Measuring Residual Stresses by Hole-Drilling and Coherent Optics Techniques: A Numerical Calibration

An improved method of indent pairs is utilised to determine residual stresses in high speed milling specimens of AA 6082-T6 and AA 7075-T6 aluminium alloys. To carry out the measurement procedure, this approach does not need specific equipment but only requires a universal measuring machine and an oven. An indentation device is incorporated to the measuring machine, which allows reducing the absolute error of measurement to just ±0.9 MPa. The geometry of the tool and cutting parameters are selected to evaluate the sensitivity of the method. The residual stress distributions generated by high speed milling are exhaustively evaluated taking into account orthogonal components of cutting speed and tangential force, which are parallel and perpendicular to feed direction.

Section: Introductionmentioning

confidence: 99%

Determination of Residual Stresses in High Speed Milled Aluminium Alloys Using a Method of Indent Pairs

Díaz

Bolmaro

Guidobono³

et al. 2009

“…Residual stresses were determined using displacement data obtained from the fringe patterns and relations between displacements and residual stresses similar in nature to those used for the strain rosette implementation of the hole drilling method. Later in that decade, and in the early 1990s, Nicoletto [25,26] presented closed form relations to determine residual stresses from fringe patterns, while Furgiuele et al [27] used a numerical approach for that purpose. In 1998, the Moire-hole drilling method was further advanced by a finite element based approach for determining how stresses vary with depth using incremental drilling [28], followed in 2000 by an approach combining Moire and Twyman-Green interferometry [29] to find stresses from the 3D displacements associated with the release of stresses by hole drilling.…”

Section: Moire Interferometrymentioning

confidence: 99%

Residual Stress Determination by Hole Drilling Combined with Optical Methods

Nelson

2010

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.

“…A modern variant, Electronic Speckle Pattern Interferometry (ESPI) has become popular because its use of a video camera allows "live" fringe patterns to be produced by image subtraction [35][36][37]. Figure 4 shows an example ESPI fringe pattern created by hole-drilling.…”

Section: Deformation Measurements-full-field Optical Techniquesmentioning

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.