The mechanical characterization of welded joints is a critical step in assessing the structural reliability of stainless-steel components employed in marine, offshore, and industrial environments. Welding processes introduce significant local variations in microstructure and hardness, leading to heterogeneous mechanical properties that strongly influence fatigue life and structural performance. This study presents an integrated experimental–numerical methodology for the evaluation of local mechanical properties in AISI 316L butt-welded joints through minimally destructive hardness measurements. The approach combines two established hardness–property correlations to derive full true stress–strain curves for each region of the weld. These were subsequently implemented in a finite element model to reproduce the local and global deformation behavior during quasi-static tensile loading. Calibration was achieved using tensile tests on non-welded specimens, and a preliminary validation was conducted through Digital Image Correlation (DIC) strain measurements of both welded and base material specimens. Unlike most existing studies that focus on structural steels, this work investigates AISI 316L welds, austenitic stainless steel widely used in high-integrity applications, through a combined microhardness–FEM–DIC framework. The proposed methodology suggests the possibility to develop robust framework for correlating indentation hardness with mechanical response, offering a rapid, reliable, and potentially non-destructive route for assessing welded structures.

Direct Bonded Copper (DBC) substrates are key components in power electronic devices, due to their ability to combine thermal, mechanical, and electrical properties in a single system. They are made of a ceramic layer coupled with copper layers on one or both sides and can be subjected to thermal cycling and significant mechanical stress during operations. The difference in thermal expansion coefficients for copper and ceramic layers causes tension and compression states at interface surfaces, which can lead to delamination, with critical consequences for the reliability of the component. For this reason, the development of innovative solutions, such as the introduction of optimized patterns or dimples to improve durability, has been essential. Strain Energy Density (SED) has been used to assess how the combination of different geometric parameters affects the strain energy close to the notch tip at the interface of ceramic and copper. Machine Learning (ML) algorithms allow to investigate several geometric configurations sampled by means of Latin Hypercubic Sampling (LHS) method, which consists in extracting design variables from predefined domains, allowing the analysis of a reduced number of configurations compared to what would be done with a Full Factorial approach. Each variable’s effect on objective function is evaluated through Spearman correlation method, and the design points are defined as the minimum of the response surface obtained by numerical simulations.

The present work investigates the compressive mechanical response of three lattice structures manufactured via VAT photopolymerization. A bio-inspired architecture, derived from the observation of Euplectella aspergillum, was compared with square and triangular lattice configurations. Experimental uniaxial compression tests and multi-step nonlinear finite element analyses were carried out for each topology to highlight differences in their mechanical behaviour. The results demonstrate that the bio-inspired structure exhibits superior mechanical performance compared to conventional square and triangular geometries. Furthermore, the proposed simulation methodology proved effective for design purposes, enabling the consideration of instability phenomena and contributing to safer structural design. Finally, micromechanical modelling was employed to link the micro-architecture to the effective macroscopic properties. In particular, a micro-mechanical model allowed to predict the elastic moduli and yield strength, highlighting a stretch-dominated behaviour in elastic regime.

The ideal sintering behaviours as a semi-crystalline thermoplastic polymer makes polyamide 12 (PA12) the most widely used material for Selective Laser Sintering (SLS) printing technique. However, the presence of defects, such as partially melted particles, compromise the structural integrity of the printed components influencing their mechanical behaviours especially in terms of fatigue life. Estimating fatigue properties is a resource-intensive process, both in terms of material and time, particularly within the rapidly evolving AM industry. If the desired properties are not achieved, the manufacturing process must be restarted with adjustments to one or more printing parameters. In this context, the need to rapidly verify the mechanical properties of components has become increasingly critical. Over the years, numerous energy-based methods have been developed to expedite the study of fatigue properties in materials, thanks to the dissipative nature of the fatigue process. Among these, the Thermographic Methods (TMs) have shown simplicity of application and rapidity to obtain results. In this work the mechanical properties of PA12 specimens obtained with SLS technique have been investigated using the Risitano’s Thermographic Method (RTM) and the Static Thermographic Method (STM). The influence of the printing direction has been analysed testing two sets of specimen’s configurations. The difference in terms of energetic release during quasi-static and fatigue tests for both configurations have been highlighted and discussed. The study demonstrates the potential of thermography as a technique for evaluating the fatigue life of polymeric materials produced by SLS, opening new perspectives for quality control and optimization of AM production processes.

In contrast to traditional man-made materials, the biological structures show superior mechanical properties including high strength and energy absorption capacity. The lattice structures were obtained by additive manufacturing using VAT photopolymerisation. Three types of structures were considered: regular square, triangular and deep-sea glass sponge.This paper investigates the mechanical response of the three considered structures and the failure modes.The specific strength of the deep-sea inspired structure has the highest specific strength and energy efficency.

