Manufacturers are continuously seeking advanced materials that can enhance the performance and durability of mechanical assemblies, particularly those employing shrink-fit technology, which has become increasingly important in modern mechanical engineering due to its precision and reliability. This study focuses on improving the materials used for critical components such as axis and hub, which are traditionally made of steel or aluminum. Recognizing the limitations of conventional metals in terms of strength-to-weight ratio and thermal stability, this research explores the use of composite materials reinforced with graphene, a nanomaterial known for its exceptional mechanical and thermal properties. The investigation involved fabricating steel samples with varying graphene concentrations and testing their mechanical performance under shrink-fit assembly conditions. The findings revealed a clear and consistent enhancement in strength as the graphene content increased. Specifically, the maximum stress value reached 270.8 MPa with a 15

Shrink-fit assembly is one of the simplest and most cost-effective assembly methods, requiring only two components and having been in use for many years. The principle is based on the outer diameter of the shaft being larger than the inner diameter of the hub. This method is widely applied in industries such as automotive, aerospace, and gas and oil pipeline construction. Assembly is achieved by heating the hub, cooling the shaft, or applying mechanical force. Although this contact interface is often assumed to be ideal, in reality it contains a variety of form defects that differ in amplitude and frequency. The aim of this study is to demonstrate the importance of accounting for both form defects and interference in order to reduce manufacturing costs. Using numerical simulations with ABAQUS, samples with varying amplitudes and wavelengths of form defects, as well as different interference values. The results showed that the von Mises stress in the presence of form defects reached 450 MPa. While it is less than 410 MPa in the absence of a shape defect. These findings confirm the necessity of considering form defects in shrink-fit assemblies, enabling cost reduction by avoiding unnecessary surface smoothing.

A two-dimensional dimensionless model is developed to investigate heat transfer during the melting of a pure phase change material (PCM) confined in a horizontal rectangular cavity. The model describes isothermal solid–liquid phase change in the presence of natural convection and is formulated using the momentum and energy conservation equations. To avoid explicit tracking of the moving solid–liquid interface, an enthalpy–porosity approach is employed, allowing the governing equations to be solved over the entire computational domain on a fixed grid. The finite volume method is used for spatial discretization, and a FORTRAN code based on the SIMPLER algorithm is implemented to simulate the melting process. Fluid motion in the solid region is suppressed through a porosity function linked to the local liquid fraction. After validation, a parametric analysis is performed to evaluate the effects of interpolation schemes, Fourier number, PCM subcooling, and liquid-phase superheating on melting dynamics and thermal energy storage. The results reveal that these parameters significantly influence melting behavior and storage performance. A predictive correlation for the dimensionless liquid volume during gallium melting is also proposed.

This study aimed to characterize the vibrational behavior of damaged Carbon Fiber-Reinforced Polymer (CFRP) plates repaired with adhesively bonded composite patches. The primary goal was to evaluate the repair’s effectiveness in restoring dynamic properties, with a specific focus on damping performance and the influence of patch characteristics. The research combined experimental and numerical methods. First, the mechanical properties of the materials were determined through tensile and three-point bending tests. Experimental modal analysis was then conducted using an impact hammer and accelerometers to obtain Frequency Response Functions (FRFs) for intact, damaged, and repaired plates under free-free and clamped-free boundary conditions. These experimental results were used to validate a finite element model developed in ABAQUS to simulate the dynamic response and analyze stress distributions. The results demonstrated that the patch repair significantly enhances structural damping, with a measured damping coefficient of approximately 0.32. The natural frequencies decreased for damaged plates but were partially restored after repair. The CFRP patch with a (45/-45) ply orientation was found to be the most effective configuration, exhibiting superior vibration damping and the lowest stress concentrations in the adhesive layer—20

Shrink-fit assemblies are widely used in rotating machinery due to their structural simplicity and high torque transmission capability. While conventional designs employ solid shafts, lightweight engineering applications increasingly require mass reduction without compromising mechanical integrity. Although analytical and numerical studies have extensively investigated interference fits, the combined influence of hollow shafts and form defects on stress distribution and contact behavior remains insufficiently explored. This study investigates the mechanical performance of shrink-fit assemblies incorporating either solid or hollow shafts, considering periodic form defects at the hub interface. A theoretical formulation based on Lamé’s equations is combined with two-dimensional finite element simulations performed in ABAQUS. A sensitivity analysis was conducted by varying the interference fit (0.02–0.08 mm) and the cavity radius ratio (0.3–0.6) to evaluate the robustness of the assembly response. The results indicate that introducing a central cavity reduces shaft mass by up to 25

