SEDL / STP / STP787-EB / STP28470S

Through-the-Thickness Tensile Strength of Fiber-Reinforced Plastics

Mao, TH
Research Associate, Institute of Mechanics, Chinese Academy of Sciences, Peking,

Owen, MJ
Professor of Reinforced Plastics, University of Nottingham,

Pages: 14    Published: Jan 1982

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Abstract

The through-the-thickness tensile strength of fiber-reinforced plastics is difficult to measure, but for some purposes it is a significant design property. This property appears to be critically dependent on the test method and specimen preparation. The authors have examined the possibility of producing tensile failures in a disk subjected to diametral compression, a method well known in the field of testing of brittle isotropic materials.

In the isotropic case there is a uniform tensile stress distribution perpendicular to the diameter which is the axis of compression. Slices of round pultruded rod are transversely isotropic, and the method of test gives convenient and consistent results.

Results are also presented for the through-the-thickness strength of laminated materials. The disks were prepared by turning a cylindrical bar from a piece of thick laminate. Stress distributions have been analyzed by finite element analysis and compared with published theory. Both methods have been compared with strain gage results obtained from orthotropic disks. The finite element results agree quite well with published theory, but there is considerable scatter in the strain gage results. Experimental results for the strength of disk samples are consistent and compare well with other methods. The disk method also appears to be economical.