bluuebunny/crossref_metadata_2025 huggingface dataset:
Failure Stresses for Pipes With Multiple Circumferential Flaws
Authors: Hasegawa Kunio , Kobayashi Hideo
Published: August 2008

Flaw evaluation for fully-plastic fracture uses the limit load criterion. As stainless steels are high toughness ductile materials, limit load criterion is applicable to stainless steel pipes. When a single circumferential flaw is detected in a stainless steel pipe during in-service inspection, the single flaw is evaluated in accordance with Article EB-4000 in the JSME Code or Appendix C in the ASME Code, Section XI. However, multiple flaws such as stress corrosion cracking are sometimes detected in the same circumferential cress-section in a pipe. If the distance between adjacent flaws is short, the multiple flaws are considered as a single flaw in compliance with combination rules. Failure stress is easily calculated by the equations given by Article EB-4000 or Appendix C. If the two flaws are separated by a large distance, it is not required to combine the two flaws. Each flaw is treated as independent. However, there are no equations for evaluating collapse stress for a pipe containing multiple independent flaws in Article EB-4000 and Appendix C. The present paper focus on a proposal of simple equations for evaluating collapse stresses for pipes containing multiple circumferential part-through wall flaws.
Experimental Study for Proximity Rule of Multiple Flaws for Ductile Fracture
Authors: Miyazaki Katsumasa , Hasegawa Kunio , Shimamura Takeshi
Published: August 2008

The proximity rule of multiple flaws in ASME B&PV Code Section XI 2003 addenda was mainly determined by the evaluation of stress intensity factors from the viewpoint of brittle fracture. Since the austenitic steel and carbon steel for class 1 piping shows a ductile manner in fracture, a new proximity rule for ductile fracture is required. To understand the fracture behavior of multiple flaws, tensile tests, using flat plate specimens made of Type 304SS with twin flaws, were conducted. When the shapes of twin flaws were semi-circular with aspect ratio, a/l = 0.5, the effect of the space of multiple flaws on maximum load is clear. On the other hand, the effect of flaw spacing on maximum load was insignificant for flat multiple flaws with 0.167 in a/l. The effect of space of multiple flaws, aspect ratio of multiple flaws on ductile fracture pattern was discussed. Finally, the proximity rule for plastic collapse was proposed in this paper.
Fracture and Deformation Behaviors of Tee Pipe With Local Wall Thinning Under Monotonic Bending
Authors: Takahashi Koji , Ando Kotoji , Hisatsune Masakazu , Hasegawa Kunio
Published: August 2008

Monotonic four-point bending tests were conducted using tee pipe specimens having local wall thinning. The effects of local wall thinning on the fracture behaviors of tee pipes were investigated. Local wall thinning was machined on the inside of pipes in order to simulate erosion/corrosion metal loss. The configurations of the eroded area were l = 100 mm in eroded axial length, d/t = 0.5 and 0.8 in eroded ratio, and 2θ = 90° in eroded angle. The area undergoing local wall thinning was subjected to either tensile or compressive stress. Fracture behaviors of the tee pipes were compared with those of straight pipes. It was found that fracture type could be classified into ovalization, local buckling, and crack initiation, depending on pipe shape, eroded ratio, and stress at the eroded area. Three-dimensional elasto-plastic analyses were also carried out using the finite element method, which is able to accurately simulate fracture behaviors.
Allowable Limit and Finite Element Analysis of Pipes With Local Wall Thinning Subjected to Bending Moment
Authors: Ahn Seok Hwan , Nam Ki Woo , Takahashi Koji , Ando Kotoji
Published: August 2008

Fracture behaviors of pipes with local wall thinning are very important for the integrity of power plant piping system. In this study, monotonic bending tests without internal pressure are conducted on 1.91-inch diameter Schedule 80 STS370 full-scale carbon steel pipe specimens. Fracture strengths of locally wall thinned pipes were calculated by elasto-plastic analysis using finite element method. The elasto-plastic analysis was performed by FE code ANSYS. We simulated various types of local wall thinning that can be occurred at pipe surface due to coolant flow. Locally wall thinned shapes were machined to be different in size along the circumferential or axial direction of straight pipes. We investigated fracture strengths and failure modes of locally wall thinned pipes by four-point bending test. From the test results, failure modes could be divided three types, ovalization, local buckling and crack initiation. And, the allowable limit of pipes with local wall thinning was investigated. In addition, we compared the simulated results by finite element analysis with experimental data. The failure mode, fracture strength and fracture behavior obtained from the tests showed well agreement with analytic results.
Embedded Crack Treatments and Fracture Toughness Evaluation Methods in Probabilistic Fracture Mechanics Analysis Code for the PTS Analysis of RPV
Authors: Onizawa Kunio , Shibata Katsuyuki , Suzuki Masahide , Kato Daisuke , Li Yinsheng
Published: August 2008

