报告题目：Experimental Mechanics Challenges Implementing DIC on the Meso-scale

报告人：Dr.Alex Arzoumanidis，CEO of Psylotech corporation，USA

主持人：李文亚教授

时间：2019年4月15日星期一10:30

地点：公字楼328会议室

Experimental Mechanics Challenges Implementing DIC on the Meso-scale

Combining microscopy and Digital Image Correlation (DIC) offers a powerful non-contact experimental technique to study phenomenon on nano to macro length scales. Optical, confocal, SEM, AFM or x-ray tomography image capture each present experimental mechanics challenges. Optical microscopes have the advantage of instant image capture and ease of use, but they also have a low depth of field, losing focus if samples move even a few microns out of plane. Scanning electron microscopes have a larger depth of field, but out-of-plane motion causes false DIC strains. Computed tomography scanners also require low out-of-plane sample motion, in addition to a clear path for X-rays during a full 360° rotation. Moreover, to maximize spatial resolution, CT scanners require the X-ray source to be only a few millimeters from the sample.

A miniature universal load frame is described that minimizes out-of-plane motion by 1/design symmetry, 2/high tolerances on reference surfaces, and 3/minimized moving parts in the actuator. The direct drive actuator implements only two moving parts, reducing tolerance stackup and eliminating the need for a gearbox. The 40mm stroke actuator can be controlled to 2nm in closed loop and its direct drive achieves speeds comparable to servohydraulics.

A number of specific examples are described. The high precision of the system enables fatigue fracture on brittle, highly filled, metal matrix composites. The system was used to experimentally validate multi-scale simulation of a 3D printed particle filled composite. Single fiber testing as well as mixed-mode adhesive bond fracture experiments are described. Finally, an experimental setup for testing rock in a CT scanner is presented.

Alex Arzoumanidis – BIO

Dr.Arzoumanidis is the founder of Psylotech, Inc., which produces miniature universal load frames that fill the gap between nano and macro scales. Leveraging microscopy and digital image correlation, these instruments enable new experimental techniques on the meso scale. In addition to surface measurement under microscopes, Psylotech produces a rotating load train test system for CT scanners and digital volume correlation. Dr. Arzoumanidis is also an expert in nonlinear viscoelastic constitutive modeling.

Prior to Psylotech, Alex was at Schlumberger Doll Research in the Materials and Mechanical Sciences Group. He holds a Doctorate and Master’s from the University of Texas at Austin, was previously a Guest Lecturer at MIT, and is currently an Affiliate at Northwestern University’s Segal Design Institute. In 2018, he stepped down as chairman of the Time Dependent Materials Technical Division of the Society for Experimental Mechanics and in 2019, he joined the Adhesion Society’s Structural Adhesives organizing committee.