Artículos (Mecánica de Medios Continuos y Teoría de Estructuras)

URI permanente para esta colecciónhttps://hdl.handle.net/11441/11397

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Mostrando 1 - 20 de 474

Nanosilica synergy: unveiling the strength and fracture mechanisms in advanced concrete composites
(Consejo Superior de Investigaciones Científicas (CSIC): Instituto Eduardo Torroja, 2025) Ríos Jiménez, José David; Ruiz López, Gonzalo; González Cabrera, Dorys Carmen; Cifuentes-Bulté, Héctor; Vicente Cabrera, Miguel Ángel; Yu, Rena Chengxiang; Leiva Fernández, Carlos; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España; TEP972: Mecánica de Materiales y Estructuras; TEP142: Ingeniería de Residuos
This study explores how nanosilica impacts the mechanical properties and fracture behavior of ultra-high-performance concrete (UHPC). We delved into the role of nanosilica in enhancing pozzolanic reactions and its effects on UHPC’s pore structure. This was investigated using advanced techniques such as scanning electron microscopy and mercury intrusion porosimetry. We prepared UHPC samples with varying nanosilica concentrations, replacing cement by 0 to 7.5%wt, to understand its influence comprehensively. Our findings reveal that higher nanosilica content, while beneficial in some aspects, compromises the self-compacting nature of UHPC. This necessitated conducting slump tests to evaluate workability. Remarkably, the addition of nanosilica led to a reduction in both capillary and macropores, enhancing the density and strength of the concrete. Specifically, a maximum of 5%wt nanosilica addition resulted in a 13% increase in compressive strength. However, this improvement in strength comes with a trade-off. The fracture energy of UHPC decreased by 23.2%, indicating an increase in brittleness due to nanosilica. Interestingly, tensile strength saw a 10.5% increase, primarily attributed to the enhanced formation of the C-S-H gel, a key component for concrete strength. This study illuminates the dual-edged effects of nanosilica in UHPC, presenting a nuanced view of its role in concrete technology and fracture mechanics.
On the evaluation of failure strain in graphite-epoxy composites
(Taylor & Francis, 2024) Marín Vallejo, Juan Carlos; Justo Estebaranz, Jesús; Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP131: Grupo de Elasticidad y Resistencia de Materiales
Determination of failure strains is a topic of great interest for the design of composite structures. To evaluate the ultimate strains of a composite, tensile tests have been carried out on specimens with a range of fiber orientations between 0° and 90°. Ultimate tensile strengths obtained present low or moderate dispersion, the average values constituting a good estimation of the failure stress. Values of failure strains obtained present high dispersion for almost all orientations, so it is proposed to take as failure strain threshold the minimum value for each orientation. Finally, the shear behavior of the material has been evaluated.
Study of fatigue damage in wind turbine blades
(Elsevier, 2009-03) Marín Vallejo, Juan Carlos; Barroso Caro, Alberto; París Carballo, Federico; Cañas Delgado, José; Mecánica de Medios Continuos y Teoría de Estructuras
The inspection of damages detected in some blades of 300 kW wind turbines revealed that the nature of these damages was probably due to a fatigue mechanism. The causes that had originated the failure (superficial cracks, geometric concentrator, abrupt change of thickness) have been studied, verifying, by means of the simplified evaluation procedure of fatigue life of the “Germanischer Lloyd” (GL) standard, that these causes can explain the failure detected in the period of time in which it happened.
Study of damage and repair of blades of a 300 kW wind turbine
(Elsevier, 2008-07) Marín Vallejo, Juan Carlos; Barroso Caro, Alberto; París Carballo, Federico; Cañas Delgado, José; Mecánica de Medios Continuos y Teoría de Estructuras
The inspection of damages detected in some blades of 300 kW wind turbines revealed that the nature of these damages was probably due to a fatigue mechanism. The causes that had originated the failure (superficial cracks, geometric concentrator, abrupt change of thickness) have been studied, verifying, by means of the simplified evaluation procedure of fatigue life of the “Germanischer Lloyd” (GL) standard, that these causes can explain the failure detected in the period of time in which it happened. A suitable configuration for the repair of the damaged blades has been studied, by means of a finite element model. The proposed modifications repair the cracks and in addition contribute to relaxing the stress state in the affected zone. The introduction of a triangular reinforcement, which smoothes the re-entrant corner existing in the original design, incorporating a laminate of reinforcement, produces a significant decrease in the stress level in the damaged zone of the blades.