The objective of this work is to validate, through finite element analysis, the use of the hotspot stress and Strain Energy Density (SED) approaches for the fatigue life assessment of welded T-joints made of structural steel and Ti-6Al-4V alloy. While these methods are well established for steel, their application to titanium is less straightforward due to the absence of material-specific FAT curves and SED scatter bands for welded configurations. To enable the application of the hotspot stress method to titanium joints, a preliminary approach based on the normalization of steel FAT curves with respect to the Young’s modulus was implemented. The SED method was instead applied by adopting the control radius and design curve derived for the base material. Both methodologies proved to be reliable for steel joints, whereas in the case of titanium, the results emphasized the limitations of these approaches and the need for further experimental data to establish suitable design references.

The mechanical behaviour of AISI 316L stainless steel manufactured via Direct Metal Laser Sintering (DMLS) was evaluated in both non-welded and welded conditions. The investigation integrated tensile testing, Vickers microhardness mapping, and thermographic monitoring with detailed post-fracture observations. To bridge the gap between global tensile response and localized performance, local true stress-true strain curves were reconstructed from hardness data using the Lopez-Fatemi and Kamaya analytical approaches. This allowed for a local assessment of the base material (BM), heat-affected zone (HAZ), and weld metal (WM). Results indicate that welding significantly degrades the overall mechanical performance and introduces pronounced local gradients, characterized by a progressive decrease in hardness and strength from the BM toward the WM. These findings, further supported by thermographic and fracture analyses of distinct deformation and failure mechanisms, provide a critical experimental foundation for the development of accurate non-linear finite element models.

Accurate assessment of bone strength is critical for predicting fracture risk, particularly in load bearing regions such as proximal tibia. In this study, we developed and validated a voxel-based finite element (FE) modelling approach to estimate the mechanical strength of the proximal tibia in the context of Schatzker Type II tibial plateau fractures. CT scans of twenty-two cadaveric tibiae were used to construct subject-specific FE models incorporating density-based heterogeneous material properties. Both linear and non-linear FE simulations were performed and compared with experimental failure loads obtained from mechanical tests. The linear FE model, using the Pistoia criterion to estimate bone strength, showed weak correlation (R2 ranging from 0.18 to 0.53) with experimental results and tended to overestimate the failure load with a bias of 1.59 kN. In contrast, the non-linear FE model, incorporating elastic-plastic material behaviour with damage softening, yielded improved predictions with a mean bias of -0.12 kN. Also, the non-linear model demonstrated strong agreement with experimental observations, accurately capturing strain localization that closely matched the actual fracture path. This study demonstrates that voxel-based mesh approach offers the ability to quantify tibial bone strength. It utilizes a highly automated and time-efficient workflow, potentially enhancing fracture risk prediction in clinical practice.

AISI 316 is a stainless steel known for its exceptional corrosion resistance and excellent mechanical properties. It is used in the chemical and pharmaceutical industries, food processing equipment, and medical devices. This alloy’s wide range of applications underscores its importance in industries requiring materials that can withstand extreme conditions while maintaining structural integrity and performance. Additionally, the excellent weldability and formability of AISI 316 allow for versatile design and production processes, ensuring durable and reliable performance in marine environments. This work aims to examine the behavior of AISI 316L and its welded joints under high-cycle fatigue loadings using infrared thermography (IR). Two kinds of experimental tests are performed on specimens with the same geometry: static tests and stepwise succession tests. The results of the static tests are in accordance with the stepwise succession test results in predicting the fatigue properties.

The increasing demand for environmentally friendly materials has driven researchers and industries to explore alternatives that combine performance with reduced environmental impact. In this framework, the possibility of replacing glass-fibre-reinforced composites (GFRCs) with basalt-fibre-reinforced composites (BFRCs) is attracting increasing attention. In this study, basalt–vinyl ester specimens and glass–vinyl ester specimens were mechanically characterized using both the Risitano Thermographic and Static Thermographic Methods. The results indicate that energy methods are effective for the mechanical characterization of complex materials like basalt and glass fibre composites. The average ultimate tensile strength was 374 ± 20.2 MPa for BFRCs and 295 ± 4.7 MPa for GFRCs, showing a 26.7% improvement with basalt. The fatigue limit was 96.5 ± 0.2 MPa for BFRCs and 104.8 ± 0.8 MPa for GFRCs, while the static stress limit estimated via thermography was 99.9 ± 6.45 MPa and 101.7 ± 5.24 MPa, respectively. Furthermore, the failure mechanisms of both BFRC and GFRC specimens were investigated. Additionally, a Life Cycle Assessment (LCA) was performed to evaluate the environmental impact of basalt and glass fibre composites. The results showed that BFRCs have lower environmental impacts, including 0.67 kg CO2-eq with respect to climate change versus 0.81 kg CO2-eq for GFRCs. This work highlights how the two materials are comparable in terms of their mechanical performance but different in terms of their sustainability and environmental impact.