Using the probabilistic fracture mechanics analysis code PASCAL, we studied the treatment method of an embedded crack and the fracture toughness evaluation methods on the probability of crack initiation and fracture of a reactor pressure vessel (RPV). For calculating the stress intensity factor (SIF) of an embedded crack, the ASME and CRIEPI procedures were introduced into the PASCAL code. The CRIEPI method enables us to calculate the SIF values at three points on the crack tip. Under a severe pressurized thermal shock (PTS) condition, the crack growth analysis methods with different SIF calculation points and crack growth directions are compared. To evaluate precisely the fracture toughness after neutron irradiation, the new fracture toughness curves based on the Weibull distribution were incorporated into the PASCAL code. The calculated results with these new curves showed little difference in the conditional probabilities of RPV fracture as compared to the curve currently used in the U.S.
KIa Crack Arrest Toughness Assessment Using Thermal Shock on Notched Disks
Authors: Hajjaj Me´jido , Bugat Ste´phane , Berdin Clotilde , Bompard Philippe
Published: August 2008

The aim of the study is to validate the KIa-T curve on a thermal shock experiment performed on a notched disk (DTSE) taken from a A533-B type steel. Several experiments have been performed. Non linear thermal analyses were carried out using the finite element method in order to obtain the full thermal field within the specimen during crack propagation. The results obtained are in excellent agreement with the experimental results. The DTSE is also interpretated in static terms to compare the obtained KIa (T) values with the limit curve. Finally, dynamic F.E. simulations allow to estimate the influence of dynamic effects in the DTSE and thus validate the methodology. According to the computations, the crack arrested when dK/da>0 and dKd/da = 0. The comparison between stress intensity factor computed from elastic-static analysis (or dynamic) and RCC-M code demonstrated the conservatism of the approach. Then static analysis is sufficient to analyse the result, since no wave interference with the crack propagation was identified.
Overview of Flaw Assessment Methods in the RSE-M Code
Authors: Le Delliou Patrick , Sermage Jean-Philippe , Barthelet Bruno
Published: August 2008

The RSE-M Code provides rules and requirements for inservice inspection of French Pressurized Water Reactor power plant components. Appendices 5.3 and 5.4 of the Code give non mandatory guidance for analytical evaluation of flaws, i.e. fracture mechanics analyses based on simplified methods. Flaw assessment aims to calculate the initiation and the subsequent propagation of the crack under cyclic loading (fatigue analysis) and then to assess the crack stability, by comparing the applied J integral to the toughness of the material. This paper shows an overview of the R&D work undergone to make possible an analytical approach: • analytical formulas for the elastic stress field in elbows under in-plane, out-of-plane and torsion moments, • stress intensity factors solutions based on the influence coefficient method for surface and embedded cracks in pipes, • simplified methods to estimate the J integral for various configurations of piping, flaws and loading. These methods are shortly presented, including their field of application and their validation.
Fracture Toughness of Ductile Cast Iron and Applicability of Fracture Mechanics to DCI Casks
Authors: Arai Taku , Saegusa Toshiari , Urabe Namio , Takaku Hiroshi
Published: August 2008

The JSME Cask Code, Rules for Construction of Metallic Casks, has a scope of using three types of casks fabricated by stainless steels, forged low alloy steels and ductile cast irons (DCI). On the other hand, the use of DCI for Cask material is not within the scope of the ASME Code, Section III, Division 3. In this paper, the fracture toughness of DCI for JSME cask code was compared with those of quenched and tempered low alloy steels. Furthermore, applicability of fracture mechanics to DCI casks is demonstrated by the results of fracture tests of reduced scale model casks. The results deny criticism arising from the fact that the DCI is not homogeneous material due to precipitation of spheroidal graphite particles for the application of the fracture mechanics.
A Limit Pressure Criterion for Cracked Cylinders and Piping Branch Junctions
Authors: Lee K. S. , Moreton D. N. , Moffat D. G.
Published: August 2008

The concepts of limit loads and plastic loads for piping components are outlined. The difficulty associated with specifying reliable definitions for these quantities is addressed. These difficulties include the selection of a deformation parameter, the selection of a location within the structure where this deformation is to be calculated or measured and the criterion to be used to assess if the deformation is sufficient for the structure to be considered to have reached its limit or plastic load. An alternative method based upon plastic work has recently been advocated [1]. This definition is based upon the plastic work that may be calculated during a routine finite element computation. Having plotted the cumulative plastic work against a load parameter, it was shown possible to identify levels at which collapse mechanisms form and where gross plastic deformation becomes evident. The present work attempts to add some precision to this definition. This has been done by determining the important geometric parameters and forming non-dimensional quantities to allow new plots in which the limit or plastic loads can be extracted directly and without any ambiguity. The technique is shown to be reliable for cracked and uncracked plain cylinders and cracked and uncracked piping branch junctions.
Shear-Dominated Fracture of Ductile Metal Under Mixed Loading and Preliminary Assessment
Authors: Wang Xiaochun
Published: August 2008

