The Annals of “Dunarea de Jos” University of Galati. Fascicle IX, Metallurgy and Materials Science

Stress and Fatigue Simulation of Structural Blades in Mechanical Clearing Operations

Florin-Bogdan MARIN, Iulian CONSTANTIN, Mihaela MARIN — Mon, 15 Dec 2025 00:00:00 +0200

This study presents a numerical investigation into the structural performance of the cutting blades used in vegetation-clearing operations, particularly within mechanical systems designed for demining or land maintenance. Using finite element analysis (FEA), the research evaluates stress distribution, fatigue behavior, and failure risk under cyclic loading conditions. Multiple simulation models were developed to replicate realistic operational forces and identify critical stress concentration zones. The fatigue simulations provided insights into lifetime predictions and cumulative damage evolution, expressed through percentage-based degradation maps. Von Mises stress analyses further validated the structural response of the blades under high-load scenarios. The results indicate that proper geometric configuration and material selection are essential for improving fatigue life and ensuring operational safety in harsh environments. The proposed methodology supports optimization efforts in blade design for enhanced durability and reliability.

Simulation Regarding the Damascus Steel Behavior on Mechanical Stress

Carmen-Penelopi PAPADATU, Dragos Bogdan OBREJA — Mon, 15 Dec 2025 00:00:00 +0200

The study of Damascus steel provided an opportunity to examine historical and specialized manufacturing techniques and to produce laboratory samples through the labour-intensive process of creating this material. It involves the freeforging of plates made from two types of high-carbon steel arranged in an interleaved structure, resulting in the "welding together" of these layers to produce a knife that is particularly resistant to stress and exhibits high hardness. The processing of the specimens and laboratory tests were carried out on Damascus steel samples produced in the laboratory, strictly following the procedure described in the specialized literature. The aim was to evaluate their mechanical properties and to process the results using Autodesk Inventor Professional 2023.

Design and Development of a Modular 3D-Printed Extruder for Recycled PET Filament Production

Valentin BEREANDĂ, Mihaela MARIN, Florin-Bogdan MARIN — Mon, 15 Dec 2025 00:00:00 +0200

This paper presents the design, fabrication, and functional validation of a low-cost, modular extruder system capable of converting manually cut PET-bottle strips into 3D-printing filament. The extruder is composed of 3D-printed structural elements, a metal heating barrel, a digital thermostat with an ON/OFF control, and a direct-drive 12 V DC motor for material feeding. The heating profile was stabilized at 230 °C to ensure proper melting and extrusion. The resulting system successfully produced filament of consistent diameter, suitable for non-loadbearing applications. This work demonstrates the feasibility of decentralized, smallscale PET recycling using accessible components and open-source design principles, contributing to circular-economy practices in the context of Fused Deposition Modeling (FDM).

Investigation of Thermal Conductivity in Advanced Metallic Materials via Computational Fluid Dynamics

Rareş AVĂDANEI, Florin-Bogdan MARIN, Mihaela MARIN — Mon, 15 Dec 2025 00:00:00 +0200

This study investigates the transient thermal behavior of Ti6Al4V alloy using computational fluid dynamics (CFD) simulations. The primary objective is to characterize the alloy’s heat-conduction performance under controlled thermalloading conditions. A dual-scale modeling approach was employed, combining a simplified body-centered cubic (BCC) lattice structure to represent the β-phase and a macroscopic solid domain to simulate the bulk material response. The simulations were performed over a 10-minute interval, with thermal data extracted at 1-, 3-, 5-, and 10-minute time steps. The results indicate delayed, uneven heat propagation in Ti6Al4V, attributed to its intrinsically low thermal conductivity (6.5 W/m·K). The findings provide insight into the alloy’s thermal limitations, particularly in applications requiring efficient heat dissipation. The study demonstrates the potential of CFD as a predictive tool for evaluating thermal performance in advanced metallic materials.

