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Paris' Law
Paris' law (also known as the Paris–Erdogan equation) is a crack growth equation that gives the rate of growth of a fatigue crack. The stress intensity factor K characterises the load around a crack tip and the rate of crack growth is experimentally shown to be a function of the range of stress intensity \Delta K seen in a loading cycle. The Paris equation is :\begin &= C\left(\Delta K\right)^, \end where a is the crack length and a/N is the fatigue crack growth for a load cycle N. The material coefficients C and m are obtained experimentally and also depend on environment, frequency, temperature and stress ratio. The stress intensity factor range has been found to correlate the rate of crack growth from a variety of different conditions and is the difference between the maximum and minimum stress intensity factors in a load cycle and is defined as : \Delta K= K_-K_. Being a power law relationship between the crack growth rate during cyclic loading and the range of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crack Propagation Curve Paris' Law
Crack frequently refers to: * Crack, a fracture in a body * Crack, a fracture (geology) in a rock * Crack, short for crack cocaine Crack may also refer to: Art, entertainment, and media * ''Cracks'' (film), a 2009 independent thriller * Crack Movement, a Mexican literary movement * Crack (band), a Spanish progressive rock group * ''Crack'' (album), an album by Z-RO * ''Cracks'' (album), an album by Nabiha * ''The Crack'', first album by The Ruts * ''Crack Magazine'', a UK-based European music and culture monthly * ''The Crack'' (magazine), a free culture magazine covering the North East of England Slang * Crack, slang for intergluteal cleft Gaining entry * Safe cracking, the process of opening a safe without the combination or the key Software * Crack (password software), a UNIX/Linux password hacking program for systems administrators * Software cracking, a computer program that modifies other software to remove or disable features usually related to digital rights ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crack Growth Equation
A crack growth equation is used for calculating the size of a fatigue crack growing from cyclic loads. The growth of fatigue cracks can result in catastrophic failure, particularly in the case of aircraft. A crack growth equation can be used to ensure safety, both in the design phase and during operation, by predicting the size of cracks. In critical structure, loads can be recorded and used to predict the size of cracks to ensure maintenance or retirement occurs prior to any of the cracks failing. ''Fatigue life'' can be divided into an initiation period and a crack growth period. Crack growth equations are used to predict the crack size starting from a given initial flaw and are typically based on experimental data obtained from constant amplitude fatigue tests. One of the earliest crack growth equations based on the stress intensity factor range of a load cycle (\Delta K) is the Paris–Erdogan equation. : = C(\Delta K)^m where a is the crack length and a/N is the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fatigue (material)
In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure. Fatigue has traditionally been associated with the failure of metal components which led to the term metal fatigue. In the nineteenth century, the sudden failing of metal railway axles was thought to be caused by the metal ''crystallising'' because of the brittle appearance of the fracture surface, but this has since been disproved. Most materials, such as composites, plastics and ceramics, seem to experience some sort of fatigue-related failure. To aid in predicting t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stress Intensity Factor
In fracture mechanics, the stress intensity factor () is used to predict the stress state ("stress intensity") near the tip of a crack or notch caused by a remote load or residual stresses. It is a theoretical construct usually applied to a homogeneous, linear elastic material and is useful for providing a failure criterion for brittle materials, and is a critical technique in the discipline of damage tolerance. The concept can also be applied to materials that exhibit ''small-scale yielding'' at a crack tip. The magnitude of depends on specimen geometry, the size and location of the crack or notch, and the magnitude and the distribution of loads on the material. It can be written as: :K = \sigma \sqrt \, f(a/W) where f(a/W) is a specimen geometry dependent function of the crack length, , and the specimen width, , and is the applied stress. Linear elastic theory predicts that the stress distribution (\sigma_) near the crack tip, in polar coordinates (r,\theta) with or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
University Of Plymouth
The University of Plymouth is a public research university based predominantly in Plymouth, England, where the main campus is located, but the university has campuses and affiliated colleges across South West England. With students, it is the largest in the United Kingdom by total number of students (including the Open University). It has 2,915 staff. History The university was originally founded as thPlymouth School of Navigation in 1862, before becoming a university college in 1920 and a polytechnic institute in 1970, with its constituent bodies being Plymouth Polytechnic, Rolle College in Exmouth, the Exeter College of Art and Design (which were, before April 1989, run by Devon County Council) and Seale-Hayne College (which before April 1989 was an independent charity). It was renamed Polytechnic South West in 1989, a move that was unpopular with students as the name lacked identity. It was the only polytechnic to be renamed and remained as "PSW" until gaining universi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power Law
