Revealing the Bulk Mechanical Property Threshold for Thin Metallic Samples to Support a Desktop-Scale Stress-Strain Apparatus

Sofia Ahmed; Matthew J. Traum

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Conference: 2023 ASEE Annual Conference & Exposition
Location: Baltimore , Maryland
Publication Date: June 25, 2023
Start Date: June 25, 2023
End Date: June 28, 2023
Conference Session: Materials Division (MATS) Technical Session 2
Tagged Division: Materials Division (MATS)
Page Count: 13
DOI: 10.18260/1-2--44137
Permanent URL: https://peer.asee.org/44137
Download Count: 108

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Paper Authors

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Sofia Ahmed University of Florida

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Sofia Ahmed is an Undergraduate Aerospace Engineering student at the University of Florida. Her research focuses on experimental mechanics and she has other research interests in aerospace structures and materials. She also has academic interests in high powered rocketry through leading in University of Florida's rocket design team.

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biography

Matthew J. Traum orcid.org/0000-0002-1105-0439

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Dr. Matthew J. Traum is a Senior Lecturer and Associate Instructional Professor in the Department of Mechanical and Aerospace Engineering at the University of Florida. He is an experienced educator, administrator, fund raiser, and researcher. As of 2022 he has co-authored a textbook, a book chapter, 20 peer-reviewed research and pedagogical journal papers, 53 refereed research and pedagogical conference articles, and given 4 invited presentations. As PI or Co-PI, Traum has attracted over $898 K in funding for research and education. Prior to UF, Dr. Traum was founding CEO of Engineer Inc., an education technology social enterprise and leader in STEM instructional lab kits.

Previously, Dr. Traum was an Associate Professor and Director of Engineering Programs at Philadelphia University. He also served on the Milwaukee School of Engineering (MSOE) faculty as well as co-founding the Mechanical and Energy Engineering Department at the University of North Texas – Denton.

Traum received Ph.D. and M.S. degrees in mechanical engineering from MIT, and he holds two B.S. from the UC Irvine in mechanical and aerospace engineering.

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Abstract

The global pandemic caused higher education materials laboratory instructors to think differently and become adaptable to sudden changes; for example, the need for classes and labs to abruptly switch to online learning. The study of material properties is important in mechanical engineering classes including Mechanics of Materials, Manufacturing, and Design. Hands-on learning is a key factor for mechanical engineering students to thoroughly understand material properties and their impact on physical behaviors, practical applications, and design principles. This raises the question of whether a stress-strain measurement apparatus can be designed more cost-effectively and on a smaller scale than brick-and-mortar scale instruments found in conventional teaching labs. Among the benefits of a small, inexpensive device is enabling students to 1) perform stress-strain experiments themselves, 2) better understand equipment and procedures, and 3) observe and measure properties in each material being studied. An inexpensive bench top stress-strain apparatus would also be useful in classes where material properties are important to know via direct measurement but this knowledge is tangential to the class’s core curriculum – for example, Capstone senior design. Previous work has revealed the existence of a stress-strain sample thickness threshold below which tests return material properties (e.g., Young’s Modulus) inconsistent with measured bulk properties. This empirical threshold must be identified to determine minimum sample thicknesses for a tabletop take-home stress-strain measurement apparatus that returns results consistent with tabulated bulk material properties. This sample thickness governs how much force the apparatus must produce to drive parts to failure. Hence, it is the central design parameter for a tabletop stress-strain tester. This paper’s goal is to show a process to determine what thickness samples undergoing stress-stain tensile testing produce material properties consistent with bulk materials for three common engineering metals (aluminum, brass, and steel).

The sample “thinness” issue was systematically studied to determine how tensile properties are affected by part thickness and to reveal the point at which experimental tensile test results produced using a benchtop stress-strain tensile tester agree with tabulated values. Waterjet cut specimens of identical shape but with increasing thickness were tensile tested to failure on an Instron 5967 Universal Testing Machine. Mechanical properties and the way properties vary with sample thickness and metal type were then studied to find the thickness threshold where bulk material properties emerge.

Citation
Format

Ahmed, S., & Traum, M. J. (2023, June), Revealing the Bulk Mechanical Property Threshold for Thin Metallic Samples to Support a Desktop-Scale Stress-Strain Apparatus Paper presented at 2023 ASEE Annual Conference & Exposition, Baltimore , Maryland. 10.18260/1-2--44137

TY  - CPAPER
AB  - The global pandemic caused higher education materials laboratory instructors to think differently and become adaptable to sudden changes; for example, the need for classes and labs to abruptly switch to online learning. The study of material properties is important in mechanical engineering classes including Mechanics of Materials, Manufacturing, and Design. Hands-on learning is a key factor for mechanical engineering students to thoroughly understand material properties and their impact on physical behaviors, practical applications, and design principles. This raises the question of whether a stress-strain measurement apparatus can be designed more cost-effectively and on a smaller scale than brick-and-mortar scale instruments found in conventional teaching labs. Among the benefits of a small, inexpensive device is enabling students to 1) perform stress-strain experiments themselves, 2) better understand equipment and procedures, and 3) observe and measure properties in each material being studied. An inexpensive bench top stress-strain apparatus would also be useful in classes where material properties are important to know via direct measurement but this knowledge is tangential to the class’s core curriculum – for example, Capstone senior design. Previous work has revealed the existence of a stress-strain sample thickness threshold below which tests return material properties (e.g., Young’s Modulus) inconsistent with measured bulk properties. This empirical threshold must be identified to determine minimum sample thicknesses for a tabletop take-home stress-strain measurement apparatus that returns results consistent with tabulated bulk material properties. This sample thickness governs how much force the apparatus must produce to drive parts to failure. Hence, it is the central design parameter for a tabletop stress-strain tester. This paper’s goal is to show a process to determine what thickness samples undergoing stress-stain tensile testing produce material properties consistent with bulk materials for three common engineering metals (aluminum, brass, and steel).  

The sample “thinness” issue was systematically studied to determine how tensile properties are affected by part thickness and to reveal the point at which experimental tensile test results produced using a benchtop stress-strain tensile tester agree with tabulated values. Waterjet cut specimens of identical shape but with increasing thickness were tensile tested to failure on an Instron 5967 Universal Testing Machine. Mechanical properties and the way properties vary with sample thickness and metal type were then studied to find the thickness threshold where bulk material properties emerge. 
AU  - Sofia Ahmed
AU  - Matthew J. Traum
CY  - Baltimore , Maryland
DA  - 2023/06/25
PB  - ASEE Conferences
TI  - Revealing the Bulk Mechanical Property Threshold for Thin Metallic Samples to Support a Desktop-Scale Stress-Strain Apparatus 
UR  - https://peer.asee.org/44137
DO  - 10.18260/1-2--44137
ER  -