Spatially Resolved Materials Property Data From a Uniaxial Cross-Weld Tensile Test

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
M. Turski ◽  
M. C. Smith ◽  
P. J. Bouchard ◽  
L. Edwards ◽  
P. J. Withers
Keyword(s):  
Plastic Strain ◽  
Weld Metal ◽  
Speckle Pattern ◽  
Welding Process ◽  
Parent Material ◽  
Image Correlation ◽  
Electronic Speckle Pattern Interferometry ◽  
Stress Strain ◽  
Spatially Resolved ◽  
Process Work

Application of electronic speckle pattern interferometry (ESPI) is described to measure the spatial variation in monotonic tensile stress-strain properties along “cross-weld” specimens machined from a stainless steel three-pass welded plate. The technique, which could also be done with digital image correlation, was applied to quantify how the material 0.2%, 1%, 2%, 5%, 10%, and 20% proof stress varied with distance from the center-line of the weldment for parent and weld material associated with the first and final passes. The stress-strain curves measured by the ESPI method correlated closely with stress-strain data measured using conventional test specimens. The measured results are consistent with the hypothesis that thermo-mechanical cycles associated with the welding process work harden previously deposited (single-pass) weld metal and the surrounding parent material. The stress-strain response of the heat affected zone adjacent to the first weld pass is consistent with an accumulated (equivalent monotonic) plastic strain of 6.5% and that of the first pass weld bead was consistent with an accumulated plastic strain of approximately 4% greater than the state of the final pass weld metal.

Tensile and Toughness Properties of Pipeline Girth Welds

2006 ◽  
Author(s):  
J. A. Gianetto ◽  
J. T. Bowker ◽  
R. Bouchard ◽  
D. V. Dorling ◽  
D. Horsley
Keyword(s):  
Weld Metal ◽  
Welding Process ◽  
Strain Curve ◽  
High Strength ◽  
Primary Objective ◽  
Stress Strain ◽  
Line Pipe ◽  
Arc Welding Process ◽  
Girth Welds ◽  
Metal Microstructure

The primary objective of this study was to develop a better understanding of all-weld-metal tensile testing using both round and strip tensile specimens in order to establish the variation of weld metal strength with respect to test specimen through-thickness position as well as the location around the circumference of a given girth weld. Results from a series of high strength pipeline girth welds have shown that there can be considerable differences in measured engineering 0.2% offset and 0.5% extension yield strengths using round and strip tensile specimens. To determine whether or not the specimen type influenced the observed stress-strain behaviour a series of tests were conducted on high strength X70, X80 and X100 line pipe steels and two double joint welds produced in X70 linepipe using a double-submerged-arc welding process. These results confirmed that the same form of stress-strain curve is obtained with both round and strip tensile specimens, although with the narrowest strip specimen slightly higher strengths were observed for the X70 and X100 linepipe steels. For the double joint welds the discontinuous stress-strain curves were observed for both the round and modified strip specimens. Tests conducted on the rolled X100 mechanized girth welds established that the round bar tensile specimens exhibited higher strength than the strip specimens. In addition, the trends for the split-strip specimens, which consistently exhibit lower strength for the specimen towards the OD and higher for the mid-thickness positioned specimen has also been confirmed. This further substantiates the through-thickness strength variation that has been observed in other X100 narrow gap welds. A second objective of this study was to provide an evaluation of the weld metal toughness and to characterize the weld metal microstructure for the series of mechanized girth welds examined.

Mechanical Property Mapping Using Image Correlation and Electronic Speckle Interferometry

2004 ◽  
Vol 1-2 ◽  
pp. 147-152 ◽  
Author(s):  
Joao Quinta da Fonseca ◽  
Michael Preuss ◽  
P. Ryan ◽  
Philip J. Withers
Keyword(s):  
Tensile Test ◽  
Strain Measurement ◽  
Mechanical Test ◽  
Speckle Pattern ◽  
Measurement Techniques ◽  
Weld Line ◽  
Surface Strain ◽  
Image Correlation ◽  
Electronic Speckle Pattern Interferometry ◽  
Proof Stress

By combining modern surface strain measurement techniques with the traditional tensile test mechanical test, a method has been developed whereby the mechanical properties of a test sample with a heterogeneous microstructure such can be characterised in one test. In this paper the applicability to such a method of two such surface strain measurement techniques, image correlation (IC) and electronic speckle pattern interferometry (ESPI), is assessed. Two commercially available systems were used to monitor, simultaneously, the surface strain on tensile test specimens during testing. Measurements on homogeneous samples were compared with measurements made using strain gauges and excellent agreement was found. Elastic modulus and proof stress values measured in these standard samples showed that the uncertainty in the measurements was below 10%. The method was then applied to an inertia friction weld, whose strength varied linearly as a function of distance from the weld line. The values of proof stress obtained were compared with micro-hardness measurements.

