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Paul T Williams - One of the best experts on this subject based on the ideXlab platform.
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shallow flaws under biaxial loading conditions part ii application of a weibull stress analysis of the cruciform bend specimen using a hydrostatic stress criterion
Journal of Pressure Vessel Technology-transactions of The Asme, 2001Co-Authors: Paul T Williams, Richard B Bass, W. J. McafeeAbstract:Cruciform beam fracture mechanics specimensl have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far- field, out-of-plane biaxird bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thernxd-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shtdlow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and three- parameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the OW Integral Definition, have been shown to correlate the experimentally observed biaxiaImore » effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.« less
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shallow flaws under biaxial loading conditions part ii application of a weibull stress analysis of the cruciform bend specimen using a hydrostatic stress criterion
ASME Pressure Vessels and Piping Conference Boston MA August 1-5 1999, 1999Co-Authors: B.r. Bass, W. J. Mcafee, Paul T WilliamsAbstract:Cruciform beam fracture mechanics specimensl have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far- field, out-of-plane biaxird bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thernxd-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shtdlow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and three- parameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the OW Integral Definition, have been shown to correlate the experimentally observed biaxiaI effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.
W. J. Mcafee - One of the best experts on this subject based on the ideXlab platform.
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shallow flaws under biaxial loading conditions part ii application of a weibull stress analysis of the cruciform bend specimen using a hydrostatic stress criterion
Journal of Pressure Vessel Technology-transactions of The Asme, 2001Co-Authors: Paul T Williams, Richard B Bass, W. J. McafeeAbstract:Cruciform beam fracture mechanics specimensl have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far- field, out-of-plane biaxird bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thernxd-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shtdlow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and three- parameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the OW Integral Definition, have been shown to correlate the experimentally observed biaxiaImore » effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.« less
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shallow flaws under biaxial loading conditions part ii application of a weibull stress analysis of the cruciform bend specimen using a hydrostatic stress criterion
ASME Pressure Vessels and Piping Conference Boston MA August 1-5 1999, 1999Co-Authors: B.r. Bass, W. J. Mcafee, Paul T WilliamsAbstract:Cruciform beam fracture mechanics specimensl have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far- field, out-of-plane biaxird bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thernxd-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shtdlow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and three- parameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the OW Integral Definition, have been shown to correlate the experimentally observed biaxiaI effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.
B.r. Bass - One of the best experts on this subject based on the ideXlab platform.
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shallow flaws under biaxial loading conditions part ii application of a weibull stress analysis of the cruciform bend specimen using a hydrostatic stress criterion
ASME Pressure Vessels and Piping Conference Boston MA August 1-5 1999, 1999Co-Authors: B.r. Bass, W. J. Mcafee, Paul T WilliamsAbstract:Cruciform beam fracture mechanics specimensl have been developed in the Heavy Section Steel Technology (HSST) Program at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far- field, out-of-plane biaxird bending stress component in the test section that approximates the nonlinear biaxial stresses resulting from pressurized-thernxd-shock or pressure-temperature loading of a nuclear reactor pressure vessel (RPV). Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shtdlow, surface flaws. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. Two and three- parameter Weibull models have been calibrated using a new scheme (developed at the University of Illinois) that maps toughness data from test specimens with distinctly different levels of crack-tip constraint to a small scale yielding (SSY) Weibull stress space. These models, using the new hydrostatic stress criterion in place of the more commonly used maximum principal stress in the kernel of the OW Integral Definition, have been shown to correlate the experimentally observed biaxiaI effect in cruciform specimens, thereby providing a scaling mechanism between uniaxial and biaxial loading states.
Vincenzo Ciampi - One of the best experts on this subject based on the ideXlab platform.
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a regularized force based beam element with a damage plastic section constitutive law
International Journal for Numerical Methods in Engineering, 2007Co-Authors: Daniela Addessi, Vincenzo CiampiAbstract:A new beam finite element is presented, with a generalized section constitutive law based on damage mechanics and plasticity, to analyse the cyclic structural response of plane frames. Both displacement-based and force-based (FB) approaches are used and compared, to demonstrate the significant advantages of the FB formulation in the presence of material non-linearity. In order to overcome the analytical problems and the pathological mesh dependency of the numerical response in the presence of strain-softening post-peak behaviour, a classical non-local regularization procedure is adopted first, based on the Integral Definition of the associated variable governing the damaging evolution process. Subsequently, for the FB element a new simple regularization technique is proposed based on a selected integration procedure along the element length, which predefines the location of the Gauss points in the beam region, where the localization phenomena take place. As for the other computational aspects, an iterative element state determination is adopted for the FB formulation and a local predictor–corrector algorithm is used to solve the incremental evolution problems of the damage and plastic internal variables. Finally, some examples are shown on simple beams and frames, subjected to monotonically increasing and cyclic loading conditions. Copyright © 2006 John Wiley & Sons, Ltd.
Paul M Weaver - One of the best experts on this subject based on the ideXlab platform.
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rapid analysis of variable stiffness beams and plates legendre polynomial triple product formulation
International Journal for Numerical Methods in Engineering, 2017Co-Authors: Matthew P Odonnell, Paul M WeaverAbstract:Copyright © 2017 John Wiley & Sons, Ltd. Numerical integration techniques are commonly employed to formulate the system matrices encountered in the analysis of variable stiffness beams and plates using a Ritz based approach. Computing these Integrals accurately is often computationally costly. Herein, a novel alternative is presented, the Recursive Analytical Polynomial Integral Definition (RAPID) formulation. The RAPID formulation offers a significant improvement in the speed of analysis, achieved by reducing the number of numerical integrations that are performed by an order of magnitude. A common Legendre Polynomial basis is employed for both trial functions and stiffness/load variations leading to a common form for the Integrals encountered. The Legendre Polynomial basis possesses algebraic recursion relations that allow these Integrals to be reformulated as triple-products with known analytical solutions, defined compactly using the Wigner (3j) coefficient. The satisfaction of boundary conditions, calculation of derivatives and transformation to other bases is achieved through combinations of matrix multiplication, with each matrix representing a unique boundary condition or physical effect, therefore permitting application of the RAPID approach to a variety of problems. Indicative performance studies demonstrate the advantage of the RAPID formulation when compared to direct analysis using Matlab's ‘Integral’ and ‘Integral2’. Copyright © 2017 John Wiley & Sons, Ltd.