Technical Sciences

Application of Transition Finite Elements in hpq-Adaptive Modeling and Analysis of Machine Elements

Magdalena Zielińska — 2024-04-12

This paper concerns the modeling and analysis of machine elements using the adaptive finite element method. The adaptation used is of hpq type, which means that the finite element dimension h and element transverse q and longitudinal p approximation order may be different in each element. These parameters are determined automatically by the program to obtain modeling and approximation error levels not higher than the assumed admissible level of the errors. The presented paper focuses on the use of transition elements between basic elements corresponding to the three-dimensional theory of elasticity and the first-order shell model. Three applied transition elements differ in their assumptions regarding the continuity of the displacement, strain, and stress fields between the basic models. The effectiveness of the application of transition elements was assessed in terms of the removal of the internal boundary layer at the boundary between the models and the convergence of adaptive solutions taking into account these models.

Comparison of pressure-loss evaluation fidelity in turbulent energy dissipation models of poppet check valves using computational fluid dynamics (CFD) software

Maciej Jerzy Kobielski — 2024-02-12

Check valves are critical components of fluid systems and have various applications, including house appliances. This article presents a methodology for mapping geometry-specific constriction pressure loss as a function of flow and turbulence in a check valve. This study aimed to gain insight on which Ansys Fluent available turbulent energy dissipation model should be used for further design optimization. This methodology consists of a statistical comparison of computational fluid dynamics (CFD) simulation results obtained using the turbulent energy dissipation models. The key components of the simulation process are discussed. The study’s main results are a comparison of empirical results among flow models’ estimated pressure loss, shown as a function of flow rate in specific geometry and identification of the most suitable model for the considered application. This study concludes that the K-Epsilon (Standard) model best represents the empirically measured behavior of naturally occurring flow energy losses in the considered geometry.

Concept and preliminary calculations of an optionally piloted research platform

Paulina Zenowicz — 2024-01-29

Along with the technological progress, unmanned aerial vehicles have found application not only in a military, but also in civil applications. The article presents Concept and preliminary calculations of an optionally piloted research platform. A literature review revealed a small number of existing aircraft of similar design. The analysis began with basic analytical calculations for airplanes, and more specifically their wings. The initial concept of the external shape of the designed aircraft was determined, and then the initial optimization of the structure was carried out on the basis of mathematical and computer analysis. Another goal of the research will be the construction of a demonstrator and its analysis.