DIC 数字图像相关原理

左边的特写显示3D系统的两个图像采集器聚焦在样件上。试件使用光纤鹅颈式灯光进行照明，可以方便地进行调节，以在整个试件上提供均匀的照度。

The close-up on the left shows the two cameras of the stereo system focused on the sample. The sample is illuminated using fiber-optic goose-neck style lights that can conveniently be adjusted to provide even illumination across the entire sample.

右侧的两幅图像分别显示了由3D系统的左侧和右侧相机拍摄的未变形状态下的狗骨试件散斑图像。

显示的试件是0.5“宽和0.1”厚。标距长度是5“。

散斑图案是使用自喷漆制作的，首先用一层白色涂料喷涂覆盖铝试件。 然后通过轻轻地喷涂黑漆雾来制备黑色散斑。

The two images on the right show the speckle images of the dog-bone sample in the undeformed state recorded by the left and right camera of the stereo system, respectively.

The sample shown was 0.5″ wide and 0.1″ thick. The gage section was 5″ in length.

The speckle pattern was applied by first coating the aluminum sample with a layer of white paint using a spray can. The black speckles were then applied by lightly over-spraying a black mist of paint.

下图显示了失效前试件上的彩色云图的离面位移（W值）。试件最终破坏发生时显示出典型的局部颈缩特征。

The graph below shows the out-of-plane displacement (W) as a color-coded overlay on the sample just prior to failure. The sample showed the typical localized necking where ultimately failure occurred.

右侧图片显示了试件的应力 - 应变曲线。测得的应变是大约1/8"标距长度上的区域平均值。

The stress-strain curve for the sample is shown on the right. The measured strains were averaged over an area corresponding to a gage length of approximately 1/8″.

由于VIC-3D计算试件表面上的拉格朗日应变张量，横向应变可用在基于体积守恒约束计算的样品横截面积减小。 在右侧的图中，以绿色显示的是用减小的横截面积计算的实际应力 - 应变曲线。

Since VIC-3D calculates the Lagrangian strain tensor on the specimen surface, the transverse strain can be used to calculate the reduction in cross-sectional area of the sample using a volume conservation constraint. In the graph on the right, the actual stress-strain curve using the reduced cross-sectional area is shown in green.