. σ , P :
σ = P / F = (p2 EJ min)/ F (m l)2 = (p2 E )/(m l)2,
= J min/ F, = .
, . , λ = m l / imin , :
- ,
- .
:
σ =p2 E /λ2, (11.7)
σ(λ) (. 11.8).
λ |
λ0 |
σ |
λ |
σ |
σ = (p2 )/λ2 |
σ |
. 11.8 |
(11.7) , σ = ∞, , . E, , σ σ.
, σ = σ (11.7) :
λ = p ,
λ .
[11] :
- 3 (σ = 195 , E = 206 ), λ = 3,14 = 102,
- (σ = 20 , E = 10 ), λ = 70.
, , , (σ), , σ P . σ(λ), , .
, σ(λ) 1 2 . , :
σ(λ) = a - b λ, (11.8)
a b .
3 a = 305 , b = 1,12 ; a = 28,7 , b = 0,19 .
(11.8) λ0, : σ σ .
3, λ0 =30 40, , (11.8), σ(λ) = σ.
, :
|
|
- (λ > λ), σ ;
- (λ0 <λ< λ), ;
- (λ< λ0), , σ = σ σ = σ.