残余应力测量---国外基于数学图像相关法的各个学科研究情况

Residual stress relaxation measurements across interfaces at macroand micro-scales using slitting and DIC

A Blair1, N Daynes1, D Hamilton1, G Horne1, PJ Heard2, DZL Hodgson1, TB Scott2,

A Shterenlikht1

1 Department of Mechanical Engineering, University of Bristol, Bristol BS8 1TR, UK

2 Interface Analysis Centre, University of Bristol, Bristol BS2 8BS, UK

corresponding author, email mexas@bristol.ac.uk

7th International Conference on Modern Practice in Stress and Vibration Analysis IOP Publishing

Journal of Physics: Conference Series 181 (2009) 012078 doi:10.1088/1742-6596/181/1/012078

Abstract. In this paper digital image correlation is used to measure relaxation of residual stresses across an interface. On the macro scale the method is applied to a tri-layer bonded aluminium sample, where the middle layer is in tension and the top and the bottom layers are in compression. High contrast speckle pattern was sprayed onto the surface. The relaxation was done with the slitting saw. Three dimensional image correlation was used. On the micro scale the technique was applied to a heat treated large grain brass loaded in tension. Mechanical and electro polishing was used for surface preparation. A focused ion beam was used for slitting across a grain boundary and for imaging. Grain orientation was measured using electron back-scattering diffraction. Two dimensional image correlation was employed. In all macro- and microscale experiments the range of measured relaxation was sub-pixel, almost at the limit of the resolution of the image correlation algorithms. In the macro-scale experiments, the limiting factor was low residual stress, due to low shear strength of the Araldite glue used for bonding. Finite element simulation of the relaxation agreed only qualitatively with the experimental results at both size scales. The methodology is intended for use with inverse methods, i.e. the measured relaxation is applied as the boundary conditions to an appropriate FE model which produces stresses equal to the relaxed residual stresses, but with opposite sign. The main conclusion is that the digital image correlation method could be used to measure relaxation caused by slitting in heterogeneous materials and structures at both macro- and micro-scales. However, the repeatability of the techniques needs to be improved before residual stresses can be determined confidently.

Micro-scale residual stress relaxation measurements using focused ion beam slotting and digital image correlation

Graeme Horne

Department of Mechanical Engineering, University of Bristol

Queen’s Building, University Walk, Bristol BS8 1TR, UK

June 2009