Uncertainties in Triaxial Residual Stress Measurements

2011 ◽  
Vol 681 ◽  
pp. 498-503 ◽  
Author(s):  
D.M. Goudar ◽  
M.S. Hossain ◽  
Christopher E. Truman ◽  
Ed J. Kingston ◽  
David John Smith
Keyword(s):  
Residual Stress ◽  
Error Analysis ◽  
Cold Water ◽  
Stress Measurement ◽  
Measurement Techniques ◽  
Mechanical Strain ◽  
Hole Drilling ◽  
Stress Distributions ◽  
Deep Hole ◽  
Deep Hole Drilling

Residual stress measurement techniques using mechanical strain relaxation depend on a number of physical quantities and are therefore sensitive to errors associated with the measured data. The resulting stress uncertainties can easily become significant and compromise the usefulness of the results or lead to misinterpretation of the behaviour of the residual stress distributions. It is therefore essential to develop an error analysis procedure for the measurements undertaken. Error analysis procedures for the deep hole drilling (DHD) method are developed to consider triaxial residual stresses. A modified deep hole drilling method, called the incremental deep-hole drilling (iDHD), was applied to measure the near yield residual stress distributions in a cold water quenched aluminium 7010 alloy forged block. The experimental results are used to illustrate the errors.

Effect of Gauge Volume on the Residual Stress Measurement Using Deep Hole Drilling Technique

2010 ◽  
Author(s):  
Amir H. Mahmoudi ◽  
David J. Smith ◽  
Chris E. Truman ◽  
Martyn J. Pavier
Keyword(s):  
Residual Stress ◽  
Material Removal ◽  
Stress Measurement ◽  
Measurement Techniques ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Gauge Volume ◽  
Drilling Technique

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.

Calibration of the Ultrasonic Technique Using the Deep Hole Drilling, Neutron Diffraction and Contour Residual Stress Measurement on a Ring Stiffened Cylindrical Structures

2016 ◽  
Author(s):  
Xavier Ficquet ◽  
Remi Romac ◽  
Douglas Cave ◽  
Ed J. Kingston
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Tensile Test ◽  
Stress Measurement ◽  
Measurement Techniques ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Cylindrical Structures

This paper presents the residual stress measurements carried out on a t-section representative of a ring stiffened cylindrical structures. This paper presents the work carried out to ascertain the residual stresses present within a T-plate section representative of a ring stiffened cylindrical structures. The contour, the deep hole drilling (DHD) and the neutron diffraction (ND) methods were applied to determine the longitudinal component of residual stress in the weld toe of the fillet weld in the as-welded condition. The results of these measurements are presented and compared to highlight agreements and discrepancies in the measured residual stress distributions using these different techniques. Finally, non-destructive residual stress measurement using the ultrasonic (US) technique was carried out on the component. The ultrasonic measurement provides a relative measurement and usually requires a tensile test in order to determine the acoustoelastic constant and the time of flight in a stress-free state. The tensile test requires some material to be extracted from the component. The tensile test can be avoided if other residual stress measurement techniques are used for the calibration. After the calibration the US technique can be deployed on a full-scale ring stiffened cylindrical structures to detect abnormal variation in the residual stress field.

Uncertainty in Residual Stress Measurements

2008 ◽  
Author(s):  
D. M. Goudar ◽  
S. Hossain ◽  
C. E. Truman ◽  
D. J. Smith
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Measurement Techniques ◽  
Diffraction Method ◽  
Hole Drilling ◽  
Invasive Technique ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Integrity Assessment ◽  
Path Lengths

Accurate characterization of residual stress in engineering components is important in structural integrity assessment. Two commonly used methods of measuring residual stress include the neutron diffraction technique and the deep-hole drilling (DHD) technique. The former is a well-known nondestructive measurement method and the latter is a semi-invasive technique which is readily available and portable. Both these measurement techniques depend on a number of physical quantities and are therefore sensitive to errors associated with the measured data. The resulting stress uncertainties can easily become significant and compromise the usefulness of the results or lead to misinterpretation of the behaviour of stress distribution. This paper describes briefly the error analysis for both techniques. Results from earlier neutron diffraction and deep hole drilling measurements are used to illustrate the errors. It is found that the average error for both techniques is about ±20MPa. In the case of the neutron diffraction method this error is acceptable for path lengths less than a few centimetres. At greater path lengths the errors become unacceptably large. In contrast the error in the DHD is independent of depth.