Mathematical Modeling and Development of a Graphical Interface (GUI) For Simulating the Orbital Forging Process

Marian-Iulian NEACȘU, Elisabeta ȚANU-LUPU — Mon, 15 Dec 2025 00:00:00 +0200

The main objective of this work was to develop a theoretical and practical tool for understanding and simulating the orbital forging process, using mathematical modeling and GUI-based graphical interfaces developed with MATLAB. This interface represents a link between theoretical analysis and practical applicability.

Smart Metallurgy: The Impact of Industry 4.0 on Materials Processing and Innovation

Patricia Isabela BRĂILEANU — Mon, 15 Dec 2025 00:00:00 +0200

This paper analyses the revolutionary effect of Industry 4.0 technologies on materials processing and innovation in the metallurgical industry. It extensively analyses how this new industrial revolution, defined by the widespread interconnection of digital systems, is systematically re-designing conventional processes into smart, networked and highly efficient systems. The study highlights the function of enabling technologies such as Internet of Things (IoT), Artificial Intelligence (AI) and Machine Learning (ML), Cyber-Physical Systems (CPS), Additive Manufacturing (AM) and Big Data analytics, revealing their cumulative ability to enhance energy efficiency, resource allocation, quality control, and predictive maintenance along the whole metallurgical value chain. While recognizing the industry’s current mid-term period of digital adoption, this analysis highlights how Industry 4.0 is already providing dramatic gains in efficiency, productivity, and sustainability, critically meeting both challenges of digitalization and decarbonization. Practical implementation highlighted includes real-time process monitoring, creation of digital twin prototypes for simulation, and the enablement of very high customization of manufacture. Theoretically, this research enriches the heavy industry discourse on digitalization by outlining technological adoption and industry-maturity interaction and discussing the novel concept of the “metallurgical Internet of Things” (m-IoT) of a globally networked, resourceefficient materials world.

Studies and Research on the Corrosion Behaviour in a 3.5% NaCl Solution of Sintered 316 Stainless Steels

Simona BOICIUC — Mon, 15 Dec 2025 00:00:00 +0200

Products made from austenitic 316 stainless steels obtained through powder metallurgy technologies are used in many applications across various industrial fields due to their resistance to corrosion from air, water, and different acids. They are also non-magnetic, possess good mechanical properties at both low and high temperatures, offer good creep resistance, and have good weldability. This paper presents a series of experimental studies on the corrosion behaviour of sintered austenitic 316 stainless steels in a 3.5% NaCl solution. The different behaviours observed can be attributed to varying compaction pressures and can be improved by reducing surface roughness, increasing chemical and structural homogeneity, and by alloying.

Finite Element Simulation of Thermoplastic Polyurethane Components for NVH Transfer Path Analysis

Florin Bogdan MARIN, Gheorghe GURĂU, Iurie DRUMOV, Mihaela MARIN — Mon, 15 Dec 2025 00:00:00 +0200

Thermoplastic polyurethane (TPU) has emerged as a versatile material for noise, vibration, and harshness (NVH) control due to its tuneable viscoelastic properties and compatibility with additive manufacturing. This study presents a finite element-based modeling framework for the characterization and evaluation of TPU in transfer path analysis (TPA). Nonlinear stiffness and damping functions were implemented based on literature data, while frequency-dependent viscoelastic behavior was introduced through storage and loss modulus functions. Contact interactions were modeled with nonlinear springs incorporating frictional effects to capture realistic interface dynamics. Vibro-acoustic coupling was investigated using a FEM-based approach, and further assessed using hybrid FEM–BEM methods. The results showed close agreement between predicted mode shapes and analytical expectations. Displacement fields were reproduced with high fidelity, and higher-order modes highlighted the importance of including frequency-dependent damping and friction models. Hybrid FEM–BEM coupling improved acoustic predictions while reducing computational cost. Parametric optimization further demonstrated that small modifications in TPU thickness and support positioning can reduce sound pressure levels by up to 15%. Overall, the simulations suggest that TPU has significant potential for application as both a structural decoupler and acoustic absorber in NVH engineering, providing a numerical framework that can guide lightweight and multifunctional designs in automotive and related engineering fields.

