A Review of State-of-the-Art Methods for Pressure Vessels Design Against Progressive Deformation

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Philippe Rohart ◽  
Stéphane Panier ◽  
Yves Simonet ◽  
Saïd Hariri ◽  
Mansour Afzali
Keyword(s):  
Design Methodology ◽  
Computation Time ◽  
Industrial Applications ◽  
Pressure Vessels ◽  
Innovative Methods ◽  
Shakedown Theory ◽  
Elastic Shakedown ◽  
Linear Matching Method ◽  
Theoretical Developments

Progressive plastic deformation is one of the damage mechanisms which can occur in pressure vessels subjected to cyclic loading. For design applications, the main rule proposed by codes against this failure mode is the so-called 3f (or 3Sm) criterion. During the last decade, studies have shown that this condition can be unreliable, and its application should be restricted. In parallel, theoretical developments enabled shakedown analyses to be considered in design methodology, and to be incorporated in codes and standards (EN13445, CODAP) from the early 2000s. This paper gives a review of innovative methods based on shakedown theory, which can be used in the determination of elastic shakedown limits, ratchet limits, or cyclic steady state. These approaches are based on different concepts, such as elastic compensation linear matching method (LMM), Gokhfeld theory (uniform modified yield, load dependent yield modification (LDYM)), or the research of stabilized cycle direct cyclic analysis (DCA). Each method is presented and applied on a Benchmark example in abaqus, and results are compared. A final assessment focuses on computation time, and underlines the benefits that could be expected for industrial applications.

A Review of State-of-the-Art Methods for Pressure Vessels Design Against Progressive Deformation

2013 ◽  
Author(s):  
Philippe Rohart ◽  
Saïd Hariri ◽  
Yves Simonet
Keyword(s):  
Reference Data ◽  
Computation Time ◽  
Industrial Applications ◽  
Pressure Vessels ◽  
Innovative Methods ◽  
Shakedown Theory ◽  
Elastic Shakedown ◽  
Linear Matching Method ◽  
Theoretical Developments

Progressive plastic deformation is one of the damage mechanisms which can occur in pressure vessels subjected to cyclic loading. For design applications, the main rule proposed by codes against this failure mode is the so-called 3f (or 3Sm) criterion. During the last decade, studies have shown that this condition can be unreliable, and proposed to restrict its application. In parallel, theoretical developments enabled shakedown analyses to be considered as an interesting design methodology, and to be incorporated in codes and standards (EN13445, CODAP) from the early 2000′s. This paper gives a review of innovative methods based on shakedown theory, that can be used in the determination of elastic shakedown limits, ratchet limits, or cyclic steady state. These approaches are based on different concepts, such as elastic compensation (Linear Matching Method), Gockfeld theory (Uniform Modified Yield, Load Dependent Yield Modification), or the research of stabilized cycle (Direct Cyclic Analysis). Each method is presented and applied on a Benchmark example in Abaqus, and results are compared to reference data from codes. A final assessment focuses on accuracy and computation time, and underlines the benefits that could be expected for industrial applications.

Locating complex eigenvalues for analytical eddy-current models used to detect flaws

2019 ◽  
Vol 38 (6) ◽  
pp. 1800-1809
Author(s):  
Grzegorz Tytko ◽  
Łukasz Dawidowski
Keyword(s):  
Eddy Current ◽  
Design Methodology ◽  
Complex Function ◽  
Precise Determination ◽  
Argument Principle ◽  
Content Type ◽  
Conductive Material ◽  
Complex Roots ◽  
Complex Eigenvalues

Purpose Discrete eigenvalues occur in eddy current problems in which the solution domain was truncated on its edge. In case of conductive material with a hole, the eigenvalues are complex numbers. Their computation consists of finding complex roots of a complex function that satisfies the electromagnetic interface conditions. The purpose of this paper is to present a method of computing complex eigenvalues that are roots of such a function. Design/methodology/approach The proposed approach involves precise determination of regions in which the roots are found and applying sets of initial points, as well as the Cauchy argument principle to calculate them. Findings The elaborated algorithm was implemented in Matlab and the obtained results were verified using Newton’s method and the fsolve procedure. Both in the case of magnetic and nonmagnetic materials, such a solution was the only one that did not skip any of the eigenvalues, obtaining the results in the shortest time. Originality/value The paper presents a new effective method of locating complex eigenvalues for analytical solutions of eddy current problems containing a conductive material with a hole.

