Practical Considerations for the Structural Analysis of Offshore Topside Structures Under Gas Explosion Accidents

2012 ◽  
Author(s):  
Dae Suk Han ◽  
Gyusung Kim ◽  
Woo Seung Sim ◽  
Young Sik Jang ◽  
Hyun Soo Shin
Keyword(s):  
Structural Analysis ◽  
Offshore Structures ◽  
Structural Members ◽  
Gas Explosion ◽  
Element Analysis ◽  
Numerical Investigations ◽  
The Finite Element Analysis ◽  
Explosion Accidents ◽  
Blast Loadings ◽  
Dynamic Structural Analysis

Gas explosion accidents have been recognized as a major hazard of offshore facilities in oil & gas industries. Due to the nature of offshore topside structures, even a single collapse of structural members or equipments may lead to enormous economic and environmental losses. Therefore, such potential hazards that cause the accidental collapse need to be evaluated closely. Gas explosion has been categorized as an important issue of the design of offshore structures regarding the severity of the accident. This paper presents practical considerations for the nonlinear dynamic structural analysis of offshore structures under blast loadings from gas explosion accidents. Numerical investigations including modeling of blast loads and idealization of structural materials and members have been conducted for the overall topside structures. As a design step for offshore structures under blast loadings, an applicable guidance on the finite element analysis (FEA) is described in this study.

Structural Analysis of Centrifugal Fan Impeller Using CATIA Software

2015 ◽  
Vol 809-810 ◽  
pp. 859-864
Author(s):  
Dănuţ Zahariea
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Design Methods ◽  
Constant Thickness ◽  
Blade Design ◽  
Centrifugal Fan ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Modes Of Vibration

In this paper, the finite element analysis for stress/deformation/modes of vibration for the centrifugal fan impeller with constant thickness backward-curved blades using CATIA software will be presented. The principal steps of the finite element analysis procedure using CATIA/Generative Structural Analysis environment will be presented: creating the 3D model; configuring the mesh; applying the restraints; applying the loads; running the numerical static analysis and the numerical frequency analysis; interpreting the results and observing the modes of vibration correlating with the impeller mode shape. This procedure will be used for 4 different centrifugal fan impellers according with the 4 blade design methods and the results will be comparatively analyzed. For each design method, two materials will be used: steel with density of 7860 kg/m3 and aluminium with density of 2710 kg/m3. Two important results have been obtained after the structural analysis: under the working conditions considered for the analysis, all 4 blade design methods leads to impellers with very good mechanical behaviour; any frequency of the main modes of vibrations for all blade design methods and for both materials is not in phase with the impeller speed, thus the possibility of resonance being eliminated.

Numerical Investigations of Leakage Performance Degradations in Labyrinth and Flexible Seals Due to Wear

2020 ◽  
Author(s):  
Xinbo Dai ◽  
Xin Yan ◽  
Kun He ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Labyrinth Seal ◽  
Leakage Rate ◽  
Labyrinth Seals ◽  
Element Analysis ◽  
Numerical Investigations ◽  
Forward Bending ◽  
The Finite Element Analysis ◽  
Before And After ◽  
Computational Fluid Dynamics Cfd ◽  
Wear Damage

Abstract The Finite Element Analysis (FEA) and Computational Fluid Dynamics (CFD) methods are utilized to investigate the leakage performance degradations in two kinds of flexible seals (i.e. forward bending and backward bending) and two kinds of shroud labyrinth seals (i.e. with straight fins and chamfered fins) in rubbing events. With the existing experimental data, FEA methods for contacting simulations and CFD methods for leakage rate and flow pattern predictions are carefully examined. The wear characteristic and leakage performance between labyrinth seals and flexible seals are compared before and after rub. The results show that, in rubbing process, the labyrinth seal with straight (symmetrical) fins is likely to undergo the mushrooming damage, whereas the labyrinth seal with chamfered (asymmetrical) fins is likely to undergo the tooth-bending damage. In rubbing process, compared with the labyrinth seal, the flexible seal has a superior characteristic in resisting the wear damage due to increased flexibility of fin. For a labyrinth seal with 0.3mm design clearance and a flexible seal with 0.15mm design clearance, the 0.5mm radial displacement of rotor will result in 110% increase of leakage rate for labyrinth seal, and 7% increase of leakage rate for flexible seal after wear. Under the same conditions, the forward bending flexible seal has a lower leakage rate than the backward bending flexible seal before and after rub.

Nonlinear Inverse Perturbation in Structural Dynamics Redesign of Risers

1985 ◽  
Vol 107 (2) ◽  
pp. 256-263 ◽  
Author(s):  
M. M. Bernitsas ◽  
C. J. Hoff ◽  
J. E. Kokarakis
Keyword(s):  
Offshore Structures ◽  
Mode Shapes ◽  
Drilling Mud ◽  
Element Analysis ◽  
Marine Risers ◽  
Geometric Stiffness ◽  
Stiffness Matrices ◽  
The Finite Element Analysis ◽  
Baseline System ◽  
Structural Redesign

Marine risers, and offshore structures in general, may have undesirable natural frequencies and/or mode shapes. Structural redesign is mandatory in such cases. An Inverse Perturbation Redesign (IPR) method, which uses only the finite element analysis of the baseline system and was developed in previous work for general structures, is extended in this work to handle systems with geometric stiffness matrices like marine risers. The IPR method is currently applicable to undamped structural systems or systems with Rayleigh damping and is valid for large or small changes which are frequently required to change modal characteristics of offshore structures. The vibratory characteristics of risers can be altered by modifying among others, the riser top tension, the drilling mud density and the geometry of the riser tubes. The effects of their change on the riser frequencies and modes are derived and applied to two typical riser redesign problems using the IPR method.

