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Failure of impulsively loaded thin-walled pipes and plates
The capability to predict the modes of deformation of thin-walled structures is a paramount safety concern in military, civil and industrial environments. Finite element analysis offers a valid, cost-effective alternative to experimental programs when performing preliminary safety studies. This thesis investigates numerical procedures to study two typical safety-related problems of impulsively loaded thin-walled structures. When a pressurised pipe experiences a guillotine break, the sudden fluid release causes a rapid whip-like motion, with possible damage to nearby structures. An element code is here developed to predict the pipe flexural and torsional behaviour, which adopts a corotational kinematic formulation for delivering reliable results at a fraction of the computational cost of conventional FEA techniques. The validated code, implemented with commercial FEA software, is employed in parametric studies leading to the discovery of new dimensionless groups that completely characterise the flexural behaviour of pipes. With the newfound understanding, simple empirical laws are established that predict the pipe response and the hazard conditions. A shell element numerical model is built to study the rupture mechanisms of steel plates subjected to impulsive blast loadings. Tensile and shear experiments on steel specimens were performed to characterise the parameters of a triaxiality-dependent failure criterion, obtaining a mesh-size independent fracture model. The numerical predictions allowed to establish a novel phenomenological criterion, providing an answer to the previously unsolved question on the transition between different types of failure modes. Dimensionless failure maps are developed that elucidate the influence of plate topology and boundary conditions on the rupture mechanisms. The study highlights the similarities in the response between simply-supported plates, and fully-clamped plates exposed to localised blast loadings. A new failure mode is discovered for simply-supported rectangular plates, ...
Failure of impulsively loaded thin-walled pipes and plates
The capability to predict the modes of deformation of thin-walled structures is a paramount safety concern in military, civil and industrial environments. Finite element analysis offers a valid, cost-effective alternative to experimental programs when performing preliminary safety studies. This thesis investigates numerical procedures to study two typical safety-related problems of impulsively loaded thin-walled structures. When a pressurised pipe experiences a guillotine break, the sudden fluid release causes a rapid whip-like motion, with possible damage to nearby structures. An element code is here developed to predict the pipe flexural and torsional behaviour, which adopts a corotational kinematic formulation for delivering reliable results at a fraction of the computational cost of conventional FEA techniques. The validated code, implemented with commercial FEA software, is employed in parametric studies leading to the discovery of new dimensionless groups that completely characterise the flexural behaviour of pipes. With the newfound understanding, simple empirical laws are established that predict the pipe response and the hazard conditions. A shell element numerical model is built to study the rupture mechanisms of steel plates subjected to impulsive blast loadings. Tensile and shear experiments on steel specimens were performed to characterise the parameters of a triaxiality-dependent failure criterion, obtaining a mesh-size independent fracture model. The numerical predictions allowed to establish a novel phenomenological criterion, providing an answer to the previously unsolved question on the transition between different types of failure modes. Dimensionless failure maps are developed that elucidate the influence of plate topology and boundary conditions on the rupture mechanisms. The study highlights the similarities in the response between simply-supported plates, and fully-clamped plates exposed to localised blast loadings. A new failure mode is discovered for simply-supported rectangular plates, ...
Failure of impulsively loaded thin-walled pipes and plates
Schiano Moriello, Dario (author)
2021-07-28
Doctoral thesis, UCL (University College London).
Theses
Electronic Resource
English
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