TY - JOUR
A1 - Staat, Manfred
T1 - Direct FEM Limit and Shakedown Analysis with Uncertain Data
N2 - The structural reliability with respect to plastic collapse or to inadaptation is formulated on the basis of the lower bound limit and shakedown theorems. A direct definition of the limit state function is achieved which permits the use of the highly effective first order reliability methods (FORM) is achieved. The theorems are implemented into a general purpose FEM program in a way capable of large-scale analysis. The limit state function and its gradient are obtained from a mathematical optimization problem. This direct approach reduces considerably the necessary knowledge of uncertain technological input data, the computing time, and the numerical error, leading to highly effective and precise reliability analyses.
KW - Finite-Elemente-Methode
KW - Einspielen
KW - FEM
KW - Einspielanalyse
KW - shakedown
KW - limit load
KW - reliability analysis
KW - FEM
KW - direct method
Y1 - 2000
ER -
TY - JOUR
A1 - Staat, Manfred
T1 - Basis Reduction for the Shakedown Problem for Bounded Kinematic Hardening Material
N2 - Limit and shakedown analysis are effective methods for assessing the load carrying capacity of a given structure. The elasto–plastic behavior of the structure subjected to loads varying in a given load domain is characterized by the shakedown load factor, defined as the maximum factor which satisfies the sufficient conditions stated in the corresponding static shakedown theorem. The finite element dicretization of the problem may lead to very large convex optimization. For the effective solution a basis reduction method has been developed that makes use of the special problem structure for perfectly plastic material. The paper proposes a modified basis reduction method for direct application to the two-surface plasticity model of bounded kinematic hardening material. The considered numerical examples show an enlargement of the load carrying capacity due to bounded hardening.
KW - Finite-Elemente-Methode
KW - Einspielen
KW - Basis Reduktion
KW - konvexe Optimierung
KW - FEM
KW - Druckgeräte
KW - Basis reduction
KW - Convex optimization
KW - FEM
KW - Shakedown analysis
Y1 - 2000
ER -
TY - JOUR
A1 - Staat, Manfred
T1 - LISA - a European project for FEM-based limit and shakedown analysis
N2 - The load-carrying capacity or the safety against plastic limit states are the central questions in the design of structures and passive components in the apparatus engineering. A precise answer is most simply given by limit and shakedown analysis. These methods can be based on static and kinematic theorems for lower and upper bound analysis. Both may be formulated as optimization problems for finite element discretizations of structures. The problems of large-scale analysis and the extension towards realistic material modelling will be solved in a European research project. Limit and shakedown analyses are briefly demonstrated with illustrative examples.
KW - Einspielen
KW - Traglast
KW - Finite-Elemente-Methode
KW - Traglastanalyse
KW - Einspielanalyse
KW - FEM
KW - limit analysis
KW - shakedown analysis
Y1 - 2001
ER -
TY - JOUR
A1 - Staat, Manfred
T1 - Local and global collapse pressure of longitudinally flawed pipes and cylindrical vessels
N2 - Limit loads can be calculated with the finite element method (FEM) for any component, defect geometry, and loading. FEM suggests that published long crack limit formulae for axial defects under-estimate the burst pressure for internal surface defects in thick pipes while limit loads are not conservative for deep cracks and for pressure loaded crack-faces. Very deep cracks have a residual strength, which is modelled by a global collapse load. These observations are combined to derive new analytical local and global collapse loads. The global collapse loads are close to FEM limit analyses for all crack dimensions.
KW - Finite-Elemente-Methode
KW - Grenzwertberechnung
KW - Axialbelastung
KW - FEM
KW - Grenzwertberechnung
KW - Axialbelastung
KW - Traglastanalyse
KW - Limit analysis
KW - Global and local collapse
KW - Axially cracked pipe
KW - Pressure loaded crack-face
Y1 - 2005
ER -