At room temperature, fracture of ductile metal often appears ductile, which is thought as the result of nucleation, dilatation and coalescence of microvoids in material. The remnant of microvoids in fracture surface is dimple. Dimple-mode fracture (void-dominated) is often accompanied with dilatation of volume of loaded material [1–4]. Fracture not accompanied with dilatation of volume was often studied at low temperature. Researchers think that the modes and mechanisms of fracture are affected by temperature and when temperature decreases ductile fracture becomes brittle fracture. No-volume-dilatation fracture is often related with low temperature fracture or brittle material’s fracture. But at room temperature, there is also no-volume-dilatation fracture, i.e., shear fracture of ductile material. There are very large differences between brittle fracture and shear fracture of ductile material, in which the deformation may be considerably larger before collapse [5]. Yamamoto [6] thought that heterogeneity of material resulted in local shear band in which there were lots of microvoids, and this led to fracture. Yang and Lee [7] described analogous process of initiation of fraction in their work. They indeed attributed shear fracture of ductile material to evolution of microvoids. In this presentation, instead of explaining shear-dominated fracture of ductile material as the result of evolution of microvoids, shear-dominated fracture of ductile metal is thought to be due to another mesomechanism, micro-shear-band. Some experiment results and simulation of finite element method of shear-dominated fracture of ductile metal are given. A kind of preliminary assessment about shear-dominated fracture of ductile material is proposed.
Temperature-Dependent Micro-Crack Propagation
Authors: Kitamura Kazuhiro , Maksimov I. L.
Published: August 2008

The crack-lattice trapping phenomenon introduce by R. Thomson et al[1] is studied for the conditions of the Frenkel-Kontrova-type experiment. By using a new method, which allows further model extension for a finite temperature case we are able to describe an equilibrium crack energetics for arbitrary externa conditions and ascertain the crack propagation conditions. Specifically, the system free energy F as a function of nonlinear bond displacement ul for an external forces P and for a finite temperature T is found. The equilibrium values for the displacement ul = ul* and for G* = G(ul*), are obtained. The free-energy barrier height G = Gmax − G* dependence upon P and T is determined. With the help of the exact solution of the equilibrium equations we obtained the free energy as function of crack length G(l,T,P). We found that local free energy barriers take place for every crack length l, which is in contrast to the Thomson model. From the microscopic viewpoint it means that crack advance is controlled by local free energy barriers. We found that near the equilibrium length the crack energy barrier is relatively high, while far from equilibrium crack position, energy barrier height decreases to a finite value. It is worth to note that the barrier height monotonically decrease with the increase of the environment temperature. On the basis of our model the temperature dependence of the crack surface energy will be found, the global energetics of the crack will be described.
Evaluation of Stress Intensity Factors by Finite Element Alternating Method
Authors: Kamaya Masayuki , Nishioka Toshihisa
Published: August 2008

The finite element alternating method (FEAM), in conjunction with the finite element analysis (FEA) and the analytical solution for an elliptical crack in an infinite solid subject to arbitrary crack-face traction, is used for evaluating the stress intensity factor (SIF) of surface cracks. The major advantage of this method is that the SIF can be calculated by using the FEA results for an uncracked body. A newly developed system allows the FEAM to be performed by a simple method, which consists of the conventional FEA for an uncracked body and a subroutine for the FEAM alternating procedure. The SIFs are evaluated for semi-elliptical surface cracks on a plate and in a cylinder as well as interacting cracks on a plate. It is also shown that, by using fine mesh, the maximum error of the evaluation by the FEAM can be suppressed less than 2 percent.
Mechanical Behavior of a Metallic Bellows Under Impact Loading
Authors: Lin Junshan , Hattori Toshio , Kobayashi Masato , Tsuchiya Kenji
Published: August 2008

The stress-strain responses of a metallic bellows under static and impact loading were studied by means of strain measurement and finite-element simulations. It was found that the simulated strain responses agree well with the measured ones, and a finite element model that considers the elasto-plastic deformation and the geometric nonlinearity can accurately simulate the mechanical behavior of a bellows with a very thin shell under static and dynamic loading. The analysis results showed that the inner corrugations endure higher stresses than the outer corrugations. Under impact loading, the corrugations near the ends of the bellows have larger stresses than the other corrugations. In addition, by comparing the stress analyzed by FEM and that calculated by the Kellogg formula generally used in the design of bellows, it was found that the Kellogg formula underestimates the maximum stress in the bellows.
Mechanical and Hydraulic Loads on the Supports of the Rotary Machine Due to Shaft Seizure in a Nuclear Power Plant
Authors: Gupta S. K. , Chatterjee B. , Kumar Rajesh
Published: August 2008

