National Repository of Grey Literature 2 records found  Search took 0.00 seconds. 
Tomographic investigation of the sandstone fracture toughness
Vavřík, Daniel ; Beneš, Pavel ; Fíla, Tomáš ; Koudelka_ml., Petr ; Kumpová, Ivana ; Vavro, Martin
It is well known that the measured values of the fracture toughness of quasi brittle materials are influenced by material heterogeneity, dimensions, boundary conditions, and unequal tension and compression properties. Standard testing methods supposing isotropic material, in contrary the quasi-brittle materials differ from this theoretical expectation, therefore this approach may fail. The authors present Local Fracture Toughness Testing (LFTT) method to overcome this obstacle. LFFT based on a complex methodology using a series of tomographic reconstructions recorded during specimen loading is calculated independently of the outside boundary conditions.
Fatigue crack initiation and growth in 316L steel in torsional cyclic loading
Karol, Michal ; Chlupová, Alice ; Mazánová, Veronika ; Kruml, Tomáš
Fatigue crack initiation and growth study in 316L austenitic stainless steel was made in cyclic\ntorsion. The experiments on hollow cylindrical specimens were performed at room temperature using fully reversed shear strain controlled cycles. The specimens used were polished mechanically and electrolytically to enable surface damage and crack propagation observation using optical light microscope, SEM. It was found that high density of extrusions and intrusions are formed on the specimen surface due to cyclic loading. TEM observations revealed that dislocation arrangement in well-known ladder-like structure is responsible for the localization of cyclic plastic deformation and for the origin of surface roughness in which the fatigue crack nucleate. The path of fatigue cracks leading to failure was observed, too. The crack path\nwas found to be dependent upon the applied shear strain amplitude.

Interested in being notified about new results for this query?
Subscribe to the RSS feed.