, Dl, , l (D l<<l).
e = D l / l
, ()
e = s / E
- , -s= Nz /F ( Nz=P),
D l = Nz / EF
(2)
EF (), EF.
, (. . 6), - . .
D b ( . 6 D b <0) , e'=D b/b - . -, , m, :
e' = - me
, 0 £ m £1/2.
(2) D l , , (EF =const, Nz =const). EF Nz (. 7) , EF Nz :
( k , ). , Nz EF l dz, ,
-5, .
() . . 8 , , :
- 1-1 (. 8, ) ;
- 2-2 (. 8, ) , ;
- 3-3 4-4 (, 8, ) , .
()
(. 9, ). , . s1 =s >0, s2=s3=0, s1=s2=0, s3=s<0.
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, a, :
t13 (. 9, ), , b=45 ( ta) t13=s/2.
t , , , b=45 . t , s13=s/2.
13
: , , , .
- (. 1). Qy=dMx/dz=0, Mx=const , . M
. , (. 2). , , , , , , , - . , (s =sy=0).
( ) , .
, s ( ). ( . 2 - ), - ( ). (n-n), , . , -, . . : s=e , 1/r (r - ) s. , (M=onst), (. 3, ), (n-n) .
(. 3, ) , . ( , , ). Ox , .
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dz, . 3, . , , . dj , , .
, :
e =1 / =1 / 1
001 011 ,
BB1 / OO1 = O1B/CO = y / r
e ,
(1)
, ,
(2)
, : 1/ r , . .
(3)
(2)
, ( / r) ¹ 0, ,
, . .
, ( ). . , :
, Jx - ,
(4)
1/s . 1/s , EJ, ( EF).
(4) (2),
(5)
. 1773 . s (5) , M>0 s y>0 . , , , . , (. 4), . .
, 3 . M max s , Wx, . . (. 5, ) J=bh3/12, ymax = h/2 Wx = Jx/ymax = bh2/6. (. 5,6 Jx =p d4/64, ymax=d/2) Wx =p d3/32, (. 5, ),
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, M
(6)
, . , ,
max M - ( ), [s] - (). , ( () , s=const).
max sp max |sc| (. 6), |s| [s]. :
14
: , , , , , .
Qy (. 1), s tyz
, , , - , tyz, ( ). h<l/4 (. 2) . . :
) . sz, , -, ;
) . , , . 2, , s y = -q/b. sz,
, sy << sz , h2 << l2, sy /sz (h/l)2 << 1.
tyz. , , (. 3). , . , tyz, b/h. (b/h)=1,0 12,6%, (b/h)=0,5 - 3,3%.
tyz , ( ) tyz, dz, , (. 3). . 4. , , , t ( ), dT= t bdz . 5. ,
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t=const b. s s + d s, ,
, , Sxw - w .
(. 5) S z = 0:
, ,
. by - , , , , , ( , ).
(. 6). ,
F=bh - .
, ,
, . , , () , . : Qy (. 7), , s t . - .
, , (. 7), , ,
, , , . max s max t , . 8:
max t<< max s, [t]/[s] 0,5 , , , ,