In a nuclear power plant there are two major equipment with high mechanical inertia, which have a rotating shaft. These are Pumps in the Primary Heat Transport System and Turbine in the secondary system. In both cases, the shaft seizure leads to transfer of very large loads to the supports. These supports, if not designed for seizure loads may fail. If the supports fail, there is a good possibility of a missile generated and hit the safety equipment. Seizure loads in these machines have three components namely mechanical inertial load, electrical load and hydraulic load. While the electrical and hydraulic loads have a limited peak value, the inertial load depends on the seizure time. For the normal observed seizures the three have a similar order of magnitude during seizure. As the casing is overdesigned the combined load is experienced by the supports. The pump of the Primary Heat Transport System (PHTS) of a nuclear power plant is centrifugal type run by an induction motor. If the pump shaft seizes, the seizure load will be experienced by the support structure. Due to the presence of the flywheel, the total moment of inertia of the pump motor assembly is quite high. Hence the resisting torque may be higher than the support’s design torque. Besides, the electric torque will continue to be applied as the motor trip on the overload current is delayed by several seconds as the corresponding relay is a thermal relay. Seizure torque will depend on pump seizure time. Lesser the seizure time, higher would be the load on the pump supports. The turbine in the secondary system has a large inertia due to blades. In case of a seizure the generator is tripped in hundreds of milliseconds. The load experienced by turbine supports due to seizure is significantly enhanced in the first few seconds due to sustained steam supply before it is cut off. This paper discusses the estimation of the three types of loads during seizure of the shafts in the pumps and turbine. It also discusses the possible safety consequences of these loads.
Multiple Void Growth Simulations in the Hyper-Elastic Material
Authors: Tsuji Tomoaki
Published: August 2008

If the hydrostatic tensile load is applied to a hyper-elastic material, the void initiates when the load exceeds the critical value. On the other hand, it is important to study multiple void growth phenomena, in order to consider the fracture by coalescence of voids. In this paper, we study the growth of multiple voids in the hyper-elastic material. The material is characterized by the energy function as the compressive material. Some experiments for the rubber, as a hyper-elastic material, are proceeded, in order to obtain these mechanical properties in the energy function. A square cell with some small voids is constructed and applied with tensile deformation by moving outer surface. The large deformation and the non-linear simulations are proceeded by using FEM. If there is only one seed, one void grows from the seed. However, when there are some seeds, we observed the void growing and the void vanishing by the influence from the other voids. The influence of the initial voids scale to the void growth is studied.
On the Implementation of Novel Generalised Nonlinear Constraints in Explicit Finite Element Formulations
Authors: Ho R. J. , Sauve´ R. G. , Meguid S. A.
Published: August 2008

This work presents a novel technique for enforcing the beam-to-shell, beam-to-solid, and shell-to-solid family of constraints in explicit finite element formulations. The limitations of classical multipoint constraint approaches are examined at length, with robustness and accuracy examined through numerical examples. Novel formulation of the new constraint method is presented, and its implementation in the explicit finite element computational cycle discussed. The results of some illustrative test cases employing the newly proposed method are given, showing excellent accuracy even in the presence of large rotations. When compared to existing works, the salient features of the current method are in evidence.
Nonlinear Dynamic Explicit Simulation of a Blast Load on a Building
Authors: Khajehpour Siavash , Morandin Greg D. , Sauve´ Richard G.
Published: August 2008

The response of buildings to a pressure pulse from a shock wave is becoming more critical to design assessments. The severe loading transients resulting from such events, provides unique challenges to analytical modelling and simulation of building survivability. In this paper, a nonlinear explicit three dimensional blast simulation of a building is undertaken with critical contents located in the most susceptible locations in order to provide an assessment of potential damage and the impact on the contents of interest. In the work described in this paper, the source and orientation of the blast relative to the building are outlined. Using developed blast procedures, the amplitude and impulse of the blast shock wave due to specified blast parameters are determined for the front, sides, roof and rear of the building. These are applied to finite element models of the building. A state-of-the-art, large deformation, non-linear finite element code that is well suited to this class of problem, is used in the blast simulations. The results indicate that the building is severely damaged, however, the internal building area, in the vicinity of the critical contents, is intact and the main roof trusses remain attached.
A Two-Stage Crack Growth Model Incorporating Environmental Effects
Authors: Dong P. , Hong J. K.
Published: August 2008

A new two-stage crack growth model has recently been proposed by Dong et al (2003) to provide a unified description from an infinitesimally small crack exhibiting anomalous crack growth behavior to long cracks that are typically characterized by Paris law. As a result, both short crack anomalous crack at notches and long crack growth data can be unified into a single curve, which provides a fracture mechanics basis for the successful development of the single master S-N curve for weldments (Dong et al, 2001). In this paper, the applicability of the two-stage crack growth model in incorporating environmental effects will be investigated by considering some of the recent available crack growth rate data on 304 SS subjected to an elevated temperature aqueous environment by Wire and Mills (2002). The applicability of the master S-N curve method for weldments for incorporating environmental effects will be discussed in light of the findings from this investigation.
Limit Load of Anisotropic Components Using the M-Beta Multiplier Method
Authors: Indermohan H. , Reinhardt W. D. , Seshadri R.
Published: August 2008

