Strain Monitoring on Damaged Composite Laminates Using Digital Image Correlation

Abstract

Composite laminates are susceptible to impact damage. Nowadays, damage detection mainly depends on visual inspection and C scan. But these two methods are limited to the technical skill of the inspectors, causing missed detection or even fault detection. The current full field digital image correlation (DIC) technique has been gradually applied to the measurement of the structural surface. This paper devotes to exploring the DIC monitoring technique and the actual surface strain data processing methods. Composite laminates with different BVID damage degrees are studied under both tensile and compressive loading conditions. It is shown that DIC method is able to capture an obvious strain singularity on damage area of the composite laminate. Strain singularity is caused by fiber crack under tensile loading condition and buckling under compressive loading condition. Influencing factors of the composite surface monitoring are then discussed.

Layup Configuration Effect on Notch Residual Strength in Composite Laminates

“…DIC technique is a full field non-contact optical technique used to measure the surface deformation. DIC registers two (or more) images of the same structure subjected to various loadings (e.g., mechanical loading or thermal loading) to obtain full-field surface strain measurements of the entire specimen [ 17 , 19 , 20 , 21 ]. Optical full-field measurement techniques are increasingly used in material testing, fracture mechanics, and vibration analysis.…”

Application of DIC Method in the Analysis of Stress Concentration and Plastic Zone Development Problems

“…These methods and their advantages and disadvantages are described in the Introduction. Considering recent possibilities of the computers and high-speed cameras with high resolution, the DIC system seems to be convenient in the application of damage detection and growth [ 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 66 ]. With the use of the professional DIC system, it is possible to achieve good quantitative and qualitative calculation of displacements and strains fields over the investigated surface.…”

“…The detailed description of the different algorithms applied in DIC software and the basics of the DIC technique can be found in [ 51 ]. Generally, the DIC is used for detection and characterization of the surface damage [ 50 , 52 , 53 , 54 , 55 , 56 , 57 ], performance analyses of the structural objects [ 58 , 59 , 60 , 61 ], characterization of material properties [ 62 , 63 ], and damage detection under impact loadings [ 64 , 65 , 66 ]. The precision of the method depends on the camera resolution, quality of its optics, light intensity, and others.…”

Expansive Clay Cracking Behavior through Digital Image Correlation

“…Digital Image Correlation (DIC) is an optical nondestructive technique for measuring strain and displacement [17]. Compared to other techniques, DIC is simple, cost effective, and accurate, leading to a great number of potential applications.…”