Experimental determination of the evolution of internal stresses in a composite material: Case of a circular bilayered laminate glass‐resin

Abstract A nondestructive method is proposed to analyze the internal stresses of a circular bilayered laminate glassresin. It is based on the measurement by optical interferometry of small deformations of the laminate under the influence of temperature, time, or applied mechanical stresses of known value. For example, the stress induced by the curing of the thermosetting resin layer is determined and the postcuring relaxation of the stress is measured. Other possibilities or improvements of the method are indicated: The determination of the Young's modulus of the thermosetting resin as a function of time, the determination of the work‐hardening rate, and the determination of the ultimate properties of the laminate are just a few of them.