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Simple Lab Exercises Using Composite Materials

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Conference

2020 ASEE Virtual Annual Conference Content Access

Location

Virtual On line

Publication Date

June 22, 2020

Start Date

June 22, 2020

End Date

June 26, 2021

Conference Session

Learning Mechanics Through Experimentation

Tagged Division

Mechanics

Page Count

11

DOI

10.18260/1-2--35191

Permanent URL

https://peer.asee.org/35191

Download Count

1177

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Paper Authors

biography

William E. Howard East Carolina University

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William E (Ed) Howard is an Associate Professor in the Department of Engineering at East Carolina University. He was previously a faculty member at Milwaukee School of Engineering, following industrial experience as a design and project engineer with Thiokol Corporation, Spaulding Composites Company, and Sta-Rite Industries.

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biography

Colleen Janeiro East Carolina University

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Dr. Colleen Janeiro teaches engineering fundamentals such as Introduction to Engineering, Materials and Processes, and Mechanics of Materials. Her teaching interests include development of solid communication skills and enhancing laboratory skills.

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Abstract

Many engineering programs include a course in composite materials, usually as an elective course at the advanced undergraduate or graduate level. These courses typically focus on the mechanics of fiber-reinforced composites. At (university), the elective composites course also contains some laboratory exercises that give the students a hands-on experience in the layup and testing of carbon-epoxy specimens. In this paper, the authors share lessons learned in making and testing these specimens for exercises that can be included either in a composite materials course or to supplement an introductory materials science or mechanics of materials course. Fiber-reinforced composites can be made by wet layup, in which liquid resin is mixed and applied to dry fabric, or with materials that are preimpregnated with resin (prepreg). Wet layup is messy and controlling the amount of resin in the composite is difficult. The main drawbacks to using prepregs have been cost, availability of small quantities, and facilities, as aerospace-quality parts are cured in an autoclave or hot press. Over the past few years, lower-cost carbon-epoxy prepregs that can be cured without an autoclave have become available. The authors share details regarding material sources, low-cost tools, and cutting plans that minimize waste in the creation of the specimens. For a composite material course, laboratory exercises include tensile tests for a variety of fiber orientations as well as bending tests. Among the concepts reinforced with these exercises include strength and stiffness variations with orientation angle, progressive failure (resin cracking prior to fiber breaks), the wide range of Poisson’s ratios possible (including negative values and values greater than one), free edge stresses, and thermal property mismatches leading to residual stresses and/or specimen warping. For an introductory materials course, a tensile test with all fibers in the axial direction is used to demonstrate the high specific strength (strength divided by density) of carbon-epoxy composites. In the paper, the authors show results of surveys of students in the composites course asking how the laboratory exercises support the lecture content. Results of a survey of students in the introductory materials class ask whether the laboratory experience stimulates students’ interest in further study of composite materials.

Howard, W. E., & Janeiro, C. (2020, June), Simple Lab Exercises Using Composite Materials Paper presented at 2020 ASEE Virtual Annual Conference Content Access, Virtual On line . 10.18260/1-2--35191

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