Computational Modeling of Interaction Between Actions and Action Effects of FPSO Topside Structures Subject to Jet Fire

2010 ◽  
Author(s):  
G. M. Katsaounis ◽  
D. Katsourinis ◽  
M. S. Samuelides ◽  
M. Founti ◽  
Jeom Kee Paik ◽  
...  
Keyword(s):  
Computational Modeling ◽  
Constitutive Relations ◽  
Finite Element Program ◽  
Effect Analysis ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Time Histories ◽  
Element Program ◽  
Computational Fluid Dynamics Cfd ◽  
Nonlinear Elastic

This paper presents a computational modeling of accidental fire actions on the topside structures of a floating, production, storage and offloading (FPSO) unit. According to the assumed scenario, the accident results in a jet fire, which loads the structure by temperature increments and pressures generation on their exposed surfaces. Temperature distributions were obtained by computational fluid dynamics (CFD) simulations, using the ANSYS CFX commercial code. The temperature versus time histories computed were first approximated (idealized) by smoother curves, based on fewer time-points, while retaining the maximum and minimum values. A similar procedure was also followed for the pressure variations. For the consequence (action effect) analysis the LSDYNA nonlinear finite element program was employed and the structures were modeled using shell finite elements with nonlinear (elastic-thermal plastic) constitutive relations. On the structure surfaces non coinciding grids were used for the two kinds of analyses (i.e., the CFD and FEM), in order to accommodate the diverse requirements of the different problems. The procedure of assignment the pressure and temperature loadings directly from the CFD results to the FEM model is described and representative results are given through the application of the methodology to a sample problem.

Virtual Testing for Frontal Impact of High-Top Cab of Heavy Truck

2011 ◽  
Vol 148-149 ◽  
pp. 1081-1084
Author(s):  
Wei Wang ◽  
Xu Liang Xie ◽  
Fu Lin Shen ◽  
Xiao Feng Wang
Keyword(s):  
Finite Element ◽  
Element Model ◽  
Front Seat ◽  
Finite Element Program ◽  
Explicit Finite Element ◽  
Commercial Code ◽  
Element Program ◽  
Heavy Truck ◽  
Survival Space ◽  
Pendulum Impact

ECE R29 regulation has legally claimed that the survival space must be guaranteed for the safety for driver and front seat passenger in event of crash during design of truck cabin. In this paper, a finite element model of a high-top cabin of a heavy truck with a manikin on the driver seat was built with commercial code Hypermesh, The explicit finite element program Ls-Dyna was used to simulate the frontal pendulum impact on the high-top cab in the light of ECE R29 regulation. Deformation of the truck cabin and the survival space of the dummy were analyzed and discussed. Also, some suggestions were given to solve the contact possibility between steering column and the knees of manikin.

A Comparative Study of the Response of Double Shearing and Hypoplastic Models

2002 ◽  
Author(s):  
Huaning Zhu ◽  
Morteza M. Mehrabadi ◽  
Mehrdad Massoudi
Keyword(s):  
Cyclic Loading ◽  
Mechanical Response ◽  
Constitutive Relations ◽  
Constitutive Models ◽  
Shear Loading ◽  
Biaxial Compression ◽  
Finite Element Program ◽  
Cyclic Shear ◽  
Hypoplastic Model ◽  
Element Program

The principal objective of this paper is to compare the mechanical response of a double shearing model with that of a hypoplastic model under biaxial compression and under cyclic shear loading. As the origins and nature of these two models are completely different, it is interesting to compare the predictions of these two models. The constitutive relations of the double shearing and the hypoplastic models are implemented in the finite element program ABACUS/Explicit. It is found that the hypoplastic and the double shearing constitutive models both show strong capability in capturing the essential behavior of granular materials. In particular, under the condition of non-cyclic loading, the stress ratio and void ratio predictions of the double shearing and the hypoplastic models are relatively close, while under the condition of cyclic loading, the predictions of these models are quite different. It is important to note that in the double shearing model employed in this comparison the shear rates on the two slip systems are assumed to be equal. Hence, the conclusions derived in this comparison pertain only to this particular double shearing model. Similarly, the hypoplasticity model considered here is that proposed by Wu, et al. [30] and the conclusions reached here pertain only to this particular hypoplasticity model.

scholarly journals The effect of non-uniformity in ground motions on the seismic response of arch dams

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Mohammad Reza Pouya ◽  
Morteza Sohrabi-Gilani ◽  
Mohsen Ghaemian
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
Dam Foundation ◽  
Finite Element Program ◽  
Common Assumption ◽  
Arch Dams ◽  
Time Histories ◽  
Element Program ◽  
The Common ◽  
Spatially Varying

AbstractRecorded ground accelerations at various locations of Karun III Dam during November 20, 2007, were recorded by an array of accelerometers located on the dam. In terms of amplitude and phase, these accelerations show non-uniformities in different elevations. In this paper, the effect of these non-uniform ground motions on the seismic response of the dam taking dam-reservoir-foundation interaction into account is investigated. The EACD-3D-2008 finite element program and ABAQUS Software are used for carrying out the seismic analyses. For this purpose, time histories of the earthquake accelerations are interpolated at nodal points located on the dam foundation interface. The analysis has been repeated, considering the common assumption of uniform ground motions. Comparing the results obtained from these two analyses reveals that the computed displacements in the crest due to the spatially varying excitations are in more conformity with the recorded information. Moreover, neglecting the non-uniform nature of ground motions in the model leads to underestimating the tensile stress values within the dam body.

