"A simple analysis was made of models representing possible conditions in glass-fiber-reinforced plastics. The analysis shows that for strains imposed in a direction transverse to a set of windings, the ratio of tensile strain in the resin to the average measured strain can approach E sub g/E sub r as the resin content is decreased to the limit for filling the interstices, where E sub g and E sub r are Young's modulus for glass and resin, respectively. For shear strains the maximum strain concentration in the resin can beAS HIGH AS 0.7 G sub g/G sub r, where G sub g and G sub r are the shear moduli of glass and resin. Measured average strains in service are as high as two percent. The strain in the resin in a direction transverse to the fibers is correspondingly about 40%. No resin in ordinary structural use can stand this strain without cracking." -- Abstract