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Studying the Physical Properties and Auxetic Behavior of 3D-printed Fasteners

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Conference

2012 ASEE Annual Conference & Exposition

Location

San Antonio, Texas

Publication Date

June 10, 2012

Start Date

June 10, 2012

End Date

June 13, 2012

ISSN

2153-5965

Conference Session

NSF Grantees' Poster Session

Tagged Topic

NSF Grantees Poster Session

Page Count

12

Page Numbers

25.1204.1 - 25.1204.12

DOI

10.18260/1-2--21961

Permanent URL

https://strategy.asee.org/21961

Download Count

266

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Paper Authors

biography

Larry D. Peel P.E. Texas A&M University, Kingsville

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Larry Peel received an A.S. from Snow College, in engineering, a B.S. in mechanical engineering from Utah State University, an M.S. in engineering mechanics from Virginia Tech, and a Ph.D. in mechanical engineering from Brigham Young University. He has taught in the area of solid mechanics, materials science, design, and manufacturing at Texas A&M University, Kingsville for the past 11 years. His research is in the area of traditional and flexible composites, morphing structures, auxetic systems, and additive manufacturing.

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Mohamed Abdelrahman Texas A&M University, Kingsville

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Abstract

Studying the Physical Properties and Auxetic Behavior of 3D-printed FastenersAbstract This paper reports the importance of fasteners and their related characteristics for specificpurposes. Fasteners are used in every industry, and in virtually every component. The idealfastener would be relatively easy to insert, but take much more force to remove. Such fastenerswould not require nuts screwed onto bolts, or other retaining rings. The current work attempts todevelop a simple fastener with a low Insertion Force / Removal Force ratio by exploiting auxeticbehavior. Auxetic materials or negative Poisson’s Ratio materials have properties that arecounter-intuitive. A rubber band, for example, becomes thinner in width when pulled atlengthwise Auxetic materials, however, will expand in width, when pulled along their length, orwhen compressed along their length, will also contract in width. Hence, normal materials havepositive Poisson’s Ratios while auxetic materials are revealed to have negative Poisson’s Ratio.By exploiting the theory behind negative Poisson’s Ratios, a suitably designed fastener canexhibit auxetic behavior. Specifically, a properly designed fastener will decrease in diameterwhen compressed through a hole and increase in diameter when pulled away from the hole.Using previously developed theory, several cylindrical fasteners were fabricated with nominaldiameters of 0.7 inches, 2 inches long, and double helix angles of (30°/45°) and (30°/60°).Aluminum sleeves were fabricated with holes of slightly different diameters, such that when thefasteners were inserted they must contract 1% to 2%. Insertion/Removal force ratios as low as18% were observed. The project is considered a success and could lead to patents and be a boonto the fastener industry. A learning module based on the legacy cycle concept is developed that challenges thestudents to think through the processes and steps required to design fasteners for specificindustry uses. A 3-D printer will allow experimentation with the best class design. This learningmodule will be introduced into a high school mathematics class during the 2011-2012 schoolyear. Assessment of the students’ performance will be carried out and reported.

Peel, L. D., & Abdelrahman, M. (2012, June), Studying the Physical Properties and Auxetic Behavior of 3D-printed Fasteners Paper presented at 2012 ASEE Annual Conference & Exposition, San Antonio, Texas. 10.18260/1-2--21961

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