Determination of the Minimum Distance Between Moving Objects Including Velocity Information

1993 ◽  
Author(s):  
Meyer Nahon
Keyword(s):  
Minimum Distance ◽  
Moving Objects ◽  
Rapid Determination ◽  
Computation Time ◽  
Optimization Techniques ◽  
Real Time Control ◽  
Time Step ◽  
Time Control ◽  
Velocity Information

Abstract The rapid determination of the minimum distance between objects is of importance in collision avoidance for a robot maneuvering among obstacles. Currently, the fastest algorithms for the solution of this problem are based on the use of optimization techniques to minimize a distance function. Furthermore, to date this problem has been approached purely through the position kinematics of the two objects. However, although the minimum distance between two objects can be found quickly on state-of-the-art hardware, the modelling of realistic scenes entails the determination of the minimum distances between large numbers of pairs of objects, and the computation time to calculate the overall minimum distance between any two objects is significant, and introduces a delay which has serious repercussions on the real-time control of the robot. This paper presents a technique to modify the original optimization problem in order to include velocity information. In effect, the minimum distance calculation is performed at a future time step by projecting the effect of present velocity. This method has proven to give good results on a 6-dof robot maneuvering among obstacles, and has allowed a complete compensation of the lags incurred due to computational delays.

“Find a flight for me, Oscar!” Motivational customer experiences with chatbots

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jano Jiménez-Barreto ◽  
Natalia Rubio ◽  
Sebastian Molinillo
Keyword(s):  
Design Methodology ◽  
Hybrid Approach ◽  
Self Determination Theory ◽  
Customer Experience ◽  
Self Determination ◽  
Content Type ◽  
Multimethod Approach ◽  
Practical Implications ◽  
Broad Understanding ◽  
Theoretical Developments

Purpose Drawing on the self-determination theory, the assemblage theory and customer experience literature, this paper aims to develop a framework to understand motivational customer experiences with chatbots. Design/methodology/approach This paper uses a multimethod approach to examine the interaction between individuals and airlines’ chatbots. Three components of self-determined interaction with the chatbot (competence, autonomy and relatedness) and five components of the customer–chatbot experience (sensory, intellectual, affective, behavioral and social) are analyzed qualitatively and quantitatively. Findings The findings confirm the direct influence of self-determined interaction on customer experience and the direct effects of these two constructs on participants’ attitudes toward and satisfaction with the chatbot. The model also supports the mediating roles of customer experience and attitude toward the chatbot. Practical implications This paper offers managers a broad understanding of individuals’ interactions with chatbots through three elements: motivation to use chatbots, experiential responses and individuals’ valuation of whether the interactions have amplified (or limited) the outcomes obtained from the experience. Originality/value This paper contributes to the hospitality and tourism literature with a hybrid approach that reflects on current theoretical developments regarding human- and interaction-centric interpretations of customer experience with chatbots.

Experimental study of pin surface precision on lubrication behavior of pin–bush pairs in industrial roller chains

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Ansheng Zhang ◽  
Mingyu Zhang ◽  
Jing Wang ◽  
Jianjun Zhang ◽  
Zhaohua Shang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Design Methodology ◽  
Industrial Applications ◽  
Experimental Basis ◽  
Reciprocating Motion ◽  
Content Type ◽  
Oil Supply ◽  
Machining Errors ◽  
Surface Precision ◽  
Straightness Error

Purpose The purpose of this paper is to study the influence of surface precision on the lubrication state of the roller chain under adequate and rare oil supply conditions, respectively. Design/methodology/approach The straightness error and roughness error of the pin generatrices were measured and the influence of surface precision on the lubrication behavior under steady state and reciprocating motion was studied through optical interference experiments. Findings The lubrication state is strongly influenced by the surface precision of the roller surface both under adequate oil supply and rare oil supply conditions. Originality/value In industrial applications, the machining errors of parts cannot be completely eliminated. Studying the influence of the surface precision on the lubrication behavior of pin–bush pairs can provide the experimental basis for the optimal design of the bush roller chains.

scholarly journals Methods for Structural Stress Determination according to EN 13445-3 Annex NA – Comparison with other Codes for Unfired Pressure Vessels

2018 ◽  
Vol 165 ◽  
pp. 10003
Author(s):  
Ralf Trieglaff ◽  
Jürgen Rudolph ◽  
Martin Beckert ◽  
Daniel Friers
Keyword(s):  
Pressure Vessel ◽  
Pressure Vessels ◽  
Structural Stress ◽  
Stress Determination ◽  
User Friendliness ◽  
Fatigue Assessment ◽  
Shell Elements ◽  
European Working ◽  
The Status

