|
Deformation Index
The deformation index is a parameter that specifies the mode of control under which time-varying deformation or loading processes occur in a solid. It is useful for evaluating the interaction of elastic stiffness with viscoelastic or fatigue behavior. If deformation is maintained constant while load is varied, the process is said to be deformation controlled. Similarly, if load is held constant while deformation is varied, the process is said to be load controlled. Between the extremes of deformation and load control, there is a spectrum of intermediate modes of control including energy control. For example, between two rubber compounds with the same viscoelastic behavior but different stiffnesses, which compound is preferred for a given application? In a strain controlled application, the lower stiffness rubber would operate at smaller stress and therefore produce less viscous heating. But in a stress controlled application, the higher stiffness rubber would operate at s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Viscoelasticity
In materials science and continuum mechanics, viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like water, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and immediately return to their original state once the stress is removed. Viscoelastic materials have elements of both of these properties and, as such, exhibit time-dependent strain. Whereas elasticity is usually the result of bond stretching along crystallographic planes in an ordered solid, viscosity is the result of the diffusion of atoms or molecules inside an amorphous material.Meyers and Chawla (1999): "Mechanical Behavior of Materials", 98-103. Background In the nineteenth century, physicists such as Maxwell, Boltzmann, and Kelvin researched and experimented with creep and recovery of glasses, metals, and rubbers. Viscoelasticity was further examined in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Material Fatigue
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 th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shingo Futamura
Shingo Futamura (April 3, 1938 -) is a rubber industry materials scientist noted for his concept of the deformation index. Education Futamura completed his undergraduate Bachelor of Science degree at Waseda University in Japan. He earned a master's degree from the University of Michigan in 1968. He received his doctorate in polymer science from the University of Akron in 1975 under advisor Eberhard Meinecke. Career By 1974, Futamura was appointed as a group leader of polymer physics at Firestone Central Research in Akron, Ohio. During a career spanning over 40 years, Futamura authored 25 scientific papers and 50 US patents. He worked for Nippon Zeon Co., Firestone Tire & Rubber Company, and Goodyear Tire & Rubber Company. He is best known for proposing the concept of a deformation index to relate viscoelastic properties to real-world tire performance. The concept is used to select rubber compounds that minimize tire rolling resistance, and it is used in finite element ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Melvin Mooney Distinguished Technology Award
The Melvin Mooney Distinguished Technology Award is a professional award conferred by the American Chemical Society, Rubber Division. Established in 1983, the award is named after Melvin Mooney, developer of the Mooney viscometer and of the Mooney-Rivlin hyperelastic law. The award consists of an engraved plaque and prize money. The medal honors individuals "who have exhibited exceptional technical competency by making significant and repeated contributions to rubber science and technology". Recipients 1980s * 1982 J. Roger Beatty - Senior Research Fellow at B. F. Goodrich known for development of rubber testing instruments and methods * 1983 Aubert Y. Coran - Monsanto researcher responsible for invention of thermoplastic elastomer Geolast * 1984 Eli M. Dannenberg - Cabot scientist known for contributions to surface chemistry of carbon black * 1985 William M. Hess - Columbian Chemicals Company scientist known for contributions to characterization of carbon black disper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polytropic Process
A polytropic process is a thermodynamic process that obeys the relation: p V^ = C where ''p'' is the pressure, ''V'' is volume, ''n'' is the polytropic index, and ''C'' is a constant. The polytropic process equation describes expansion and compression processes which include heat transfer. Particular cases Some specific values of ''n'' correspond to particular cases: * n=0 for an isobaric process, * n=+\infty for an isochoric process. In addition, when the ideal gas law applies: * n=1 for an isothermal process, * n=\gamma for an isentropic process. Where \gamma is the ratio of the heat capacity at constant pressure (C_P) to heat capacity at constant volume (C_V). Equivalence between the polytropic coefficient and the ratio of energy transfers For an ideal gas in a closed system undergoing a slow process with negligible changes in kinetic and potential energy the process is polytropic, such that p v^ = C where ''C'' is a constant, K = \frac, \gamma = \frac, and with the po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
