5.1 A constituent content of a composite material must be known in order to analytically model the material properties (mechanical, physical, thermal, or electrical) of the composite which are affected by the reinforcement or matrix. Also, knowledge of the constituent content is required for evaluation of the quality of a fabricated material and the processes used during fabrication.

5.2 The void volume of a composite material may significantly affect some of its mechanical properties. Higher void volumes usually mean lower fatigue resistance, greater susceptibility to moisture penetration and weathering, and increased variation or scatter in strength properties. Knowledge of the void volume of a composite material is desirable as an indication of the quality of a composite.

5.3 Reinforcement content may be used to normalize mechanical properties affected by amount of reinforcement in the coupon.