The mβ multiplier method is based on Mura’s extended variational theorems in plasticity, and has been applied previously to isotropic components containing notches and cracks. Lower bound limit loads rapidly converge to inelastic analysis results when the method is used in conjunction with linear matching techniques. In this paper, the mβ-multiplier method is applied to pressure components exhibiting anisotropy. Specifically, the method is applied to the limit load determination of a steam generator tubesheet, wherein the tubesheet is modeled as an equivalent solid plate with anisotropic properties. Results are presented for a finite element model where plasticity is represented with Hill’s yield criterion, and a model using a fourth order yield criterion that accounts for compressibility of the tubesheet.
A Study on the Elastic Compensation Method for Design by Analysis Codes
Authors: Nishiguchi Isoharu , Sasaki Masataka
Published: August 2008

In the Design by Analysis (DBA) codes, it is important to ensure that the integrity of the structures can be maintained under the various loadings. For this purpose, elastic analyses are not sufficient and generally, elastic-plastic analyses are necessary. However, elastic-plastic analyses are still costly, especially for three-dimensional complex components. To solve this problem, the Elastic Compensation Method (ECM) has been studied, in which a conservative plastic collapse load can be obtained based on the lower bound theorem. In this paper, this investigation, including application of the ECM for combined loadings and body forces has been summarized. Application of the method on a structure consisting of dissimilar materials is also discussed.
Ultrasonic Study on Crystal Orientation Effects Upon Point Defect Growth Caused by Cross Slip Under Plastic Deformation
Authors: Kobayashi Michiaki
Published: August 2008

Concerned with the longitudinal wave velocity changes under plastic deformation in pure shear state, the experimental results of longitudinal wave velocity are categorized to two types: (i) simple decreasing change tendency at polished surface specimens, and (ii) chaotic change tendency at unpolished surface specimens. In the present paper, the effects of surface roughness and crystal orientation on the amount of cross slip under plastic deformation are studied via finite element polycrystal model (FEPM) from the viewpoint of longitudinal wave velocity change showing a sensitive response to the point defects caused by cross slip.
Non-Linear Finite Element Analysis of a Pipe Denting Problem During a Pipe Transfer Operation
Authors: Pierson Hazel M. , Suchora Daniel H. , Viviano Anthony V.
Published: August 2008

This paper investigates the problem of a pipe rolling down a transfer skid and becoming permanently dented as it hits the stops at the end of the skid. See Figure 1. The transfer skid stops under consideration had been successfully used in other applications. However, in this application there was an increase in distance between stations connected by the transfer skid. Thus, as the pipe rolled down the skid it built up significant kinetic energy, which needed to be dissipated upon impact with the skid stop. Unfortunately in this case, the skid stops did not always absorb enough energy to ensure integrity of the pipe. Consequently, certain sizes and grades of pipe experienced denting as they would impact the stops. The skid stop and the pipe must absorb the total kinetic energy possessed by the pipe just before impact. The energy absorbing characteristics of both the skid stop and pipe were developed using a static method. For the skid stop a physical test was performed to obtain the contact force versus deflection curve. For the pipe a finite element analysis was conducted to determine the contact force versus deflection curve. In the finite element model the effect of local yielding of the pipe material was incorporated into the analysis. The energy absorbed by each component was estimated as the area under the contact force-deflection curve and for each component the energy absorbed versus contact force curve was developed. Combining these two results gives the total system energy absorbed by both the pipe and skid stop as a function of contact force. This is compared to the total energy in the pipe just before contact to determine the actual maximum contact force and the actual energy absorbed by each component. The energy that could be elastically given back to the system was also obtained from the model. These results were compared to actual field measurements of dent size and pipe rebound height. The comparisons proved the validity of the model.
Fatigue Reliability Based Optimal Replacement Decision of Mechanical Components
Authors: Tang Jun , Park Young Ho
Published: August 2008

This paper introduces a maintenance decision-making strategy in the general area of replacement and reliability of mechanical components. The decision-making strategy involves the optimization of replacement interval based on fatigue failure of mechanical components. This new approach is based on the cumulative damage distribution function for evaluating mean fatigue life. By using the approach, the analytical expressions for the mean and the variance of the cumulative damage distribution under both stationary narrow-band and stationary wide-band random process are provided. The mean value and variance of the fatigue life distribution are thus evaluated to determine the optimal replacement intervals under fatigue failure. An algorithm of evaluating the mean and standard deviation of fatigue life is also presented. Therefore, the reliability of a component under random cyclic loading for a specified duration is quantified accordingly. Even though the new method introduces a great deal of complexity in the analytical models, this method can efficiently determine replacement intervals for component whose operating costs increases with use and replacement intervals for component subject to failure induced by the random process. An example is presented to demonstrate the application of the present method.
Force Identification Using Neural Network
Authors: Kozukue Wakae , Miyaji Hideyuki
Published: August 2008