The European Pressure Vessel Standard EN 13445 provides in its part 3 (Design) a simplified method (Clause 17) and a detailed method for fatigue assessment (Clause 18). Clause 18 “Detailed Assessment of Fatigue Life” is under revision within the framework of the European working group CEN/TC 54/WG 53 – Design methods with the aim of reaching a significant increase in user-friendliness and a clear guideline for the application. This paper is focused on the new informative annex NA ”Instructions for structural stress oriented finite elements analyses using brick and shell elements”. As an essential amendment for the practical user, the determination of structural stress ranges for fatigue assessment of welds is further specified in this new annex. Different application methods for the determination of structural stresses are explained in connection with the requirements for finite element models and analyses. This paper will give a short overview of the proposed approaches of structural stress determination in annex NA of the revised EN 13445-3. It will present the status of the approaches based on the results of fatigue analyses according to EN 13445-3 Clause 18 for different application examples. For verification purposes, the results of the approaches proposed in EN 13445-3 are compared with the results of other pressure vessel design codes for nuclear and non-nuclear application.

Design Formulas of Blind End Closures for High Pressure Vessels

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
R. D. Dixon ◽  
E. H. Perez
Keyword(s):  
High Pressure ◽  
Fatigue Life ◽  
Maximum Stress ◽  
Accurate Determination ◽  
Pressure Vessels ◽  
Stress Distributions ◽  
Fatigue And Fracture ◽  
Asme Code ◽  
Section Viii

The available design formulas for flat heads and blind end closures in the ASME Code, Section VIII, Divisions 1 and 2 are based on bending theory and do not apply to the design of thick flat heads used in the design of high pressure vessels. This paper presents new design formulas for thickness requirements and determination of peak stresses and stress distributions for fatigue and fracture mechanics analyses in thick blind ends. The use of these proposed design formulas provide a more accurate determination of the required thickness and fatigue life of blind ends. The proposed design formulas are given in terms of the yield strength of the material and address the fatigue strength at the location of the maximum stress concentration factor. Introduction of these new formulas in a nonmandatory appendix of Section VIII, Division 3 is recommended after committee approval.

Framework for a Combined Netting Analysis and Tsai-Wu-Based Design Approach for Braided and Filament-Wound Composites

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Rifat Hossain ◽  
Jason P. Carey ◽  
Pierre Mertiny
Keyword(s):  
Composite Structures ◽  
Longitudinal Direction ◽  
Industrial Applications ◽  
Pressure Vessels ◽  
Design Tool ◽  
Combined Loading ◽  
Axially Symmetric ◽  
Reinforced Polymer ◽  
Failure Theory ◽  
Filament Wound

Axially symmetric fiber-reinforced polymer composite structures, such as pressure vessels and piping, are being widely used in different industrial applications where combined loading conditions may be applied. It is imperative to determine a suitable fiber angle, or a distribution of fiber angles, along the longitudinal direction of the structure in order to achieve best performance in terms of mechanical behavior and strength for structures subjected to combined loadings. To this end, an approach combining netting analysis and Tsai-Wu failure theory was employed as a design tool to assess critical fiber angles at which applied loadings would cause a structure to fail. Together, the proposed netting analysis and failure theory-based approach constitute a simple, expedient, and convenient design process for complex-shaped structures.

scholarly journals The Dynamic Response and Characteristics of an Oxygen Vacuum Swing Adsorption Process to Step Perturbations. Part 2. Sensitivity Analysis and Controller Pairings

2003 ◽  
Vol 21 (4) ◽  
pp. 349-362
Author(s):  
C.C.K. Beh ◽  
P.A. Webley
Keyword(s):  
Batch Process ◽  
Step Response ◽  
Empirical Modelling ◽  
Response Data ◽  
Unit Operations ◽  
Vacuum Swing Adsorption ◽  
Modelling Techniques ◽  
Input Variables ◽  
Theoretical Developments

The application of vacuum swing adsorption (VSA) as a method for the production of low-purity oxygen is now a mature and widely used technology. However, unlike other unit operations, VSA processes remain difficult to understand and, coupled by the lack of theoretical developments in batch process control, make them difficult to control. The objective of the second part of this study was to characterise the step response data gained from Part 1 using empirical modelling techniques. This information was then used to analyse the sensitivity of the input variables and hence permit determination of the extent of closed-loop interaction and identification of suitable controller parings.

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