scholarly journals Preliminary description of a new creep-fatigue design method that reduces over conservatism and simplifies the high temperature design process

2020 ◽  
Author(s):  
B. Barua ◽  
M. Messner ◽  
T. Sham ◽  
R. Jetter ◽  
Y. Wang
Keyword(s):  
High Temperature ◽  
Design Process ◽  
Design Method ◽  
Fatigue Design ◽  
Creep Fatigue ◽  
Preliminary Description

Selection Criteria for Clad Materials to Use With a 316H Base Material for High Temperature Nuclear Reactor Cladded Components

2020 ◽  
Author(s):  
B. Barua ◽  
M. C. Messner ◽  
R. I. Jetter ◽  
T.-L. Sham
Keyword(s):  
High Temperature ◽  
Selection Criteria ◽  
Nuclear Reactor ◽  
Design Method ◽  
Base Material ◽  
Class A ◽  
Ratcheting Strain ◽  
Creep Fatigue ◽  
Work Supports

Abstract The clad selection criteria proposed in this work supports a design approach provided in [PVP2020-21469] for cladded component for high temperature nuclear service. The proposed design method guards the clad material against the creep-fatigue failure and ratcheting strain accumulation in elevated temperature nuclear service without the requirement of long-term material properties. However, it limits the type of clad materials that can be used with the existing Class A materials qualified for ASME Section III, Division 5 rules. The analysis approach and design rules allow the use of two types of clad materials — soft clads that creep much faster than the base material and hard clads that creep much slower and have higher yield stress than the base material. This work proposes selection criteria for such soft and hard clad materials to use with a Class A metallic alloy — austenitic steel 316H. The criteria are developed based on the effect of relative elastic modulus and creep rate on the long term stress redistribution between the 316H base and the clad material. The proposed clad selection criteria are applicable up to a design temperature of 750°C and for 1% to 10% thick cladding. The selection criteria are evaluated on two materials — nickel and a molybdenum based alloy TZM — categorizing them as soft or hard clad for 316H base material.

High temperature creep-fatigue design

2010 ◽  
Vol 63 (2-3) ◽  
pp. 235-244 ◽  
Author(s):  
A. -A. F. Tavassoli ◽  
B. Fournier ◽  
M. Sauzay
Keyword(s):  
High Temperature ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fatigue Design ◽  
Creep Fatigue

High Temperature Creep-Fatigue Design and Service Experience

2008 ◽  
Vol 1125 ◽  
Author(s):  
A-A. F. Tavassoli ◽  
B. Fournier ◽  
M. Sauzay
Keyword(s):  
High Temperature ◽  
Austenitic Stainless Steels ◽  
Oxide Dispersion Strengthened ◽  
Cyclic Softening ◽  
Fatigue Tests ◽  
Oxide Dispersion ◽  
Martensitic Steels ◽  
Fatigue Design ◽  
Creep Fatigue

ABSTRACTGeneration IV fission and future fusion reactors envisage development of more efficient high temperature concepts where materials performances under creep-fatigue hold the key to success. This paper presents extended experimental results obtained from creep, fatigue and creep-fatigue tests on the main structural materials retained for these concepts, namely: stainless steel type 316L(N), the conventional Modified 9Cr-1Mo martensitic steel and its low activation derivatives such as Eurofer steel, and their more advanced grades strengthened by oxide dispersion. It shows that the existing recommendations made in design codes adequately cover individual damage due to creep or fatigue but often fall short under combined creep-fatigue interaction. This is partly due to the difficulties of reproducing service conditions in laboratory. In this paper, results from tests performed on components removed from reactor, after long service, are used to refine code recommendations.Using the above combined assessment, it is concluded that there is good confidence in predicting creep-fatigue damage for austenitic stainless steels. For the martensitic steels the effects of cyclic softening and microstructure coarsening throughout the fatigue life need more consideration in creep-fatigue recommendation. In the long-term development of ferritic/martensitic oxide dispersion strengthened grades with stable microstructure and no cyclic softening, appears promising provided problems associated with their fabrication and embrittlement are resolved.

Development of the design method for the optimal design of the Neutron Converter experimental plant

2020 ◽  
Author(s):  
Timur Smetani ◽  
Elizaveta Gureva ◽  
Vyacheslav Andreev ◽  
Natalya Tarasova ◽  
Nikolai Andree
Keyword(s):  
Optimal Design ◽  
Flux Density ◽  
Design Process ◽  
Design Method ◽  
Fast Neutrons ◽  
Experimental Plant ◽  
Plant Design ◽  
State Technical ◽  
Research Organizations ◽  
Neutron Converter

The article discusses methods for optimizing the design of the Neutron Converter research plant design with parameters that are most suitable for a particular consumer. 38 similar plant structures with different materials and sources were calculated, on the basis of which the most optimal options were found. As part of the interaction between OKBM Afrikantov JSC and the Nizhny Novgorod State Technical University named after R. E. Alekseev, the Neutron Converter research plant was designed and assembled. The universal neutron converter is a device for converting a stream of fast neutrons emitted by isotopic sources into a "standardized" value of flux density with known parameters in the volume of the central part of the product, which is the working part of the universal neutron converter. To supply neutron converters to other customer organizations (universities, research organizations and collective centers), it is necessary to take into account the experience of operating an existing facility, as well as rationalize the design process of each specific instance in accordance with the requirements of the customer.