Due to various causes, a machine generates and undergoes dynamic loads during its operation. These dynamic loads are the main source of vibration and noise. If dynamic loads can be identified exactly, it will become possible to provide data effective for the reduction of vibration and noise. However, by the method of identification of dynamic loads of the conventional multiple input systems, noise has large influence on the accuracy. Thus, in this paper, the identification method based on neural network (NN) are proposed for independent multiple input loads, and the result of the simulation by using the conventional method and NN are shown and compared in detail.
Function Representation of an Image by Means of CSRBF: An Application for Resolution Conversion
Authors: Kitago M. , Taniguchi Y. , Hagiwara I.
Published: August 2008

As the need to use various devices increases today (e.g. computer monitor, digital camera, cell phone), the production of images at different resolutions is needed. In this paper, we propose CSRBF (Compactly-Supported Radial Basis Functions) image format to store CSRBF coefficients. CSRBF is popular for scattered data interpolation. Since this image format has function representation of an image, resolution conversion can be easily performed with high precision. Because resampling is easy once it performs function representation by means of CSRBF. Furthermore, in an environment with restriction such as storage or network, we propose CSRBF using wavelet transform preprocessing (WTP) to reduce points for image compression. This technique can reconstruct a high precision image with less image degradation than the conventional techniques. We show the superiority by data reduction rate comparison of CSRBF interpolation and conventional techniques.
MOAA and Topology Judgment for Mesh Construction
Authors: Cheng Wen-Jie , Sorguc Arzu Gonenc , Shinoda Junichi , Hagiwara Ichiro
Published: August 2008

In this paper, the Maximum Opposite Angulation Approach (MOAA) for 3-D including the topology optimization is discussed. The MOAA algorithm is developed to generate meshes in 2-D and 3-D. The basic principles of the algorithm both in 2-D applications and in 3-D applications, is to pre-set uniformity to the initial data set to form point pairs yielding possible shortest line segments. These line segments are connected with the points providing the maximum angle for the vertex of the triangular mesh to be constructed. Thus, the algorithm provides triangular meshes having well balanced interior angles and good aspect ratios. The MOAA algorithm can be proved similar to the Delaunay’s approach in 2-D from the principle and with the quickest speed. In 3-D, it was also shown that it is much more efficient than many Delaunay class algorithms with mesh architectures preserving the topology, for uniformly organized data points. In this study, the topology optimization together with the MOAA algorithm is presented to improve the precision of reconstruction of the original surface. In this context, topology judgment for intersection problem in 3-D, distortion phenomenon, the possibility of loosing some characteristics of the original surface is thoroughly investigated.
FEM Analysis of Magnetic Field Induced by Martensitic Phase Transformation Around Fatigue Cracks in SUS 304 Stainless Steel
Authors: Nakasone Yuji , Iwasaki Yoshifumi
Published: August 2008

The present study has attempted to analyze the distributions of vertical magnetic flux density Bz above growing fatigue cracks subjected to various stress ratios R in SUS 304 stainless steel in which plasticity-induced martensitic transformation has occurred at room temperature in air. FEM calculations have been made to obtain Bz distributions above fatigue cracks by using composite permanent magnet models. The martensitic transformation regions around fatigue cracks were modeled as composites of permanent magnets having different B-H properties varying according to the content of α′ martensitic phase transformed. The resultant distributions of leakage magnetic flux density above fatigue cracks obtained by FEM agree well with those obtained by experiments.
An Application of Modified Predictor-Corrector Method
Authors: Mesˇtrovic´ Mladen
Published: August 2008

The explicit numerical integration method, introduced and proposed in the paper given by Chiou and Wu [1], is further developed. The method is based on the relationship that m-step Adams-Moulton method is linear convex combination of the (m − 1)-step Adams-Moulton and m-step Adams-Bashforth method with a fixed weighting coefficients. The general form taken from Chiou and Wu [1] is used to evaluate the recurrence expressions using the different number of previous mesh points. The explicit expressions are given for modified 3-step predictor-corrector method. The numerical algorithms are given for first and second-order nonlinear initial value problems and for system of ordinary differential equations. Some numerical examples, for different kind of problems, are used to demonstrate the efficiency and the accuracy of the proposed numerical method. The calculated numerical solutions show superiority of presented modified predictor-corrector method to standard Adams-Bashforth-Moulton predictor-corrector method.
Behavior of Shipment Casks Under Explosive Loading
Authors: Cheval Karine , Loiseau Olivier , Autrusson Bruno , Gue´rin Jean-Marc , Pre´mont Didier
Published: August 2008

The behavior of the casks used for the shipment of nuclear material must be assessed for a set of various normal and accidental situations. The security of the casks must also be studied in the case of an explosion. To perform this study, the « Institut de Radioprotection et Suˆrete´ Nucle´aire » (IRSN) led a multi-years program since 1996, including numerical simulations and a set of 9 experimentations on reduced-scale mock-ups. Such a complete program is necessary to validate numerical models used to simulate the mechanical behavior of constitutive materials of the representative mock-up. On a counterpart, since numerous experimentations would be costly prohibitive, numerical simulations are used to find the worse conditions of loading considering the security of the casks. These conditions being established, different points are investigated (check of leaks, effects of surrounding casks, ...). The two last experimentations are devoted to specific aspects which could not be studied, in details, with numerical simulations because of the high number of degree of freedom or because the physical phenomena associated are not correctly modeled with computer codes yet.
Model Based Structural Evaluation and Design of Overpack Container for Bag-Buster Processing of TRU Waste Drums
Authors: Clark Don T. , Siahpush Ali S. , Anderson Gary L.
Published: August 2008

