The article deals with experimental and numerical research of the layered reinforced concrete slab with plastic inserts. The investigated layered reinforced concrete slab is made of prefabricated and monolithic reinforced concrete layers. Voids were formed in the plate with spherical plastic inserts. With reference to the built-up bars theory, the paper proposes an analytical method for calculating the deflection of the layered reinforced concrete structures in non-linear stage, when bond between layers is partially rigid. The article also focuses on the numerical simulation of the layered slab, compares the estimated theoretical values of deflection with the experimental values and assesses the shear stiffness of the bond of prefabricated and monolithic concrete layers for calculating the deflection of the reinforced concrete slab. Paper presents the parametric analysis of deflection dependence on shear stiffness and the width of the contact zone of the layers. It was established that proposed analytical method and numerical analysis properly characterise the behaviour of the slab. Calculation results were close to experimental data. Moreover, it was determined that performance of this type of slab is highly influenced by shear stiffness of the bond between the concrete layers. Analysis confirmed that slab fails when bond is damaged, and layers slip in the support zone.

The behaviour of the interface between two concrete layers, subjected to shear, is a complex process that is influenced by many different parameters. Knowledge of concrete interface performance is insufficient to this day. Most of the existing analytical methods are only suitable for determining the highest interface shear resistance and do not consider the interface behaviour at other stages. This article focuses on smooth concrete interfaces, which have their layers cast at different times (cold-joint interface). By analysing the results of different experimental push-off tests, presented in the literature, a novel analytical method was developed for the previously described concrete interface. Furthermore, numerical models of push-off tests were developed. A parametric numerical analysis was employed to determine the influence of various physical parameters that might affect interface shear behaviour. Most importantly, the results acquired using the proposed analytical method were compared with the findings of numerical analysis and experimental results acquired by other authors. The values of shear stress and slippage were found to be relatively close. Therefore, the proposed analytical method is suitable for the analysis of smooth concrete interfaces cast at different times.

This research paper focuses on determining the pressure wave propagation velocity in closed hydraulic pipes, a fundamental parameter relevant to a wide range of engineering applications, from aerospace to land-based and marine systems. It was indicated that, under transient conditions, the pressure wave propagation velocity depends, among other factors, on temperature, pressure, and the substitute bulk modulus. Furthermore, it was also indicated that accurate knowledge of this velocity is crucial for predicting pressure amplitudes during transient flows, including water-hammer phenomena. Finally, the analysis indicated that excessive pressure amplitudes in the pipe can lead to critical damage to the pipeline and increased vibration. Experimental investigations were carried out to determine the pressure wave propagation velocity in flexible steel-braided pipes and in a rigid pipe over a wide range of internal pressures.

This paper focuses on determining the propagation velocity of pressure waves in closed hydraulic pipes. It is shown that under transient conditions, the propagation velocity of pressure waves depends, among other things, on temperature, pressure and the substitute bulk modulus. Accurate knowledge of the pressure wave propagation velocity is crucial for predicting pressure amplitudes during transient flows, including the phenomenon of water hammer. Excessive pressure amplitudes in the pipe can lead to critical pipeline damage and increased vibrations. Experimental studies were conducted to determine the pressure wave propagation velocity in flexible steel-braided pipes and in a rigid pipe over a wide range of internal pressures. The results of the analyses presented in the papers may be helpful to scientists and engineers when designing pipelines and selecting the strength parameters of pipes, taking into account the possible maximum values of internal pressure amplitudes.

Piezoelectric unimorph actuators are promising candidates for precision actuation systems in small satellites, where their electromechanical performance must remain predictable under vacuum and temperature variations. However, actuator performance is determined not only by the piezoelectric material but also by the passive layer and bonding interface, whose combined influence under thermal-vacuum conditions requires systematic evaluation. This study presents a numerical and experimental investigation of the temperature-dependent electromechanical characteristics of piezoelectric unimorph actuators incorporating PIC 181 piezoceramic plates, passive layers made of 7075-T6 aluminum or Ti-6Al-4V titanium, and three different vacuum-compatible bonding materials. Numerical analyses were performed to determine modal, impedance–frequency, and displacement–frequency characteristics over the temperature range of 253.15–323.15 K, while experimental investigations under vacuum conditions quantified the additional influence of the bonding interface. Increasing temperature caused a decrease in resonance frequency for both passive-layer configurations. Actuators with Ti-6Al-4V passive layers generally exhibited higher resonance frequencies, lower impedance values, and larger displacement amplitudes than those with 7075-T6 aluminum passive layers. The maximum measured displacement amplitudes reached 23.11 µm for the aluminum-based actuator and 29.67 µm for the titanium-based actuator at 323.15 K. Among the investigated bonding materials, BM No. 3 consistently provided the lowest impedance and highest displacement response. The results demonstrate that passive-layer and bonding-material selection should be considered jointly and identify the Ti-6Al-4V/BM No. 3 combination as the most favorable among the investigated configurations for resonant piezoelectric unimorph actuation under the tested thermal-vacuum conditions.