Background

Digital Image Correlation (DIC) is a popular experimental technique for measuring full-field deformations in materials. Accurate motion and displacement field reconstruction in DIC depend heavily on the intrinsic material texture or speckle patterns painted on the material prior to deformation. Many traditional techniques such as spray painting, ink stamping, or manual texturizing have provided adequate performance but are often challenging to apply on highly compliant, porous or non-planar surfaces.

Objective

To address this challenge we present a new, robust and efficient technique to print DIC speckle dot patterns on both planar and non-planar sample surfaces using a custom-modified 3D printer in an automated fashion.

Methods

In this new technique, a 3D printer is modified by replacing the conventional extrusion head with a syringe filled with ink. The motion of the 3D printer is controlled via customizable G-code scripts, precisely controlling both the extrusion volume and spatial positioning of the print head in a well-controlled and predictable fashion.

Results

The printed speckle dots have radii on the order of O(\(10^2\)) \(\upmu\)m, and the subsequent DIC reconstructed deformations have an accuracy on the order of O(\(10^{-2}\)) pixels and O(\(10^{-4}\)) in measuring displacements and strains, respectively. Furthermore, we demonstrate that this technique has the capability to print suitable patterns for tracking large and heterogeneous deformations in highly compliant and porous materials, as well as materials with significant 3D topographies.

中文翻译：

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通过 3D 打印的智能数字图像关联模式

背景

数字图像相关 (DIC) 是一种流行的实验技术，用于测量材料的全场变形。DIC 中精确的运动和位移场重建在很大程度上取决于在变形之前涂在材料上的固有材料纹理或斑点图案。许多传统技术，例如喷漆、油墨压印或手动纹理化，已提供足够的性能，但通常难以应用于高度柔顺、多孔或非平面的表面。

客观的

为了应对这一挑战，我们提出了一种新的、强大且高效的技术，可以使用定制修改的 3D 打印机以自动化方式在平面和非平面样品表面上打印 DIC 散斑点图案。

方法

在这项新技术中，3D 打印机通过用充满墨水的注射器代替传统的挤出头进行了改进。3D 打印机的运动是通过可定制的 G 代码脚本控制的，以良好控制和可预测的方式精确控制打印头的挤出量和空间定位。

结果

打印散斑点的半径约为O ( \(10^2\) ) \(\upmu\) m，随后的 DIC 重构变形精度约为O ( \(10^{-2 }\) ) 像素和O ( \(10^{-4}\) ) 分别用于测量位移和应变。此外，我们证明该技术能够打印合适的图案，以跟踪高度柔顺和多孔材料以及具有显着 3D 地形的材料中的大型和异质变形。