FLEXURE THEORY OF STRUCTURAL FIBERGLASS BEAMS,
Abstract:
Investigations of the linear stress-strain relation in fiberglass beams particularly in cold-cured ones revealed their special features a high sensitivity to shear, a difference between the elasticity moduli in tension and compression, and the linearity of the stress-strain diagram up to failure. The theory of static flexure of fiberglass beams is presented with the effects of the shearing strain and different elastic moduli taken into account. The hypothesis of plane cross sections and the assumption on the smallness of pressure between fibers are used in deriving formulas for normal and tangential stresses. The effect of the shear force on the angle of slope of the elastic curve is evaluated, and a differential equation of flexure is derived which reflects the effects of shear and of the bimodularity of the material. The integration of this equation by the method of initial parameters is explained on an example of an I-beam under a transverse force combined with a concentrated moment. Design formulas for flexural stress analysis are obtained.