This study numerically compares the performance of circular and elliptical hydrodynamic journal bearings in the presence of misalignment. A finite element method, applied to the Reynolds equation, was used to analyze the influence of variations in load, speed and misalignment angle on the main characteristics of these bearings. The results show that elliptical bearings are clearly superior to circular bearings under misalignment conditions. Specifically, the minimum film thickness of the elliptical bearings was approximately 10.56

Purpose This study aims to design a damage detection and characterization system (targeting cracks and delamination) for aeronautical composite structures. Design/methodology/approach This methodology relies on a multidisciplinary approach combining polymer-reinforced/metallic carbon fiber hybrid structures with an integrated network of PZT sensors. It leverages experimental data and employs advanced signal processing and imaging techniques to monitor structural integrity and assess the severity of damage. Findings Verified experimental results confirm the method's reliability in real-life situations. Research limitations/implications Research Limits: “The primary challenges involve signal processing complexity due to the hybrid nature of AL7075-T6 and CFRP materials, as well as the potential influence of environmental factors (temperature, pressure) on PZT sensor reliability”. Research Implications: “This work enables a shift toward condition-based maintenance, significantly reducing operational costs while enhancing structural safety and extending the service life of critical aerospace and maritime assets.” Practical implications This study enables a shift from scheduled to real-time structural monitoring. There is a drastic reduction in inspection time and aircraft downtime. Monitoring the fatigue of hybrid AL/CFRP structures helps to safely extend their service life. The study helps in providing precise diagnostics to optimize repair strategies and minimize human error. Social implications There is a drastic reduction of structural failure risks through early-stage damage detection. Cost savings in maintenance can lead to more affordable air travel for the general public. The study helps in promoting a circular economy by safely extending the lifespan of complex structures and reducing material waste and also in shifting maintenance roles toward high-tech data analysis and specialized software expertise. Originality/value The study investigates the complex damage mechanics at the interface of AL7075-T6 and CFRP laminates and helps in combining PZT sensor networks with advanced imaging software for real-time damage characterization. Beyond mere detection, the system assesses “structural criticality,” providing high-value diagnostic data for maintenance optimization and cost reduction.

In this study, we present an experimental and numerical analysis of single-stepped-lap joint (SSLJ) and single-lap joint (SLJ) assemblies made from carbon/epoxy composites (CFRP). The study aims to evaluate the impact of joint geometry and substrate thickness (2.0 mm and 4.0 mm) on the mechanical behavior and structural integrity of the joints. CFRP composite plates were machined using CNC milling and then bonded using a structural epoxy adhesive before being subjected to tensile testing. A three-dimensional finite-element model in Abaqus, incorporating cohesive zone modeling (CZM) for the adhesive and the LaRC05 criterion coupled with the extended finite element method (XFEM) for the composite substrate, was developed. The numerical predictions show very good agreement with the experimental data. The results show that the stepped joint (SSLJ) consistently outperforms the conventional SLJ joint, increasing the ultimate load at failure by 11.15% for a thickness of 2.0 mm (reaching 7,584 N compared to 6,823 N for the SLJ). This improvement is due to better alignment of the load line and a reduction in the secondary bending moment (Goland and Reissner effect). Conversely, increasing the substrate thickness from 2.0 mm to 4.0 mm results in a gradual reduction in ultimate strength for both configurations (a decrease of 4.13% for the stepped joint and 6.36% for the SLJ). Although a thicker substrate increases the overall flexural stiffness of the plate outside the joint, the increased eccentricity of the load accentuates the local out-of-plane bending moment and intensifies the combined stresses at the ends of the adhesive joint. The LaRC05/XFEM model accurately captured the transition from cohesive failure of the adhesive to localized delamination of the substrate. This work demonstrates that the stepped configuration, combined with an optimal substrate thickness of 2.0 mm, offers the best mechanical performance.

