NUMERICAL MODELING OF ULTRASONIC ASSESSMENT IN ADDITIVELY MANUFACTURED COMPOSITE MATERIALS

Additive manufacturing (AM) is a layer-by-layer process of building the parts that allows to create objects with different shapes and geometries. AM is especially suited for fabrication of composite materials. The mechanical properties of the composite parts depend on fiber density, distribution and orientation. However, variability of printing parameters leads to uncertainties in the composite properties or initiation of damage. In this contribution, we demonstrate potential of ultrasonic techniques for damage detection and assessment of materials properties through experimental testing and numerical modeling. Numerical models were validated with laboratory data and enable further guidelines for experimental testing. A set of nylon composite samples were fabricated via Markforged Mark Two™ composite 3D printer with different layer thicknesses. The samples include solid blocks and blocks with simulated cracks. This enables exploration of the influence of the process parameters on the mechanical properties of the additively manufactured nylon cubes. Elastic properties were calculated for all tested samples in three directions using the ultrasonic technique. Crack detection was conducted for damaged specimens. Numerical model for wave propagation within the nylon specimens was developed and validated using experimental data. Also, numerical simulations for wave propagation within the additively manufactured Onyx™ composite (reinforced with carbon fiber) specimens were conducted.