Fracture Mechanics |
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Fracture mechanics deal with a study of fracture behavior of cracked/notched specimens. Different factors that influence fracture are usually considered, such as flaws or cracks, repeated endured service loads, or environment. NSEL is capable of conducting fracture tests, according to ASTM standards, on various specimen types for different materials. Fracture tests consist of breaking a specimen and examining the fracture surface with the unaided eye or with a low power microscope to determine such properties as composition, grain size, cash depth, and internal defects. Currently, concrete fracture tests are being conducted in the lab by Sal Chapa, Prof. J. Roesler and Prof. D. Lange. These tests aim to determine fracture properties of concrete at its early age, in particular fracture energy and stress intensity factor. The test consists of a wedge displaced at a rate of 0.5 mm per minute in a notched cube, as shown above. This wedge, of a determined angle, transfers the load to the cubic concrete specimen through a set of loading devices. The displacement caused by the splitting force is monitored by LVDTs mounted at the same height where the load is being transferred. With this data, the total fracture energy and K Ic are calculated. |
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