This study numerically investigates the impact of optimal textures location on the performance of hydrodynamic porous self-lubricating journal bearings with sealed ends, subjected to a stationary load. The analysis employs a modified Reynolds equation coupled with Darcy’s law to model fluid flow in both the lubricating film and the porous matrix, considering the hydrodynamic self-lubrication problem. The governing nonlinear PDE systems were solved numerically using the finite difference method, combined with Reynolds boundary conditions and continuity conditions for velocity and pressure at the film-bush interface. A Binary Genetic Algorithm (BGA) is employed to optimize the topological distribution of square dimples in the textured porous layer to enhance bearing performance. The study investigates the influence of key parameters, including applied load, rotational speed, permeability, and texture depth, on bearing characteristics such as minimum film thickness and friction coefficient. Results show good agreement with benchmark data and indicate a positive enhancement in porous bearing performance. In addition, findings demonstrate that increasing the permeability of the porous structure reduces bearing performance (up to 25% in minimum film thickness and 8% in friction coefficient). However, the application of the optimization technique identified an optimal arrangement of textures that compensates for these performance losses, even under severe working conditions. Texturing the outlet region of the contact (beyond 180°) at the cavitation zone causes a micro-step bearing mechanism, generating localized pressure recovery within the textured area, significantly enhancing the minimum film thickness (up to 12%), reducing friction (up to 23%), and minimizing cavitation (up to 24%).

The main objective of this work is to characterise sandwich panels with carbon/epoxy composite skins and cores of different materials (Expanded polystyrene foam, polyurethane foam injection and polyurethane foam sample) under three-point bending tests in free/free vibration and under repeated impact. The analysis of the behavior of the different sandwich panels under bending and vibration aims to determine the flexibility or stiffness of these panels. However, the analysis under repeated impact aims to determine the failure modes and the strength of the three sandwich panels. Indeed, the damage analysis was carried out using piezoelectric sensors connected to an acquisition chain using an advanced signal processing technique, which allows precise detection and quantification of damage. Using piezoelectric technology, this detection system ensures structures’ safety and reliability by allowing early and accurate detection of potential damage. Indeed, relying on piezoelectric sensors bonded to sandwich panels to capture vibration responses can improve its safety, thus reducing maintenance costs and ensuring an extension of its service life. The results of the various tests showed that carbon fibre resin matrix composite skin offers good protection to the different types of cores used in the sandwich panels. In addition, the composite sandwich panel with an expanded polystyrene core responded better than the other panels in bending and vibration tests. In repeated impact tests, the composite sandwich panel with foam core and the composite sandwich panel with injected polyurethane foam core proved effective in absorbing initial impacts. On the other hand, the sandwich panel with an expanded polystyrene core showed its ability to absorb repeated impacts while ensuring more extended degradation than the other two sandwich panels.

The significance of this work lies in the application of the XFEM method to the fatigue analysis of a helicopter's main rotor pitch links, which are responsible for transmitting motion from the swashplate to the blade. This research combines both experimental and numerical methods to systematically investigate the defect-position and size study validated by experiments on AISI 1045 steel on the pitch links. We conducted tensile and fatigue tests on specimens made of AISI 1045 steel to provide data for validating the numerical model. Furthermore, we used a 3D finite element method in ABAQUS to evaluate residual stresses and deformations, and finally, we determined the SIF by applying XFEM to a fatigue crack in the rod. The variation of SIF with crack length enabled the prediction of fatigue life based on Paris's law. At the beginning of this work, we performed a heat treatment, finding that tempering is crucial for improving the mechanical properties of AISI 1045 steel by relieving internal stresses. While tempering at 350 degrees C yields the optimum tensile strength (approximately 1490 MPa), using higher temperatures, up to 550 degrees C, significantly reduces this strength (by up to 36\%). In the second part, the results successfully confirmed the accuracy of the numerical model in simulating the experimental stress-strain curve. Fatigue tests showed that XFEM effectively matched numerical predictions, highlighting the influence of stress state and cyclic load levels on fatigue life. Crack position and depth were linked to the number of cycles to failure and SIF variations. Following this study, the AISI 1045 steel model was deemed suitable for a helicopter main rotor control rod.

Turbine blade performance degrades under dynamic stresses from high temperatures and vibrations. design is challenging due to material limitations. Designers must minimize stresses, especially centrifugal forces, within acceptable material limits. the complex nature of these blades requires a seamless integration of design, material selection, and manufacturing processes to achieve the highest performance. thus, graded material properties are essential to control their behavior and ensure the longevity of the turbine blades during operation. this project aims to develop novel metal/ceramic functionally graded material (fgm) blade designs to enhance the lifespan of gas turbine rotors. A numerical study using the mesh method (umm) with the abaqus code will produce a 3d graded multifunctional material with controlled strength under different loading conditions. Our numerical analyzes of the behavior of a blade was carried out in two parts. The first studies the static behavior, using the tto homogenization method to define the elastoplastic zone of the fgm and a damage criterion for the fgm up to failure via the xfem technique. The second part analyzes the vibration behavior of the blade, considering various parameters such as the direction of the distribution of the fgm’s material properties according to thickness, and the effect of combinations of metals and ceramics, characterized by the exponent n of the power law. Numerical analyses using abaqus code for the metal model were validated experimentally. Analyzes of the fgm design has confirmed its validity in relation to the metal model. The results emphasize the importance of the distribution of material properties in fgm blades that significantly affect the stress distribution and modal analysis.