Numerical Simulation of Thermofluid Dynamics of Pollutants’ Dispersion by Thermal Electricity Production

2016 ◽  
Vol 366 ◽  
pp. 135-143
Author(s):  
Antonio José Ferreira Gadelha ◽  
Tony Herbert Freire de Andrade ◽  
Severino Rodrigues de Farias Neto ◽  
Antonio Gilson Barbosa de Lima
Keyword(s):  
Power Plants ◽  
Respiratory Diseases ◽  
Thermal Power ◽  
Diesel Oil ◽  
Electricity Production ◽  
Ansys Cfx ◽  
Commercial Code ◽  
Global Demand ◽  
Computational Fluid Dynamics Cfd ◽  
Pollutants Dispersion

The growing global demand for energy has led researchers to seek the improvement of technology in order to maximize the generation of electricity by different ways. Among the different methods of production is the energy produced by thermal power plants, which account for more than 60% of the energy produced in the world. This energy is generated through combustion of fuels such as coal, diesel oil, natural gas and others. The main problem caused by the production of thermal energy is the emission of gaseous pollutants into the atmosphere, such as carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen oxides (NOx), and also particulate matter which causes environmental problems such as acid rain, greenhouse effect, and health problems, especially respiratory diseases. Computational fluid dynamics (CFD) is presented as an important tool in solving problems involving the dispersion of chemicals into the atmosphere. In this sense, this study aims to evaluate the thermofluid dynamics of pollutants’ dispersion emitted from the chimney of a thermal power plant, based on numerical simulations using the Ansys CFX 12.0 commercial code. Fields of velocity and mass concentration of the component involved in the process are presented and analyzed.

Mechanical Analyses of Wipp Disposal Rooms Backfilled with Either Crushed Salt or Crushed Salt-Bentonite

1990 ◽  
Vol 207 ◽  
Author(s):  
Ralph A. Wagner ◽  
G. D. Callahan ◽  
B. M. Butcher
Keyword(s):  
Finite Element ◽  
Constitutive Models ◽  
Creep Model ◽  
Finite Element Program ◽  
Waste Isolation Pilot Plant ◽  
Modeling Methodology ◽  
Salt Creep ◽  
Consolidation Model ◽  
Element Program ◽  
Nonlinear Elastic

AbstractNumerical calculations of disposal room configurations at the Waste Isolation Pilot Plant (WIPP) near Carlsbad, NM are presented. Specifically, the behavior of either crushed salt or a crushed salt-bentonite mixture, when used as a backfill material in disposal rooms, is modeled in conjunction with the creep behavior of the surrounding intact salt. The backfill consolidation model developed at Sandia National Laboratories was implemented into the SPECTROM-32 finite element program. This model includes nonlinear elastic as well as deviatoric and volumetric creep components. Parameters for the models were determined from laboratory tests with deviatoric and hydrostatic loadings. The performance of the intact salt creep model previously implemented into SPECTROM-32 is well documented.Results from the SPECTROM-32 analyses were compared to a similar study conducted by Sandia National Laboratories using the SANCHO finite element program. The calculated deformations and stresses from the SPECTROM-32 and SANCHO analyses agree reasonably well despite differences in constitutive models and modeling methodology. These results provide estimates of the backfill consolidation through time. The trends in the backfill consolidation can then be used to estimate the permeability of the backfill and subsequent radionuclide transport.

Study of beam–soil interaction using finite element and centrifugal models

1982 ◽  
Vol 19 (3) ◽  
pp. 345-359 ◽  
Author(s):  
D. Leshchinsky ◽  
S. Frydman ◽  
R. Baker
Keyword(s):  
Finite Element ◽  
Load Transfer ◽  
Finite Element Analyses ◽  
Finite Element Program ◽  
Buried Structures ◽  
Centrifuge Models ◽  
Element Program ◽  
Principal Directions ◽  
Centrifugal Model ◽  
Nonlinear Elastic

A comparison is presented between the results of centrifugal model tests and finite element analyses for the problem of load transfer to a rigid tie beam buried in sand. The finite element program utilized a nonlinear elastic (hyperbolic) soil constitutive relation, obtained from tests in simple shear. It was found that, for this particular type of problem, the finite element solution may reasonably represent the interaction between the beam and the surrounding soil. It is pointed out that this agreement does not ensure that the use of such finite element analyses would be justified in problems involving rotation of principal directions, and local unloading.The effect of compaction of the fill was investigated, and it was found that compaction leads to an increase in load transferred to the beam above that which is due to density effects alone.Key words: finite elements, centrifuge, models, soil–structure interaction, buried structures.

Evaluation of a Pseudo-Elastic Model for the Mullins Effect

2004 ◽  
Vol 32 (3) ◽  
pp. 120-145 ◽  
Author(s):  
W. V. Mars
Keyword(s):  
Pure Shear ◽  
Strain Curve ◽  
Elastic Behavior ◽  
Elastic Model ◽  
Mullins Effect ◽  
Stress Strain ◽  
Finite Element Program ◽  
Simple Tension ◽  
Element Program ◽  
Nonlinear Elastic

Abstract Typically, the stress-strain response in filled rubbers depends strongly on the maximum loading previously encountered. The phenomenon, known as the Mullins effect, can be idealized for many purposes as an instantaneous and irreversible softening of the stress-strain curve that occurs whenever the load increases beyond its prior all-time maximum value. At times when the load is less than a prior maximum, nonlinear elastic behavior prevails. Ogden and Roxburgh proposed an empirical model capable of describing this phenomenon, based on a pseudo-elastic concept. Their model, with minor adaptations, has recently been implemented in a commercial finite element program. This paper demonstrates the effectiveness of the implemented model for several benchmark cases including uniform hydrostatic loading, simple tension, pure shear, and equibiaxial tension. The paper also compares model predictions with experimental results for a series of experiments conducted with various combinations of axial tension/compression and torsion loading.

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

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