The principal in‐plane compressive strengths of pultruded E‐glass fiber‐reinforced flat sheet material were measured using a nonstandard test procedure. Over 100 specimens, each having nominal dimensions of 7.0 by 2.0 by 0.635 cm, were tested with the longest side either parallel or perpendicular to the pull direction in the pultrusion process. The experimental test procedure and the test rig for thick (up to 1.6‐cm) specimens are described. The strength data are used in a comparison between statistical methods that may be used to determine design allowables for the purpose of structural design. These strength allowables are compared with the corresponding values (in accordance with standard ASTM D695‐90) provided by the manufacturer. Results show that compression strengths of the material have coefficients of variation of 9% in a parallel direction and 6% perpendicular to this. This large variation indicates that the ASTM D695‐90 specimen batches of five are too low. Design allowable strengths determined from the log‐normal distribution are 25% and 12% higher than manufacturer's allowables.
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J. Toby Mottram (1994) studied this question.