MRI: Acquisition of Digital Image Correlation System for Real-Time 3D Measurements and Closed-Loop Control

University Of Houston, Houston TX

Investigators

Abstract

This Major Research Instrumentation (MRI) project involves acquisition of a Digital Image Correlation System. The photogrammetric technology provides full-field non-contact measurements of 3D displacements of complex test systems in real-time. The intent is two-fold, (a) to detect and visualize emerging cracks and strain concentrations on test articles without the use of traditional contact measurements such as strain gauges and differential transducers, and (b) to develop an adaptive feed-back signal for controlling the force input in the pre- and post-failure regime. The 3-D DIC measurement system by Trilion Inc. includes four pairs of 12 megapixel digital cameras, the Tritop coordinate measurement system, an image processing workstation and controller, and the Aramis processing software with a real-time interface for control. Each pair of digital cameras is mounted on a tripod with dedicated lighting to provide a series of stereoscopic images of the test article within the field of view. The Aramis processing software tracks the coordinates of 10,000+ facet points. It provides deformation field data for structural materials testing up to and beyond their maximum load resistance, and progressive failure such as crack initiation and propagation in structural components and systems. The portable instrumentation system will provide new opportunities for undergraduate and graduate students to acquaint themselves with the capabilities of digital image correlation systems and their application to a variety of research projects spanning from testing materials and infrastructural components to biomedical applications. Under the direction of eleven faculty, students in Civil and Mechanical Engineering will be trained in (a) the use of powerful imaging to track emerging failure mechanisms, and (b) the field of servo-controlled testing of materials and structures.