scholarly journals Development of Optimal Design Method for Steel Double-Beam Floor System Considering Rotational Constraints

2021 ◽  
Vol 11 (7) ◽  
pp. 3266
Author(s):  
Insub Choi ◽  
Dongwon Kim ◽  
Junhee Kim
Keyword(s):  
Optimal Design ◽  
Design Process ◽  
Design Method ◽  
Steel Beams ◽  
High Gravity ◽  
Double Beam ◽  
Iterative Analysis ◽  
Floor Systems ◽  
Optimal Design Method ◽  
Floor System

Under high gravity loads, steel double-beam floor systems need to be reinforced by beam-end concrete panels to reduce the material quantity since rotational constraints from the concrete panel can decrease the moment demand by inducing a negative moment at the ends of the beams. However, the optimal design process for the material quantity of steel beams requires a time-consuming iterative analysis for the entire floor system while especially keeping in consideration the rotational constraints in composite connections between the concrete panel and steel beams. This study aimed to develop an optimal design method with the LM (Length-Moment) index for the steel double-beam floor system to minimize material quantity without the iterative design process. The LM index is an indicator that can select a minimum cross-section of the steel beams in consideration of the flexural strength by lateral-torsional buckling. To verify the proposed design method, the material quantities between the proposed and code-based design methods were compared at various gravity loads. The proposed design method successfully optimized the material quantity of the steel double-beam floor systems without the iterative analysis by simply choosing the LM index of the steel beams that can minimize objective function while satisfying the safety-related constraint conditions. In particular, under the high gravity loads, the proposed design method was superb at providing a quantity-optimized design option. Thus, the proposed optimal design method can be an alternative for designing the steel double-beam floor system.

Impact of Secondary Flow on the Accuracy of Simplified Design Methods for Steam Turbine Stages

2012 ◽  
Author(s):  
Jan Schumann ◽  
Ulrich Harbecke ◽  
Daniel Sahnen ◽  
Thomas Polklas ◽  
Peter Jeschke ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Steam Turbine ◽  
Design Process ◽  
Design Method ◽  
Computing Time ◽  
Leading Edge ◽  
Design Methods ◽  
Preliminary Design ◽  
Line Design ◽  
Radial Equilibrium

The subject of the presented paper is the validation of a design method for HP and IP steam turbine stages. Common design processes have been operating with simplified design methods in order to quickly obtain feasible stage designs. Therefore, inaccuracies due to assumptions in the underlying methods have to be accepted. The focus of this work is to quantify the inaccuracy of a simplified design method compared to 3D Computational Fluid Dynamics (CFD) simulations. Short computing time is very convenient in preliminary design; therefore, common design methods work with a large degree of simplification. The origin of the presented analysis is a mean line design process, dealing with repeating stage conditions. Two features of the preliminary design are the stage efficiency, based on loss correlations, and the mechanical strength, obtained by using the beam theory. Due to these simplifications, only a few input parameters are necessary to define the primal stage geometry and hence, the optimal design can easily be found. In addition, by using an implemented law to take the radial equilibrium into account, the appropriate twist of the blading can be defined. However, in comparison to the real radial distribution of flow angles, this method implies inaccuracies, especially in regions of secondary flow. In these regions, twisted blades, developed by using the simplified radial equilibrium, will be exposed to a three-dimensional flow, which is not considered in the design process. The analyzed design cases show that discrepancies at the hub and shroud section do exist, but have minor effects. Even the shroud section, with its thinner leading-edge, is not vulnerable to these unanticipated flow angles.

ECA Methodology for Fatigue Design of Risers and Flowlines

2007 ◽  
Author(s):  
C. H. Luk ◽  
T. J. Wang
Keyword(s):  
Fracture Mechanics ◽  
Design Method ◽  
Steel Catenary Riser ◽  
Fatigue Design ◽  
Wide Range ◽  
Fatigue And Fracture ◽  
Level 3 ◽  
Fatigue Loads ◽  
Vessel Motion ◽  
Level 2

Engineering Criticality Assessment (ECA) is a procedure based on fracture mechanics that may be used to supplement the traditional S-N approach and determine the flaw acceptance and inspection criteria in fatigue and fracture design of risers and flowlines. A number of design codes provide guidance for this procedure, e.g. BS-7910:2005 [1]. However, more investigations and example studies are still needed to address the design implications for riser and flowline applications. This paper provides a review of the existing ECA methodology, presents a fracture mechanics design method for a wide range of riser and flowline fatigue problems, and shows flaw size results from steel catenary riser (SCR) and flowline (FL) examples. The first example is a deepwater SCR subjected to fatigue loads due to vessel motion and riser VIV. The second example is a subsea flowline subjected to thermal fatigue loads. The effects of crack re-characterization and material plasticity on the Level-2 and Level-3 ECA results of the SCR and flowline examples are illustrated.

Sign in / Sign up

Export Citation Format

Share Document