Normal stress flow evaluation in composite aircraft wing sections by strength of material models
(Elsevier, 2022-02) Marín Vallejo, Juan Carlos; Graciani Díaz, Enrique; Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
The increasingly widespread use of composite materials in structural elements of commercial aircrafts (Airbus 350, Boeing 787), has led to consider the design of wings in composite material. Finite Element (FE) models have been used as a numerical tool for analysis and design, due to the geometrical complexity of these elements, together with the anisotropic nature of the composite material. However, the structural design of elements made of composite laminates using FE models is very expensive in terms of time needed for processing the results and for introducing modifications. The use of simpler Strength of Materials (SM) models has shown to be very efficient for the design of wind turbine blades. The objective of this work is to investigate the feasibility of using these SM models for composite layered aircraft wing design. To this end, a specific model that considers the geometric characteristics of these structural elements (multicellular sections and presence of longitudinal spars and transverse stiffeners) has been developed. The application of the SM model on a specific geometry of a wing torsion box under a given loading condition has allowed us to successfully compare the results, in terms of longitudinal stress flows, with those obtained by a numerical FE model for the same problem, using equivalent discretization.
Evaluation of shear flow in composite wind turbine blades
(Elsevier, 2011-06) Fernandes da Silva, G; Marín Vallejo, Juan Carlos; Barroso Caro, Alberto; Mecánica de Medios Continuos y Teoría de Estructuras
The present work addresses the evaluation of the shear flow as an extension of the Jourawski’s formula. This idea is developed here for the case of a multi-celled composite thin-walled section. Firstly, the explicit formulation of the shear flow due to shear forces and torsion is derived, noting the simplificative hypothesis adopted. Then, the implemented model is verified by means of a benchmark problem with a known analytical solution. Finally, this model is utilized to evaluate the shear flow on an actual blade configuration, comparing the results obtained with those of a Finite Element model of the same blade, with a similar discretization.
Analytical solution for dynamic response of multi-span bridges under moving loads: an efficient method based on time-discrete analysis using sinc interpolation
(Elsevier, 2026) Romero Ordóñez, Antonio; Moliner, Emma; Martínez-Rodrigo, María Dolores; Galvín, Pedro; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía
This paper proposes an analytical method for calculating the dynamic response of multi-span bridges subjected to moving loads. The proposed approach uses sinc interpolation time-discrete analysis based on the Nyquist-Shannon sampling theorem. The proposed method enables the computation of dynamic responses with analytical precision and minimal computational effort. This work provides closed-form explicit formulas for bridge response with significant advantages over conventional numerical approaches, reducing complexity and computational cost without compromising accuracy. Validation cases demonstrated the robustness and reliability of the proposed solution for different bridge configurations and loading scenarios. To facilitate adoption, the proposed methodology is implemented in open-source Julia code, which is available at GitHub. In addition to providing a powerful toolbox for structural engineers, this study establishes a foundational framework for extending sinc-based interpolation techniques to other structural dynamics and civil engineering problems.
The Impact of Steel Fiber Length and Dosage on Microstructure and Mechanical Performance in UHPFRC: A Hybrid Approach
(Asociación Española de Ingeniería Estructural (ACHE), 2025) Ruiz Martínez, Jaime Delfino; Ríos Jiménez, José David; Pérez-Soriano, Eva María; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Ingeniería Química y Ambiental; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España
This study evaluates the effects of steel fiber length (6 and 13 mm) and dosage on the microstructural and mechanical properties of an ultra-high-performance fiber-reinforced concrete (UHPFRC). The incorporation of 6 mm fiber significantly improved the material's workability characteristics. Microscopic evidence indicates better alignment and distribution of 13 mm fibers within the concrete matrix compared to 6 mm fibers, resulting in reduced porosity and enhanced matrix-fiber interaction. Mechanical testing confirmed that the inclu-sion of 13 mm steel fibers at various dosages consistently outperformed 6 mm fibers in enhancing compressive and flexural strengths. The optimal dosage, among those tested, for compressive strength was found to be 196 kg/m³ with 13 mm fibers, while the best performance in flexural strength was observed at 226 kg/m³. To address the challenges inherent in UHPFRC—specifically the intricate metallic fiber distri-bution and limited workability prompted a comprehensive investigation into fiber mixture optimization strategies. Hybrid fiber approach was explored by substituting 10%, 20%, and 30% of the 13 mm fiber dosage (196 kg/m³) with 6 mm steel fibers. Among these, the mix containing 80% of 13 mm steel fibers and 20% of 6 mm steel fibers demonstrated the highest flexural strength, even than those with higher steel fiber content (226 kg/m3). This hybridization suggests an optimized combination of fiber lengths for enhanced flexural performance without compromising compressive strength, providing insights into effective fiber-reinforcement strategies for UHPFRC applications.
