Analiza propagacije višestrukih zamornih pukotina u tankim pločama

undergraduate thesis

• Title (english): Analysis of multiple site fatigue cracks propagation in thin plates
• Author: Vlatko Jakupčić
• Mentor: Željko Božić (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2020-09-23, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Aviation, Rocket and Space Technology; Aviation Technology and Maintenance

Abstract

U ovom radu su izložene neke od metoda analize propagacije zamornih pukotina pri cikličkom opterećenju, temeljene na mehanici loma i poznatim eksponencijalnim zakonima napredovanja zamornih pukotina. Za uzorak ploče sa središnjom pukotinom dani su eksperimentalni rezultati rasta zamornih pukotina preuzeti iz literature. Primjenjujući Parisovu jednadžbu temeljenu na linearno elastičnoj mehanici loma, simuliran je rast zamorne pukotine za promatrani uzorak. Primjenom metode konačnih elemenata izračunati su koeficijenti intenzivnosti naprezanja, gdje je za područje oko vrha pukotine postavljena mreža singularnih elemenata. Numeričkom integracijom Parisove jednadžbe pomoću programskog paketa MATLAB2020a simulira se životni vijek napredovanja zamorne pukotine kojeg potom uspoređujemo s danim eksperimentalnim rezultatima. Također su utvrđene veličine plastične zone vrha pukotine i izračunate vrijednosti koeficijenta intenzivnosti naprezanja u odnosu na duljine pukotina.

Abstract (english)

In this work some of the methods used for fatigue crack propagation analysis based on fracture mechanics and well known power laws are presented. By using the Paris equation, based on linear elastic fracture mechanics, fatigue crack growth was simulated for considered specimens. For the plate specimen with a central crack experimental results for fatigue life data, a-N, taken from literature are given. Finite element method was used to calculate stress intensity factors, where the crack tip region was meshed by singular elements. By numerical integration of the Paris equation by means of MATLAB2020a package fatigue crack propagation lifetime is simulated which is afterwards compared with given experimental results. In addition, crack tip plastic zone size was assessed and effective stress intensity factor values were calculated with respect to crack length.

• Keywords: zamor; napredovanje pukotine; koeficijent intenzivnosti naprezanja; tankostjene konstrukcije
• Keywords (english): fatigue; crack propagation; stress intensity factor; thin-walled structures
• Language: croatian
• URN:NBN: urn:nbn:hr:235:765917
• Study programme: Title: Aeronautical Studies; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka zrakoplovnog inženjerstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka zrakoplovnog inženjerstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2022-09-24
• Created on: 2020-09-25 00:02:36