This paper describes a materials and computational model based analysis utilized to design an engineered “overpack” container capable of maintaining structural integrity for confinement of transuranic wastes undergoing the cryo-vacuum stress based “Bag-Buster” process and satisfying DOT 7A waste package requirements. The engineered overpack is a key component of the “Ultra-BagBuster” process/system being commercially developed by UltraTech International for potential DOE applications to non-intrusively breach inner confinement layers (poly bags/packaging) within transuranic (TRU) waste drums. This system provides a lower cost/risk approach to mitigate hydrogen gas concentration buildup limitations on transport of high alpha activity organic transuranic wastes. Four evolving overpack design configurations and two materials (low carbon steel and 300 series stainless) were considered and evaluated using non-linear finite element model analyses of structural response. Properties comparisons show that 300-series stainless is required to provide assurance of ductility and structural integrity at both room and cryogenic temperatures. The overpack design were analyzed for five accidental drop impact orientations onto an unyielding surface (dropped flat on bottom, bottom corner, side, top corner, and top). The first three design configurations failed the bottom and top corner drop orientations (flat bottom, top, and side plates breached or underwent material failure). The fourth design utilized a protruding rim-ring (skirt) below the overpack’s bottom plate and above the overpack’s lid plate to absorb much of the impact energy and maintained structural integrity under all accidental drop loads at both room and cryogenic temperature conditions. Selected drop testing of the final design will be required to confirm design performance.
Developing Quality Assurance Programs That Satisfy 10 CFR 71, Subpart H and Department of Energy Requirements for Packaging Organizations at Department of Energy Sites
Authors: Ryan Evelyn M. , Russell Edward W.
Published: August 2008

Many differences exist in Department of Energy (DOE) and Nuclear Regulatory Commission (NRC) Quality Assurance (QA) requirements documents, work scope, organizational structures, and graded application and assessment approaches. These differences must be understood and reconciled to ensure consistent and effective implementation and cost effective assessments of QA Programs for DOE organizations participating in the design, purchase, fabrication, handling, shipping, storing, cleaning, assembly, inspection, testing, operation, maintenance, repair, use and/or modification of the radioactive material packaging. This paper discusses those differences and provides practical recommendations that can serve as stepping stones to more effective and efficient QA programs and value added assessments at DOE sites participating in radioactive material packaging activities.
Monte Carlo Simulations to Determine Failure Temperatures and Pressures for 3013 Outer Can Under Room Fire Conditions
Authors: Gupta Narendra K. , McKeel Charles A.
Published: August 2008

One of the current missions of the Savannah River Site (SRS) is to provide storage and disposition of DOE excess plutonium and highly enriched uranium (HEU) materials. Most of the materials to be stored at SRS will be packaged in accordance with DOE-STD-3013. The 3013 containers are removed from the shipping container and stored in racks. There was a concern that the outer 3013 containers could burst during a fire and release the contents in the environment. This paper analyzes the structural integrity of the 3013 outer can under different fire conditions and then determines the limiting fire temperature and its duration for loss of containment. The structural analysis uses a Monte Carlo technique that considers the variance in material strength, material creep properties, failure criteria, and vessel dimensions to calculate the median failure pressures for the different fire temperatures and duration. These failure pressures are compared against the increase in internal pressures as the content temperature rises inside the outer can, yielding failure temperature and duration of the fire conditions.
Drop Tests for the 6M Specification Package Closure Investigation
Authors: Smith Allen C. , Gelder Lawrence F.
Published: August 2008

Results of tests of drum-type RAM packages employing conventional clamp-ring closures have caused concern over the DOT 6M Specification Package. To clarify these issues, a series of tests were performed to determine the response of the clamp-ring closure to the regulatory Hypothetical Accident Condition (9m) drop test for packages at maximum allowable weight. Three enhanced closure designs were also tested: the Clamshell, plywood disk reinforcement, and J-Clip. The results of the tests showed that the standard closure was unable to retain the lid for both Center-of-Gravity-Over-Corner and Shallow Angle cases for the standard package at its maximum allowed weight. Similar results were found for packages dropped from a reduced height. The Clamshell design provided the best performance of the enhanced closures.
Dynamic Analysis of Radioactive Material Package With Clamp-Ring Closure
Authors: Wu Tsu-te , Gelder Lawrence F. , Smith Allen C.
Published: August 2008

