TY  - EJOU
AU  - Damjanović, Božo 
AU  - Konjatić, Pejo 
AU  - Katinić, Marko 

TI  - Stress Intensity Factor, Plastic Limit Pressure and Service Life Assessment of a Transportation-Damaged Pipe with a High-Aspect-Ratio Axial Surface Crack
T2  - Computer Modeling in Engineering \& Sciences

PY  - 2025
VL  - 145
IS  - 2
SN  - 1526-1506

AB  - Ensuring the structural integrity of piping systems is crucial in industrial operations to prevent catastrophic failures and minimize shutdown time. This study investigates a transportation-damaged pipe exposed to high-temperature conditions and cyclic loading, representing a realistic challenge in plant operation. The objective was to evaluate the service life and integrity assessment parameters of the damaged pipe, subjected to 22,000 operational cycles under two daily charge and discharge conditions. The flaw size in the damaged pipe was determined based on a failure assessment procedure, ensuring a conservative and reliable input. The damage was characterized as a long axial surface crack with a depth of <i>a</i> = 2 mm and half-length <i>c</i> = 50 mm (<i>c</i>/<i>a</i> = 25), a geometry not well covered by existing Stress Intensity Factor solutions. To address this limitation, a modified magnification factor (M*) was introduced and tested for the present damage case (<i>c</i>/<i>a</i> = 25) and for additional crack geometries (<i>c</i>/<i>a</i> = 28–70), which showed improved agreement with Finite Element Analysis (FEA) than Newman’s original formulation. Stress Intensity Factor and Plastic Limit Pressure, essential parameters for structural integrity assessment, were computed numerically using FEA and validated against analytical predictions. Fatigue crack growth was evaluated using the Paris law with crack propagation simulated numerically by Ansys’s S.M.A.R.T. The Failure Assessment Diagram (FAD) was used to assess service life, incorporating constant working pressure and fracture toughness while considering evolving crack size during propagation. Results showed that analytical predictions with the modified magnification factor matched FEA within 5%, while the original Newman formulation overestimated results. The analytical service life solution predicted approximately 8500 fewer cycles than the numerical, remaining conservative but efficient. These findings are based on the present case of a long axial surface crack with high aspect ratios (<i>c</i>/<i>a</i> = 25–70, depending on crack depth), and while the modified magnification factor may also improve predictions for other geometries, this requires structured validation in future studies.
KW  - Stress intensity factor; plastic limit pressure; structural integrity; fatigue crack growth; failure assessment diagram (FAD)

DO  - 10.32604/cmes.2025.072256