| Deficiencies such as pore or tiny fissure exits in metal materials of machines andinstallations during the manufacture and application. The actual strength of metal ismuch lower than that of the theoretical model because of these deficiencies. However,fracture mechanics is a subfield of solid mechanics of studying fracture and crackdevelopment of material and structure. The theory can be applied to research themechanisum of materials failour in order to enhance them strength and toughness, andto avoid engineer construction breakage. So it may reduce the loss of economics andavoid fracture accident. The facture performance of cast iron and Q235steel wasanalyzed by microcosmic instrument in the dissertation. The content of main studies isas following.1. The Scanning electron microscopy (SEM) was used to observe the fractureappearance of iron and carefully analyze its mechanisms.2. The crack developing mechanism of cast iron structure with notched wasinvestigated, in order to find the calculation method of the ultimate bearing capacity ofdifferent notched samples. The iron specimen soaked in the sea water of roomtemperature was also stretched and its stress intensity factor calculated out. At the meantime, the double-K criterion was applied to figure the ultimate capacity of cast iron,which was compared with the experimental data.3. The three-point bend load was applied to test the specimen of Q235steel beamwith different size of notch and short-term sea water immersion. The facture mechanismand loading capacity of specimen were analyzed so as to research the law ofcombination influence of loading stress and sea water corrision on it4. The ABAQUS software was applied in the numerical simulation of three-pointbending Q235steel beam with notched in order to discuss the calculation of stressintensity factors of the specimen and its result was compared with the experimentaldata. |
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