Application of optical methods in tests of new materials with gradient structure

I S Kamantsev,S I Stepanov,M A Chesnokov,N A Drukarenko,A V Kuznetsov

doi:10.1088/1757-899x/848/1/012029

Abstract

The main idea of the article is to demonstrate the possibility of applying the laser dynamic speckle interferometry technique to control the processes of fatigue failure of specimens with a gradient structure. A distinctive feature of the described technique is the possibility of practical application on high-frequency machines as an experimental non-contact method for recording surface changes in the studying objects with a complex structure. Besides, the proposed technique can be used as an indicator characterizing irreversible processes during fatigue failure and for analyzing the fatigue crack growth kinetics.

Highlights

At present finding the fracture precursors of structural elements as well as monitoring existing fracture centers under conditions of multi-cycle fatigue loading is an urgent not yet completely solved task
The proposed technique can be used as an indicator characterizing irreversible processes during fatigue failure and for analyzing the fatigue crack growth kinetics
The use of Digital Image Correlation method (DIC) in the analysis of the fracture kinetics of materials with complex geometry under high-frequency fatigue loading is difficult due to the shallow depth of field, which is due to the wide field of view, relatively low sensitivity and implementation features of the algorithm for constructing strain distribution diagrams, which does not allow controlling the object when exposed to small loads

Summary

Introduction

At present finding the fracture precursors of structural elements as well as monitoring existing fracture centers under conditions of multi-cycle fatigue loading is an urgent not yet completely solved task. Among the existing methods for observing the fracture process, such as the use of contact measuring instruments (strain gauges, foils, piezoelectric elements) and non-contact based on measurements of magnetic and thermal properties optical methods deserve special attention. One of the most common and widely used optical control methods is the Digital Image Correlation method (DIC) [1]. The use of DIC in the analysis of the fracture kinetics of materials with complex geometry under high-frequency fatigue loading is difficult due to the shallow depth of field, which is due to the wide field of view, relatively low sensitivity and implementation features of the algorithm for constructing strain distribution diagrams, which does not allow controlling the object when exposed to small loads. The methods of electronic speckle interferometry and holographic interferometry which are successfully used in non-destructive testing of materials and products to detect defects that cannot be detected by visual examination are devoid of these disadvantages [2]

Methods

Results

Conclusion