Impact Simulation of Radioactive Material Package During Forklift Truck Collision

2004 ◽  
Author(s):  
Tsu-te Wu
Keyword(s):  
Structural Integrity ◽  
Computing Time ◽  
Constitutive Models ◽  
Material Model ◽  
Computer Code ◽  
Complex Problem ◽  
Radioactive Material ◽  
Contact Method ◽  
Material Degradation ◽  
Forklift Truck

This paper discusses the evaluation of the structural integrity of the SAFKEG radioactive material package to ensure hazardous material confinement during the postulated accident event of forklift truck collision. When a SAFKEG Package carried by a forklift truck traveling at 7 miles per hour collides with another forklift truck moving at the same speed but in the opposite direction, the structural response of the package components represents a complex problem. Because of its complex geometric configuration and complicated contact conditions between the neighboring component interfaces, the problem can not be solved using the implicit numerical scheme that would involve solving a large number of simultaneous equations through numerical iteration. In addition, material degradation and failure caused by collision can create severe convergence difficulties in the implicit analysis. Consequently, the explicit solution method is used in the present analysis, and thus the problem has to be treated as a dynamic one even though the inertia effect is insignificant due to the low speed of the forklift trucks. Applying the explicit dynamic technique to quasi-static problems involving very large deformation and material degradation require special considerations in overcoming solution convergence and extremely long computing time. The techniques used to overcome these difficulties are discussed in this paper. This paper also discusses the development of the constitutive models of the thermal insulating and shock absorbing materials used in the SAFKEG. The resin-bounded cork material is represented by the “crushable foam” plasticity with volumetric hardening. On the other hand, the material model of the brittle foam is developed by using the combination of the Mohr-Coulomb and Drucker-Prager plasticity theories. The analysis utilizes the finite-element method and the ABAQUS/Explicit Computer Code, version 6.3. A combination of the “General Contact” method and the “Contact Pair” method is employed to simulate the complicated interface variations among the neighboring components of the model.

scholarly journals Effect of Impact Limiter Material Degradation on Structural Integrity of 9975 Package Subjected to Two Forklift Truck Impact

2007 ◽  
Author(s):  
Tsu-Te Wu
Keyword(s):  
Structural Integrity ◽  
Material Degradation ◽  
Containment Vessel ◽  
Forklift Truck ◽  
Analytical Results ◽  
The Impact

This paper evaluates the effect of the impact limiter material degradation on the structural integrity of the 9975 package containment vessel during a postulated accident event of forklift truck collision. The analytical results show that the primary and secondary containment vessels remain structurally intact for Celotex material degraded to 20% of the baseline value.

Determination of a Rubber-Like Material Model as an Inverse Problem

2011 ◽  
Vol 70 ◽  
pp. 225-230 ◽  
Author(s):  
Agnieszka Derewonko ◽  
Andrzej Kiczko
Keyword(s):  
Selection Process ◽  
Axial Stress ◽  
Constitutive Models ◽  
Material Model ◽  
Polyester Fabric ◽  
Point Of View ◽  
Air Cushion ◽  
Ill Conditioning ◽  
Stress States

The purpose of this paper is to describe the selection process of a rubber-like material model useful for simulation behaviour of an inflatable air cushion under multi-axial stress states. The air cushion is a part of a single segment of a pontoon bridge. The air cushion is constructed of a polyester fabric reinforced membrane such as Hypalon®. From a numerical point of view such a composite type poses a challenge since numerical ill-conditioning can occur due to stiffness differences between rubber and fabric. Due to the analysis of the large deformation dynamic response of the structure, the LS-Dyna code is used. Since LS-Dyna contains more than two-hundred constitutive models the inverse method is used to determine parameters characterizing the material on the base of results of the experimental test.

A Continued Evaluation of the Role of Material Hardening Behavior for the NeT TG1 and TG4 Specimens

2014 ◽  
Author(s):  
David J. Dewees ◽  
Phillip E. Prueter ◽  
Seetha Ramudu Kummari
Keyword(s):  
Structural Integrity ◽  
Plastic Material ◽  
Critical Factor ◽  
Material Model ◽  
Standard Test ◽  
Material Behavior ◽  
Weld Residual Stress ◽  
Hardening Models ◽  
Elastic Plastic Material

Modeling of cyclic elastic-plastic material behavior (hardening) has been widely identified as a critical factor in the finite element (FE) simulation of weld residual stresses. The European Network on Neutron Techniques Standardization for Structural Integrity (NeT) Project has provided in recent years both standard test cases for simulation and measurement, as well as comprehensive material characterization. This has allowed the role of hardening in simulation predictions to be isolated and critically evaluated as never before possible. The material testing information is reviewed, and isotropic, nonlinear kinematic and combined hardening models are formulated and tested. Particular emphasis is placed on material model selection for general fitness-for-service assessments, as it relates to the guidance for weld residual stress (WRS) in flaw assessments of in-service equipment in Annex E of the FFS standard, API 579-1/ASME FFS-1.