The Mock Circulation Loop is a mechanical system designed to mimic the cardiovascular system in vitro. Its primary purpose is to conduct tests on various cardiovascular support devices. This becomes particularly crucial due to the insufficient availability of heart donations compared to the demand. In vitro testing using the MCL enables the anticipation of potential physiological scenarios, allowing the surgical team to practice by simulating critical situations that may arise, without causing harm to individuals. The MCL must accurately reproduce the pulsatile nature of the atria and ventricles, vascular resistance, fluid inertia, compliance of blood vessel walls, as well as pressure, flow, and volume of fluid. This study aims to develop a mathematical model of the MCL to identify optimal input parameters for assisting in the design and construction of a physical MCL in a Simulink/MATLAB environment. To achieve this goal, equations have been formulated to divide the physical system into ten subsystems, representing the four heart chambers, systemic and pulmonary circulation for both arteries and veins, and two regulators to control ventricular contraction. Once the pressure and flow equations are derived, they are incorporated into the model alongside input parameters such as conduit and chamber lengths and diameters and regulators pressure. With the model established, conducting parameter variations becomes a straightforward task, enabling the execution of repetitive simulations to analyze the system frequency response across different scenarios, rest and heart failure. This iterative approach serves as a crucial step towards utilizing the mathematical model as a basis for constructing a physical Mock Circulation Loop.

The aerodynamic performance of racing motorcycles plays a crucial role in improving speed, stability, and rider control under dynamic conditions. While most existing studies focus on front-mounted winglets and fairing extensions, the aerodynamic role of rear fairing appendages remains comparatively unexplored despite their potential influence on drag, downforce distribution, and wake behaviour. In this work, three alternative rear winglet configurations were parametrically designed in Siemens NX and systematically evaluated within a validated CFD framework based on Simcenter STAR-CCM+, with the aim of assessing how geometric variations influence aerodynamic performance and achieve a favourable trade-off between reduced aerodynamic resistance and enhanced rear downforce. The numerical setup employed has been previously validated against wind-tunnel measurements in similar aerodynamic applications, ensuring the reliability and accuracy of the predicted flow fields. A Design Space Exploration (DSE) was performed through an automated multi-software workflow, enabling systematic variation in key geometric parameters and real-time assessment of their aerodynamic effects. The study revealed distinct influences of the different configurations on drag and lift coefficients, as well as on wake structure and flow detachment, highlighting the critical aerodynamic mechanisms governing rear stability and flow closure. Through iterative design and simulation, the workflow identified the most effective configuration, achieving a balance between reduced aerodynamic resistance and increased downforce, both essential for competitive racing performance. The results demonstrate the potential of integrating parametric modelling, automated CFD simulation, and DSE optimization in the aerodynamic design phase. This methodology not only offers new insights into the scarcely studied rear aerodynamic region of racing motorcycles but also establishes a replicable framework for future developments involving advanced optimization algorithms, experimental validation, and wake-interaction analyses between leading and trailing riders.

Infrared (IR) thermography is increasingly recognized as a powerful diagnostic tool in the field of fuel cells, where technical and economic challenges hinder large-scale diffusion. This study presents two novel methodologies based on IR thermography as a tool to address two critical aspects of fuel cells: the uniformity of catalyst deposition on the electrode surface and the detection of hydrogen leaks to the ecternal environment. The first method is based on the exothermic reaction of a reactive H2/N2 gas mixture on the catalyzed electrode surface, where the thermal response is correlated with local platinum content. The second method enables localization of hydrogen leaks based on the heat generated by the catalytic reaction between hydrogen and ambient air on an active tracer surface. Both methodologies are non-destructive, cost-effective, automatable and suitable for quality assurance in both production and operational contexts. These results expand the diagnostic capabilities of IR thermography and support its integration into next-generation fuel cell development and manufacturing workflows.

Hydrogen leakage in Proton Exchange Membrane (PEM) fuel cells poses critical safety, efficiency, and operational reliability risks. This study introduces an innovative infrared (IR) thermography-based methodology for detecting and quantifying hydrogen leaks towards the outside of PEM fuel cells. The proposed method leverages the catalytic properties of a membrane electrode assembly (MEA) as an active thermal tracer, facilitating real-time visualisation and assessment of hydrogen leaks. Experimental tests were conducted on a single-cell PEM fuel cell equipped with intact and defective gaskets to evaluate the method’s effectiveness. Results indicate that the active tracer generates distinct thermal signatures proportional to the leakage rate, overcoming the limitations of hydrogen’s low IR emissivity. Comparative analysis with passive tracers and baseline configurations highlights the active tracer-based approach’s superior positional accuracy and sensitivity. Additionally, the method aligns detected thermal anomalies with defect locations, validated through pressure distribution maps. This novel, non-invasive technique offers precise, reliable, and scalable solutions for hydrogen leak detection, making it suitable for dynamic operational environments and industrial applications. The findings significantly advance hydrogen’s safety diagnostics, supporting the broader adoption of hydrogen-based energy systems.