Local Stress-Strain Response of an Axial X100 Girth Weld Under Tensile Loading Using Digital Image Correlation

2006 ◽  
Author(s):  
Samer Adeeb ◽  
Dave Horsley ◽  
Junhui Yan ◽  
Michael A. Sutton ◽  
Anthony P. Reynolds
Keyword(s):  
Digital Image Correlation ◽  
Digital Image ◽  
Thermal Cycle ◽  
Strain Aging ◽  
Welding Process ◽  
Tensile Tests ◽  
Image Correlation ◽  
Strain Response ◽  
Stress Strain ◽  
Dic Technique

An important design, construction and maintenance concern for pipelines is the integrity of flaws in the girth welds. Numerous fitness for purpose codes are available to assess weld flaws, many of which were calibrated with reference to wide plate test data. Often, wide plate tests are conducted on girth welded pipe in the as-received condition, i.e. without application of a pipeline coating. The area adjacent to the weld is thus subjected to a thermal cycle due to the heat generated from the welding process. In some pipe materials this thermal cycle might be sufficient to induce strain aging. It is not clear how the welding process changes the behaviour of the area next to the weld. The results of such wide plate experiments are very important in assessing the acceptable flaws in a girth weld under a strain-based design. Therefore, it was important to understand the extent of the aging, specifically the stress-strain behaviour on either side of the girth weld. This paper presents results of cross-weld tensile tests, which utilized a two-dimensional digital image correlation (DIC) technique to determine displacement, and thus infer strain. The local strains were mapped to global stress to obtain local constitutive properties every 12.5mm along the length of the specimen. The DIC test results were very consistent and were also similar to results obtained from standard circumferential tensile tests at corresponding locations. The strength of the specimens, as defined by the relative strength of their stress-strain curves, was found to be highest in the girth weld region, to drop in the HAZ, and then to reach a plateau in the base metal. It was also shown that strain localization in one of the HAZ regions was clearly visible during the loading process and the near-HAZ regions had a stress-strain response with a yield stress value higher than the base metal. This behaviour was observed at 12.5mm away from the girth-weld centerline in both the transverse and longitudinal directions. The reason for this slight change of behaviour can be attributed to the effect of heating supplied to this part during welding (strain aging). The described DIC technique is very promising in obtaining local strain fields within very small areas of the tested specimens.

Measuring Stress and Strain Fields in Connecting Rods Using Laser Interferometry (ESPI)

2011 ◽  
Author(s):  
Bruno F. Vaz ◽  
Rafael A. L. e Silva ◽  
Auteliano A. S. Junior
Keyword(s):  
Strain Field ◽  
Complex Geometry ◽  
Speckle Pattern ◽  
Laser Interferometry ◽  
Electronic Speckle Pattern Interferometry ◽  
Stress And Strain ◽  
Testing Time ◽  
Connecting Rod ◽  
Stress Strain ◽  
Strain Fields

The understanding of how mechanical stresses influence in the behavior of automotive components is of great interest to the automotive industry. The design of products must be performed considering these efforts, always aiming to ensure smooth operation and no failures. To learn more about these efforts, numerical simulation can be done. However, the results obtained from these simulations must be confirmed by carrying out physical experiments. Many methods are available to obtain the stress/strain fields of the object been tested, among which the best known and widespread is the use of strain-gauges. This technique requires a relatively long time of preparation as well as several measurement places to obtain the full stress/strain field. The laser interferometry technique, on the other hand, reduces considerably the testing time to obtain the full stress/strain field, and no intervention on the object is required. This work aims to present a methodology for measuring stress/strain fields in connecting rods using an Electronic Speckle Pattern Interferometry (ESPI) device. In this work we will focus on obtaining the stresses in a flat surface of the rod. The region corresponds to the inner portion of the rod body, excluding only the edges of it that are slightly higher. In this region it’s easier to obtain the stress and strain fields than in the whole rod, which has many non-planar regions with a relatively complex geometry, especially near the ends. To plan the experiments, an experimental design was developed, based mainly on the concepts of Design of Experiments — DOE, to eliminate or at least reduce the influence of the noise over the results. The tests were performed with a forged connecting rod from a local manufacturing, which was submitted to compressive efforts. Finally we present the results of the measurements of the stress and strain fields obtained by the ESPI technique.

