1,720,983 research outputs found
FEM numerical strategies for the evaluation of the accumulated plastic strain due to a cyclic load condition
No full textIn this study, the phenomenon of accumulation of residual plastic deformation is numerically evaluated for a stiffened panel subjected to uniaxial cyclic loading. In particular, three strategies are investigated through the use of FEM (Finite Element Method) in the ADINA Software environment. The models presented are characterized by the same geometrical characteristics, but differ in the numerical parameters, i.e. mesh density and element type. Namely, a full shell-element model, a full 3D-solid-element model, and a combine shell-solid elements model are investigated. The output of the analyses carried out on the three models are the assessment of the accumulated plastic strain recorded in the unloaded phase of the cyclic analysis and the effect of these residual plastic deformations on the ultimate strength capacity of the structure. Finally, the results of the three models are compared in order to understand which one could be more suitable and reliable for the evaluation of this phenomena, i.e. the arise of plastic residuals and the reduction of the load bearing capacity of the panel
RESIDUAL PLASTIC STRAIN EFFECTS ON THE ULTIMATE CAPACITY FOR A HSLA STIFFENED PANEL SUBJECTED TO TWO DIFFERENT CYCLIC LOAD CONDITIONS
No full textCumulative buckling deformation of stiffened panel under cyclic loading
No full textIn this study, the cumulative process of buckling deformation is evaluated for a stiffened panel sub jected to uniaxial cyclic loading. The impact of cyclic loading on the ultimate strength of the panel is then estimated. It is noted that the arising of permanent deflection could be simulated by finite element method analysis using a suitable model able to capture the strain components properly. The results show that the structure accumulates a deformation that seems to grow almost linearly hence, as a consequence, is realistic to expect that if a large number of load cycles of such magnitude is imposed, the accumulated plastic strain can be quite severe. In addition, it is revealed that such residual deformations, caused by a cyclic load magnitude lower than the design limit, affects the ultimate strength of the stiffened panel. Finally, effects on the numerical evaluation of the ultimate strength of the structure are shown
Evaluation of residual plastic strain on a stiffened panel subjected to compression and tension-compression cyclic load
No full textIn this study, the process of accumulation of residual plastic deformation is numerically investigated for a stiffened panel under compression and traction-compression cyclic loading conditions. In particular, the difference between results obtained from the only compression cyclic loading case and the tractioncompression loading is shown, highlighting the influence of the changing in the load sign. This is investigated also taking into account different hardening models of the material, namely isotropic or kinematic. The numerical model describes a stiffened panel including the transversal frames, cyclically subjected to axial loading under different time histories: in particular, the maximum compressive load is applied as a fraction of the ultimate load of the intact structure. Finally, the effect of the accumulated plastic deformations on the ultimate strength of the structure is analyzed, in order to evaluate the influence of the cyclic load history
Recent Industrial Developments of Marine Composites Limit States and Design Approaches on Strength
No full textTo further exploit the potential of marine composites applications in building ship hulls, offshore structures, and marine equipment and components, design approaches should be improved, facing the challenge of a more comprehensive and explicit assessment of appropriately defined limit states. The structure ultimate/limit conditions shall be verified in principle within the whole structural domain and throughout the ship service life. What above calls for extended and reliable materials characterization on the one hand and for accurate and wide-ranging procedures in structural analyses. This paper presents an overview of recent industrial developments of marine composites limit states assessments and design approaches, as available in open literature, focusing on pleasure crafts and yachts as well as navy ships and thus showing a starting point to fill the gap in this respect. After a general introduction about composites characterization techniques, current design practice and rule requirements are briefly summarized. Both inter-ply and intra-ply failure modes and corresponding limit states are then presented along with recently proposed assessment approaches. Three-dimensional aspects in failure modes and manufacturing methods have been identified as the main factors influencing marine composite robustness. Literature review highlighted also fire resistance and hybrid joining techniques as significant issues in the use of marine composites
Cumulative buckling deformation of stiffened panel under cyclic loading
No full textIn this study, the cumulative buckling deformation process is evaluated for a stiffened panel subjected to two different uniaxial cyclic loading conditions, namely compressive loading only and alternating tensile-compressive loading. The impact of the cyclic load on the ultimate strength of the panel is then estimated. It should be noted that the occurrence of permanent deformations could be simulated by finite element analysis using a suitable model capable of correctly capturing the deformation components. The results show that the structure accumulates a deformation that appears to grow almost linearly therefore, consequently, it is realistic to expect that if a large number of load cycles of this magnitude are imposed, the accumulated plastic deformation can be quite severe. Furthermore, it is found that these residual deformations, caused by an entity of the cyclic load lower than the design limit, affect the tensile strength of the stiffened panel. Finally, the effects on the numerical evaluation of the ultimate strength of the structure are shown
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