Residual Stress Measurement Using the Hole Drilling Method and Laser Speckle Interferometry. Part Ii: Analysis Technique

An overview is provided of the use of eight different optical methods with hole drilling to determine residual stresses. The methods considered are: brittle and photoelastic coatings, Moire interferometry, holographic interferometry, electronic speckle pattern interferometry, interferometric strain rosette, digital image correlation and shearography. A number of applications are summarized, such as the use of hole drilling with holographic interferometry to investigate stresses in rock structures accessed by deep boreholes and to determine manufacturing-induced residual stresses in fillets of small radii.

Section: Espimentioning

confidence: 98%

Residual Stress Determination by Hole Drilling Combined with Optical Methods

Nelson

2010

“…Least-squares [83,84] and orthogonalization [85] techniques have been developed that meet these criteria. The substantial data averaging that is implicit in the calculations substantially reduces measurement noise and enhances measurement accuracy.…”

Section: Stress Calculation Techniquesmentioning

confidence: 99%

Relaxation Methods for Measuring Residual Stresses: Techniques and Opportunities

Schajer

2010

Relaxation methods, also called "destructive" methods, are commonly used to evaluate residual stresses in a wide range of engineering components. While seemingly less attractive than non-destructive methods because of the specimen damage they cause, the relaxation methods are very frequently the preferred choice because of their versatility and reliability. Many different methods and variations of methods have been developed to suit various specimen geometries and measurement objectives. Previously, only specimens with simple geometries could be handled, but now the availability of sophisticated computational tools and of high-precision machining and measurement processes has greatly expanded the scope of the relaxation methods for residual stress evaluation. This paper reviews several prominent relaxation methods, describes recent advances, and indicates some promising directions for future developments.

“…In addition, the excess data enable data consistency checking to be done, and this ability provides a valuable tool for identification and size estimation of experimental errors. Linear computation methods, for example using a least-squares approach [62][63][64] have been applied successfully. Non-linear procedures can also be used, but only when essential because they are much more computationally intensive and potentially less stable.…”

Section: Stress Computation From Optical Datamentioning

confidence: 99%

Hole-Drilling Residual Stress Measurements at 75: Origins, Advances, Opportunities

Schajer

2009

Since its inception by Mathar in the 1930s, the hole-drilling method has grown to be the most widely used general-purpose technique for measuring residual stresses in materials. During its history, the method has progressed greatly in both sophistication and scope, with substantial advances in all three of its main aspects. Drilling procedures have developed from the early use of a conventional low-speed drill to the modern use of highspeed orbiting endmills and, for very hard materials, abrasive machining. Deformation measurements have advanced from the use of a mechanical extensometer to strain gauges and full-field optical measurements such as Moiré, ESPI and Digital Image Correlation. Computation techniques have progressed from empirical calibrations for discrete measurements within uniform stress fields to finite-element inverse solutions for multiple measurements within non-uniform stress fields. This paper gives an overview of the history and progress of all three aspects of the hole-drilling method, and indicates some promising directions for future developments.