Ultrasonic Evaluation of Mechanical Properties in Heritage Buildings Constructed with Córdoba Freestone
(MDPI, 2025) Zapico Blanco, Beatriz; Rodríguez Mariscal, José Daniel; Solís Muñiz, Mario; Estructuras de Edificación e Ingeniería del Terreno; Mecánica de Medios Continuos y Teoría de Estructuras
This study characterises the natural stone used in the Great Mosque of Córdoba (Spain) and establishes correlations to enable non-destructive, in situ assessment of the mechanical strength of the material. Quarry ashlars of the same biocalcarenite were tested to determine bulk density, ultrasonic wave propagation velocity (UWPV), and mechanical properties from uniaxial compression, splitting tension, and three-point bending tests (over 100 specimens). The stone showed no significant anisotropy or specimen size effects within the investigated ranges. Reference mechanical values were obtained, with a mean uniaxial compressive strength of about 6 MPa. A strong linear correlation was found between UWPV and compressive strength (R2 ≈ 0.86), supporting the use of ultrasonic testing to estimate compressive strength on site. In addition, flexural strength can be also estimated since it correlated strongly with compressive strength (R2 ≈ 0.95); in contrast, the correlation with tensile strength was moderate (R2 ≈ 0.31). The results provide validated relationships for Córdoba freestone that improve the reliability of ultrasonic tests for providing valuable information for structural analysis, maintenance, and conservation strategies for heritage buildings constructed with this kind of stone. The proposed approach offers a practical pathway for damage-free evaluation of mechanical performance in historical masonry.
A phase field formulation for modeling intralaminar damage onset and propagation in composites including residual stresses
(Springer, 2025) Bushpalli, Sindhu; López Romano, Bernardo; Graciani Díaz, Enrique; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC)
Unfolding failure is a sudden delamination occurring in highly curved fiber-reinforced polymer composite laminates when they are subjected to opening bending moments. Depending on the stacking sequences involved, unfolding failure includes intralaminar damage, interlaminar damage and their complex interactions. The use of these laminates in primary structural components of commercial aircrafts has intensified interest in understanding this failure mechanism. To tackle this, a simple phase field formulation to model the onset and propagation of transverse damage in highly curved laminates is presented. Firstly, the Abaqus implementation of the phase field to model intralaminar damage in composite laminates is established, exploiting the analogy between phase field and the heat transfer model to use Abaqus temperature as the phase field damage parameter. In addition, since residual stresses developed during manufacturing processes affect damage propagation, they are incorporated into the formulation as constant residual strains. Secondly, the proposed implementation is validated by performing tests on benchmark problems. Finally, a preliminary analysis of the unfolding failure test is provided to highlight the importance of including residual stresses in the transverse damage evolution.
Influence of deep foundations in a deck slab high-speed railway bridge: A theoretical study
(Asociación Española de Ingeniería Estructural (ACHE), 2025) Martínez de la Concha, Antonio; Suescum Morales, David; Martínez Sánchez, Manuel; Cifuentes-Bulté, Héctor; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Economía y Competitividad (MINECO). España; Ministerio de Educación. España; TEP972: Mecánica de Materiales y Estructuras
In this research, the importance of properly modeling the infrastructure of high-speed railway bridges with deep foundations when using the finite element method (FEM) is discussed. To do so, an isolated deck and several complete models with different character-istics were compared. Parameters such as the length of the piles, the stiffness of the supporting layers and the type of dynamic load (10 different trains) were explored. This study started with the analysis of various parameters that determine the behavior of deep foundations with piles in simplified models. Based on these findings, a complete model was built. This research shows the importance of including not only the surrounding terrain but also the main substructure (i.e., piers and abutments) in the model. Recommendations on the amount of soil to include, its mechanical properties and the length of the piles needed are also provided to ensure the reliability of results when considering the soil-structure dynamic interaction. With this research, a contribution to current knowledge is intended through a series of guidelines and tools to help structural engineers in dynamic simulations through a theoretical case study.
