ENLO-SED: an innovative method for large-scale Strain Energy Density (SED) estimation in welded joints using structural stresses derived from Element Nodal LOads (ENLO)

Welded joints have always been critical elements of industrial mechanical structures, often being the source of failures related to the presence of fatigue loads. Although the academic world has presented advanced methodologies for the assessment of local fatigue, such as the Strain Energy Density (SED) approach, which offers high accuracy, their high computational requirements hinder their adoption by the industrial world. This paper introduces a new hybrid methodology, called ENLO-SED, which integrates the SED approach by calculating the Strain Energy Density using the element Nodal load approach (ENLO), with the aim of maintaining high accuracy while significantly reducing the computational effort.  The proposed method is validated on a complex case study, representative of a real industrial case, demonstrating a prediction error within 8% compared to the application of the classic SED method. Furthermore, the innovative ENLO-SED approach reduces the meshing and solution times by 15 and 5 times, respectively. These results confirm the robustness, efficiency, and scalability of the method, making it suitable for large-scale industrial applications

Advanced algorithms for early detection of first damage during static tensile tests

The Static Thermographic Method (STM) involves analyzing the thermal behavior of a specimen subjected to a quasi-static tensile test. The temperature trend, measured by an infrared camera, follows three phases where the first and second are cooling phases, while the third a heating phase. A limit stress value can be determined, corresponding to the macroscopic stress level at the point of slope change between the first and second phase, indicating the occurrence of initial damage. The onset of plasticity is the reason of fatigue failure; thus, the limit stress can be adopted as a first indication of failure stress level for design purposes. This work aims to objectify the Static Thermographic Method, which currently relies on the operator's experience and skill in identifying the different thermal phases during the static tensile test. Three different algorithms have been developed to determine the best mathematical model for the temperature trend over time, eliminating the subjectivity of data observation

Optimizing mechanical properties of AA7075 Metal Matrix Composites reinforced with TiB2 and ZrO2 particulates

Hybrid metal matrix composites (MMCs), recognized for their superior strength-to-weight ratios and synergistic property enhancements, are emerging as advanced materials capable of mitigating the inherent limitations observed in conventional monolithic composites. While traditional composites offer structural benefits, their susceptibility to creep deformation and abrasive wear restricts their broader applicability. In sectors such as aerospace, automotive, and marine engineering, aluminum-based hybrid MMCs reinforced with ceramic particulates like titanium diboride (TiB2) and zirconium dioxide (ZrO₂) have garnered considerable interest due to their enhanced mechanical integrity and tribological performance. This investigation is an extension of previous work by authors AA7075 MMCs. This work systematically examines the influence of TiB2 (fixed at 5 wt%) coupled with incremental ZrO₂ reinforcement levels (2, 4, and 6 wt%) on the microstructure, mechanical strength, hardness, and wear resistance of AA7075 alloys fabricated via the stir casting process. The study aims to elucidate the compositional optimization of hybrid reinforcements to tailor material properties for high-performance applications. Microstructural analysis revealed an equiaxed grain structure with uniform reinforcement distribution, particularly in AA7075/5% TiB2/4% ZrO2 composition. The addition of reinforcements improved hardness up to 85.45%, increasing from 55 Hv (base alloy) to 102.40 Hv. And, also the yield strength increased from 107 MPa (base alloy) to 123 MPa, an increase of 15%, attributed to the improved particle detachment resistance. Introducing TiB2 and ZrO2 particles remarkably enhanced wear resistance with a wear rate of 155 µm with 10N load due to reinforcements that act as the lubricating agent between the metal matrix and the rotating disc. Among the compositions studied, AA7075/5% TiB2/4% ZrO2 exhibited superior performance, highlighting the potential of tailored hybrid composites for advanced mechanical and tribological applications in automotive, aerospace and marine industries

The static and modal analysis of concrete tank filled with water

Tanks and reservoirs are structural systems designed for storing various liquids, gravels, granular or other bulk materials. Special attention is usually given to the potable water storage. Regarding the increasing scarcity of clean water and the recent lack of it in some regions worldwide, it is essential that these structures have to be carefully analysed and properly designed. Water tanks are significant architectonic works as well. They are typically constructed from steel or reinforced concrete, and most commonly, they adopt the cylindrical shape. Considering their future utilization and regarding other essential circumstances related to the site of their planned placement, they can be situated on the ground, above the ground, partially buried, or fully underground. Due to the expected static and dynamic effects, both static and modal analysis have to be carried out prior to building them up, even within the designing process. This paper provides the numerical analysis of a cylindrical surface-mounted water reservoir by using the Finite element method in Ansys Workbench. The hydrostatic pressure simulating the water acting to the wall was imposed. The static and modal analysis were carried out for empty and fully filled tank. Mutual comparison of various approaches is provided

Investigation on the characterization and modelling of Fracture Process Zone behavior in Concrete Beams subjected to Three-Point Loading Tests

The fracture behavior of quasi-brittle materials such as concrete is characterized by the presence of a fracture process zone (FPZ) that precedes the main crack. Within this zone, various mechanisms, including the formation of microcracks, crack deflection, aggregate interlocking, and crack branching, contribute to the complex nature of the fracture behavior. Traditional experimental methods and other techniques often face challenges in fully capturing the micromechanical mechanisms occurring in the fracture process.To address this challenge, numerical models have been developed in the present study to investigate the evolution mechanisms of the FPZ. These models serve as valuable tools for simulating and analyzing the intricate behavior occurring at the microstructural level during the fracture process. By complementing experimental observations, these numerical approaches provide deeper insights into the fracture behavior of quasi-brittle materials and enhance the understanding of material failure. The outcome of present investigation clearly provides the evaluation method of FPZ in concrete beams of different sizes