Topology Optimization for Mass Reduction of a Structural Component in a Surgical Robotic Arm

Florin Bogdan MARIN, Daniela Laura BURUIANĂ, Larisa IONICĂ, Mihaela MARIN — Mon, 15 Dec 2025 00:00:00 +0200

This paper presents a case study on the topology optimization of a structural component in a surgical robotic arm, aiming to reduce mass while maintaining mechanical performance. The component, made of aluminium alloy Al7075-T6, was subjected to finite element analysis and topology optimization using Altair OptiStruct. The objective of the study was to minimize mass under the imposed constraints of maximum displacement (≤ 0.2 mm) and von Mises stress (≤ 250 MPa). The stress limit was selected as 50% of the alloy’s yield strength (≈ 503 MPa), to ensure an additional safety margin. Finite element analysis (FEA) was employed to evaluate and validate the optimized geometry. The initial design exhibited a displacement of 0.21 mm and a maximum stress of 240 MPa, which corresponds to a safety factor of 1.04. After optimization, the final design achieved a displacement of 0.18 mm and a maximum stress of 227 MPa, which results in a safety factor of 1.3. These results demonstrate that the adopted topology optimization strategy can effectively reduce structural mass (≈34%) while maintaining compliance with displacement and stress constraints, ensuring reliability for robotic applications.

Simulation with the Help of Matlab of the Forging Technology for the Rotor Shaft Reference of a Wind Turbine Installation

Marian-Iulian NEACSU — Mon, 15 Dec 2025 00:00:00 +0200

In this paper, a simulation of the forging process was carried out to obtain the rotor shaft of a wind turbine.
The simulation program used for the forging process in the referenced work is based on the mathematical formulations specific to plastic deformation during forging, integrated into a computational model that faithfully reproduces the real technological conditions.

Modernisation of Irrigation Systems – A Sustainable Solution for Efficient Water Resource Management in Agriculture

Daniela-Felicia BABENCU, Gina Genoveva ISTRATE — Mon, 15 Dec 2025 00:00:00 +0200

In the current context, marked by accelerated climate change, population growth, and the development of anthropogenic activities, pressure on water resources is increasing. Therefore, the need to develop efficient and sustainable agriculture through effective water resource management is becoming a priority at both global and national levels. Romania is increasingly facing challenges in adapting the agricultural sector to new climatic conditions. These conditions are characterized by increasingly pronounced fluctuations in precipitation and a rising frequency of drought years – characteristics that negatively affect crop productivity and stability.
This article aims to analyse the benefits of modernizing irrigation technologies, focusing on innovative, smart, and environmentally friendly solutions, such as precision irrigation. An innovative alternative solution is examined, namely the use of fog collectors as a complementary method of passive water collection, with potential for application in favourable microclimates, including the hilly areas of Romania.

Aspects of Dynamic Modelling of Motor Vehicles with Emphasis on the Influence of the Nonlinear Character of Elastic Forces in Tyres

Adrian LEOPA — Mon, 15 Dec 2025 00:00:00 +0200

The study of oscillatory motions in vehicles is of particular interest from the perspective of improving their dynamic performance. This aspect has been highlighted in the present work by emphasizing the scientific interest that has been identified in the specialized literature, with several representative studies brought to the forefront. The study proceeds with the presentation of a four-degree-offreedom dynamic model capable of characterizing the oscillatory regime of a vehicle when passing over an obstacle. Based on this dynamic model, the kinematic parameters of the oscillatory motion of a vehicle as it passes over an obstacle were investigated, highlighting the influence of the nonlinear nature of the elastic forces in the tires on these parameters. The conclusions of the study indicate that accounting for the nonlinear characteristics of the tire elastic forces is necessary to achieve a more realistic characterization of the dynamic behavior of the analysed phenomenon; however, for the numerical values considered, the amplitudes of the displacements and velocities of the analysed masses do not differ significantly from those predicted by the linear model.