3D finite fracture mechanics under mode I loading: the flat elliptical crack
(Académie des Sciences, 2025) Cornetti, Pietro; Mantic, Vladislav; Yosibash, Zohar; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP131: Grupo de Elasticidad y Resistencia de Materiales
La détermination de la contrainte à distance provoquant la propagation d’une fissure dans un domaine 3D infini contenant une fissure elliptique plane est ici revisitée dans le cadre du Critère Couplé de la Mécanique de la Rupture Finie. Nous commençons par passer en revue les approches de la Mécanique Linéaire de la Rupture, qui diffèrent selon la prise en compte de différentes croissances infinitésimales de la fissure. Ensuite, nous présentons la solution basée sur la Mécanique de la Rupture Finie : si le défaut elliptique est suffisamment petit, la fissure croît le long de lignes iso-contraintes. Pour des tailles plus grandes, d’autres modes de croissance de fissure peuvent se produire. Ainsi, cette étude montre que supposer un front de fissure iso-contraintes peut effectivement fournir la solution exacte en Mécanique de la Rupture Finie, en particulier pour les petits défauts ; en revanche, cela peut être erroné pour des défauts de plus grande taille, entraînant de surcroît des prédictions non conservatrices. Toutefois, pour la géométrie considérée, cela donne des estimations de contrainte de rupture ne différant que de quelques pourcents de la valeur réelle. Ainsi, l’hypothèse d’iso-contraintes, avancée par Leguillon [D. Leguillon, “An attempt to extend the 2D coupled criterion for crack nucleation in brittle materials to the 3D case”, Theor. Appl. Fract. Mech. 74 (2014), pp. 7-17], impliquant des simplifications importantes dans l’implémentation numérique du critère couplé dans des problèmes 3D, semble largement justifiée par les résultats présents. En outre, quelle que soit la taille initiale de la fissure, la croissance finie prédite par le modèle aboutit à une nouvelle forme elliptique de la fissure, plus proche d’un cercle, ce qui signifie que l’excentricité diminue systématiquement au fur et à mesure de la propagation de la fissure.
Application of the coupled criterion to interface crack growth in the end-notched flexure test considering friction between the crack faces
(Springer, 2025) Herrera Garrido, María Ángeles; Mantic, Vladislav; Leguillon, Dominique; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP131: Grupo de Elasticidad y Resistencia de Materiales
A novel computational analysis is developed to model mode II fracture of a bimaterial specimen in an End Notched Flexure test considering frictional sliding contact between the crack faces. In the Comninou contact model of interface cracks, the frictional contact zone at the tip of an interface crack between dissimilar linear elastic materials entails a stress singularity, which is weaker than the square root singularity. This weak singularity results in a zero Energy Release Rate (ERR) G11=0 in such cracks. Therefore, the classical Griffith criterion cannot be used to predict crack growth in this case. To address this challenging issue, a new approach based on the Coupled Criterion (CC) introduced by Leguillon (Eur. J. Mech. A/Solids 21, 61-72, 2002), which adopts the Finite Fracture Mechanics (FFM) hypothesis proposed by Hashin (J. Mech. Phys. Solids, 44, 1129-1145, 1996), is developed. The CC is satisfied when both the stress and incremental energy criteria are satisfied simultaneously. A novel CC implementation is required to address the nonlinearity caused by the frictional contact between the interface crack faces, particularly the frictional dissipation of energy during the growth of such interface cracks. The methodology developed involves Finite Element Analysis (FEA) to compute shear stress and relative displacements along the crack path, the change of the potential energy and the energy dissipated by friction. Finally, the implemented CC provides the critical load and finite crack advance at the initiation of crack propagation. The numerical study presented considers various combinations of isotropic materials and friction coefficients.
