Crack Initiation Process for Semi-Circular Notched Plate in Fatigue Test at Elevated Temperature

Crack initiation and propagation process of fatigue test in semi-circular notched plates at elevated temperature were observed by the CCD video camera. Test specimens are made of SUS304 stainless steel, and temperature is kept to be 550°C, and geometry of semi-circular notched plate specimens are changed by diameter size of the circular hole. Photographs in all cycles were recorded to investigate crack initiation process in structural components having stress concentration and obtain number of cycle of crack initiation (Nc). The test results were compared with predictions by Stress Redistribution Locus (SRL) method and Neuber’s rule’s method.

Fatigue Evaluation in Mixing Zones: Comparison of Different Criteria of Fatigue

The distribution of unsteady temperatures in the wall of the 6" FATHER mixing tee mock-up is calculated for a loading configuration: The results seem realistic even if they are not still very accurate (see paper PVP2005-71592 [11]). On this basis, thermal stresses are evaluated for elastic and elastic-plastic material behavior. Then, different types of fatigue criteria are used to evaluate the fatigue damage. The paper develops a brief description of the criteria, the corresponding fatigue damage evaluation and attempts to explain the differences.

Multi-Objective Optimal Design of Sandwich Composite Laminates Using Simulated Annealing and FEM

Multi-objective optimal design of sandwich composite laminates consisting of high stiffness and expensive surface layers and low-stiffness and inexpensive core layer is addressed in this paper. The object is to determine ply angles and number of surface layers and core thickness in such way that natural frequency is maximized with minimal material cost and weight. A simulated annealing algorithm with finite element method is used for simultaneous cost and weight minimization and frequency maximization. The proposed procedure is applied to Graphite-Epoxy/Glass-Epoxy and Graphite-epoxy/Aluminum sandwich laminates and results are obtained for various boundary conditions and aspect ratios. Results show that this technique is useful in designing of effective, competitive and light composite structures.

Selecting the Optimum Bolt Assembly Stress: Influence of Flange Type on Flange Load Limit

In previous papers, practical limits on the maximum applied load for standard ASME B16.5 and B16.47 carbon steel, weld neck pipe flanges were examined. A new code equation for the tangential (hoop) stress at the small end of the hub for a weld neck flange was developed to facilitate calculation of the limits using elastic analysis. The results were verified against elastic-plastic Finite Element Analysis (FEA). In this paper, the work is extended to include other flange configurations, including loose ring flanges, slip-on flanges and flat plate flanges. This paper is a continuation of the papers presented during PVP 2006 and PVP 2007 (Brown [1, 2]) and it extends the scope of the proposed methodology for determining flange stress limits in determining the maximum allowable bolt load for any given flange size and configuration.

Investigation of a Shell and Tube Exchanger in Process Gas Heating Service

The design requirements for a large shell and tube vertical heat exchanger (to be used in a sulfur recovery tail gas treatment unit) included startup, shutdown and upset conditions that would subject the exchanger to significant temperature changes. The exchanger was designed to the requirement of the ASME Boiler and Pressure Vessel Section VIII Division 1 [1]. A detailed analysis of the thermal profiles and related stresses was performed to confirm the use of a flexible tube sheet design. The heat exchanger uses high pressure superheated steam on the shell side to heat a low pressure process gas on the tube side. The heat exchanger was sized and thermally rated, using commercially available analysis software. The proposed design was analyzed by Finite Element methods that included both thermal and stress analysis. These evaluations confirmed that a flexible tube sheet design was satisfactory when using specific dimensions.

Elastic-Plastic Analysis of an Elbow With Axial Part-Through Internal Crack at Crown Under In-Plane Bending

Piping elbows under bending moment are vulnerable to cracking at crown. The structural integrity assessment requires evaluation of J-integral. The J-integral values for elbows with axial part-through internal crack at crown under in-plane bending moment are limited in open literature. This paper presents the J-integral results of a thick and thin, 90-degree, long radius elbow subjected to in-plane opening bending moment based on number of finite element analyses covering different crack configurations. The non-linear elastic-plastic finite element analyses were performed using WARP3D software. Both geometrical and material nonlinearity were considered in the study. The geometry considered were for Rm/t = 5, and 12 with ratio of crack depth to wall thickness, a/t = 0.15, 0.25, 0.5 and 0.75 and ratio of crack length to crack depth, 2c/a = 6, 8, 10 and 12.

An Analytical Solution for Calculating Stresses on Lap Patches Used on Pipes and Pressure Vessels

Lap patch repairs are used regularly in petrochemical industries as temporary repairs for short term operations. In this paper a simple methodology is proposed on how to calculate the stresses on a lap patch using simple analytical approximation. The simple analytical results are compared with finite element results and they are found to be in reasonable agreement.

Dynamic Burst Pressure Simulation of Cylinder-Cylinder Intersections

In this study, the determination of the burst pressure of a series of cylinder-cylinder intersections representing vessels of diameter D and wall thickness T, and nozzles of diameter d and wall thickness t subjected to short-term dynamic loading is investigated. Dynamic simulations via the use of the finite element method are carried out to determine the effects of dimensionless parameters d/D, D/T and t/T as well as pressure vs. time history. The LS-DYNA software is employed to model and analyze various intersections for the geometric parameter ranges 0.1 ≤ d/D < 1.0, 0.1 ≤ t/T ≤ 3 and 50 ≤ D/T ≤ 250. The use of both solid and shell elements is investigated and applied in this study. A correlation equation to predict the dynamic burst pressure of cylinder-cylinder intersections is proposed based on the parametric finite element analyses. Static test data is used to verify the dynamic correlation equation by applying a relatively long pressure pulse duration.

EPR: Tests Performed to Confirm the Mechanical and Hydraulic Design of the Vessel Internals

The EPR is an Evolutionary high-Power Reactor which is based on the best French and German experience of the past twenty years in plant design construction and operation. In the present detailed engineering phase of the plant under construction in Finland (Okiluoto 3) and in France (Flamanville 3), some actions were conducted in order to improve the knowledge of the hydraulic behavior of the innovative Reactor Pressure Vessel internals (RPV). The RPV internals are mainly derived from former French N4 or German Konvoi with some evolutions to take into account the operating experience. Design and validation of the internals were performed within AREVA’s engineering teams, which develop state of the art methods in the field of thermohydraulic testing. The experimental validation program was closely followed by EDF. Moreover, an EDF R&D project, whose results are not addressed here, was held to consolidate the RPV internals conception. The aim of the paper is to present the hydraulic tests performed on mock-ups to characterize the hydraulic behavior of the innovative EPR Reactor Pressure Vessel internals, and to introduce the role of these tests in the global conception process of the EPR RPV internals (CFD code qualification, design validation, database...). The qualification of the CFD computer codes will be described in a forthcoming paper. Three different mock-ups are presented to illustrate these tests: • JULIETTE for the reactor pressure vessel lower internals, • ROMEO for the reactor pressure vessel upper internals, • MAGALY for the design of the skeleton-type control rod guide assembly.

Initial Investigation Into Optimizing Design of a Pressure Vessel Saddle

The ASME Boiler and Pressure Vessel Code does not provide details of the pressure vessel saddle supports. The existing design guidelines are based on classical stress analysis with several assumptions to simplify the problem. With the advances in the computational technology and numerical methods, it is now possible to obtain more detailed information about stress distribution and hence provide optimal saddle design guidelines. This study will present an initial investigation into a 3D computational modeling and analysis of the saddle design. Results are presented for maximum von Mises stress occurring in various parts of the saddle with the increase in load.