This paper presents an experimental and numerical study on the low-energy impact fatigue and bending behavior of sandwich panels reinforced with composite laminate glass and carbon fabric facesheets, supported by a honeycomb core made of Nomex. The crushing behavior of honeycomb sandwich specimens subjected to the impact test was compared and discussed. Our results indicate that the carbon composite facesheets have a significant effect on the impact, resulting in an increase in impact resistance and a 157.14% increase in crack depth in the elastic region compared to glass facesheets reinforcement. This increase serves as an indicator of the laminate's ability to resist damage initiation and impact fracture mechanisms. Also, an increasing in flexural strength about 45.72% was observed in carbon facesheets honeycomb specimens compared to glass facesheets reinforcement. Microscopic illustration of the damaged honeycomb sandwich specimens was conducted to evaluate the interfacial characteristics and describe the damage mechanics of the composite facesheets and core adhesion under the impact test. The numerical approach proves to be efficient in terms of accuracy and simplicity compared to existing methods for predicting the damage mechanisms of honeycomb sandwich structures. It was noted that results of numerical study show best agreements with experiment results and the model can be used to predict the low-energy impact fatigue.

Since the implementation of repair processes by composite patch bonding, this process has consistently demonstrated high performance across various industrial sectors, especially in the fields of aeronautics, aerospace and civil engineering. Consequently, there are situations in which the riveting process becomes the sole solution, particularly when the structure is subjected to severe mechanical or thermo-mechanical stresses, since adhesives have low mechanical strength after aging. Each method has its own set of advantages and disadvantages. The current trend is to combine these two processes to minimise their drawbacks as much as possible. The objective of this work is to present an experimental study on the repair of an aluminium plate AL2024-T3 with a central circular notch using a patch of different nature (metal or composite), under tensile loading conditions. The repair composite considered is a carbon/epoxide. The results of the tensile tests showed that the repair by the combination of the two processes improves the mechanical strength of the damaged structure. A comparison of the results of the experimental curves obtained on riveted, bonded and hybrid assemblies has been taken into consideration.

PurposeThe purpose of this research is to evaluate the effectiveness of different repair patch materials in reducing the stresses at the crack tip of a 2024-T3 aluminum plate. This involves a numerical analysis using the finite element method (FEM) to estimate the reduction in the J-integral value, with the goal of identifying how various parameters related to the patch materials, adhesive properties and loading conditions influence the structural integrity of the repaired plate.Design/methodology/approachThe methodology of this research involves conducting a numerical analysis using the FEM to estimate the reduction in the J-integral value at the crack tip of a 2024-T3 aluminum plate. Three types of patches - metal, composite and functionally graded material (FGM) - were examined under tensile loading conditions, and Adekit-A140 adhesive was used to bond these repair patches to the aluminum plate.FindingsThe analysis considered various parameters, including crack length, the nature of fibers in the composite material, the gradation exponent for FGM patches and the nature of the face in contact with the adhesive for the FGM patch. Additionally, stress analysis was conducted, examining the J-integral values for the plate, shear stress in the adhesive layer and peel stress in the composite patch. The findings highlight that modifying the nature of the repair patch used can significantly enhance the structural integrity of the repaired plate.Originality/valueThe study analyzed J-integral values, shear stress in the adhesive and peel stress in the composite patch. Various parameters, including crack length, fiber type, gradation exponent and adhesive contact face nature, were considered. Results demonstrate that the J-integral value can be significantly reduced by altering the repair patch type, highlighting the effectiveness of customized patch materials in enhancing structural integrity.

