Abstract: Thermal spraying is a technique within the field of surface treatment processes, where molten or semi molten metal droplets are heated and propelled onto a solid substrate. Then, the deposition of these droplets results in the formation of a splats, which progressively accumulate to form the coating. Therefore, it is crucial to understand the dynamics of droplets impingement, spreading and solidification in order to improve coatings quality. The main objective of this paper is to analyze, how the tilt angle of the substrate influences on the coating quality in industrial applications. Thus, this study simulates the deposition of successive aluminum droplets on a tilted stainless-steel substrate during the formation of the metallic lamella using Ansys code. The volume of fluid (VOF) method is employed to track the free surface of the droplets. In addition, the incompressible Navier–Stokes equation is applied to capture the dynamics of the droplets motion. The main findings reveal that an angled substrate can cause asymmetrical spreading of the impingement droplets, the droplets tilt to gravity direction, leading to poor droplet/substrate adhesion, and non-uniform thickness of coatings.

Key words: Thermal spraying , deposition, coating, VOF method, tilted substrate.

Abstract: This study analyzes three seismic isolation bearing devices to evaluate their effectiveness in the three-dimensional dynamic response of a box girder bridge and the complexities associated with their modeling. It examines energy dissipation mechanisms, including Natural Rubber Bearings (NRB), elastomeric bearings with High Damping Rubber (HDRB), and neoprene bearings with a Lead Core (LRB), to enhance seismic design performance and optimize the dimensions of this specific category of bridge structures. For this purpose, a three-dimensional finite element numerical model of a standard bridge is developed. Nonlinear dynamic analysis is conducted using models that represent the bilinear hysteretic behavior of the seismic isolation systems. The findings indicate that these isolators significantly influence the seismic response in the longitudinal direction and effectively reduce seismic demand on the bridge.
Keywords: Seismic isolation systems, box girder bridge, NRB, HDRB, LRB, Nonlinear dynamic analysis

Abstract: The Design of Experiments (DoE) is a powerful statistical approach that enables the optimization of process parameters through a limited number of well-structured tests. In this study, the Taguchi method is applied to the punching test to investigate the influence of key parameters on the maximum punching force (Fmax). Four control factors are considered: punch speed (V), clearance between punch and die (J), punch diameter (D), and sheet thickness (e). Two mathematical models are developed to predict Fmax: a first-order model that neglects factor interactions, and a second-order model that accounts for them. The comparison between both models demonstrates that the second-order formulation provides a significantly better fit to experimental data. These findings underline the importance of considering factor interactions in the analysis and optimization of the punching process to achieve improved cutting accuracy and predict Fmax.
Key words: Taguchi design of experiments, Optimization, Punching test, Analytical model.