Electrospun nanofibers are very popular in polymer nanocomposites because they have a high aspect ratio, a large surface area, and good mechanical properties, which gives them a broad range of uses. The application of nonwoven structures of electrospun nanofiber mats has historically been limited to enhancing the interlaminar responses of fiber-reinforced composites. However, the potential of oriented nanofibers to improve the characteristics of bulk matrices cannot be overstated. In this research, a multilayered laminate composite was created by introducing polyamide (PA6)-oriented nanofibers into an epoxy matrix in order to examine the effect of the nanofibers on the tensile and thermal characteristics of the nanocomposite. The specimens’ fracture surfaces were examined using scanning electron microscopy (SEM). Using differential scanning calorimetry (DSC) analysis, the thermal characteristics of the nanofiber-layered composites were investigated. The results demonstrated a 10.58% peak in the nanocomposites’ elastic modulus, which was compared to the numerical simulation and the analytical model. This work proposes a technique for the development of lightweight high-performance nanocomposites.

Fluid rigid body interaction is commonly occurring phenomenon and this phenomenon is of high importance in many engineering applications. The main objective of the present paper is to analyse vibrations due to fluid-rigid body interactions by inclining the frontal area of flat plate to flow. As understood from the existing research, the main challenge is the understanding of non-stationary fluid body interactions. Interaction analysis, optimization and synthesis tasks include space-time programming methods and approximate analytical methods. This article discusses an approximate analytical method in which the object's interaction with fluid flow is divided into two parts in the fluid body interaction space. The first part is the frontal pressure side that arise as a result of change of momentum in the system that can be conveniently represented in a differential form. The second part includes the idea of describing the interaction behind the plate as a certain thin (vacuum) side was accepted. This thin vacuum side also depends on the frontal area flow interaction. The use and precision of the approximate analytical method was verified by experiments in the wind tunnel. The method was used for good analysing of varying frontal area (until flattening) of flat plate in fluid flow. The main parameters for motion excitation are the changes in plate-flow interaction area, velocity and angle of inclination of the flat square plate to the fluid flow. Experiments were performed at 10 m•s-1 keeping in view the wind speeds that were observed in the past in Riga, Latvia.

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In engineering, for many practical applications fluid-body interactions are commonly encountered and thereby these interactions have to be extensively studied. Though this body-fluid interaction is studied in the past, the concept of interaction analysis, form optimization relating to axis symmetry geometries till date mostly need to be further explored. The present work is devoted to the analysis of fluid (air) to body (prism) interaction, form (or shape) optimization taking into account various criteria and energy extraction from air flow by using an axial symmetric body (circular disc shaped geometry with alternate perforated quadrants) with plane symmetry (cylinders) is considered. A simplified mathematical model for engineering calculations is proposed. The model is based on the concept of pressure (compression) and suction zones, when a body is subjected to fluid (air) flow. Initially, all calculations are performed for the geometry under study in constant dimensions. Further, for better efficiency of the overall system, the system parameters are changed in constant continuous steps by a detailed analysis of the fluid-body interaction response surface. The mathematical model has the following assumptions: the fluid (air) flow is laminar, non-compressible (density constant) and the fluid (air) viscous is ignored. All the results obtained are discussed in graphs and explained. Three-dimensional fluid flow simulations are performed in ANSYS, steady state RANS is solved using Kε realizable turbulence model, the interaction force (Drag) is obtained for the geometry under study. Finally, the results relating to form (or shape) optimization and the application of the concept are widely discussed.

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The work is dedicated to the authors' latest research on the interaction of moving inflexible objects when subjected to non-constant velocity fluid flow (air, water) without the use of work-intensive space-time programming methods. In the first part of the study, the differential equation of the plane pendulum motion is derived using the novel approach of fluid-rigid body interaction phenomenon, in this equation, the moment caused by the fluid interaction is simplified by ignoring the flow viscosity. This makes it possible to obtain the usual second-order differential equation of pendulum motion, which contains components of relative velocity in a simplified way, instead of the partial differential equations in a continuous mathematical space. The application of the obtained equation is further used in solving specific tasks of engineering importance. The first task analyzes the pendulum swing motion in a still airflow. Here, the equation described above is numerically integrated and the results are compared with an experiment in a natural environment. The comparison resulted in a drag interaction factor that was further used in other more complex cases. The second task analyzes the pendulum motion when fluid flow velocities are a decreasing function of time in a harmonic behavior. In addition, in this case, the possibilities of applying the developed theory to other forms of flow rate change, such as pulse or poly harmonic forms, are considered. In the third task, the synthesis of motion control in a mechatronic system was performed. In this case, the possibility of regulating the additional resistance torque arising from the rotary damping generator is considered. The work is illustrated with graphical results. The outcomes obtained in the work can be used in the analysis of the interaction of existing moving objects with the fluid flow, as well as in the synthesis of new technological processes, for example, for obtaining energy from vibrating objects immersed in fluid flow.

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