03/27/2023
By Danielle Fretwell

The Francis College of Engineering, Department of Mechanical Engineering, invites you to attend a Master’s thesis defense by Marinos Blanas on “Biaxial and Dynamic Characterization of Fabrics."

Candidate Name: Marinos Blanas
Degree : Master’s
Defense Date: Friday, April 7, 2023
Time : noon to 2 p.m.
Location: Ball Hall 323, North Campus


Committee Members

  • Advisor Alireza Amirkhizi, Associate Professor, Mechanical Engineering, University of Massachusetts Lowell
  • James Sherwood, Ph.D, Dean of College of Engineering, University of Massachusetts Lowell
  • Kari White, Assistant Teaching Professor, Mechanical Engineering, University of Massachusetts Lowell

Abstract:

Material characterization of canopy fabric will aid in the advancement and design of aerodynamic decelerators. Traditional material characterization for such fabrics is conducted mostly in uniaxial configuration and to a lesser extent, via cruciform biaxial testing. While these tests provide crucial information, further characterization is needed associated with testing in application-relevant conditions. Cruciform biaxial samples introduce stress concentrations, and the grip effects do not allow for perfect biaxial extension of the material. New biaxial setups that utilize point gripping and scissor link systems to expand the material within the grips allow for a better biaxial stress test, which closely represents the end use of the material. In this thesis, two biaxial systems will be introduced: a constant width system and a large-scale scissor link biaxial system. Operation and challenges of each system are presented, and examples results are shown to demonstrate the benefits and needs of such testing. Additionally, most testing conducted on canopy material is performed in the quasistatic strain rate zone of <1/s. However, the most crucial point of use in a decelerator is the deployment, in which strain rates exceed the quasistatic zone and enter into an intermediate strain rate, estimated to be around 10-100/s. Traditional material testing systems are incapable of achieving these high strain rates for large enough deformation suitable for fabrics, and thus a dynamic system has been created and improved upon for further characterization of canopy fabrics under intermediate strain rates. Data acquisition and analysis for such a test is discussed in detail. An FEA model has been generated to further analyze and improve the performance of this setup, e.g. via identifying methods to eliminate unwanted oscillation. Using experimental data for more accurate descriptions of the material in simulations will provide accurate results and further expand FEA modeling limits. Ultimately, an accurate material description is desired for FEA analysis that attempts to represent the unique material response of canopy fabrics such as those used in civilian, military, and space exploration applications, including history dependence, anisotropy, and energy dissipation.