Mechanical and self-monitoring behaviors of 3D printing smart continuous carbon fiber-thermoplastic lattice truss sandwich structure

Abstract

A novel method for manufacturing smart continuous carbon fiber (CCF)-thermoplastic lattice truss sandwich structures (LTSSs) is presented in this study, combining the conventional fused deposition modeling (FDM) technique and the free-hanging three-dimensional (3D) printing technique. Self-monitoring of LTSSs is achieved by measuring the fractional change in electrical resistance (ΔR/R0) of the LTSSs. Monotonic out-of-plane compression test and cyclic loading test are carried out to investigate the mechanical properties, failure modes and self-monitoring capacity of the printed LTSSs. Results show that the LTSSs with truss inclination angle of 50° have an optimal compressive strength with a value of 1.236 ± 0.063 MPa, while LTSSs with truss inclination angle of 60° have an optimal compressive modulus with a value of 17.134 ± 1.92 MPa. A bilinear relationship between ΔR/R0 and stain during the whole loading process is observed, indicating that ΔR/R0 can be used to sense the compressive strain, stress and predict the damage. Matrix fracture, Euler buckling, as well as carbon fiber debonding are found within damaged LTSSs using X-ray tomography. Generally, the results indicate that the LTSSs have superior mechanical properties and self-monitoring capacity, which can help to promote the smart LTSSs applications in many engineering fields, such as aerospace and automotive industry.