D. Y. LI ET AL.
Copyright © 2013 SciRes. ENG
Figure 7. Variat ion of s tres s at point-N.
Figure 8 . Changing c urve of stress concentr ation fact or.
Impacted by the internal pressure, the mechanical
stress and the internal pressure are sharing the similar
changing tendency.The value of mechanical stress is va-
rying from 56.61MPa to 121.01MPa.
3.3. Stress Concent ration Factor
The mechanical stress concentration factor is indepen-
dent of ru nni n g co nd it ion[ 7] . T he str ess o n t he s tudy a re a
is directly proportional to the value of the internal pres-
sure. Define stress concentration factor as follow[9]:
(4)
where
= maximum stress. The changing curve of
the stress concentration factor during the process of load
pick-up at point-N is shown i n Figure 8.
Based on above computations, in the later period of
the load pick-up process, the stress concentration factor
with its value 2.51 can be considered keeping stable dur-
ing the whole process because of the tiny changes on the
amplitude o f the factor.
4. Conclusion
● Refers to the computations, the phenomenon of stress
centralization at the inside conjunction area between
the pipe and the header cylinder is obvious. Far from
the intersecting line area changes less in stress; it can
be considered as the membrane stress of the cylinder.
● The maximum stress is distributed mainly at point-N
which is focu sed o n the inters ectin g line. Accor din g to
the numerical calculation, the stress concentration
factor of point-N is 2.51.
● These analysis results, especially the stress concentra-
tion factor, can be used in life expenditure on-line
monitoring system in following research.
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