Residual Stress Investigation in a Stainless Steel Ring Welded Circular Disc by Over-Coring Deep Hole Drilling Simulation and Measurement

2014 ◽  
Author(s):  
Gang Zheng ◽  
Sayeed Hossain ◽  
Mike C. Smith ◽  
David J. Smith
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Stress Measurement ◽  
Circular Disc ◽  
Residual Stress Measurement ◽  
Hole Drilling ◽  
Deep Hole ◽  
Deep Hole Drilling ◽  
Welding Simulation ◽  
Drilling Simulation

A circular disc containing a partial ring weld has been devised to permit high levels of residual stress to be created in a relatively small specimen. The purpose of this research is to investigate the residual stress within the weld whilst developing a residual stress measurement method called the over-coring deep hole drilling (oDHD) method. The welding simulation, incremental deep hole drilling (iDHD) simulation and measurement and neutron diffraction were previously studied and reported in [1]. In this paper, the welding simulation results were mapped into a 3D model that included the necessary mesh and boundary conditions to simulate the process of residual measurement using the oDHD method. An experimental programme of residual stress measurement using the oDHD method was then conducted on a welded circular disc. The results from the oDHD simulation and measurement matched well with previous iDHD simulations on the original stress field in the ring weld, which also matched earlier neutron diffraction results.

Measurement of Internal Strains in Graphite Using the Deep Hole Drilling Technique

2008 ◽  
Author(s):  
Soheil Nakhodchi ◽  
Peter E. J. Flewitt ◽  
Chris Truman ◽  
David J. Smith
Keyword(s):  
Volume Fraction ◽  
Stress Measurement ◽  
Reactor Core ◽  
Hole Drilling ◽  
Stress Distributions ◽  
Deep Hole ◽  
Stress Strain ◽  
Deep Hole Drilling ◽  
Drilling Technique ◽  
Internal Strains

Currently, measurement of internal strains deep inside graphite is extremely difficult. As a consequence there is a need to assess the ability of a deep-hole drilling (DHD) method to measure internal strains in reactor core graphite and explore the potential for in-situ measurement. DHD technique is a semi-destructive method for measurement of the through thickness residual stresses. The technique previously has been applied successfully to metallic and composite materials. In this paper, the method for stress measurement in graphite is examined particularly when a significant volume fraction of porosity is present. Two types of graphite were used, PGA and PG25 filter graphite. In PGA graphite the Young’s modulus of elasticity was orientation dependent. As a consequence samples were cut from blocks in two directions. PG25 filter graphite is a surrogate for service exposed material. Known loads were applied to graphite beam samples and the DHD method was used to measure the stress/strain profile through the material. The results were compared with the strain data obtained from strain gauges bonded to the samples. Overall, there was an excellent agreement between the DHD measured stress/strain and applied stress. It is shown that deep-hole drilling technique can measure linear stress distributions in graphite.

Measurement of Residual Stress in an A533B Ferritic Steel Plate Containing a Repair Weld

2006 ◽  
Vol 524-525 ◽  
pp. 653-658 ◽  
Author(s):  
X. Ficquet ◽  
Christopher E. Truman ◽  
David John Smith
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Ferritic Steel ◽  
Steel Plate ◽  
Measurement Techniques ◽  
Lattice Parameter ◽  
Hole Drilling ◽  
Deep Hole ◽  
Secondary Circuit ◽  
Deep Hole Drilling

The paper presents the results of residual stress measurements on a ferritic steel plate containing a repair weld. The repair was considered representative of that found in the secondary circuit piping in power plant. The paper primarily uses the deep hole drilling (DHD) technique, but compares results found by this technique with those obtained using neutron diffraction. Both sets of measurements confirmed that highly tensile residual stresses exist in the repair weld. The two measurement techniques produced results that were in acceptable agreement, but the neutron diffraction results were consistently higher than the deep hole drilling results. It was thought this was due to the use of a constant stress-free lattice parameter d0 .

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