Mechanical Engineering MS Thesis Defense by Mr. Austin John Taylor
When: Monday,
January 11, 2021
11:00 AM
-
12:30 PM
Where: > See description for location
Description: Mechanical Engineering MS Thesis Defense by Mr. Austin John Taylor
DATE:
January 11, 2021
TIME:
11:00 a.m. - 12:30 p.m.
LOCATION:
Zoom Conference Call Meeting ID: 934 5195 2672 (Passcode: 645019)
TOPIC:
Electro-Mixed Mode Fracture Characterization of Natural Fiber Reinforced Composites, & Development of Split Tensile Hopkinson Pressure Bar
ABSTRACT:
Piezo-resistance based damage sensing of Flax/epoxy composites under quasi-static mixed-mode fracture loading conditions was conducted. Three-dimensional electrically conductive network was developed in these composites by embedding multi-wall carbon nanotubes (MWCNTs) and micro carbon fibers (CF). Alkali and silane treatments were performed to make flax plain-weave fabrics hydrophobic for improved service life. Novel four circumferential probe method was employed along with high resolution Kiethley
instrumentation for electrical measurements. Mixed-mode open notch flexure (MONF) specimen configuration was employed to determine the fracture initiation energy and electrical resistance associated with both crack initiation and propagation. The effect of two CF lengths (150μm and 350μm) at four CF fiber areal densities (500:500:2000 fibers/mm2) on electrical and mixed mode fracture response was investigated. For all configurations, mixed-mode fracture toughness increased compared to control specimens without CF. All 150μm CF configurations tended to exhibit greater electrical response than 350μm CF configurations.
A modified innovative split tensile Hopkinson pressure bar (SHTB) was designed using AutoDesk Inventor Professional, machined entirely with UMassD machine shop, and validated with 6061 aluminum specimens. This design uses a U-shaped striker bar as a projectile and offers several advantages over classical STHB designs such as 1.) longer stress pulse duration with respect to U-shaped striker bar length, 2.) ability for a wide range of pulse shaping methods, 3.) easy access to loading bar and striker bar, 4.) ability
to fire with low air pressures, and 5.) efficient manual reloading.
ADVISOR:
Dr. Vijaya Chalivendra,
Professor & Graduate Program Director, Department of Mechanical Engineering, UMass Dartmouth
COMMITTEE MEMBERS:
-Dr. Yong Kim, Chancellor Professor of Bioengineering, UMass Dartmouth
-Dr. Alireza Asadpoure, Assistant Professor of Civil & Environmental Engineering, UMass Dartmouth
Open to the public. All MNE students are encouraged to attend.
For more information, please contact Dr. Vijaya Chalivendra (vchalivendra@umassd.edu, 508-910-6572).
Thank you,
Sue Cunha
scunha@umassd.edu
DATE:
January 11, 2021
TIME:
11:00 a.m. - 12:30 p.m.
LOCATION:
Zoom Conference Call Meeting ID: 934 5195 2672 (Passcode: 645019)
TOPIC:
Electro-Mixed Mode Fracture Characterization of Natural Fiber Reinforced Composites, & Development of Split Tensile Hopkinson Pressure Bar
ABSTRACT:
Piezo-resistance based damage sensing of Flax/epoxy composites under quasi-static mixed-mode fracture loading conditions was conducted. Three-dimensional electrically conductive network was developed in these composites by embedding multi-wall carbon nanotubes (MWCNTs) and micro carbon fibers (CF). Alkali and silane treatments were performed to make flax plain-weave fabrics hydrophobic for improved service life. Novel four circumferential probe method was employed along with high resolution Kiethley
instrumentation for electrical measurements. Mixed-mode open notch flexure (MONF) specimen configuration was employed to determine the fracture initiation energy and electrical resistance associated with both crack initiation and propagation. The effect of two CF lengths (150μm and 350μm) at four CF fiber areal densities (500:500:2000 fibers/mm2) on electrical and mixed mode fracture response was investigated. For all configurations, mixed-mode fracture toughness increased compared to control specimens without CF. All 150μm CF configurations tended to exhibit greater electrical response than 350μm CF configurations.
A modified innovative split tensile Hopkinson pressure bar (SHTB) was designed using AutoDesk Inventor Professional, machined entirely with UMassD machine shop, and validated with 6061 aluminum specimens. This design uses a U-shaped striker bar as a projectile and offers several advantages over classical STHB designs such as 1.) longer stress pulse duration with respect to U-shaped striker bar length, 2.) ability for a wide range of pulse shaping methods, 3.) easy access to loading bar and striker bar, 4.) ability
to fire with low air pressures, and 5.) efficient manual reloading.
ADVISOR:
Dr. Vijaya Chalivendra,
Professor & Graduate Program Director, Department of Mechanical Engineering, UMass Dartmouth
COMMITTEE MEMBERS:
-Dr. Yong Kim, Chancellor Professor of Bioengineering, UMass Dartmouth
-Dr. Alireza Asadpoure, Assistant Professor of Civil & Environmental Engineering, UMass Dartmouth
Open to the public. All MNE students are encouraged to attend.
For more information, please contact Dr. Vijaya Chalivendra (vchalivendra@umassd.edu, 508-910-6572).
Thank you,
Sue Cunha
scunha@umassd.edu
Topical Areas: Faculty, General Public, Staff and Administrators, Students, Students, Graduate, Students, Undergraduate, University Community, Bioengineering, Civil and Environmental Engineering, College of Engineering, Mechanical Engineering, Lectures and Seminars