The aim of the research is to develop a diagnostic method for non-destructive damage detection and imaging in additive manufactured (AM) composite elements based on ultrasonic wave propagation. The phenomenon of elastic wave interaction with structural defects will be analyzed by advanced signal processing tools and finite element method (FEM) simulations. The motivation of the research results from the current trend to arrange innovative, effective, and low time cost diagnostic methods. The following hypothesis can be formulated that the measurement of propagating ultrasonic waves supported with advanced data treatment has the capability to detect and visualize geometric and material discontinuities in composite AM elements. The novelty of the research consists in: (i) the development of two-stage guided wave-based algorithm for non-destructive diagnostics of composite AM elements, (ii) preparation of authorial approaches for the determination of optimal calculation parameters for the processing of wave signals based on wave energy indicators, and (iii) the use of FEM simulations of wave propagation to support the experimental investigations. The project consists of a few corresponding tasks. As the initial step, static tests aimed at the identification of static material properties of intact composite AM elements will be conducted. Measurements of ultrasonic wave signals will be used to determine the dynamic elastic constants based on dispersion curves. Different degrees of porosity such as directions of fabrication will be considered in samples made of various filaments. A main part of the measurements will be focused on the evaluation of structural damage in plate elements. A two-step algorithm will be developed, including damage identification, providing information about the presence of a defect, and damage imaging enabling detailed defect visualization. The signals will be processed using weighted root mean square (WRMS) calculations. The optimal values of the calculation parameters will be determined. Additionally, modelling of elastic wave propagation in AM elements will be conducted using FEM. The signals collected during the numerical simulation will be processed analogically to the experimental data. The project is significant for the GUT, because it will allow purchasing a valuable equipment for performing of scientific research which will have a considerable impact on the state of knowledge concerning NDT diagnostics of AM elements.