As the paperclip is bent back and forth, the paperclip is subjected to three stages. The best way to visualize this fracture mode is to bend a paperclip back and forth until it breaks. The amount of energy and effort to break the chocolate bar is low (i.e., low energy featuring little to no deformation of the fractured material) and the brittle fractures are smooth, flat, and look alike when compared to each other.įatigue fractures are associated with repetitive and/or cyclic loading. The best way to visualize this type of fracture mode is to think of a thick chocolate bar that is broken in half. As such, dimple ruptures are most often associated with ductile fractures.Ĭleavage is a low-energy type of fracture that displays matched faces, flat and featureless surfaces that are most often associated with brittle breaks. The cuplike depressions are referred to as dimples. When the part fractures into two sections the tiny bubbles break leaving cuplike depressions. As the part is being pulled apart, the ductile material (think salt water taffy) creates tiny bubbles (microvoid coalescence) in the material. Was the part pulled apart, sheared, twisted or bent? Once this is established, a review of the history of the breakage or failure may assist in answering the questions: Why did it break? or What was the cause? The four principle fracture modes are: dimple rupture, cleavage, fatigue, and decohesive rupture.ĭimple rupture is caused by a common process known as microvoid coalescence. In effect, you can zoom in on very small areas and see what’s there and determine the type of material used in making the part.īy using a SEM/EDS to study the surface of a fracture, the question of how the part broke - or the mode of fracture - can be answered. In addition, the SEM includes Energy Dispersive Spectroscopy (EDS) which uses x-ray technology to determine material composition (atomic elements). (The amount of radiation is small–less than the radiation in half of one CT scan.) This scan helps identify damaged bones.As noted in our previous blog, Fractures Part I, our Scanning Electron Microscope (SEM) is capable of 100,000X magnification, allowing a close-up look at material surfaces for defects, inclusions, and fracture characteristics. Nuclear bone scan: a diagnostic procedure in which a radioactive substance is injected into the body to measure activity in the bones.CT scans are more detailed than general X-rays. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. ![]()
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