fluctuating cycle 1n=0 max max O=0 max min O 2 3).Static cycle max min min O=0 5, Stable alternating stress: cycle characteristics 0=O max and the cycle period are not changed. In

t  2).Fluctuating cycle： 0 max min = =   r 2  max   = a = m 3).Static cycle： 1 max min = =   r  a =0  m = max 5、Stable alternating stress：cycle characteristics and the cycle period are not changed. min max a t  m m min max = min o o