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PASS/NOZZLE-FEM 3.5. Program Manual | |
To assess the static strength of the junction of the vessel component, the maximum values are used:
| — | reduced local membrane stresses from pressure σmp; |
| — | reduced total (local membrane + local bending + total temperature + com-pensation) stresses against combined action of pressure and external loads σb. |
For taking into consideration external loads on the local membrane stresses a supplementary criteria for local membrane stresses against combined action of pressure and external loads σml is introduced.
Reduced stress values are defined by maximum shear stress criterion for two-dimensional stress state:
| $$ \sigma_{eqv} = \max{ \left\{ \begin{array}{l} \frac{\textstyle 1}{\textstyle 2}\left|\sigma_\theta+\sigma_x\pm\sqrt{(\sigma_\theta-\sigma_x)^2+4\tau^2_{\theta{x}}}\right|, \\ \sqrt{(\sigma_\theta-\sigma_x)^2+4\tau^2_{\theta{x}}} \end{array} \right\} }. $$ | (5.26) |
Assessment for reduced local membrane stresses from pressure:
| \[ \sigma_{mp} \le 1.3 [\sigma], \] | (5.27) |
where $[\sigma] = \min{ \left\{ \frac{R_{p0,2}}{1.5}; \frac{R_m}{2.6}; \frac{R_{m/10^{5}}}{1.5} \right\} }$ - nominal allowable stress [17].
Assessment for total reduced stresses against combined action of internal pressure and external loads as per [17]:
| $$ \sigma_{b} \le \min{ \left\{ \begin{array}{l} \left(2.5-\frac{R_{p0,2}}{R_m}\right)R_{p0,2} \\ 2R_{p0,2} \\ R_{m/10^{5}} \end{array} \right\} }. $$ | (5.28) |
For austenitic steels σ1,0 is taken instead of σ0,2.
If design temperature is above 380°N for carbon steel, above 420°N for low alloyed steel, above 525°N for austenitic steel, it is necessary to take into consid-eration material creep, when assigning values for allowable stresses.
Also, using the FEM, strength analysis of conical reducers and heads are performed in accordance with p. 3.2.9.a GOST 34347-2017 [21].
PASS/NOZZLE-FEM 3.5. Program Manual
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