Laminate composites are increasingly being used in the transport sector due to their lightweight structures, resulting in fuel savings. However, waste is generated in the form of post-industrial or post-consumer goods that end up in landfill or incineration. One way to minimize the impact of these disposals is through recycling or reuse, but introducing reused fibers with reduced length has been a challenge to keep the mechanical properties. In this context, this research aims to evaluate the influence of the fabric (satin weave) length on the tensile properties of discontinuous laminate and investigate the failure process of such composites manufactured with carbon fabric waste generated at the cutting process. For this purpose, two types of laminates were manufactured, each comprised of five plies (i) three continuous plies and two discontinuous plies; and (ii) one continuous ply and four discontinuous plies with varied fiber length. The laminates were tested by tensile loading, and the strain field was monitored by a non-contact technique called digital image correlation (DIC), which allowed the investigation of the local strain variation due to the interrupted section. It was possible to observe a sharp stress range in which the joint failure was evidenced by strain field variation over the joint. For both laminates, it was possible to depict the events that constrain the tensile strength of the discontinuous laminates, which is severe in laminates with surface discontinuity, and it shows to be advantageous to employ a continuous ply on both surfaces, improving loading transfer between plies. Highlights: Environmental problem related to carbon fiber waste from the cutting process. Take advantage of using small pieces of carbon fiber fabric in laminate architecture. Investigation of the influence of fabric disposition and fabric length on in-plane mechanical properties. Analysis of failure events using strain field measurements via DIC.

After half a century of developing fatigue delamination prediction models, where accuracy seems more important than physical understanding, this research aims to merge both aspects. To that aim, strain energy release (SER) within the fatigue load cycle was studied using acoustic emission. The correlation between the measured strain energy release and the acoustic emission energy was formulated through a conversion factor to convert one into the other. The strain energy release distribution within the loading cycle indicated that different damage mechanisms are activated in different increments of the load cycle associated with different energy thresholds. The presence of multiple energy thresholds indicated that the application of different loading cycles results in distinct resistances to damage propagation (dU/dA) depending on which energy threshold is crossed.