نتایج جستجو برای: mission creep

تعداد نتایج: 44916  

2013
Shun-Peng Zhu Hong-Zhong Huang Yu Liu Rong Yuan Liping He

Low cycle fatigue–creep is the main reason for the failures of many engineering components under high temperature and cyclic loading. Based on the exhaustion of the static toughness and dissipation of the plastic strain energy during fatigue failure, a new low cycle fatigue–creep life prediction model that is consistent with the fatigue–creep damage mechanism and sensitive to the fatigue damage...

2012
Y. Sakanashi S. Gungor P. J. Bouchard

A high temperature measurement system for creep deformation based on the digital image correlation (DIC) technique is described. The new system is applied to study the behaviour of a multi-pass welded joint in a high temperature tensile test and a load controlled creep test at 545°C. Spatially resolved tensile properties and time dependent creep deformation properties across a thick section typ...

2004
Christopher J. Cowen Dingqiang Li Carl J. Boehlert

Two Ti2AlNb intermetallic orthorhombic (O) alloys, Ti-15Al-33Nb and Ti-21Al29Nb(at.%), were subtransus processed into sheets, using pancake forging and hot-pack rolling, and evaluated in tension (25 and 650°C) and creep (650-710°C) and the properties and deformation behavior were related to microstructure. Some of the microstructural features evaluated were grain boundary character, grain size,...

2001
Oleg D. Sherby Eric M. Taleff

Diffusion-controlled-creep processes are used to assess the creep behavior of dispersion and solute hardened materials at coarse and fine grain sizes. It is shown that the creep behavior of a dispersion strengthened (DS) Al–Mg alloy is similar to the creep behavior of pure Al–Mg alloys. Both materials show dislocation climb and dislocation solute-drag contributions to creep. It is shown that th...

2012
Y. Sakanashi S. Gungor P. J. Bouchard

A high temperature measurement system for creep deformation based on the digital image correlation (DIC) technique is described. The new system is applied to study the behaviour of a multi-pass welded joint in a high temperature tensile test and a load controlled creep test at 545°C. Spatially resolved tensile properties and time dependent creep deformation properties across a thick section typ...

Journal: :C&RL 2010
Charles Martell

405 Perspectives concerning the makeup of the core mission of academic libraries and the relative balance between its two major components – physical and virtual resources, vary widely leading to false expectations and unnecessary apprehensiveness. One false expectation is the assumption by some that books are headed rapidly to the junk heap of history. Anthony Grafton (Daedalus, Winter 2009) p...

2013
Lili An Qiang Xu Donglai Xu Zhongyu Lu

This paper presents a review of creep deformation and rupture mechanism of P91 alloy for the development of its creep damage constitutive equations under lower stress level. Creep damage is one of the serious problems for the high temperature industries and computational approach (such as continuum damage mechanics) has been developed and used, complementary to the experimental approach, to ass...

2015
Qiang Xu Zhongyu Lu Xue Wang

This paper summarizes and presents research progress on the fundamentals of the development of creep damage constitutive equations for high Cr steels including 1) a brief summary of the characteristics of creep deformation and creep damage evolution and their dependence on the stress level and the importance of cavitation for the final fracture; 2) a critical review of the state of art of creep...

2004
A. D. Howard

Introduction: Simple models of geomorphic modification of planetary surfaces by erosion or deposition are reported here. These processes are linear and non-linear creep, uniform accrescence and decrescence, and non-linear airfall deposition. They do not include models of flow whose depth is of the same order of magnitude as the landform, such as glacial flow or relaxation of crater forms in pla...

2015
Qihua Xu Qiang Xu Zhongyu Lu Simon Barrans

This paper presents a review of creep deformation and rupture mechanisms of low Cr-Mo alloy for the development of its creep damage constitutive equations under lower stress. The most popular Kachanov-Robatnov-Hayhurst (KRH) formulation was not necessarily developed and calibrated for low stress and cannot depict the creep strain accurately under multi-axial state of stress due to the three-dim...

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