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Supersonic Fracture
Supersonic fractures are fractures where the fracture propagation velocity is higher than the speed of sound in the material. This phenomenon was first discovered by scientists from the Max Planck Institute for Metals Research in Stuttgart (Markus J. Buehler and Huajian Gao) and IBM Almaden Research Center in San Jose, California ( Farid F. Abraham). The issues of intersonic and supersonic fracture become the frontier of dynamic fracture mechanics. The work of Burridge initiated the exploration for intersonic crack growth (when the crack tip velocity V is between the shear in wave speed C^8 and the longitudinal wave speed C^1. Eurekalert.org. Accessed May 19, 2012. Supersonic fracture was a phenomenon totally unexplained by the classical theories of fracture. |
Fracture
Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band or dislocation. Brittle fractures occur with no apparent deformation before fracture. Ductile fractures occur after visible deformation. Fracture strength, or breaking strength, is the stress when a specimen fails or fractures. The detailed understanding of how a fracture occurs and develops in materials is the object of fracture mechanics. Strength Fracture strength, also known as breaking strength, is the stress at which a specimen fails via fracture. This is usually determined for a given specimen by a tensile test, which charts the stress–strain cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Speed Of Sound
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. At , the speed of sound in air is about , or one kilometre in or one mile in . It depends strongly on temperature as well as the medium through which a sound wave is propagating. At , the speed of sound in air is about . The speed of sound in an ideal gas depends only on its temperature and composition. The speed has a weak dependence on frequency and pressure in ordinary air, deviating slightly from ideal behavior. In colloquial speech, ''speed of sound'' refers to the speed of sound waves in air. However, the speed of sound varies from substance to substance: typically, sound travels most slowly in gases, faster in liquids, and fastest in solids. For example, while sound travels at in air, it travels at in water (almost 4.3 times as fast) and at in iron (almost 15 times as fast). In an exceptionally stiff material such as diamond, sound travels a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Max Planck Institute For Metals Research
Founded on 18 March 2011, the Max Planck Institute for Intelligent Systems (MPI-IS) is one of the 86 research institutes of the Max Planck Society. With locations in Stuttgart and Tübingen, it combines interdisciplinary research in the growing field of intelligent systems. Intelligent systems are becoming increasingly important in many areas of life – as virtual systems on the Internet or as cyber-physical systems in the physical world. Artificial intelligent systems can be used in a broad range of areas, for instance in autonomous vehicles or to diagnose and fight diseases. Research departments * Autonomous Motion (under interim management, Bernhard Schölkopf), Tübingen * Empirical Inference (Bernhard Schölkopf), Tübingen * Haptic Intelligence ( Katherine Kuchenbecker), Stuttgart * Modern Magnetic Systems (Gisela Schütz), Stuttgart * Perceiving Systems (Michael J. Black), Tübingen * Physical Intelligence (Metin Sitti), Stuttgart * Robotic Materials (Christoph Kepling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Markus J
Marcus, Markus, Márkus or Mărcuș may refer to: * Marcus (name), a masculine given name * Marcus (praenomen), a Roman personal name Places * Marcus, a main belt asteroid, also known as (369088) Marcus 2008 GG44 * Mărcuş, a village in Dobârlău Commune, Covasna County, Romania * Marcus, Illinois, an unincorporated community * Marcus, Iowa, a city * Marcus, South Dakota Marcus is an unincorporated community in Meade County, in the U.S. state of South Dakota South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is n ..., an unincorporated community * Marcus, Washington, a town * Marcus Island, Japan, also known as Minami-Tori-shima * Mărcuș River, Romania * Marcus Township, Cherokee County, Iowa Other uses * Markus, a beetle genus in family Cantharidae * ''Marcus'' (album), 2008 album by Marcus Miller * Marcus (comedian), finalist on ''Last Comic Standing'' season 6 * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huajian Gao
Huajian Gao (, born December 7, 1963) is a Chinese-American mechanician who is widely known for his contributions to the field of solid mechanics, particularly on the micro- and nanomechanics of thin films, hierarchically structured materials, and cell-nanomaterial interactions. He is a Distinguished University Professor at Nanyang Technological University in Singapore and Walter H. Annenberg Professor Emeritus of Engineering at Brown University. He is the editor-in-chief of Journal of the Mechanics and Physics of Solids. Gao was elected a member of the National Academy of Engineering in 2012 for contributions to micromechanics of thin films and hierarchically structured materials. In 2021 he received the Timoshenko Medal for "pioneering contributions to nanomechanics of engineering and biological systems." Education and career Huajian Gao was born in Chengdu, Sichuan on December 7, 1963. He received his B.S. in Engineering Mechanics from Xi'an Jiaotong University of Chin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Farid F
Farid ( Arabic: فَرِيد ''fariyd'', ''farīd''), also spelt Fareed or Ferid and accented Férid, is an Arabic and Persian masculine personal name or surname meaning "unique, singular ("the One"), incomparable". For many communities, including in the Middle East, the Balkans, North Africa, and South East Asia, the name Fareed is common across generations. Given name Farid * Farid Abboud, Lebanese Ambassador *Farid F. Abraham, scientist * Farid Alakbarli, Azerbaijani researcher * Farid Azarkan (born 1971), Dutch politician of Moroccan descent * Farid al-Atrash (1910-1974), Syrian Egyptian singer, music composer, and actor * Farid ad-Din Attar, Iranian Sufi poet * Farid Bang (born Farid Hamed El Abdellaoui in 1986), German rapper of Moroccan-Spanish descent * Farid Esack, South African anti-apartheid activist and Muslim scholar *Fariduddin Ganjshakar, 12th-century Punjabi Muslim mystic * Farid Ghadry, Syrian political activist *Farid Kamil, Malaysian male model turned acto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transonic Speed