scholarly journals Studies on wheel mounting options on shafts

2019 ◽  
Vol 290 ◽  
pp. 01016
Author(s):  
Carmen Purcar ◽  
Mircea Bădescu ◽  
Marinela Inţă
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Static Analysis ◽  
General Description ◽  
Element Analysis ◽  
Advantages And Disadvantages ◽  
The Finite Element Analysis

The paper presents a general description of chains and chain transmissions, their advantages and disadvantages. A triple chain wheel is then projected into the CATIA V5 program. A static analysis of some wheel mounting variants on a camshaft with the Generative Structural Analysis module in the CATIA V5 program is then made. The orientation-fastening variants with a wedge, two feathers or three screws positioned equidistant at 120 degrees on a diameter are analysed. As a result of the finite element analysis, the conclusion is that the three-screw variant is the most appropriate. Material stresses and deformations are smaller, simpler processability, fewer types of components are present overall, maintenance is simpler, and the excentricity of the assembly is lower, with lower vibrations in operation.

Compression Failure Analysis of Adhesively Stiffened Composite Panels

2012 ◽  
Vol 503-504 ◽  
pp. 322-325
Author(s):  
Chun Lan Zhang ◽  
Pu Rong Jia ◽  
Liang Li ◽  
Gui Qiong Jiao
Keyword(s):  
Finite Element ◽  
Composite Panels ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Numerical Investigations ◽  
Compression Failure ◽  
Stiffened Composite Panels ◽  
The Finite Element Analysis ◽  
Load Carrying ◽  
Mechanical Approach

Experimental and numerical investigations of adhesively stiffened composite panels were performed to discuss the load-carrying capacity of different design at stiffener run-out. The compression experiment revealed that the failure was initiated at the edge of the run-out and propagated across the skin-stiffener interface. A fracture mechanical approach to utilize cohesive finite element was adopted in the numerical analysis of these specimens. It was shown that the finite element analysis using solid element and cohesive element was able to qualitatively predict the crack growth characteristics for each specimen

scholarly journals Preconditioning the Quad Dominant Mesh Generator for Ship Structural Analysis

Algorithms ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 2
Author(s):  
Luka Grubišić ◽  
Domagoj Lacmanović ◽  
Josip Tambača
Keyword(s):  
Heuristic Method ◽  
Offshore Structures ◽  
Element Analysis ◽  
Mesh Generator ◽  
Quality Requirements ◽  
Shell Elements ◽  
Low Degree ◽  
The Finite Element Analysis ◽  
Fully Automatic ◽  
Automatic Mesh

This paper presents an algorithm for the fully automatic mesh generation for the finite element analysis of ships and offshore structures. The quality requirements on the mesh generator are imposed by the acceptance criteria of the classification societies as well as the need to avoid shear locking when using low degree shell elements. The meshing algorithm will be generating quadrilateral dominated meshes (consisting of quads and triangles) and the mesh quality requirements mandate that quadrilaterals with internal angles close to 90° are to be preferred. The geometry is described by a dictionary containing points, rods, surfaces, and openings. The first part of the proposed method consists of an algorithm to automatically clean the geometry. The corrected geometry is then meshed by the frontal Delaunay mesh generator as implemented in the gmsh package. We present a heuristic method to precondition the cross field of the fronatal quadrilateral mesher. In addition, the influence of the order in which the plates are meshed will be explored as a preconditioning step.

Finite Element Analysis of Different Flexure Springs

2010 ◽  
Vol 44-47 ◽  
pp. 2065-2069
Author(s):  
Xi Chen ◽  
Ying Liu ◽  
Hua Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Geometrically Nonlinear ◽  
Advisory Opinion ◽  
Element Analysis ◽  
Radial Stiffness ◽  
The Finite Element Analysis ◽  
High Fatigue ◽  
Nonlinear Static

Flexure spring suspensions have demonstrated the ability to provide long operating lifetimes for cryocoolers. The good flexure spring need high radial stiffness and high fatigue life. The profile curves are very important for flexure spring. In this paper, based on the finite element analysis software (ANSYS), geometrically nonlinear static structural analysis and nonlinear dynamics structural analysis were made to several different flexure springs. The fatigue strength, axial and radial stiffness, modal frequency were calculated and listed. The different performance between linear flexure spring and spiral flexure spring were discussed, which would provide an advisory opinion for the design and application of flexure spring in space cryocooler.

Finite Element Analysis for Analog Modes of SCS Series Truck Scale with Different Loads

2011 ◽  
Vol 201-203 ◽  
pp. 121-125
Author(s):  
Wei Tao Shi ◽  
Jian Li ◽  
Jun He
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Structural Analysis ◽  
Stress Distribution ◽  
Traditional Method ◽  
Stress And Strain ◽  
Element Analysis ◽  
Simply Supported ◽  
The Finite Element Analysis ◽  
Loading Modes

The weighing platform of the truck scale is a load-bearer, which is used for bearing a load. Its structure has many forms, in this paper, the finite element analysis of a structure with u-beam which is currently the most widely used for different loading modes, the traditional method of structural analysis of truck scale is to simplily the platform as a simply supported beam. As the model is too simplified, the result of this method will be unreliable and it cannot make part analysis about stress and strain . In this research, ANSYS was used to model, and loaded analysis. Through different loading, get the structure of weighing platform stress distribution and deformation. By analysing,we give reasonable proposals and provide valuable reference for the design and production of truck scale .

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