Italian Group Fracture (IGF): E-Journals / Gruppo Italiano Frattura
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Experimental calibration of a virtual raster section for high-accuracy FDM simulation in Abaqus
Full text linkThis study presents an experimentally calibrated methodology to enhance the predictive accuracy of finite element simulations for Fused Deposition Modeling (FDM) parts in Abaqus by replacing idealized filament geometry with a physically accurate “corrected virtual raster section.” A Box-Behnken Design of Experiments (DoE) across 27 ABS specimens systematically quantifies how key printing parameters, layer thickness, raster width, extrusion temperature, and print speed, influence the true cross-sectional geometry of deposited filaments, as measured via Scanning Electron Microscopy (SEM). These data inform a predictive mathematical model that transforms the conventional circular filament shape into an experimentally grounded oval-rectangular profile, accurately capturing extrusion-induced flattening and lateral spreading. The calibrated virtual section is integrated into a custom Python-based tool that parses G-code toolpaths and sweeps the corrected geometry along deposition trajectories to generate high-fidelity, mesh-ready Abaqus models. The workflow is validated through tensile testing of ASTM D638 specimens printed at 0°, 45°, and 90° raster orientations (n=3 per orientation). Error analysis against the experimental mean demonstrates that the corrected model reduces simulation errors from catastrophic levels in the non-corrected approach (7–92% relative error, 2.5–19 MPa absolute) to engineering-grade precision (0.03–7% relative error, ≤1.3 MPa absolute). This workflow bridges G-code to physical behavior, enabling reliable simulation of FDM anisotropy
Seismic performance of steel frames with a hybrid bracing system combining concentric steel bracing and friction dampers
Full text linkThis paper assesses a hybrid bracing system involving concentric steel bracing in combination with friction dampers to improve seismic performance in steel moment frame buildings. Three prototype (5, 10, and 15 stories) steel moment frame configurations were analyzed under a nonlinear time history and pushover sequences as per performance-based design procedure, to examine the effects of the without, brace-only, damper-only, and hybrid systems. The hybrid system is most effective in decreasing roof displacement and story drift for all height configurations, with the maximum drift reductions of approximately 59% for the base brace system in the 5-story frame, while maintaining the optimal reductions of 15% - 31% (displacement) and 40% - 48% (drift) in 10- and 15-story frames. The hybrid method, unlike a brace-only solution, which can intensify the response of a tall structure through shortening of the periods of the oscillation and resonance, and damper-only solution, which lacks a stiffness control, is composed of both: initial stiffness and stable frictional energy dissipation. For taller frames, damping due to the vertical difference in load and slip should be taken into account, and then the suspension distribution should be adjusted to account for these higher mode effects
Numerical assessment of the seismic vulnerability of the historical earthen remains of the Mansourah enclosure (Tlemcen, Algeria): influence of geometry and identification of critical damage zones
No full textThis work primarily aims to carry out a numerical assessment of the seismic vulnerability of the historical Rammed Earth (RE) remains of the enclosure of Mansourah, a small town in the Wilaya (Province) of Tlemcen, in northwestern Algeria. For the purpose of successfully conducting this work, it was deemed appropriate to consider six geometric configurations, which were analyzed using three-dimensional finite element models developed in ANSYS with elastoplastic behavior based on the Drucker-Prager criterion. Two seismic excitations were applied successively along the two orthogonal horizontal directions X and Y. In addition, the analysis essentially focused on five major physical indicators, i.e. the principal tensile and compressive stresses, equivalent stress, equivalent plastic deformation, and maximum displacement. The results showed a spatial coherence of the critical zones that are most exposed to damage, for all the cases studied. These zones are located mainly at the base of the intermediate walls, at the ends of the free walls, and in the thickness transition zones of the walls constituting the towers. The vulnerability classification, from the most critical to the most stable case, was found to be as follows: Structure 05, 04, 01, 03, 02, 06. These findings facilitate the orientation and prioritization of strategies for the reinforcement and preservation of historic monuments built with RE
Rolling contact fatigue of AISI 440C TiN coated by plasma based ion implantion and deposition
No full textIn 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
An innovative analytical approach for predicting the fundamental time period of moment-resisting frames
Full text linkMost seismic design codes provide formulas for estimating base shear and lateral loads. To determine lateral loads, the building's fundamental vibration period must be calculated, either theoretically or experimentally. However, there is no simplified equation that accurately calculates this parameter. This paper proposes a new simplified formula for computing the fundamental period of reinforced concrete moment-resisting frames (MRFs). The proposed formula is validated through eigenvalue analysis of the mathematical models of various building frames using finite element methods (FEM), with varying structural properties along their height. The proposed model achieved an average prediction error of around 4% and an R² (coefficient of determination) value of 0.999 when compared to FEM results, outperforming existing empirical formulas. A sensitivity analysis was conducted to identify the effect of each of the design parameters, accompanied by a comparative evaluation against some formulas from the literature. The novelty of the suggested method is that it can calculate the fundamental period more accurately and easily by considering the stiffness and seismic mass of the building
