Mechanical characterization of the static and fatigue compressive properties of a new glass/flax/epoxy composite material using digital image correlation, thermographic stress analysis, and conventional mechanical testing

Abstract

This study characterized the static and fatigue compressive properties of a new hybrid composite material made of synthetic and natural fibers with an epoxy matrix. The glass/flax/epoxy composite material was manufactured as a “sandwich structure” with a Type A configuration (i.e. [0G2/0F12/0G2] using unidirectional glass (G) and flax (F) fibers) and Type B configuration (i.e. [0G2/±45F12/0G2] using unidirectional glass (G) and ±45° oblique flax (F) fibers). Digital image correlation was used to obtain the static properties of compressive elastic modulus (Type A, 24.4 GPa; Type B, 14.7 GPa), ultimate compressive strength (Type A, 261.7 MPa; Type B, 231.9 MPa), and Poisson's ratio (Type A, 0.37; Type B, 0.58). Thermographic stress analysis was used to measure a high cycle fatigue strength (HCFS) of 53% (Type A and B) of ultimate compressive strength. Conventional experimental fatigue methods (i.e. stress vs. number of cycles to failure) yielded a HCFS of 56–61% (Type A) and 51–56% (Type B), as well as almost constant dynamic compressive moduli of 15 GPa (Type A) and 10 GPa (Type B) over the entire loading regime. This new composite material may have various potential applications, such as aerospace, automotive, biomechanics, sports, etc., based on the compressive properties measured.