(4.6) X 1, X 2, , Xn , . , , `M 10, `M 20,, `Mn 0 Mp 0 , :
Mp = Mp 0 + S `Mi 0 Xi;
Qp = Qp 0 + S `Qi 0 Xi; (4.7)
Np = Np 0 + S `Ni 0 Xi,
Mp, Qp, Np ; Mp 0, Qp 0, Np 0 ; `Mi 0, `Qi 0, `Ni 0 Xi = 1.
. 4.5
, , (4.7) Mp. Qp Mp, Qp = dMp / dx, Np Qp, .
, . 4.6, .
k - i j - l Mp , i - j, , .
, Mp , (. 4.6, ), :
Mp (x) = Mp 0 (x) + Mp (x), (4.8)
Mp 0 (x) , Mp (x) , . 4.6, .
l |
. 4.6
(4.8), , :
Qij = Qij 0 + (M M )/ lij, (4.9)
Qij Qij 0 i - i - j (. 4.6, ), , . Qji j - . = Mj, = Mi,
Qij = ql /2 + (Mi Mj)/ lij;
Qji = ql /2 + (Mi Mj)/ lij.
i - , (. 4.6, ):
S X = 0; _ Nij = Qik;
S Y = 0; _ Nik = Qij.
, j - i - j , .
. 4.5, .
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4.3. (. 4.5, ).
.
1. (4.7):
Mp = Mp 0 + `M 10 X 1 + `M 20 X 2,
X 1 X 2 . 4.2.
`M 10 X 1 (. 4.5, ), Mp 0 `M 20 . Mp 1- (. 4.5, ): M 1 = 2 + (1/7) (12/7) = 3/7.
2. , . (4.9) :
Q 12 = ql 12/2 + (M M )/ l 12 = (1×2)/2 + [(1/7) (3/7)]/2 = 1 + 1/7 = 8/7;
Q 21 = - ql 12/2 + (M M )/ l 12 = - 1 + 1/7 = - 6/7.
, (. 4.5, ):
Q 23 = Q 32 = (1/7)/2 = 1/14.
3. Np 2- :
S X = 0; _ N 23 = Q 21 = 6/7 ;
S Y = 0; _ N 21 = Q 23 = 1/14 .
(. 4.5, ), , A B, :
S X = 2 6/7 8/7 = 0;
S Y = 2/7 2/7 = 0;
S MA = 3/7 2×1 + (6/7)×2 (1/14) ×2 = 0.