基本氯习 材料试验 O MPa b 450 400 350 300 250 200 150 ool op oeol 50 0 0.05 0.10 0.15 0.20gh10.25 E 低碳钢σc曲线上特征点
材料试验 sp se ss sb s a b ep et ee st f g h e s(MPa) 0.05 0.10 0.15 0.20 0.25 450 400 350 300 250 200 150 100 50 0 低碳钢s−e曲线上特征点 p e
Review of basic deformations Three elastic constants 1. Allowable stress is:o E Ga 2(1+) 2. Limiting stress is: 0x=0,002,0,) E 3. Safety coefficient: n G y us/e Posson's ration(or the lateral contraction coefficient
1. Allowable stress is: jx n s s = 0.2 2. imiting stress is: { , , } jx s b L s s s s = 3. Safety coefficient：n Posson’s ration (or the lateral contraction coefficient e e = Three elastic constants t G= e s E= 2(1+) = E G
基本氯习 三个弹性常数 1、许用应力= E G 2(1+) 2、极限应力1x=OsO020b E 3、安全系数:n G y us/e 泊松比(或横向变形系数)
1 : jx n s 、 许用应力 s = , , } 0.2 2 : { s j x s s s s b 、极限应力 = 3、安全系数：n 泊松比（或横向变形系数） e e = 三个弹性常数 t G= e s E= 2(1+) = E G
Review of basic deformations Practical calculations of shear and bearing O (Resultant) A P P n n O P Resultant b Restricted torsion of the rod with rectangularsections ma h max W=ahb W P 6 Ip=Bhb I 1=Vt T max 1 GⅠ P e:松b
n n （Resultant ） （Resultant ） P P Pc n n Q h b h t 1 T t max Note: b Practical calculations of shear and bearing t= t A Q c c c c A P s = s Restricted torsion of the rod with rectangular sections max 2 max , n P M W hb W p t = = 3 , n P P M I hb GI q = = 1 t max t =