The trade-off between structural control and vibration-based energy harvesting: Experimental assessment on a lightweight footbridge
(Elsevier, 2025-04-15) Naranjo Pérez, Javier; Macías Infantes, María; Gallegos Calderón, Christian; Jiménez Alonso, Javier Fernando; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP245: Ingeniería de las Estructuras
This paper presents a promising trade-off strategy for simultaneous vibration control and energy harvesting in lightweight structures, addressing the increasing need for real-time and autonomous monitoring of actual civil engineering infrastructures. Sensor networks typically require a power supply for data measurement and transmission, which entails significant challenges for structures in remote areas due to battery maintenance issues. This study explores the feasibility of piezoelectric energy harvesting through an experimental campaign involving a controlled fibre-reinforced polymer footbridge equipped with a tuned mass damper. Different configurations are analysed with the aim of evaluating the novel possibility of placing the harvester on the vibration absorber, in order to leverage its relatively high amplitude and harmonic motion. Dynamic loads due to pedestrians include gait frequency variations tests, group of pedestrians and pedestrian streams. Peak response statistics are used to evaluate the harvested energy for the different configurations, highlighting the potential for optimizing energy harvester placement to maximize power output. Also, a feasibility study of the power output of the harvester device to supply energy to sensors is conducted. The methodology, experimental setup, and analysis of different configurations are detailed, with conclusions reinforcing the effectiveness of placing the harvesting device on the control device. This dual-function device concept balances vibration control and energy harvesting, presenting a practical solution for the current paradigm of structural design. This strategy is particularly relevant for footbridges, which often face high-level accelerations and vibration serviceability limit state challenges. The study underscores the potential of this approach to enhance the sustainability and efficiency of monitoring systems for civil engineering infrastructures, demonstrating significant promise for enhancing the performance of piezoelectric harvesters in operational structural vibrations, advancing towards self-powered sensors.
Round-robin programme for longitudinal tensile testing of unidirectional composites: results, conclusions, and recommendations
(Elsevier, 2025) Fazlali, Babak; Breite, Christian; Czél, Gergely; Fiedler, Bodo; Gibhardt, Dennis; Hojo, Masaki; Koerber, Hannes; Kumar, Rajnish; Velasco López, María Luisa; McEnteggart, Ian; Mikkelsen, Lars P.; París Carballo, Federico; Mecánica de Medios Continuos y Teoría de Estructuras; European Union (UE). H2020; National Research Development and Innovation Ofice (NRDI, Hungary); Ministry of Culture and Innovation of Hungary
The longitudinal tensile behaviour is one of the most important and basic characteristics of a unidirectional composite, yet its experimental characterisation is not straightforward. Therefore, we conducted a round-robin programme with seven test labs and six coupon designs where the panels were manufactured and cut by the same lab. Our results indicate that careful manufacturing and cutting enable consistent and reliable results for the different labs and coupon designs. High-speed videos confirmed that many coupons failed away from the grips, which is the targeted failure location. In addition to the modulus, failure strain and strength results, we present results and novel recommendations related to the coupon preparation and testing methodology. We recommend using a non-contact strain measurement method and discarding tests with significant stress drops before final failure.
Characterization by fracture mechanics of intra and interlaminar damage in composite laminates
(Elsevier, 2025-02-21) Blázquez Gámez, Antonio; Velasco López, María Luisa; Caballos, Paula; París Carballo, Federico; Mecánica de Medios Continuos y Teoría de Estructuras
Composite materials present a complicated internal structure that may generate different mechanisms of damage associated with events of failure. The prediction of the onset and propagation of such events requires the knowledge of properties that may appear at different levels: micro (level of fibres and matrix), meso (homogenized version of a lamina) and macro (the total structure with properties of the whole laminate). Determining these properties requires special tests where it is difficult to replicate the conditions that appear in an actual composite component, and additionally, in a controlled manner. In this paper, experimental testing and numerical analysis are performed on a [0,90n,0] laminate. The experimental campaign aims to observe and measure the damage (both intralaminar and interlaminar) in the laminate subjected to tension. These experimental results are then used to define a Boundary Element Method (BEM) model to determine the stresses and displacements, enabling the energy release rates associated with the cracks existing in the model to be calculated. This approach requires the capacity of having damages under control, in such a way of having the properties that want to be determined involved in the mechanism of damage. The results clearly indicate the potential for conducting tests on cross-ply laminates that can produce controlled damage patterns for determining key properties of composites.
