Microtesting rig

The measurement of mechanical behavior in very small samples, whose dimensions are on the order of microns and below, can offer advantages over conventional macroscopic testing in many instances. Motivations for investigating materials at this length scale include seeking information about size-dependent properties in monolithic materials, studying local variation in properties throughout a microstructure, and measuring the mechanical response of fabricated structures that have small dimensions.

Air Force researchers have designed and constructed a device for the quantitative measurement of deformation properties in micron-sized specimens while imparting an exceedingly small constraining force to the deforming body. Existing ex-situ test methodologies can provide high precision data that relate quantitative stress and strain response during deformation. The Air Force device provides an alternative in-situ testing approach that also employs simultaneous electron imaging of very small test specimens within a scanning electron microscope or dual beam focused ion beam (DBFIB) during the deformation experiment. These images can be used to correlate the stress-strain data with the spatial and temporal nature of deformation-induced flow and fracture events that develop during the course of a test. Real-time imaging facilitates the operation of tests on micro-samples that rely on complex set-ups, such as the alignment of tension grips around very small free-standing specimens.

The device incorporates a high-precision piezoelectric actuator, a high-precision inertial force positioning stage, a small, low-profile load cell, and a variety of highly compliant contact platens and grips that can be manufactured from a SiC or similar compliant fiber.