Session: DA-01-05 Design and Analysis of Heat Exchangers and Components

Paper Number: 122732

122732 - Interpretation of Progressive Deformation in Tube Plates (Tp) 

When we calculate the stresses in a TP from a homogeneous equivalent medium of the multi-perforated part, the question arises of the application of the 3Sm rule with (or not) the application of an elastic-plastic correction?

We propose here an approach to try to provide an answer to this question.

We start from a Representative Elementary Volume (REV) of a multi square pitch perforation of the PT subjected to a state of biaxial stress (σX, σY) such that σY = β.σX, β is a coefficient of bi-βaxiality which will be varied, figure below.

We conduct the study according to the following main stages:

Step 1: elastic analysis of the REV in order to calculate the circumferential stresses at the edge of the hole σϕϕ which we express by σϕϕ = aϕ.σX + bϕ.σY = (aϕ + β bϕ).σX by varying β such that the average stress in the small ligament of the REV varies between 3Sm and 6Sm.

Step 2: elastic-plastic analysis of the VER from the law of behavior (σ-ε) of the material and as previously by varying β within the limits obtained to reach 3Sm and 6Sm in the elastic analysis in order, here, to calculate the circumferential deformation at the edge of the hole εϕϕ.

Step 3: the elastic analysis provides us with the amplitude ∆σϕϕ from which we calculate an elastic Usage Factor (UFe) using the elastic design fatigue curve (∆σ-N) of the material.

Step 4: the elastic-plastic analysis provides us with the amplitude ∆εϕϕ from which we calculate an elastic-plastic Usage Factor (UFep) using the elastic-plastic fatigue curve (∆ε-N) of the material.

Step 5: comparative analysis of the usage factors FUe and UFep obtained and exploitation of this comparison in order to determine whether an elastic-plastic correction must be applied and from what level of excess of 3Sm in the small ligament and what correction value must be brought. We will notably look at whether the correction proposed by the RCC-M or ASME Code applies.

The application of the 3Sm analysis of the TP can thus be carried out directly from the analysis of the stresses in the equivalent homogeneous medium making it possible to determine on the surface the stress in the small ligament by multiplying the stress by the ligament coefficient p/h of membrane plus equivalent bending obtained by linearizing the stresses in the thickness of the PT at the position of any REV (or hole) of the PT and in particular where the value would be maximum.

 

 

Presenting Author: Billon François ONET Technologies

Presenting Author Biography: Dr. BILLON has 55 years of activities in the civil nuclear field with Alstom Energy (pumps and turbines) as Design Engineer; with FRAMATOME (NSSS 900, 1300, 1450MWe and EPR) as Head of the Steam Generator Section and of the Engineering Department for Security and Backup Systems; with ORANO (fuel cycle engineering) as Head of the Mechanical Section and Director of Engineering and Licensing Studies and expatriated 5 years in Chernobyl as Head of the European Commission's Aid Project (dismantling and management of waste). Presently at ONET TECHNOLOGIES (nuclear equipment, systems and maintenance services) as Technical Director and Principal Expert in Reactor Technologies.

Eng. degree in General Mechanics from the National Engineering Institute CNAM in Paris; Eng. D. in Mechanics Applied to Construction and Sc. D. in Mechanics and Energetics from the Sorbonne Paris VI University. Throughout his career, he has acquired skills in the fields of digital scientific calculations and multi-physics simulations, materials physics, manufacturing processes, application of design and construction Codes and Standards and the production of regulatory justification files. He is a Member of the ESPN Permanent Group of Experts as well as Member of the RCC-M Code Sub-Commission.

Authors:

Billon François ONET Technologies
Jourden Erwan ONET Technologies