Negative Poisson’s Ratio

Laminate Design

Marley Miller, George Rodriguez, Alex

Powers, and Garrett Reed

Negative Poisson’s Ratio Laminate Design Purpose: To develop a carbon fiber and epoxy laminate which exhibits a

negative Poisson’s ratio in tensile testing.

Theory: Negative Poisson’s ratios occur when a12 and a11 terms have the same

sign - this results in εx and εy having the same sign.

Method: Use CLT code to loop through a [0/i/j]s AS4/3501-6 laminate and find

the greatest negative Poisson’s ratio. Obtained -0.098 Poisson’s ratio with

[0/17/72]s laminate.

Negative Poisson’s Ratio Laminate Test Results Results:

➢ [02/172/722]s Panex P35 laminate

➢ Tested 2 samples, 1 to failure.

Strain-to-failure specimen

measured data shown in graph.

➢ Load on specimen plotted against

εx and εy strains.

➢ Magnitude of νxy increased as

normalized εx increased.

➢ νxy ranges from -0.1 to -0.15, with

the average νxy equal to -0.132.

y = 0.1508x - 35.994

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εy

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εx (με)