DIC: Digital Image Correlation Strain analysis

Digital Image Correlation

Digital Image Correlation

DIC (Digital Image Correlation) analyzes the degree of deformation by analyzing the image before and after sample deformation. Not only the deformation amount but also the deformed direction can be detected. By using this system, it is possible to quantify the distortion and deformation of an object in non-contact and non-destructive manner. By using a high-speed camera, analysis of high-speed phenomena and vibration is also possible.

Digital image

Digital image

 

A digital image consists of a collection of pixels. In addition, the luminance value (brightness information) of each pixel is quantized and takes a discrete value. Such a digital image is often made by photographing the subject using an image sensor in many cases. The brightness value of the subject is sampled for each pixel of the image sensor and then quantized by the A / D converter.In this process, information between pixels and quantized luminance value and luminance value is lost. This figure is a schematic representation of how the information of one line of the subject changes with sampling and quantization. The information of the subject is smooth like a line with analog display, but after sampling and quantization it gets a discrete value and some information is lost. The fineness of sampling is determined by the number of pixels, and the granularity of quantization is determined by the bit depth. Because it happens when acquiring digital images, you need to decide to consider the parameters carefully when shooting.

Speckle pattern

Speckle pattern

 

The random pattern as shown in the figure is called speckle pattern. In the digital image correlation method, it is possible to measure deformation and distortion of a subject with high resolution by constructing a speckle pattern on the subject's surface. To construct speckle patterns, there are various methods such as painting and spraying of minute substances.

Subset

Subset

 

In the digital image correlation method, as shown in the red frame in the figure, the subject is divided into a minute area called a subset. Each subset is the measurement point. Calculate deformation and strain by measuring the displacement amount of the subset.

Features

Features
  • Measure coordinate, displacement,velocity, strain, shape and deformation
  • Vector diagram / Contour diagram
  • Supported image format: TIFF etc.
  • Easy to use and intuitive interface
  • Offline analysis, Online analysis(Optional)  3D analysis(Optional)
  • Process tree structure
  • Various post processing functions    (FFT analysis, POD analysis, etc.)
  • Supporting various high speed cameras and high resolution cameras
  • Japanese and English available

Movie

Application

  • Tension, Compression, Torsion, Vibration Test
  • Thermal expansion / thermal deformation
  • Destruction · Impact · Drop test
  • Micro test by electron microscope

Measurement example

System configuration example

System variation

Standard model specification

  2D 3D(stereo)
 System configuration
 camera One Two
 illumination 2 lights 3 lights
 Software sDIC(2D) sDIC(3D)
 Calibration target ×
 tripod 3 sets 4 sets
 Camera mount
 Control PC 1 set 1 set
 Camera
 format 2/3 inch
 resolution  2,448 × 2,048 pixels
 Dynamic range  12 bit monochrome
 Maximum frame rate  23fps
 shutter  global
 Connection interface  Ethernet (1000BASE-T)
 Applicable lens  C-Mount/F-Mount
 Illumination
 method LED
 Color temperature  2700-6500°K
 Maximum illuminance 55,100lx(6500°K)
 Beam angle  13°
 Control PC
 OS windows 10PRO For Workstation
 processor  Intel Xeon processor (4 cores)
 memory  32GB DDR-4 SDRAM
 storage 512 GB M.2 slot SSD 2 TB hard disk drive
 monitor 24 inch wide monitor
 Software specification
 Image format tiff
 Image correction ○ (Gaussian filter)
 Mask · ROI  〇
 display 2D  3D
 Measurement item Shape, deformation, various strain
 Calculation precision 1/100 pixels or less 1/100 pixels or less (in-plane direction)
1/50 pixels or less (out-of-plane direction)





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