Comparative Evaluation of Combustion Codes for Low-Btu Gas Applications

1991 ◽  
Author(s):  
Tah-Teh Yang ◽  
Ajay K. Agrawal
Keyword(s):  
Structural Integrity ◽  
Combustion Process ◽  
Computer Code ◽  
Physical Models ◽  
Gas Combustion ◽  
Combustion Modeling ◽  
Coal Gas ◽  
Combustion Models ◽  
Efficient Combustion ◽  
User Friendly

Four computer codes (PHOENICS, PCGC, FLUENT and INTERN) representing a spectrum of existing combustion modeling capabilities were evaluated for low-Btu gas applications. In particular, the objective was to identify computer code(s) that can be used effectively for predictions of (a) the flow field to yield efficient combustion, (b) the temperature field to ensure structural integrity and (c) species concentrations to meet environmental emission standards in a gas turbine combustor operating on low-Btu coal gas. Detailed information on physical models, assumptions, limitations and operational features of various codes was obtained through a series of computational runs of increasing complexity and grouped as (a) experimental validation, (b) code comparison and (c) application to coal gas combustion. INTERN is not suitable for the present application since it has been tailored to model combustion process of premixed hydrocarbon fuels. FLUENT is easy to use and has detailed combustion models (in Version 3), however, it is not favored here because the user is unable to alter, modify or change the existing model(s). While PCGC-2 has the most comprehensive models for combustion, it is not user friendly and is inherently limited to axisymmetric geometry. PCGC-3 is expected to overcome these drawbacks. Built in combustion models in PHOENICS are similar to those in FLUENT. However, the user can implement advanced models on PHOENICS leading to a flexible and powerful combustion code.

Application of a Smooth Approximation of the Schmid’s Law to a Single Crystal Gas Turbine Blade: Part 1—Theory and Governing Equations

2012 ◽  
Author(s):  
Alessandro D. Ramaglia
Keyword(s):  
Single Crystal ◽  
Constitutive Models ◽  
Material Model ◽  
Research Literature ◽  
Elastic Behaviour ◽  
Full Potential ◽  
Smooth Approximation ◽  
Suitable Material ◽  
Von Mises ◽  
Term Creep

In industrial practice, the choice of the most suitable material model does not solely rely on the ability of the model in describing the intended phenomena. Most of the choice is often based on a trade-off between a great variety of factors. Robustness, cost and time for the minimum testing campaign necessary to identify the model and pre-existing standard practices are only a few of them. This is particularly true in the case of nonlinear structural analyses because of their intrinsic difficulties and the higher level of skills needed to carefully exploit their full potential. So, despite the great progress in this field, in certain cases it is desirable to use plasticity models that are rate-independent and possess very simple hardening terms. This is for example the case in which long term creep can be an issue or when the designer may want to treat separately different phenomena contributing to inelastic deformation. If the material to be modelled is isotropic, commercial FE packages are able to deal with such problems in almost every case. On the contrary for anisotropic materials like Ni-based super-alloys cast as single crystals, the choice of the designer is more limited and despite the large amount of research literature on the subject, single crystal constitutive models remain quite difficult to handle, to implement into FE codes, to calibrate and to validate. Such difficulties, coupled with the unavoidable approximations introduced by any model, often force the practice of using oversimplifications of the material behaviour. In what follows this problem is addressed by showing how single crystal plasticity modelling can be reduced to the adoption of an anisotropic elastic behaviour with a sort of von Mises yield surface.

Development of a Biofidelic Material Model for Brain Tissue

2011 ◽  
Author(s):  
Sandeep Kulathu ◽  
David L. Littlefield
Keyword(s):  
Brain Tissue ◽  
Grey Matter ◽  
Mechanical Response ◽  
Constitutive Models ◽  
Material Model ◽  
Small Sample ◽  
Material Models ◽  
Computational Mesh ◽  
Injury Mechanisms ◽  
The Brain

Computational simulations of brain injury mechanisms have advanced to a level of sophistication where in addition to capturing different anatomic regions, the computational mesh is capable of distinguishing white and grey matter in the brain. Brain tissue is typically modeled as an isotropic, viscoelastic material. Experiments have shown that the mechanical response of brain tissue to an external load varies depending on the location from which the tissue is harvested and also the direction of loading. Some researchers have developed anisotropic constitutive models by appealing to the composite material case wherein cylindrical axon fibers are immersed in a cellular matrix. Though such material models have been developed over a small sample, they have not been applied over the entire brain for simulation purposes.