Most failures in engineering components and structures are determined by the fatigue phenomenon, known for being lengthy to be experimentally investigated and challenging to be properly accounted in design. These aspects can represent a barrier for companies working on the edge of new technologies due to the duty and need to ensure reliability for their products. This study aims to propose a methodology to couple the economic and sustainability advantages of Thermographic Methods in investigating the fatigue behaviour of materials with those of local approaches to provide a simple, yet reliable, fatigue design tool. To pursue this aim we intentionally conducted in the present paper the minimum required experimental campaign needed by Thermographic Methods to achieve the basic information to calibrate a local approach, the Strain Energy Density one. The proposed methodology has been satisfactorily validated by applying the calibrated local approach to foresee the fatigue behaviour of a vast experimental database, characterized by a variety of notched geometries, retrieved from literature.

In the modern industrial context, many manufacturers design universal testing machines (UTMs) equipped with servo-hydraulic or electromechanical linear actuators, which offer excellent control capabilities and high-quality force signal measurement, at the expense of high costs due to the need for hydraulic power units or dedicated electrical networks. The complexity of these systems discourages manufacturers of mechanical components, especially the ones produced through additive manufacturing (AM), from investing in machines for the determination of mechanical properties according to international standards, settling instead for information derived from technical datasheets of the base material (filament or powders), which rarely include information about fatigue life. Within this context, the Fast Fatigue Machine (FFM), designed by KnoWow srl and ItalSigma srl, makes mechanical characterization of materials a process accessible to any organization that may require it. This was made possible by designing a pneumatic benchtop testing machine with a built-in setup for Thermographic Methods (TMs) usage. The aim of this work is to validate pneumatic actuators as a viable alternative to servo-hydraulic systems, demonstrating their effectiveness and reliability. Frequency analysis on both sinusoidal waveforms, root mean square error (RMSE) evaluation, and percentage total harmonic distortion (THD%) calculations showed that, while the servo-hydraulic system closely follows the load signal with a THD of around 5%, regardless of the applied load intensity, the pneumatic system exhibits higher distortion (THD of approximately 9%, strongly dependent on the load levels) and a high-frequency harmonic component, which, however, does not affect the overall results. Life cycle assessment (LCA) analysis confirmed the convenience of the pneumatic system and TMs in material testing and fatigue characterization.

Additive manufacturing (AM) is a production process that allows the creation of customizable devices which could satisfy modern industry requirements.The aim of this work is to study the mechanical behaviour of PA12 filament reinforced with 15% of carbon fibres, obtained by Fused Deposition Modelling (FDM) process, to evaluate the influence of 3D printing machine on material behaviour, and to estimate fatigue limit through energy methods.Mechanical characterization tests were performed using an innovative testing machine, patented by University of Messina’s academic spin-off Knowow and designed in collaboration with ItalSigma srl., called Rapid Fatigue Machine (RFM) crafted to use IR thermography and DIC analysis on the specimen. Results demonstrate that the stress limit estimated by Static Thermographic Method is related with fatigue limit estimated by Risitano’s Thermographic Method. The results reveal a good approximation between the fatigue behaviour studied with energetic methods and the fatigue life determined with classical methods.

Additive manufacturing (AM) allows the creation of structural components adopting several printing strategies and materials. Polyamide-12 (PA12) obtained by MultiJet-Fusion (MJF) printing process is taking place as one of the most adopted materials on the market, offering fast, economical and large production of functional parts which can undergo to several loading conditions, including fatigue. It was observed how MJF PA12 mechanical properties are characterized by wide dispersion associated with large processing window of this novel technology. Although the fatigue life of this material and the aging effect on its mechanical properties have already been investigated, there are no studies on aging influence on fatigue life. In the present work, two sets of PA12 specimens obtained by MJF technology, stored under ambient conditions, were tested after 90 days. Tensile properties were evaluated adopting DIC analysis while infrared camera was adopted to monitor the energy release of PA12 during quasi-static monotonic tensile and fatigue test conditions. Constant amplitude fatigue tests and stepwise fatigue tests have been carried out to investigate material's fatigue life. A novel and rapid approach, compared to fatigue test campaign prescribed by standards and staircase methodology, was adopted applying the Risitano's Thermographic Method and the Static Thermographic Method. They allow fast fatigue characterization providing reliable information, useful for mechanical design, monitoring the material behaviour over time rapidly. Experimental observations and comparisons with previous studies about HP PA12 MJF lead to validation of Thermographic Methods as a tool for rapidly monitoring fatigue properties of material subject to physical aging phenomena.