다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Overview of constitutive laws, kinematics, homogenization and multiscale methods in crystal plasticity finite-element modeling: Theory, experiments, applications

1. Introduction and overview 2. Film stress and substrate curvature 3. Stress in anisotropic and patterned films 4. Delamination and fracture 5. Film buckling, bulging and peeling 6. Dislocation formation in epitaxial systems 7. Dislocation interactions and strain relaxation 8. Equilibrium and stability of surfaces 9. The role of stress in mass transport.

Thin Film Materials: Stress, Defect Formation and Surface Evolution

http://web.mit.edu/durint/PDF/Dao_et_alFR.pdf

Computational modeling of the forward and reverse problems in instrumented sharp indentation

A class of phenomenological strain gradient plasticity theories is formulated to accommodate more than one material length parameter. The objective is a generalization of the classical J2 3ow theory of plasticity to account for strain gradient e4ects that emerge in deformation phenomena at the micron scale. A special case involves a single length parameter and is of similar form to that proposed by Aifantis and co-workers. Distinct computational advantages are associated with this class of theories that make them attractive for applications requiring the generation of numerical solutions. The higher-order nature of the theories is emphasized, involving both higher-order stresses and additional boundary conditions. Competing members in the class of theories will be examined in light of experimental data on wire torsion, sheet bending, indentation and other micron scale plasticity phenomena. The data strongly suggest that at least two distinct material length parameters must be introduced in any phenomenological gradient plasticity theory, one parameter characterizing problems for which stretch gradients are dominant and the other relevant to problems when rotation gradients (or shearing gradients) are controlling. Flow and deformation theory versions of the theory are highlighted that can accommodate multiple length parameters. Examination of several basic problems reveals that the new formulations predict quantitatively similar plastic behavior to the theory proposed earlier by the present authors. The new formulations improve on the earlier theory in the manner in which elastic and plastic strains are decomposed and in the representation of behavior in the elastic range. ? 2001 Elsevier Science Ltd. All rights reserved.

http://www-mech.eng.cam.ac.uk/profiles/fleck/papers/143.pdf

A reformulation of strain gradient plasticity

Use of scaling functions to determine mechanical properties of thin coatings from microindentation tests

A Framework for Quantifying Crack Tip Constraint

https://spiral.imperial.ac.uk/bitstream/10044/1/76/1/Theoretical%20and%20numerical%20modelling%20of%20creep%20crack%20growth%20in%20a%20carbon-manganese.pdf

Theoretical and numerical modelling of creep crack growth in a carbon-manganese steel

This paper presents a framework for including constraint effects in the failure assessment diagram approach for fracture assessment. As parameters for describing constraint are still the subject of development, the framework is illustrated using both the elastic T-stress and the hydrostatic Q-stress. It is shown that constraint effects can be treated by modifying the shape of the failure assessment curves. In their simplest form, the modifications involve only two parameters: one quantifying the magnitude of structural constraint which depends on geometry and crack size; and the second quantifying the influence of constraint on fracture toughness.

Constraint in the failure assessment diagram approach for fracture assessment

The mixed-mode interfacial fracture toughness of an alumina/niobium system is investigated. The interface was formed by solid-state bonding bulk Coor's AD-999 fine-grain alumina with a commercial purity niobium. The interface is very sharp; data acquired from high-resolution electron microscopy indicate that the width of the interface is no more than ten atomic planes. Furthermore the thermal expansion coefficients of the two materials differ by less than 5% so that residual stresses produced by the bonding process are minimal. The interfacial fracture toughness of the alumina/niobium system under tension-dominated load states and various combinations of in-plane shear and tension have been measured. For comparison purposes, the toughness of alumina under mixed-mode loading conditions was also measured. The fracture toughness of alumina is relatively insensitive to mode mixity. In contrast, the fracture toughness of the alumina-niobium interface depends strongly on mode mixity. At a phase angle o...

Noel P. O’Dowd

Papers

Use of scaling functions to determine mechanical properties of thin coatings from microindentation tests

A Framework for Quantifying Crack Tip Constraint

Theoretical and numerical modelling of creep crack growth in a carbon-manganese steel

Constraint in the failure assessment diagram approach for fracture assessment

Fracture toughness of alumina-niobium interfaces : experiments and analyses