Evaluation of thinning behaviour under the influence of plastic hardening and surface friction during small punch test

Understanding the deformation response of the material involving thinning under small punch loading is vital to ensure structural integrity. This paper systematically investigates the effects of plastic hardening on the thinning process under different levels of surface friction between the punch, die and specimen. The small punch test conditions are modeled using Finite Element (FE) software of Abaqus. An axisymmetric model with a bi-linear constitutive material model incorporating different plastic hardening slopes is employed. Furthermore, the Coulomb’s friction coefficient between the disc-shaped specimen and the punch as well as the die varies between 0 (frictionless) to 0.7. The study found that the effect of plastic hardening on thinning process is negligible. On the other hand, the effect of thinning at the center of the specimen is significant under frictionless surface conditions. Thinning is observed to be dominant during the membrane stretching and plastic instability deformation stages. As the surface friction increases, the resistance to sliding deformation decreases. As a result, tensile instability is predicted at the location offset from the center of the specimen. Future efforts to model material behaviour and determine mechanical properties using small punch load conditions must consider the effects of friction

Numerical study of residual stress fields after double-sided symmetric laser shock peening of blade edge

This paper deals with numerical modelling of the residual stress field formed after laser shock peening of a thin blade edge from TC4. It is shown that the application of double-sided symmetric laser shock peening is an effective way of treatment, as it allows to reduce deformation and geometrical changes caused by laser shock peening in comparison with treatment from one side. The results of numerical modelling obtained by varying the machining parameters (power density, spot shape, number of passes, % overlapping) were used to form a database for further training of the neural network. It is shown which machining parameters lead to compressive residual stresses over the entire thickness of the edge, and which ones induce tensile stresses on the surface

Rolling contact fatigue of AISI 440C TiN coated by plasma based ion implantion and deposition

In this work, the microstructural evolution, surface characteristics and wear behavior of high hardness AISI 440C samples coated with a TiN film synthesized at room temperature were investigated. The coating was deposited using a combined process of plasma-based ion implantation and deposition (PBII&D). Rolling contact fatigue (RCF) tests were conducted and compared with those of the uncoated steel. Tests were carried out in a flat washer type testing rig under lubricated pure rolling conditions. The results indicate that the microstructure of the substrates remained unchanged after the deposition process. The application of the coatings produced an increase in the arithmetic average height of the roughness profiles and a change in their skewness. The adhesion of the TiN coating on AISI 440 C proved to be satisfactory. RCF test generated typical fatigue spalls in the uncoated samples. In coated samples partial delamination of the coating occurred along the rolling track. Taking partial delamination of the coating as a failure criterion, it was found that the RCF life of the coated samples was higher than that of the uncoated ones

Multidisciplinary characterisation, weathering patterns, and durability assessment of stone blocks for the conservation of Tamentfoust fort (ex. Rusguniae) in Algiers.

This study investigates the physico-mechanical properties, mineralogical composition, deterioration processes, weathering patterns, and durability of building materials in the Ottoman Fort of Tamentfoust, Algiers, to inform heritage conservation strategies. Stone block samples were taken from a highly damaged wall and, the mechanical and physical characterisation was carried out with through laboratory and on-site methods. These methods included destructive tests (compressive and flexural strength) and non-destructive techniques (Schmidt hammer rebound, ultrasonic pulse velocity, thermal imaging, density, porosity, and capillarity coefficients. Mineralogical and petrographical analyses were conducted using X-ray diffraction (XRD) and X-ray fluorescence (XRF), while durability was evaluated through sodium chloride crystallization and hydrogen chloride ageing tests, with scanning electron microscopy (SEM-EDX) analysing microstructural properties. Weathering forms were assessed and documented using 3D laser scanning, thus generating a weathering mapping for the most damaged facade. The results revealed two stone types: one with high porosity, low strength, and poor durability, and another with high compactness and excellent durability. These findings provide critical insights into material behaviour, enabling tailored preservation strategies for the fort and contributing to the broader field of heritage conservation

Investigation on the tensile strength, hardness and wear properties in n-B4C reinforced Al7075 composites

The impact of n-B4C on the mechanical and tribological behavior of Al7075 particle reinforced composites were assessed by analyzing samples of the resultant nano-composites for micro-structure, hardness, tensile strength, and wear behavior using stircasting technology. According to microstructural research, nanoparticles were dispersed throughout the specimen space. Adding the wt. % of nano B4C resulted in a considerable improvement in hardness (17.89%) and tensile strength (13.75%). Because of the cleavage that forms on the fractured surfaces of Al+n-B4C nanocomposites, fractography analysis on the fractured tensile specimens revealed brittle fracture for the n-B4C reinforcement composites and ductile fracture for unreinforced aluminum. By adjusting the process conditions, the dry sliding wear characteristics of n-B4C reinforced aluminum alloys were investigated using Taguchi's Design of Experiment Methodology. The independent process factors were determined to be the applied load (7-21N), the sliding speed (750-1250 rpm), and the reinforcement composition (0-3 weight percent of n-B4C). The L27 orthogonal array by Taguchi was selected to react based on the coefficient of friction and wear rate. The following processing parameters were determined to be optimal for the highest wear rates: 750 rpm sliding speed, 7 N load, and 3 weight percent reinforcement. Similarly, the optimal processing parameters for assessing Coefficient of Friction (COF) were determined to be 3 wt. % reinforcement, 21 N load, and a sliding distance of 1250 rpm