Separation of the closure lid from the drum-type radioactive material packages employing the conventional clamp-ring closure has been a safety concern. Currently, the evaluation of drum-closure separation problems resorts to expensive and time-consuming tests. Therefore, an analytical capability to predict drum-closure separation is desired. However, the conventional methods of dynamic analysis are not applicable to this subject. The difficulty of the problem mainly lies in solving the complicated preload stresses on the multiple contacted surfaces during claim-ring tightening and in integrating the preload results with the subsequent drop simulation. A technique has been previously proposed by Wu for the dynamic analyses of containers with locking-ring closures (Reference 1). This paper presents a refinement of the proposed technique and also extends the technique from the dynamic simulation of one single drop to the simulation of two sequential drops. The finite-element method with explicit numerical integration scheme is utilized to simulate both the closure bolt tightening process and the drop impact. The essential aspects of the proposed technique include: quasi-static simulation of clamp-ring tightening process; association of the floor motion with the package motion before the drop simulation starts; and creation of the package velocity before impact starts. To verify the proposed numerical technique, an analysis is performed for the 6M Package with a standard clamp-ring closure to simulate the following three sequential loading conditions: the preload caused by tightening the clamp ring; a NCT 4-foot drop; and a HAC 30-foot drop. The analytical results are compared with the results of the sequential NCT and HAC drop tests of a 6M Package with the standard clamp-ring closure. The test results have verified that the proposed numerical technique is capable of predicting the drum closure separation with respect to drop heights as well as the deformed shape of the package.
Influence of the Environment on the General Corrosion Rate of Alloy 22 (N06022)
Authors: Rebak Rau´l B. , Crook Paul
Published: August 2008

Nickel (Ni) can dissolve a large amount of alloying elements while still maintaining its desirable austenitic microstructure. The resulting alloys are generally divided in families depending on the type of alloying elements they contain. Each one of these families is aimed to specific applications. Corrosive environments in industrial applications are generally divided for example in reducing acids, oxidizing acids, contaminated acids, caustic environments, oxidizing salts, etc. Depending on the application and the environment (electrolyte composition and temperature) several or single alloys may be recommended to fabricate components. The Ni-chromium-molybdenum (Ni-Cr-Mo) series contains a balanced selection of beneficial alloying elements so it can handle a variety of aggressive environments. By design, Alloy 22 or N06022 is one of the most versatile corrosion resistant nickel alloys since it has outstanding corrosion resistance both in reducing and oxidizing conditions.
CAFE-3D: A Fast Running Computational Tool for Analysis of Radioactive Material Packages in Fire Environments
Authors: Are Narendra , Greiner Miles , Suo-Anttila Ahti
Published: August 2008

The Container Analysis Fire Environment (CAFE-3D) is a computer code developed at Sandia National Laboratories to simulate heat transfer from large fires to engulfed packages for transportation risk studies. These studies require accurate estimates of the total heat transfer to an object and the general characteristics of the object temperature distribution for a variety of fire environments. Since risk studies require multiple simulations, analysis tools must be rapid as well as accurate. In order to meet these needs, CAFE-3D links Isis-3D (a general purpose computational fluid dynamics/radiation heat transfer code that calculates fire behavior) to commercial finite element (FE) codes that calculates package response. In this scheme, CAFE-3D runs Isis-3D only periodically during the calculation to update local fire boundary conditions to the FE model. The frequency and duration of the fire update calculations are user controlled based on the fire time and/or package temperature rise. In this paper we outline various models employed by Isis-3D and the method for finding the soot volume fraction used to define the edge of the diffusively radiating fire zone. Then, the linkage between Isis-3D and the MSC P\Thermal finite element code is explained. Finally a benchmarking simulation, which reproduced the temperature data from the 30-minute light-crosswind fire using only 10 hrs of computational time on a standard workstation, is described.
Revision of NNSA Packaging Certification Division’s Safety Guide 100 (SG-100)
Authors: Feldman Matthew R.
Published: August 2008

The Transportation Technologies Group (TTG) of Oak Ridge National Laboratory (ORNL) is currently tasked, by National Nuclear Security Administration (NNSA) Service Center (SC), Office of technical Support (OTS), National Security Department (NSD), Packaging Certification Division (PCD), to revise the Defense Programs’ Safety Guide 100 (SG-100). SG-100, formally entitled “Design Guide for Packaging and Offsite Transportation of Nuclear Components, Special Assemblies, and Radioactive Materials Associated with the Nuclear Explosives and Weapons Safety Program” is being revised to reflect current regulations as well as to incorporate lessons learned over the past several years. SG-100 was last published in 1994 as Revision 1, and has served as the key guidance document for the development of Defense Programs’ Type B package designs as well as their testing and testing and certification. Since that time, there have been two major revisions to the U.S. packaging and transportation regulations (due to revisions to US federal regulations, IAEA guidelines, and national standards), re-engineering of the DOE establishing the semi-autonomous NNSA, as well as numerous improvements in the analytical tools and methodologies used in package design and confirmatory review. This revision to SG-100 will capture these changes as well as reflect various lessons learned from certification reviews which have taken place over the past decade. TTG has also been tasked by PCD to present a workshop based on the revised SG-100 in September 2004.