http://doras.dcu.ie/17607/1/Review_of_residual_stresses-Final.pdf

Methods of measuring residual stresses in components

Recent progress of residual stress measurement methods: A review

This study forms part of a literature survey on residual stresses in continuous fibre reinforced thermoplastic composites. After identification of the factors responsible for the thermal residual stress build-up in Part I [Parlevliet PP, Bersee HEN, Beukers A. Residual stresses in thermoplastic composites – A study of the literature – Part I: Formation of residual stresses. Composites Part A – Appl Sci Manuf, in press, doi:10.1016/j.compositesa.2005.12.025 ], experimental techniques to determine the magnitude and distribution of these stresses on various mechanical levels are outlined. The techniques are placed in the following categories: techniques utilising the intrinsic composite constituents’ material properties; techniques employing embedded “foreign” stress sensors; techniques based on in-plane and out-of-plane deformations, and destructive techniques.

Residual stresses in thermoplastic composites—A study of the literature—Part II: Experimental techniques

The conventional contour method determines one component of residual stress over the cross section of a part. The part is cut into two, the contour (topographic shape) of the exposed surface is measured, and Bueckner’s superposition principle is analytically applied to calculate stresses. In this paper, the contour method is extended to the measurement of multiple residual-stress components by making multiple cuts with subsequent applications of superposition. The theory and limitations are described. The theory is experimentally tested on a 316L stainless steel disk with residual stresses induced by plastically indenting the central portion of the disk. The multiple-cut contour method results agree very well with independent measurements using neutron diffraction and with a computational, finite-element model of the indentation process.

/pdf/measuring-multiple-residual-stress-components-using-the-1jd4xxt74t.pdf

Measuring Multiple Residual-Stress Components using the Contour Method and Multiple Cuts

Residual stress measurements by hole-drilling have developed greatly in both sophistication and scope since the pioneering work of Mathar in the 1930s. Advances have been made in measurement technology to give measured data superior in both quality and quantity, and in analytical capability to give detailed residual stress results from those data. On the technology side, the use of multiple strain gauges, Moire, Holographic Interferometry and Digital Image Correlation all provide prolific sources of high quality data. In addition, modern analytical techniques using inverse methods provide effective ways of extracting reliable residual stress results from the mass of available data. This paper describes recent advances in both the measurement and analytical areas, and indicates some promising directions for future developments.

Advances in Hole-Drilling Residual Stress Measurements

A mathematical method is proposed for calculating residual stresses from hole drilling electronic speckle pattern interferometry (ESPI) data, independent of rigid-body motions. Even though the signal-to-noise ratio of typical ESPI data is modest, the method achieves good computational stability by averaging a large amount of data. It does this without excessive numerical effort by exploiting known trigonometric relationships among the data. The resulting stress calculations are very rapid, and are well suited for future application to non-uniform stress measurements.

Full-field calculation of hole drilling residual stresses from electronic speckle pattern interferometry data

The traditional contour method maps a single component of residual stress by cutting a body carefully in two and measuring the contour of the cut surface. The cut also exposes previously inaccessible regions of the body to residual stress measurement using a variety of other techniques, but the stresses have been changed by the relaxation after cutting. In this paper, it is shown that superposition of stresses measured post-cutting with results from the contour method analysis can determine the original (pre-cut) residual stresses. The general superposition theory using Bueckner’s principle is developed and limitations are discussed. The procedure is experimentally demonstrated by determining the triaxial residual stress state on a cross section plane. The 2024-T351 aluminum alloy test specimen was a disk plastically indented to produce multiaxial residual stresses. After cutting the disk in half, the stresses on the cut surface of one half were determined with X-ray diffraction and with hole drilling on the other half. To determine the original residual stresses, the measured surface stresses were superimposed with the change stress calculated by the contour method. Within uncertainty, the results agreed with neutron diffraction measurements taken on an uncut disk.

/pdf/measuring-inaccessible-residual-stresses-using-multiple-20xyrp9ott.pdf

Measuring Inaccessible Residual Stresses Using Multiple Methods and Superposition

The objective of this research is to define drill speeds that produce acceptable results when using the hole-drilling technique for measuring residual stress. For this study, three common engineering materials; alloy 6061-T651 aluminum, 304 stainless steel, and A36 carbon steel were used. This was achieved by performing ESPI/hole-drilling stress measurement of a known applied stress in discrete rpm intervals ranging from 2-40K rpm for each material. To produce a known state of stress specimens were bent elastically in a four-point bend fixture. Stress measurements were taken using single-axis electronic speckle-pattern interferometry (ESPI). It was found that for 6061-T6 aluminum, accurate and repeatable results can be achieved between speeds of 2-40K rpm. For 304 stainless steel, result accuracy diminishes when drill speeds go below 6K rpm. The A36 steel had a large as-received stress gradient across the longitudinal dimension and was therefore removed from this study.

Influence of Drilling Parameters on the Accuracy of Hole-drilling Residual Stress Measurements

http://public.lanl.gov/clausen/Brown_et_al_Acta_Mater_2009.pdf

M. Steinzig

Papers

Full-field calculation of hole drilling residual stresses from electronic speckle pattern interferometry data

Measuring Inaccessible Residual Stresses Using Multiple Methods and Superposition

Influence of Drilling Parameters on the Accuracy of Hole-drilling Residual Stress Measurements

Development of intergranular thermal residual stresses in beryllium during cooling from processing temperatures

S113 Mapping Multiple Residual Stress Components Using the Contour Method and Superposition