Mixed Mode (KI+KII) Stress Intensity Factor Measurement by Electronic Speckle Pattern Interferometry and Image Correlation

2004 ◽  
Vol 1-2 ◽  
pp. 107-112 ◽  
Author(s):  
A. Shterenlikht ◽  
F.A. Díaz Garrido ◽  
Pablo Lopez-Crespo ◽  
Philip J. Withers ◽  
E.A. Patterson
Keyword(s):  
Fourier Series ◽  
Mixed Mode ◽  
Speckle Pattern ◽  
Tensile Load ◽  
Surface Displacement ◽  
Compact Tension ◽  
Complex Stress ◽  
Image Correlation ◽  
Electronic Speckle Pattern Interferometry ◽  
Multiple Point

The surface displacement fields of a fatigue precracked compact tension sample under tensile load were registered by electronic speckle pattern interferometry and image correlation. The in-plane elastic strain fields calculated from the displacement data were used to obtain the first stress invariant, which for the case of plane stress is proportional to the real part of the first complex potential in Muskhelishvili's approach. Solutions for the stress fields around the crack tip, KI and KII were sought in the form of the Fourier series using Muskhelishvili's complex stress functions. The Fourier series coefficients were calculated from the displacement data using multiple point overdeterministic method (MPODM). The nominal and inferred KI values differ by around 10%; this is probably due in part to mixed mode (KII) loading introduced by some degree of misalignment during the experiment.

The Knowledge Acquired by Using of Optical Methods by Strain Fields Investigation

2013 ◽  
Vol 486 ◽  
pp. 141-146
Author(s):  
Martin Hagara ◽  
František Šimčák ◽  
Matúš Kalina
Keyword(s):  
Experimental Investigation ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Speckle Pattern ◽  
Image Correlation ◽  
Optical Methods ◽  
Optical Systems ◽  
Electronic Speckle Pattern Interferometry ◽  
Strain Fields ◽  
Pros And Cons

These days are preferably used contactless optical methods for experimental investigation of strains and displacements, which give some information on whole investigated surface. In this contribution the optical systems working on electronic speckle pattern interferometry (ESPI) principle and digital image correlation (DIC) method are described. By using of ESPI and DIC methods the displacements and strains fields on chosen types of specimens are determined. Pros and cons of particular methods and influence of various factors on reached results accuracy are compared. There are also mentioned the possibilities of using of optical methods in application of devices on authors department.

scholarly journals Suitability of DIC and ESPI optical methods for monitoring fatigue damage development in X10CrMoVNb9-1 power engineering steel

2021 ◽  
Vol 21 (4) ◽  
Author(s):  
M. Kopec ◽  
A. Brodecki ◽  
D. Kukla ◽  
Z. L. Kowalewski
Keyword(s):  
Fatigue Damage ◽  
Optical Measurement ◽  
Speckle Pattern ◽  
Measurement Techniques ◽  
Power Engineering ◽  
Image Correlation ◽  
Optical Methods ◽  
Electronic Speckle Pattern Interferometry ◽  
Damage Development ◽  
Engineering Steel

AbstractThe aim of this research was to compare the effectiveness of two different optical measurement techniques (digital image correlation—DIC and electronic speckle pattern interferometry—ESPI) during fatigue damage development monitoring in X10CrMoVNb9-1 (P91) power engineering steel for pipes. The specimens machined from the as-received pipe were subjected to fatigue loadings and monitored simultaneously using DIC and ESPI techniques. It was found that DIC technique, although characterised by lower resolution, was more effective than ESPI. DIC allows to monitor the fatigue behaviour of steel specimens and accurately indicate the area of potential failure even within the initial stage of fatigue damage development.

Sign in / Sign up

Export Citation Format

Share Document