USU's Mechanics at Extreme Temperatures Lab is looking for four (4) Undergraduate Research Assistants for Summer or Fall 2019.

General Qualifications

  • Open to undergraduate students from any year or major at USU, but those with an interest in engineering or physical sciences are preferred.
  • Ability to work independently or in teams as needed.
  • Must have good writing skills. All students are expected to produce scientific literature.  Students with an interest in graduate school are especially encouraged.
  • Cannot graduate in May 2020 or earlier. A huge chunk of my lab already graduates then; I can't afford to lose more all at the same time. Seniors will only be interviewed if they express interest in graduate school.
  • Underrepresented groups in STEM (i.e. veterans, LGBTQ+ students, women and gender non-conforming individuals, racial/ethnic minorities, etc.) are encouraged to apply.

Specific Projects

1. Vibration-based Fatigue Testing
In current and next-generation aerospace vehicles, structural components are subject to extreme temperatures and fluctuating loads, such as those encountered in gas turbine engines and along leading edges in hypersonic flight. Thus, to ensure the safety, reliability, and performance of the vehicle, structural materials must be characterized to withstand extreme temperature fatigue. The Air Force Research Lab (AFRL) uses a vibration-based method in which they excite a square plate in resonance, thereby accumulating many load cycles very quickly.
1.a. Miniaturization of Vibration-based Fatigue Specimens
In its current state, one key limitation of the technique is that the vibrating plate is much too large to fit within the scanning electron microscope (SEM) at USU's Microscopy Core Facility (MCF). As fatigue damage initiates at the micro-scale, the overly large plates cannot be examined micro-structurally until the completion of a fatigue test, meaning we cannot compare failed specimens against their pristine state prior to testing.

In this research, you will first assist one of my PhD students in performing vibration experiments to validate his shape optimization simulations.  You will then repeat and re-validate his simulations at a smaller length scale to develop miniaturized plates, thus enabling better micro-structural characterization before and after fatigue testing.
Photo of AFRL's vibration-based test setup
1.b. Relative Uncertainties of Motion Blur vs. Depth of Field
Our lab uses camera-based measurements to monitor the deformation of the plates.  In the vibration-based method, the parts of the plate which move fastest (and are thus most susceptible to motion blur) also move the most out-of-plane (and are thus susceptible to poor depth of field). 

In this research, you will de-couple these sources of error by comparing a sequence of three measurements: (1) Out-of-plane quasi-static rigid-body motion, thus isolating poor depth of field while eliminating motion blur; (2) In-plane rigid-body rotation, thus isolating motion blur while eliminating out-of-plane motion; and (3) Out-of-plane vibration, which contains both sources of error.
Simulation of the plate's resonant mode showing stress (left) and out of plane displacement (right)
1.c. Custom UV Light Source for Extreme Temperature Imaging
Generally speaking, our camera measurements should be performed using as bright a light source as is safely available.  This allows shorter exposure times on the cameras (to reduce motion blur) and smaller apertures on the lenses (to improve depth-of-field), both of which otherwise result in much darker images.  At extreme temperatures, the measurements must also be performed using ultraviolet (UV) lights, cameras, lenses, and filters to mitigate the light emitted by objects when they glow white-hot.

In this research, you will identify and then cannibalize a tanning bed to use as a UV light source.  We will then implement the light source to record deformation during extreme temperature testing.
Images of a specimen surface under various temperatures and lighting. The UV images remain visible at temperatures well above which the others have saturated.
2. Micromechanics-Informed Models of Knitted Metamaterials
Woven fibers are a mainstay of fiber composites, but compared to woven fabrics, knits are considerably stretchier and can absorb higher impact. Knits get these properties from the ordered combinations of stitches (knits and purls) from which they are patterned. Similarly, the microstructures of metallic alloys are composed of ordered lattices. Such alloys can be strengthened to improve mechanical performance by introducing defects into the lattice that act as obstacles against deformation.  Analogous "defects" can be found in knitting: for example, slipped stitches may be comparable to vacancies in a lattice; increases or decreases may be comparable to edge dislocations; and seams may be comparable to grain or phase boundaries.  By manipulating stitch patterns, composites manufacturers can potentially tailor new emergent behaviors to achieve more favorable mechanical performance.

In this project, you will first assemble a test fixture to apply force to a swatch of knitted fabric.  We will then use camera-based deformation measurements to assess how load distributes through the fabric, and compare how the distributions change in the presence of defects. The results of this work will be published in a series of journal articles in peer-reviewed scientific literature.
Select "lattice structures" observed in knitting. Left to right: (i) stockinette stitch (knit side); (ii) stockinette stitch (purl side); (iii) 1-1 ribbing; (iv) garter stitch; (v) seed stitch.
Select "defects" observed in knitting. Left to right: (i) slipped stitch; (ii) an increase followed immediately by a decrease; (iii) a purl substituted for a knit; (iv) additional rows via short-row shaping; (v) an additional column via an increase followed a few rows later by a decrease; (vi) a seam between two knit panels; and (vii) a "grain boundary" between two mismatched regions of ribbing.

To Apply

Please send a resume and a brief statement of your research and career interests to ryan.berke@usu.edu.

If hired, you will also be asked to formally apply on Aggie Handshake to job #900293: Undergraduate Researcher (Experimental Solid Mechanics).