Session: CS-01-02/03-01 Structural Integrity of Pressure Components & Environmental Fatigue Issues (Joint M&F, D&A)

Paper Number: 62429

Start Time: Tuesday, July 13, 2021, 09:00 AM

62429 - A Method for Investigating Multi-Axial Fatigue in a PWR Environment 

A significant amount of fatigue testing has taken place over the years to generate relationships between applied stress or strain range and cycles to failure.  This has mainly been conducted on uniaxial test specimens in an air environment.  More recently, fatigue testing has been conducted in a PWR environment as it is now well known that this has a deleterious impact on life.  The test method presented in this paper considers bi-axial loading on a specimen that is compatible with PWR fatigue testing rigs.  In order to achieve this, a specimen was designed to convert a uniaxial load into a biaxial load with no internal mechanism.  Finite Element Analysis (FEA) was conducted to develop and refine the design, which accounted for frictional contact and bolt up stresses.

The initial testing was conducted on a 304L stainless steel specimen in a room temperature air environment. Digital Image Correlation (DIC) was used to validate the FEA andthere was excellent agreement between predicted and observed strains.  Once the strains were validated, a fatigue test was conducted to confirm that the cracking was in the expected location, and that the number of cycles to failure was reasonable.  Direct Current Potential Drop (DCPD) was used to indicate when a fatigue crack initiated, which was confirmed by visual inspection.  The results showed that cracking occurred in the location of highest accumulated plastic strain and Von Mises Stress, and the number of cycles to failure was slightly lower than predicted but still within scatter.

Presenting Author: Peter Gill Jacobs

Authors:

Peter Gill Jacobs
Ben Coult Jacobs
Tom Schofield Jacobs
Russell Smith Jacobs
Mike Hilton Jacobs
Chris Currie Rolls Royce
Paul Onwuarolu Jacobs
Alec Mclennan Jacobs
Mark Kirkham Jacobs
Karen Cooper Jacobs
Colin Madew Jacobs
Matt Sutcliffe Jacobs