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Abstract

The dimensional change of some composite materials induced by ambient air pressure change was discovered and dubbed pneumatic strain in 2000. This pneumatic behavior closely resembles hygric behavior, and pneumatic strain is proportional to the ambient air pressure change by the coefficients of the pneumatic expansion. A method termed the suspension method was employed in this work to characterize the pneumatic behavior of unidirectional T700 carbon/epoxy composite laminate and other materials, such as Kevlar 49 fiber, aluminum plate, aluminum foil, paper, celluloid sheet and pure epoxy plate. Longitudinal and transverse pneumatic strains of T700 carbon/epoxy composite lamina induced by 1 atm air pressure change were measured. The results also indicated that Kevlar 49 fiber and aluminum have no pneumatic behavior, while paper, celluloid film and epoxy plate do have pneumatic behavior. Two major contributions of this work are verifying the effectiveness of suspension method for the pneumatic characterizing and discovering more materials having pneumatic behavior.

Keywords

pneumatic strain

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References

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Pneumatic Characterization of Composite Materials

Abstract

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