Measurement of Residual Stress in Water Pipe Welds Using the Hole-Drilling Technique

2007 ◽  
Vol 353-358 ◽  
pp. 2419-2422
Author(s):  
Jung Hun Choi ◽  
Jong Hyun Baek ◽  
Dae Jin Kim ◽  
Jae Mean Koo ◽  
Chang Sung Seok

In case of large steel water pipe, it have been observed that its fracture mostly occurs due to the complicated outside fatigue load on the pipe in the underground. It is also well known that its damage and leakage happen mainly in a weld zone. In this study we evaluated the fatigue characteristics based on size effect and residual stress by comparing the test results on the standard specimen collected from real pipe with those on full scale pipe.

Author(s):  
Alexandros Skouras ◽  
Martyn J. Pavier ◽  
Anton Shterenlikht

This paper describes a study of the ability of the DHD technique to measure the spatial distribution of residual stresses. A two dimensional finite element model of a metal plate has been generated together with a representative state of residual stress. A simulation of the DHD technique is then carried out to provide a series of measurements of the residual stress which can be compared with the known residual stress. This simulation allows the effect of the varying trepan diameters on the accuracy of the DHD technique to be explored. The results of the simulation show that the DHD technique can be used to measure residual stress with a high accuracy, but the increase in the trepan diameter introduce some errors. Suggestions and techniques for reducing these errors are presented.


Author(s):  
Amir H. Mahmoudi ◽  
David J. Smith ◽  
Chris E. Truman ◽  
Martyn J. Pavier

Accurate evaluation of residual stress is essential if is to be taken into account in structural integrity assessments. For thick components, many non-destructive residual stress measurement techniques cannot be used since they are unable to measure the stresses deep within the component. Measurement techniques which involve mechanical strain relief through material removal are the only alternative. Recently, it has been found that these techniques may fail to measure the stresses correctly when highly triaxial stresses are present because plastic redistribution can occur when the material removal is carried out. The Deep Hole Drilling technique is a very powerful method to measure the stresses within very thick engineering components. However, it can suffer from high levels of plasticity and lead to inaccurate results. It is shown in the present research that the effect of plasticity on the measured stresses can be eliminated. In the present work, the effect of gauge volume on the plasticity effect is investigated.


2005 ◽  
Vol 490-491 ◽  
pp. 62-66 ◽  
Author(s):  
Jian Luo ◽  
Guillaume Montay ◽  
Jian Lu

For measuring in-depth residual stress in 3D cylinder structure easily in this paper, the semi-destructive incremental hole drilling technique combined with finite element method is used, the calibration coefficients of 3D cylinder components are calculated, and the relationship between strain and stress is determined, the changes of calibration coefficients are analysed, the residual stress of one steering joint of automobile is measured, and the errors of residual stress are discussed.


Author(s):  
Gang Zheng ◽  
Sayeed Hossain ◽  
Feng Shen ◽  
Chris Truman

The aim of the present study was to utilize a complex residual stress generated within a welded circular disc to further investigate the standard deep-hole drilling (DHD) technique and the newly developed over-coring deep-hole drilling (oDHD) technique in accurately measuring residual stresses well over yield stress. Finite Element Analysis (FEA) was used to optimize and extend the deep-hole drilling technique and improve its accuracy. The standard DHD procedure involves 4 steps. (1) A reference hole is gun-drilled through the component. (2) The internal diameter of the reference hole is measured at different angular positions through the depth of the component. (3) A cylindrical section with the reference hole as its longitudinal axis is trepanned free from the component. (4) Finally, the relaxed internal diameter is re-measured at the same angular positions and the same depths. The drilling, trepanning procedures and the parameters of the deep-hole drilling technique were all studied in detail to optimize the technique. Comparison is made between the FEA predicted residual stress in the weld, the measurements and the reconstructed residual stresses of the measurements. The close correlations confirmed the suitability of new modifications made in the deep-hole drilling technique to account for plasticity when measuring near yield residual stresses present in a component.


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