In statistics, a power law is a Function (mathematics), functional relationship between two quantities, where a Relative change and difference, relative change in one quantity results in a proportional relative change in the other quantity, independent of the initial size of those quantities: one quantity varies as a Exponentiation, power of another. For instance, considering the area of a square in terms of the length of its side, if the length is doubled, the area is multiplied by a factor of four. Empirical examples The distributions of a wide variety of physical, biological, and man-made phenomena approximately follow a power law over a wide range of magnitudes: these include the sizes of craters on the moon and of solar flares, the foraging pattern of various species, the sizes of activity patterns of neuronal populations, the frequencies of words in most languages, frequencies of family names, the species richness in clades of organisms, the sizes of power outages, volcanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-axis
A Cartesian coordinate system (, ) in a plane is a coordinate system that specifies each point uniquely by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in the same unit of length. Each reference coordinate line is called a ''coordinate axis'' or just ''axis'' (plural ''axes'') of the system, and the point where they meet is its ''origin'', at ordered pair . The coordinates can also be defined as the positions of the perpendicular projections of the point onto the two axes, expressed as signed distances from the origin. One can use the same principle to specify the position of any point in three-dimensional space by three Cartesian coordinates, its signed distances to three mutually perpendicular planes (or, equivalently, by its perpendicular projection onto three mutually perpendicular lines). In general, ''n'' Cartesian coordinates (an element of real ''n''-space) specify the point in an ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rainflow-counting Algorithm
The rainflow-counting algorithm is used in calculating the fatigue life of a component in order to convert a uniaxial loading sequence of varying stress into an equivalent set of constant amplitude stress reversals. The method successively extracts the smaller interruption cycles from a sequence, which models the material memory effect seen with stress-strain hysteresis cycles. This simplification allows the number of cycles until failure of a component to be determined for each rainflow cycle using either Miner's rule to calculate the ''fatigue damage'', or in a crack growth equation to calculate the crack increments. Both methods give an estimate of the ''fatigue life'' of a component. In cases of multiaxial loading, critical plane analysis can be used together with rainflow counting to identify the uniaxial history associated with the plane that maximizes damage. The algorithm was developed by Tatsuo Endo and M. Matsuishi in 1968. The rainflow method is compatible with the cy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paul C
Paul may refer to: *Paul (given name), a given name (includes a list of people with that name) *Paul (surname), a list of people People Christianity *Paul the Apostle (AD c.5–c.64/65), also known as Saul of Tarsus or Saint Paul, early Christian missionary and writer *Pope Paul (other), multiple Popes of the Roman Catholic Church *Saint Paul (other), multiple other people and locations named "Saint Paul" Roman and Byzantine empire *Lucius Aemilius Paullus Macedonicus (c. 229 BC – 160 BC), Roman general *Julius Paulus Prudentissimus (), Roman jurist *Paulus Catena (died 362), Roman notary *Paulus Alexandrinus (4th century), Hellenistic astrologer *Paul of Aegina or Paulus Aegineta (625–690), Greek surgeon Royals *Paul I of Russia (1754–1801), Tsar of Russia *Paul of Greece (1901–1964), King of Greece Other people *Paul the Deacon or Paulus Diaconus (c. 720 – c. 799), Italian Benedictine monk *Paul (father of Maurice), the father of Maurice, Byzan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crack Closure
Crack closure is a phenomenon in fatigue loading, where the opposing faces of a crack remain in contact even with an external load acting on the material. As the load is increased, a critical value will be reached at which time the crack becomes ''open''. Crack closure occurs from the presence of material propping open the crack faces and can arise from many sources including plastic deformation or phase transformation during crack propagation, corrosion of crack surfaces, presence of fluids in the crack, or roughness at cracked surfaces. Description During cyclic loading, a crack will open and close causing the crack tip opening displacement (CTOD) to vary cyclically in phase with the applied force. If the loading cycle includes a period of negative force or stress ratio R (i.e. R < 0), the CTOD will remain equal to zero as the crack faces are pressed together. However, it was discovered that the CTOD can also be zero at other times even when the applied force is positi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Toughness
In materials science, fracture toughness is the critical stress intensity factor of a sharp crack where propagation of the crack suddenly becomes rapid and unlimited. A component's thickness affects the constraint conditions at the tip of a crack with thin components having plane stress conditions and thick components having plane strain conditions. Plane strain conditions give the lowest fracture toughness value which is a material property. The critical value of stress intensity factor in mode I loading measured under plane strain conditions is known as the plane strain fracture toughness, denoted K_\text. When a test fails to meet the thickness and other test requirements that are in place to ensure plane strain conditions, the fracture toughness value produced is given the designation K_\text. Fracture toughness is a quantitative way of expressing a material's resistance to crack propagation and standard values for a given material are generally available. Slow self-sust ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