Influence of the bonding method on interlaminar fracture toughness for composite material non-symmetric configurations
(Elsevier, 2025-02) Cañas Delgado, José; Justo Estebaranz, Jesús; Blázquez Gámez, Antonio; Velasco López, María Luisa; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; TEP131: Grupo de Elasticidad y Resistencia de Materiales
The DCB test is the most widely used method to assess the quality of composite bonded joints. However, in non-symmetric configurations, experimental testing has shown that cracks can propagate cohesively, adhesively, or migrate, leading to varying fracture toughness values. This study examines the influence of bonding methods (co-curing and secondary bonding) on fracture toughness in non-symmetric joints with unidirectional composite laminates. To achieve this, both an experimental campaign and numerical analysis were conducted. It is obtained that, as long as the thinner adherent is previously cured and the thickness ratio between adherents is less than 75 %, crack migration will occur, reducing the value of the energy necessary to make the crack propagate. Cohesive failure resulted in fracture toughness values about 100 % higher than those of adhesive failure. This fact raises questions about the applicability of the fracture toughness obtained from the DCB test to joints in real structures, as the strength and stiffness of the joint depend not only on the adhesive but also on the adherents. Results from the meso-mechanical analysis and experimental data allow for defining a cohesive law for the adhesive joint, suitable for implementation in macro-mechanical models.
The effect of stress singularities in the failure of composite off‐axis specimens subjected to tension
(Wiley, 2025-08-29) Marín Vallejo, Juan Carlos; Barroso Caro, Alberto; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades; TEP131: Grupo de Elasticidad y Resistencia de Materiales
This work is motivated by the observation of premature failures in off-axis tension test specimens for the characterization of intralaminar shear strength in unidirectional composite materials. These failures have been mainly observed in the neighborhood of the corners formed by the test coupon with the tab used to place the specimen inside the jaws of the testing machine. A study of the singular stress state in these critical points and its influence on the geometric and mechanical parameters that characterize the problem has been carried out. The parametric study carried out has allowed for the obtaining of variation plots of the parameters that define the singular stress state with the geometric parameters of the problem. These results have been checked against experimental results, observing that the 3D model can be a more precise representation of the singular stress state in the corner of the off-axis specimen.
A computational framework for predicting the effect of surface roughness in fatigue
(Elsevier, 2025-10) Jiménez Alfaro, Sara; Martínez Pañeda, Emilio; Mecánica de Medios Continuos y Teoría de Estructuras
Surface roughness is a critical factor influencing the fatigue life of structural components. Its effect is commonly quantified using a correction coefficient known as the surface factor. In this paper, a phase field based numerical framework is proposed to estimate the surface factor while accounting for the stochastic nature of surface roughness. The model is validated against existing experimental data. Furthermore, we investigate the influence of key parameters on the fatigue life of rough surfaces, such as surface topology and failure strength. An important effect of surface roughness is observed when the average surface roughness increases and the correlation length of the surface profile decreases. This effect becomes more pronounced with higher failure strengths.
Stress singularities in the generalised Comninou frictional contact model for interface cracks in anisotropic bimaterials
(Elsevier, 2025-10) Herrera Garrido, María Ángeles; Mantic, Vladislav; Ingeniería y Ciencia de los Materiales y del Transporte; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Junta de Andalucía; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); TEP131: Grupo de Elasticidad y Resistencia de Materiales
Characterisation of the singular asymptotic solution at the tip of interface cracks between dissimilar materials is essential for assessing the structural integrity of heterogeneous material systems. In the present article, the Comninou contact model, one of the most relevant and widely used models, originally introduced for isotropic bimaterials, is generalised for the first time to any anisotropic linear elastic bimaterial under generalised plane strain, considering a frictional sliding contact zone adjacent to the crack tip. The classical Coulomb friction law is considered. A novel procedure, based on the Stroh formalism of linear anisotropic elasticity, is developed to derive a system of two new coupled nonlinear eigenequations given in closed form for two unknown parameters of such singular solutions, the singularity exponent 𝜆 and the sliding angle 𝜔 in the contact zone. In general, this eigensystem is solved by an iterative method, although in some cases, closed-form solutions are provided. Parametric studies of the influence of material orientations and the friction coefficient value on variations of 𝜆 and 𝜔 reveal several surprising features of this asymptotic solution. The present approach is successfully verified by comparing some of the results obtained with those reported in previous studies, wherever possible. Note that previous studies essentially focused on bimaterials with specific orientations, considerably simplifying the problem. The singular solutions obtained can also be used in the asymptotic analysis of elastic fields at the boundary between stick and slip zones in partial slip contact problems for anisotropic materials.

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