The mass application of FDM technology is slowed down due to the difficulty of selecting 3D printing parameters in order to manufacture an article with the required characteristics. This paper reports a study into the impact of 3D printing parameters (temperature, print speed, layer height) on mechanical parameters (strength, elasticity module), as well as on the accuracy of printing and roughness of the surface of a specimen based on thermoplastic (PLA plastic). Several batches of specimens were fabricated for this study in accordance with ASTM D638 and ASTM D695, which were tested for tension, geometric accuracy, and roughness. Based on the experimental data, regression analysis was carried out and the functional dependences of the strength, elasticity module, printing precision, roughness of a surface on 3D printing parameters (temperature, speed, thickness of the layer) were constructed. In addition, the derived mathematical model underlying a method of non-linear programming has established such printing parameters that could provide for the required properties of a structure. The analytical dependences reported in the current work demonstrate a high enough determination factor in the examined range of parameters. Using functional dependences during the design phase makes it possible to assess the feasibility of its manufacture with the required properties, reduce the time to work out the process of printing it, and give recommendations on the technological parameters of 3D printing. The recommendations from this study could be used to make PLA-plastic articles for various purposes with the required properties

The widespread use of carbon fiber-reinforced polymers (CFRPs) in unmanned aerial vehicle (UAV) structures increases the importance of understanding low-velocity impact damage, which is often barely visible yet can significantly reduce residual strength and lead to structural failure during service. This study investigates the impact behavior and healing capability of a multidirectional CFRP laminate with a thermally activated self-healing matrix (CompPair HealTech^®). Laminates with a thickness of 1.45 mm were subjected to drop-weight impacts at 5 J and 10 J. After impact, specimens were thermally activated at 150 °C for 30 min and re-impacted under identical conditions. Impact response was evaluated from force, energy, and displacement histories, while residual properties were assessed by compression after impact (CAI) testing and X-ray phase-contrast imaging (XPCI). At 5 J, the re-impact response was nearly identical to the initial impact, with a peak force of approximately 2.1 kN, indicating largely reversible damage. At 10 J, the peak force decreased from ~3.0 kN to ~2.6 kN and displacement increased, reflecting incomplete stiffness recovery caused by more severe damage. Nevertheless, residual compressive strength recovered to ~99% and ~91% of the virgin level for the 5 J and 10 J conditions, respectively. The corresponding healing efficiencies were 86% and 49%. X-ray observations revealed a transition from localized matrix cracking and interfacial damage at 5 J to more extensive internal damage at 10 J. The combined analysis of impact response, residual strength, and damage morphology establishes a direct relationship between damage severity and healing efficiency, demonstrating the potential of thermally activated self-healing composites for rapid recovery of lightweight aerospace structures and UAV components.

Carbon-fiber-reinforced polymer (CFRP) laminates can exhibit different low-velocity impact responses and post-impact performance depending on laminate configuration. This study compares three self-healing CFRP configurations manufactured from CompPair HealTech^® materials: 1.45 and 3.30 mm unidirectional (UD) laminates and a 2.66 mm woven laminate. Low-velocity impact tests were performed at 5 and 10 J. Internal damage was qualitatively examined using visual inspection and X-ray phase-contrast imaging (XPCI), while post-impact performance and recovery were assessed by compression-after-impact (CAI) testing before and after thermal healing. The 1.45 mm UD laminate exhibited the largest displacement and lowest maximum impact force, whereas the 3.30 mm UD laminate showed the highest force and smallest displacement, with the woven laminate exhibiting an intermediate response. Despite its greater impact stiffness, the 3.30 mm UD laminate showed the largest relative reduction in residual compressive strength after 10 J, with strength retention decreasing from approximately 98% after 5 J to 64% after 10 J. The 1.45 mm UD and woven laminates retained 89% and 88% after 5 J and 82% and 72% after 10 J, respectively. After healing, the 1.45 mm UD and woven laminates recovered to approximately 99% of their virgin strengths after 5 J. After 10 J, strength retention reached 91%, 79%, and 81% for the 1.45 mm UD, 3.30 mm UD, and woven laminates, with corresponding healing efficiencies of 49%, 42%, and 31%, respectively. XPCI revealed configuration-dependent internal damage patterns that became more pronounced at 10 J. Overall, the investigated laminate configurations exhibited distinct impact responses, internal damage patterns, residual strengths, and levels of mechanical recovery after healing.

This paper investigates approaches to improving the energy efficiency of the manufacturing process of thermosetting polymer composites through optimization of curing parameters. It is shown that the isothermal dwell stage is the longest and most energy-intensive phase of the technological cycle, while curing schedules commonly used in industrial practice and often based on averaged datasheet properties of the resin are not always rational when the part geometry, composite lay-up structure, and heat transfer conditions are taken into account.Within the study, two principal approaches to determining optimal technological parameters are analysed: the experimental approach and the online method. The experimental approach involves selecting curing schedules based on a series of tests for a specific structure, which ensures compliance with the required material properties but is associated with significant time and energy costs. The online method is based on continuous monitoring of parameters characterising the degree of completion of chemical reactions in the resin and enables adaptive adjustment of temperature–time profiles during the forming process without the need for additional experiments.To analyse the curing process, well-established physical and mathematical models of heat transfer and polymerisation kinetics are employed, allowing prediction of the spatial–temporal distributions of temperature and degree of cure within the composite laminate. Particular attention is paid to the investigation of the stress–strain state formed as a result of the combined effects of thermal, shrinkage, and relaxation processes. It is demonstrated that the level of residual stresses can be reduced by ensuring a uniform temperature field, applying double-sided heating, optimising tooling design, and exploiting the relaxation properties of the material.As a result of curing schedule optimisation for a given composite laminate configuration, the duration of the isothermal dwell was reduced by a factor of 1.7, leading to a decrease in energy consumption of the forming process from 40 to 23 kWh without deterioration of processing conditions or product quality. The obtained results are methodological in nature and can be applied in the development of energy-efficient manufacturing technologies for polymer composite structures and in the creation of computer-integrated process control systems.