Numerical Analysis of Crack Propagation and Lifetime Estimation: Fracture Mechanics and Numerical Programming
Author
Jensen, Bo Ernst Westergren
Term
4. semester
Education
Publication year
2015
Submitted on
2015-06-15
Pages
84
Abstract
Denne speciales afhandling undersøger, hvordan revner vokser i en todimensionel struktur, og hvor længe strukturen kan holde under givne randbetingelser. Arbejdet bygger på lineær elastisk brudmekanik (LEFM) og anvender centrale størrelser som spændingsintensitetsfaktorer (hvor belastningen er størst ved revnespidsen) og energifrigivelsesrate (den energi, der driver revnen frem). Desuden inddrages udbredte revnevækstmodeller: Paris, Forman og NASGROW. Der er udviklet et program i ANSYS Mechanical APDL, som simulerer revnens bane og estimerer levetiden som følge af revnevækst. Verifikation viser, at den beregnede revnebane stemmer godt overens med referencegrundlag. Estimatet af levetid afviger med omkring 42%; når kendte fejlkilder medregnes, reduceres afvigelsen til omkring 17%.
This thesis examines how cracks grow in a two-dimensional structure and how long the structure can last under specified boundary conditions. It is based on Linear Elastic Fracture Mechanics (LEFM) and uses key quantities such as stress intensity factors (which describe how severe the stress is at the crack tip) and energy release rate (the energy available to drive crack growth). It also applies widely used crack growth laws: Paris, Forman, and NASGROW. A custom program in ANSYS Mechanical APDL simulates the crack path and estimates the remaining life due to crack propagation. Verification shows good agreement for the predicted crack trajectory. Lifetime estimates deviate by about 42%; when known sources of error are accounted for, the deviation reduces to about 17%.
[This abstract was generated with the help of AI]
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