DETERMINING RESIDUAL STRESSES IN WELDED CONNECTIONS OF ORTHOTROPIC STEEL BRIDGE DECKS WITH A HOLE-DRILLING TECHNIQUE

Author(s):  
Wim Nagy ◽  
Philippe Van Bogaert ◽  
Hans De Backer

Manufacturing processes such as welding operations cause residual stresses that are present in most civil structures. They cause plastic deformations without any external loads and are therefore often overlooked during design. Nevertheless, residual stresses can have profound influences on material strength and fatigue life. This is also true for orthotropic steel bridge decks, which have many complex welding details. Because little is known about the distribution of residual stresses due to welding, a semi-destructive experimental test setup is developed for a stiffener-to-deck plate connection on an orthotropic steel bridge deck. In particular, the hole-drilling technique is used. With this experimental test setup, a clear distribution of the residuals stresses becomes visible. Residual stresses up to the yield strength can be found near the weld and up to 50% of the yield strength elsewhere. However, more research is needed to verify why the sign of the stresses is opposite to the expected stresses in the literature.

Author(s):  
Evy Van Puymbroeck ◽  
Wim Nagy ◽  
Hans De Backer

Complex welding operations in orthotropic steel bridge decks introduce residual stresses near the weld region. To estimate fatigue failure of this type of bridge deck, tensile residual yield stresses are usually assumed around the weld region. However, to estimate the residual stress distribution near a weld connection more precisely, a test setup is developed. The weld connection of a closed longitudinal trapezoidal stiffener with the deck plate of an orthotropic bridge deck is investigated. The incremental hole-drilling technique is used to measure the residual stresses with strain gauge rosettes. Strain gauge rosettes are positioned on the deck plate and on a longitudinal stiffener of the orthotropic steel deck. A small hole is drilled through the center of the strain gauge rosettes and strains are measured at incremental depths. The residual stresses are calculated and based on these experimental measurements a distribution of the residual stresses is obtained. Compressive residual stresses exist near the longitudinal stiffener-to-deck plate weld. On the deck plate, the compressive residual stresses are equal to 60% of the yield strength while the compressive residual stresses on the stiffener are 42% of the yield strength. There are tensile residual stresses on both sides of the weld region. However, more research is necessary to confirm this distribution since it is contradictory to expected stresses in literature.


2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.


2013 ◽  
Vol 53 (7) ◽  
pp. 1223-1231 ◽  
Author(s):  
A. H. Mahmoudi ◽  
G. Zheng ◽  
D. J. Smith ◽  
C. E. Truman ◽  
M. J. Pavier

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.


2013 ◽  
Vol 768-769 ◽  
pp. 101-106
Author(s):  
Harri Lille ◽  
Jakub Kõo ◽  
Jaak Valgur ◽  
Alexander Ryabchikov ◽  
Renno Reitsnik ◽  
...  

The paper presents a method for measuring residual stresses in normal thermo-bimetal Fe-Ni-Mn/Invar strips with a thickness of 0.76 mm. For this purpose, a setup was designed which permits to remove layers from a strip substrate by electrochemical etching. Residual stresses in the directions that are longitudinal and transversal to rolling are determined by the curvature method based on the layer growing/removing techniques. As a reference, residual stresses were also determined by hole-drilling technique. Tensile and compressive residual stresses arose both in active and in passive layers and were considerably higher when determined by the hole-drilling technique.


2013 ◽  
Vol 99 (8) ◽  
pp. 1571-1578 ◽  
Author(s):  
Johan Maljaars ◽  
David Gration ◽  
Edo Vonk ◽  
Frank van Dooren

2014 ◽  
Vol 996 ◽  
pp. 634-639 ◽  
Author(s):  
Mohamed N.A. Nasr

The current study examines the effect of grain size on machining-induced residual stresses (RS), during turning, using finite element modelling. Based on the well-known inverse relation between grain size and material strength, the grain size effect was simulated via changing the workpiece yield strength. This was also done at different strain hardening rates. The model was validated using four materials. Larger grain size (lower yield strength) resulted in higher surface tensile RS. This is attributed to the surface layer being subjected to higher compressive plastic deformation, as well as higher workpiece temperatures, which both contribute to higher tensile RS.


1992 ◽  
Vol 114 (3) ◽  
pp. 292-299 ◽  
Author(s):  
R. W. Hampton ◽  
D. V. Nelson

The strain gage blind hole-drilling technique may be used to determine residual stresses at and below the surface of components. In this paper, the hole-drilling analysis methodology for thick plates is reviewed, and experimental data are used to evaluate the methodology and to assess its applicability to thin plates. Data on the effects of gage pattern, surface preparation, hole spacing, hole eccentricity, and stress level are also presented.


1976 ◽  
Vol 16 (6) ◽  
pp. 226-232 ◽  
Author(s):  
A. M. Nawwar ◽  
K. McLachlan ◽  
J. Shewchuk

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