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. The exact range of speeds depends on the object's critical Mach number, but transonic flow is seen at flight speeds close to the speed of sound (343 m/s at sea level), typically between Mach 0.8 and 1.2. The issue of transonic speed (or transonic region) first appeared during World War II. Pilots found as they approached the sound barrier the airflow caused aircraft to become unsteady. Experts found that shock waves can cause large-scale separation downstream, increasing drag and adding asymmetry and unsteadiness to the flow around the vehicle. Research has been done into weakening shock waves in transonic flight through the use of anti-shock bodies and supercritical airfoils. Most modern jet powered aircraft are engineered to operate at transonic air speeds. Transonic airspeeds see a rapid increase in drag from a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fracture Mechanics
Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture. Theoretically, the stress ahead of a sharp crack tip becomes infinite and cannot be used to describe the state around a crack. Fracture mechanics is used to characterise the loads on a crack, typically using a single parameter to describe the complete loading state at the crack tip. A number of different parameters have been developed. When the plastic zone at the tip of the crack is small relative to the crack length the stress state at the crack tip is the result of elastic forces within the material and is termed linear elastic fracture mechanics (LEFM) and can be characterised using the stress intensity factor K. Although the load on a crack can be arbitrary, in 1957 G. Irwin foun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molecular Dynamics
Molecular dynamics (MD) is a computer simulation method for analyzing the physical movements of atoms and molecules. The atoms and molecules are allowed to interact for a fixed period of time, giving a view of the dynamic "evolution" of the system. In the most common version, the trajectories of atoms and molecules are determined by numerically solving Newton's equations of motion for a system of interacting particles, where forces between the particles and their potential energies are often calculated using interatomic potentials or molecular mechanical force fields. The method is applied mostly in chemical physics, materials science, and biophysics. Because molecular systems typically consist of a vast number of particles, it is impossible to determine the properties of such complex systems analytically; MD simulation circumvents this problem by using numerical methods. However, long MD simulations are mathematically ill-conditioned, generating cumulative errors in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continuum Mechanics
Continuum mechanics is a branch of mechanics that deals with the mechanical behavior of materials modeled as a continuous mass rather than as discrete particles. The French mathematician Augustin-Louis Cauchy was the first to formulate such models in the 19th century. Explanation A continuum model assumes that the substance of the object fills the space it occupies. Modeling objects in this way ignores the fact that matter is made of atoms, and so is not continuous; however, on length scales much greater than that of inter-atomic distances, such models are highly accurate. These models can be used to derive differential equations that describe the behavior of such objects using physical laws, such as mass conservation, momentum conservation, and energy conservation, and some information about the material is provided by constitutive relationships. Continuum mechanics deals with the physical properties of solids and fluids which are independent of any particular coordinate sy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperelasticity
A hyperelastic or Green elastic materialR.W. Ogden, 1984, ''Non-Linear Elastic Deformations'', , Dover. is a type of constitutive model for ideally elastic material for which the stress–strain relationship derives from a strain energy density function. The hyperelastic material is a special case of a Cauchy elastic material. For many materials, linear elastic models do not accurately describe the observed material behaviour. The most common example of this kind of material is rubber, whose stress- strain relationship can be defined as non-linearly elastic, isotropic and incompressible. Hyperelasticity provides a means of modeling the stress–strain behavior of such materials. The behavior of unfilled, vulcanized elastomers often conforms closely to the hyperelastic ideal. Filled elastomers and biological tissues are also often modeled via the hyperelastic idealization. Ronald Rivlin and Melvin Mooney developed the first hyperelastic models, the Neo-Hookean and Moon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Characteristic Energy Length Scale
The characteristic energy length scale \chi describes the size of the region from which energy flows to a rapidly moving crack. If material properties change within the characteristic energy length scale, local wave speeds can dominate crack dynamics. This can lead to supersonic fracture Supersonic fractures are fractures where the fracture propagation velocity is higher than the speed of sound in the material. This phenomenon was first discovered by scientists from the Max Planck Institute for Metals Research in Stuttgart (Markus .... Materials science {{Materials-sci-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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