Applied Sciences

The structural segmentation of wind turbine blades offers advantages in transportation, manufacturing, and maintenance; however, it introduces interfaces that may compromise load transfer and fatigue performance. This study presents the experimental and numerical validation of a composite coupling system designed for small wind turbine blades compliant with IEC 61400-2 requirements. A 2 m representative section extracted from the mid-span region of a 9 m blade was manufactured using vacuum-assisted resin infusion and tested under static loading conditions. A detailed finite element model based on classical laminate theory and orthotropic material properties was developed to predict structural response. Experimental measurements showed a maximum tip deflection of 15 mm under the applied load, compared to 13.76 mm predicted numerically, corresponding to a deviation of 8.9%. Surface strain measurements obtained from eight strain gauges installed across the blade–coupling interface indicated maximum mean values of +632.4 με in tension and −664.2 με in compression, with no evidence of localized strain amplification at the instrumented locations. These findings demonstrate that fully composite permanent segmentation can preserve stiffness continuity while maintaining strain levels below reported fatigue initiation thresholds, supporting the structural feasibility of segmented blade architectures for small wind turbine applications.

Dredged Fill Soil, as a primary foundation material in reclamation projects, exhibits complex physical and mechanical properties, characterized by a high plasticity index, high water content, low density, high compressibility, large void ratio, and low bearing capacity. Its creep behavior is highly sensitive to temperature changes. This study systematically investigates the temperature-dependent creep behavior of reclaimed soil from Humen Port through laboratory experiments, theoretical modeling, and experimental validation. Triaxial creep tests conducted at different temperatures (5 °C, 15 °C, 25 °C, 35 °C) show that increasing temperature significantly exacerbates creep deformation: under undrained conditions, creep strain at 35 °C is nearly 300% higher than at 5 °C, while drainage reduces the strain by approximately 29.3%. Based on these results, a Burgers-type creep constitutive model considering temperature effects is developed, incorporating the impact of temperature on viscosity and elastic modulus. The model’s predictions show good agreement with the experimental results (15 °C: R² = 0.9788; 35 °C: R² = 0.9890), confirming the model’s validity. The research findings provide theoretical and practical references for the long-term stability evaluation and engineering design of reclaimed foundations in complex marine environments.

This study investigates the acoustic pressure field in a 20 kHz sonoreactor filled with water. A modular sonoreactor and ultrasonic stack were developed at the Łukasiewicz-ITR laboratory. Modal, harmonic response, and harmonic acoustic analyses were performed using the ANSYS Workbench, considering two reactor heights (800 mm and 550 mm). Experimental tests using aluminium foils were conducted, and the results were compared with FEM simulations. The bulk viscosity of the liquid was found to have a significant impact on the numerical results. The novelty of this work lies in estimating an effective bulk viscosity that enables accurate representation of the pressure field distribution within the tank. This parameter is theoretical and, as defined in this study, accounts for the overall energy losses associated with cavitation rather than representing an intrinsic material property. The proposed simulation approach reduces computational time and cost while maintaining agreement between predicted and experimental pressure fields. Good consistency was achieved when the effective bulk viscosity was set to 1300 Pa·s. The presented methodology may support further development and optimization of sonoreactors. It enables rapid evaluation of various geometries, providing a foundation for prototype development or subsequent detailed analyses.