Correlation Between Process Parameters and Mechanical Properties of Ti6Al4V Alloys Processed by Electron Beam Melting
Full text linkThe present study of Ti6Al4V alloy production via Electron Beam Melting (EBM) represents a cutting-edge research topic impacting different strategic engineering applications. This can be attributed to the widespread use of this alloy and by the unique characteristics of the EBM process. Operating under vacuum and with powder pre-heating, EBM enables the fabrication of components with higher density and reduced residual stress compared to other additive manufacturing techniques. The research reported in this paper analyses the effect of process parameters used in the manufacturing process on defect formation and then on mechanical properties. The results highlighted that the presence of lack of fusion defects leads to a markedly anisotropic behavior of the alloy. This is due to the different morphology of the defects in the different considered directions and to their effect in concentrating stresses
Numerical and experimental analysis of mechanical and fatigue properties of special shaped 3D printed sample
Full text linkResearch in the field of property analysis of 3D printed structural elements raises many new questions. A major challenge is to understand the behavior of the material, as the raw material and the resulting printed sample cannot be considered the same in this respect. In 3D printing, the properties of the sample change due to high temperatures, changes in the state of the raw material and different setups. Currently, there is no standard for determining certain properties, which leads to the need for appropriate use of experimental and numerical tools. This study highlights the results of tensile testing and numerical analysis of a special 3D printed shape. Different material settings were used to allow a complete inverse analysis of the specimen behavior and calibration between experiment and model. The model was created in Ansys software and was prepared in several variations to be as close as possible to the real specimen. Subsequently, the numerical model was subjected to a simplified fatigue analysis with respect to the S-N curves and the predicted fatigue life of the specimen was determined
Flood-induced load effects on real-scale structures: a 3D multilevel dynamic analysis
Full text linkIn this work, the structural behavior of masonry buildings under flash flood actions is analyzed by using a novel 3D multilevel fluid/structure model. The proposed numerical framework consists of a macro-scale model based on the computational fluid dynamic, able to simulate the dynamic free-stream flow of a fluid impacting rigid solids and a meso-scale structural model that employs a coupled damage-plasticity approach to describe the nonlinear behavior of the masonry buildings, subjected to the fluid dynamic pressure extracted by the macro-scale fluid analysis. The integrated model was employed to assess the fluid-structure interaction effects on the global structural response, in terms of load-carrying capacity and damage patterns, of a real-scale masonry structure subjected to flood-induced loading conditions. Finally, a parametric analysis is performed in order to understand the influence of the fluid inlet velocity and water depth on the failure mechanisms of the structure. The results highlight the good numerical capabilities of the proposed multilevel model, establishing it as a valuable numerical tool for the structural vulnerability assessments under flood actions
Prediction of crack length in thin-walled plates under different mode conditions using machine learning algorithms
No full textThis study uses theoretical stress intensity factor data to assess how well machine learning models predict crack length. Thin-walled damage plate under various modes was evaluated based on the theoretical relation. Using theoretical data, this study implemented various ML algorithms to determine the most accurate model for thin-walled crack length prediction. The prediction/true class was used to assess each algorithm using an evaluation matrix, and each class was divided into four levels of crack length for testing and training data. According to theoretical results, SIF increases as the crack length increases, which shows that higher crack lengths cause the structures. The ability of ML algorithms trained on theoretical data to predict crack length using SIF values is investigated in this work. To estimate crack length in thin-walled structures under Mode I, Mode II, and Mode III conditions, the current work successfully evaluated the accuracy in predicting the crack length using ML algorithms. By eliminating the need for experimental/theoretical trials, the suggested ML algorithms not only simplify the process of identifying important input parameters but also provide cost-effective approaches. Finally, the results demonstrate the algorithms’ ability to yield accurate predictions
Studies on influence of seashell-based filler on water absorption behaviour of bamboo-epoxy composite: mechanical and fractured surface characterization
Full text linkThe hydrophilic nature of bamboo fiber makes them prone to moisture uptake and subsequent property degradation. In this study, bamboo fiber–epoxy composites were hybridized with clamshell-derived particulate fillers to mitigate the adverse effect of moisture absorption and enhance performance. Composites with 0, 3, 6, and 9 wt% filler were fabricated via compression molding technique. Moisture absorption and its influence on tensile and flexural strength were evaluated following ASTM standards. Results revealed that unfilled composites exhibited highest water uptake and severe strength loss upon moisture exposure, whereas filler addition reduced water uptake and improved strength retention. The 6 wt% filler showed optimal performance with 30.4% reduction in water uptake, 67.5% retention of tensile strength, and 70% retention of flexural strength. Fractography analysis confirmed the role of filler acting as a barrier against moisture ingress and restricting interfacial degradation