Determination of the Moduli of Elasticity of Materials by the Method of Digital Image Correlation
- PDF / 777,573 Bytes
- 7 Pages / 594 x 792 pts Page_size
- 14 Downloads / 227 Views
DETERMINATION OF THE MODULI OF ELASTICITY OF MATERIALS BY THE METHOD OF DIGITAL IMAGE CORRELATION O. P. Maksymenko,1, 2 L. F. Frankevych,1 and O. M. Sakharuk1
UDC 620.174.22;528.854
On the basis of the results of digital correlation processing of images, we develop a method of noncontact determination of the strain distributions on the surfaces of beam specimens and the moduli of elasticity of the specimens made of duralumin and glass-fiber plastic and loaded by bending moments. We describe the procedure of measurements and the algorithm used for data processing. Keywords: modulus of elasticity, digital correlation, strain distribution, image processing.
In the development of new composite materials (CM), as well as in the design of structures and products made of these materials, it is necessary to be able to experimentally determine their mechanical characteristics in the process of deformation up to the time of spontaneous fracture. The application of the existing procedures of testing the specimens of materials is based on the mechanical contact with the surface of composite specimens, which leads to the appearance of additional measurement errors. The use of contact or glued strain gauges for low-modulus CM leads to their strengthening, whereas the deviations of the axis of sensitivity of the gauges from the orientation of the structure of reinforcement causes significant errors in strain measurements [1].
Hence, the development of noncontact methods and instruments aimed at finding the displacements of the surfaces and the levels of strains in specimens under loading seems to be quite urgent. Furthermore, the noncontact methods of measurements can be used for the investigation of specimens subjected to the action of corrosive media and elevated temperatures.
Among the noncontact methods, an important place is occupied by optical and interferometric methods intended for the investigation of the properties of CM [2]. However, they require complex laboratory equipment. Moreover, they are labor-consuming and sensitive to vibrations with a small range of measurements D : in the case of their high sensitivity !D , the dynamic range
V=
D ≈ 150–240 [3]. !D
To study the strain characteristics of CM and new low-modulus materials, it is necessary to have measuring devices guaranteeing larger dynamic ranges of strain measurements and stable under vibrations. Among the noncontact methods, the procedure of digital image correlation (DIC) of the specimen surface possesses the indicated properties [4]. This method has a lower sensitivity but ensures the dynamic range of measurements larger by an order of magnitude, namely, V ≈ 2000 [5]. 1 2
Karpenko Physicomechanical Institute, Ukrainian National Academy of Sciences, Lviv, Ukraine. Corresponding author; e-mail: [email protected].
Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 48, No. 6, pp. 115–120, November–December, 2012. Original article submitted July 3, 2012. 1068-820X/13/4806–0825
© 2013
Springer Science+Business Media New York
825
O. P.
Data Loading...