scholarly journals A Review on Recent Advances in the Constitutive Modeling of Bone Tissue

2020 ◽  
Vol 18 (6) ◽  
pp. 696-704
Author(s):  
Dieter H. Pahr ◽  
Andreas G. Reisinger
Keyword(s):  
Cortical Bone ◽  
Constitutive Models ◽  
Simulation Models ◽  
Material Model ◽  
Element Analysis ◽  
Physical Mechanisms ◽  
Constitutive Material Model ◽  
Recent Advances ◽  
Osteoporosis Research

Abstract Purpose of Review Image-based finite element analysis (FEA) to predict and understand the biomechanical response has become an essential methodology in musculoskeletal research. An important part of such simulation models is the constitutive material model of which recent advances are summarized in this review. Recent Findings The review shows that existing models from other fields were introduced, such as cohesion zone (cortical bone) or phase-field models (trabecular bone). Some progress has been made in describing cortical bone involving physical mechanisms such as microcracks. Problems with validations at different length scales remain a problem. Summary The improvement of recent constitutive models is partially obscured by uncertainties that affect overall predictions, such as image quality and calibration or boundary conditions. Nevertheless, in vivo CT-based FEA simulations based on a sophisticated constitutive behavior are a very valuable tool for clinical-related osteoporosis research.

Application of Anand-Type Viscoplastic Solder Material Model for Thermal Stress Analysis/Life Prediction of Concentrating Photovoltaic (CPV) Module

2007 ◽  
Author(s):  
M. Cao ◽  
S. Butler ◽  
J. T. Benoit ◽  
Y. Jiang ◽  
R. Radhakrishnan ◽  
...  
Keyword(s):  
Thermal Stress ◽  
Stress Analysis ◽  
Fatigue Test ◽  
Structural Integrity ◽  
Material Model ◽  
Structural Failure ◽  
Thermal Stress Analysis ◽  
Cell Components ◽  
Structure Strength ◽  
Energy Community

Aiming at understanding the structural integrity of a concentrating photovoltaic (CPV) module configuration, Finite Element (FE) thermal stress analysis is carried out in this investigation. Nonlinear viscoplastic analysis using the temperature profile of CPV cell fatigue test, is performed to evaluate the structure strength and subsequently predict the life of a CPV module. The result reveals that the maximum characteristic stresses of the PV cell components and heat sink are below the strength allowable for the corresponding materials under both the steady-state and over-night idle conditions. Critical locations on the solder that are potentially susceptible to structural failure after a few thousand thermal cycles due to excessive shear stress are identified. A rough estimation of the module life is provided and compared with the fatigue test. This investigation provides firsthand understanding of the structural integrity of CPV modules and is thus beneficial for the solar energy community.

Simulation of Gas Stratification Build-Up in the Containment Under Severe Accident Conditions

2014 ◽  
Author(s):  
Michele Andreani
Keyword(s):  
Structural Integrity ◽  
Computer Code ◽  
Severe Accident ◽  
Test Sequence ◽  
Small Scale ◽  
High Concentration ◽  
Initial Transient ◽  
Loss Of Coolant Accident ◽  
Computer Codes ◽  
Accident Conditions

The presence of hydrogen stratification in a NPP containment in the case of a severe accident is a source of concern, as pockets of the gas in high concentration could lead to a deflagration or detonation risk, which might challenge the containment structural integrity. These issues, as well as the capability of various computer codes to predict the evolution of a representative accident, are addressed in the coordinated projects ERCOSAM of the 7th EURATOM FWP and the project SAMARA sponsored by ROSATOM. The projects aim to establish whether in a test sequence representative of a severe accident in a LWR hydrogen stratification can be established during the initial transient following a loss of coolant accident (LOCA) and whether and how this stratification can be broken down by the operation of Severe Accident Management systems (SAMs): sprays, coolers and Passive Auto-catalytic Recombiners (PARs). Experiments with helium (as simulant of hydrogen) have been performed at “small scale” in TOSQAN (IRSN, Saclay), and “medium scale” in the MISTRA (CEA, Saclay), PANDA (PSI, Villigen) and SPOT ((JSC “Afrikantov OKBM”, Nizhny Novgorod) facilities. The present paper presents the analysis of the initial transient of some tests in the PANDA, TOSQAN and SPOT facilities using the GOTHIC computer code. The work therefore addresses the capability of the code and a relatively coarse mesh to simulate the pressurisation and build-up of steam and helium stratification for conditions representative of a postulated severe accident scenario, properly scaled to the various facilities. The prediction of the pressurisation is excellent, and the position of the gas concentration stratification front at the end of the steam and helium releases is generally well captured.

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