Air Emissions and Environmental Challenges in the Energy Industry: A Review

Nicoleta CIOBOTARU — Mon, 15 Dec 2025 00:00:00 +0200

The global energy sector, owing to the high complexity of its installations, technological processes, and the waste streams it generates, has a profound and multifaceted impact on the environment. Electric power generation influences ecosystems, alters local microclimatic conditions, and poses risks to human health. Conventional thermal energy production based on fossil fuels remains the most polluting source, whereas renewable energy technologies and nuclear power generally exhibit lower environmental footprints, though they may still involve indirect or long-term ecological effects. Pollutants originating from the energy sector contribute to the degradation of air, soil, and water quality, as well as to climate change and broader ecological imbalances. Patterns of energy production and consumption differ significantly among countries, reflecting disparities in resource availability, geographic characteristics, and policy frameworks. Despite the accelerating deployment of renewable energy, fossil fuels continue to dominate the energy mix in many regions of the world.

A Current Minireview on the Aquatic Environment: Impact of Some Ions from the Food and Metallurgical Industries

Romică CREȚU, Liviu Cătălin ȘOLEA, Nicolae ȚIGĂU — Mon, 15 Dec 2025 00:00:00 +0200

Recent research has shown the high degree of pollution that the metallurgical and food industries can cause to the environment. In this minireview, the impact that various polluting ions, emitted as a result of technological processes specific to the metallurgical and food industries, can have on the aquatic environment was analysed. Our research also provides an assessment of the potential interactions and the most likely transformations of these chemical forms once they are released into the aquatic environment, as well as the likely impact on the ecosystem.

Static Analysis of a Thermal Support

Ionel PETREA, Marian-Iulian NEACȘU — Mon, 15 Dec 2025 00:00:00 +0200

In this paper, a simulation is performed using CATIA software and the finite element method, regarding the static analysis of a thermally stressed support. The simulations were performed for several temperatures: 20 ^oC, 100 ^oC, 200 ^oC, and 300 ^oC, in order to observe the behavior of the support made of different materials at these temperatures.

Evaluation of Edge Detection and Fusion Methods for Angiographic Image Processing

Cristian-Dragoș OBREJA — Mon, 15 Dec 2025 00:00:00 +0200

This study explores the application of digital image processing techniques to improve the diagnostic accuracy of coronary artery disease through enhanced analysis of angiographic images. A curated dataset of 40 grayscale, single-vessel angiograms was used to evaluate the effectiveness of various preprocessing and edge detection methods. Preprocessing steps included noise reduction, histogram equalization, and morphological operations aimed at improving image clarity and highlighting vascular structures. Three edge detection algorithms, Otsu, Canny, and Roberts, were applied, and their outputs were further combined using the Dempster-Shafer fusion theory. Performance was assessed using edge-based structural similarity (ESSIM) and the percentage error in vessel diameter measurements. The Canny algorithm demonstrated the highest individual accuracy, while the fusion of Canny and Roberts yielded superior results, achieving the lowest error and the highest similarity index.

Mathematical Modeling of the Carbonitriding Process for OLC 25 Steel

Marian-Iulian NEACȘU — Mon, 15 Dec 2025 00:00:00 +0200

The paper is based on research on several experimental carbonitriding regimes of OLC25 steel samples.
Following the experiment for each regime, the HV microhardness values of the treated samples were measured at various points (identical for all samples) along the depth of the carbonitrided layer. The results of these measurements were compiled into a database that was used to create a mathematical model of the carbonitriding process.
The paper presents the results of mathematical modeling based on an active experimental study of the carbonitriding process applied to OLC25 steel samples.