Presently, Functionally Graded Materials (FGMs) are extensively utilised in several industrial sectors, and the modelling of their mechanical behaviour is consistently advancing. Most studies investigate the impact of layers on the mechanical characteristics, resulting in a discontinuity in the material. In the present study, the extended Finite Element Method (XFEM) technique is used to analyse the damage in a Metal/Ceramic plate (FGM-Al/SiC) with a circular central notch. The plate is subjected to a uniaxial tensile force. The maximum stress criterion was employed for fracture initiation and the energy criterion for its propagation and evolution. The FGM (Al/SiC) structure is graded based on its thickness using a modified power law. The plastic characteristics of the structure were estimated using the Tamura-Tomota-Ozawa (TTO) model in a user-defined field variables (USDFLD) subroutine. Validation of the numerical model in the form of a stress-strain curve with the findings of the experimental tests was established following a mesh sensitivity investigation and demonstrated good convergence. The influence of the notch dimensions and gradation exponent on the structural response and damage development was also explored. Additionally, force-displacement curves were employed to display the data, highlighting the fracture propagation pattern within the FGM structure.

This study focuses on the evaluation of the dynamic mechanical properties, molecular structure, density, hardness, swelling behavior of natural rubber blends (NR) and nitrile rubber (NBR) reinforced with carbon black and/or nano-silica. An experimental work has been conducted to study of the effects of increasing NR content and incorporating nano-silica on the mechanical properties and molecular structure were studied using dynamic mechanical analysis (DMA) and Fourier transform infrared (FTIR) spectroscopy. The results show that increasing the NR content and/or incorporating nano-silica into the elastomer leads to a higher storage modulus with no significant change in the glass transition temperature. FTIR analysis indicates the compatibility of the polyblends and the presence of oxidation of the main polymer chain generated during the grinding of the rubber. Additionally, the results of the swelling study demonstrate that stronger molecular interactions occur on the surface of the nano-silica between the nitrile radicals in the NBR and the silanol (Si-OH) radicals. These findings suggest that blending NR and NBR with carbon black and/or nano-silica can improve the mechanical properties and compatibility of the resulting polyblends, with potential applications in the development of advanced elastomeric materials.

Luffa cylindrical (LC) has an exceptionally multipartite architecture, a hierarchical and light structure, and a low density. Such a structure is potentially suitable to replace conventional porous-type composites for low-energy absorption and material reinforcement applications. This paper presents an experimental study of the impact behavior of four different luffa/epoxy composites, named (A), (B), (C), and (D) subjected to low-velocity impact (LVI) at energies ranging from barely visible impact damage (BVID) to perforation (5,15, and 20J). Acoustic emission (AE), scanning electron microscopy (SEM), and digital image correlation (DIC) were introduced to the indentation test to offer additional information on damage mechanisms and on strain and displacement fields since the LVI test has a short duration and real-time damage monitoring is not always achievable. The results showed that the values of the peak force of laminates (A), (B), and (D) are relatively lower compared to laminates (C). In the case of perforation impact energy (20J), the Coefficients of Restitution (CoR) of composites (A), (B), and (D) are equal to 0, which indicates that the nature of the impact is completely plastic, except for composite (C) had a value of 0.11, and a lower degree of damage at all impact energies. Composites (C) exhibit the highest impact resistance, followed by composites (A), while composites (D) display the highest energy absorption, followed by composites (B). Multivariable statistical analysis of the AE signals identified four classes of damage: matrix cracking, fiber-matrix debonding, delamination, and fiber breakage. The damage modes found by AE are well presented and proven by SEM analysis. The luffa fiber-reinforced composite has better impact properties than other natural fiber-reinforced composites.

Materials from demolition are only recycled if they are economically competitive on the one hand and technically acceptable on the other, meaning they can be implemented without risking disruption to the performance of the construction material. Among these materials are demolished concretes. This type of material (waste) is currently reused as recycled aggregate, commonly referred to as gravel. Indeed, the latter contains grains of anhydrous clinker, which may play a significant role in determining the properties of concrete. In the context of waste valorization, this study focuses solely on the influence of incorporating finely crushed concrete demolition waste (CDW) as an active additive or as a supplementary cementitious material in the cement matrix used to make concrete. The results showed that the addition of up to 10% of concrete demolition waste significantly improved physical properties such as the air void content and workability of fresh concrete. Furthermore, the compactness of hardened concrete also improved based on adding 10% of CDW as a result of increasing the speed of sound. Therefore, the compressive strength of concrete was also improved by 20% when 10% waste was added compared to the control concrete. This indicates that concrete demolition waste (finely crushed) can replace cement and therefore contribute to reducing binder consumption.