Abstract:
This paper considers the deformation
process of a typical section of a steel trunk
pipeline with a defective zone, strengthened
with a carbon fiber composite lining, under
the influence of stationary internal pressure. Defects in the form of thinning of the
pipe thickness and cracks were investigated. The stressed-strained state of the structure at critical pressure was analyzed. The
thickness of the composite lining was determined, at which the bandage compensates
for the effect of internal pressure on the
damaged section of the pipeline. Research
was carried out numerically based on finite
element modeling in the ANSYS software
package.
When studying the stressed-strained
state of a pipe with a defect of an arbitrary
complex shape under the influence of critical pressure, a compensating value was
obtained. The result showed that a carbon
fiber lining with a thickness of 17 % of the
rated thickness of the pipe could completely
compensate for the effects of internal pressure in the defect area. In this case, the
stresses in the carbon fiber lining were close
to minimal. When studying the stressedstrained state of a pipe with a large crack of
arbitrary shape at critical pressure, a compensating value was also obtained.
It has been established that to compensate for the concentration of internal pressure in the crack zone, the thickness of the
composite lining should be at the level of
34 % of the rated thickness of the pipe. In
this case, the deformation of the steel pipe
in the area of the crack occurs in the elastic region. The exception is the crack tips,
where plastic deformations are observed,
and stresses arise up to 93 % of the ultimate
strength of the pipe steel. At the same time,
the stresses in the carbon fiber lining remain
close to minimal. Thus, it is recommended
to use carbon fiber linings with a thickness
of 17 % or more of the rated pipe thickness
to bandage damage constituting up to 75 %
of the thickness of a steel pipe. To bandage cracks, it is recommended to use carbon fiber linings with a thickness of at least
34 % of the rated pipe thickness
