Artículos (Mecánica de Medios Continuos y Teoría de Estructuras)

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

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Time–Frequency Analysis of Railway Bridges Forced and Free Vibrations Identified by Wavelet Transform
(Multidisplinary Digital Publishing Institute (MDPI), 2025-11) Galvín, Pedro; Romero Ordóñez, Antonio; Solís Muñiz, Mario; Moliner, Emma; Martínez-Rodrigo, María Dolores; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía; European Union (UE)
In this work, a time–frequency analysis of two railway bridges included in the InBridge4EU project database is presented. The study focuses on the identification of modal parameters from free responses after train passages and their comparison with estimations obtained from ambient vibration data. The wavelet transform is introduced as a valuable tool for detecting both free and forced bridge responses due to different train passages, as well as for conducting time–frequency analysis. This approach is particularly relevant for the identification of structural damping, given its dependence on vibration amplitude, as it enables the estimation of realistic values representative of bridge behavior under operational conditions. Additionally, the paper examines the complementary use of free vibrations for identifying natural frequencies and comparing them with results from ambient vibration tests. Wavelet analysis further reveals the predominant frequencies in the structural response before, during, and after train crossings, thereby capturing the influence of the moving vehicle on bridge dynamics.
Efficient simulation of the soil–structure interaction on the dynamic response of a portal frame railway bridge
(Elsevier, 2025-12) Chordà-Monsonís, Josep; Sánchez-Quesada, Juan Carlos; Moliner, Emma; Romero Ordóñez, Antonio; Galvín, Pedro; Martínez-Rodrigo, M.D.; Mecánica de Medios Continuos y Teoría de Estructuras; Universitat Jaume I; Ministerio de Ciencia e Innovación (MICIN). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Junta de Andalucía; Centro Informático Científico de Andalucía; European Union (UE)
The dynamic response of railway bridges can be highly influenced by the effect of soil–structure interaction. This occurs as the soil dissipates energy and modifies the flexibility of the bridge supports, which impacts the modal parameters of the structure and its response to passing trains. In the case of partially-buried structures such as portal frames, this interaction mechanism is of particular relevance. However, simulating the soil effect is complex, and may require an elevated computational effort. Under these conditions, obtaining accurate predictions of the bridge dynamic behaviour becomes challenging. For this reason, the interplay between the bridge and the soil is usually disregarded. To address this limitation, a numerical approach devoted to implement soil–structure interaction with reduced computational cost is presented in this contribution. The method is based on a substructuring scheme, and considers two numerical models: (i) a full three-dimensional finite-element interaction model, including the track, the bridge, and the surrounding soil, and (ii) a simplified version of it, in which the soil is substituted by a series of linear spring-dampers. The first model is used to derive frequency-dependent dynamic stiffness functions that describe the mechanical coupling between the bridge and the ground. Then, these functions are used to calibrate the spring-damper elements representing the soil in the subsequent simplified model, and the dynamic problem is solved by complex modal superposition. The suitability of the proposed methodology is evaluated through its application to an existing portal frame railway bridge. The effect of other relevant aspects on the bridge response such as the track irregularities and the contribution of the vehicle–bridge interaction is also taken into account. The results highlight the potential of this approach to obtain satisfactory predictions of the bridge performance in an efficient manner.
Modelling the Anisotropic Elasto-Plastic Response of 3D-Printed Polymer Parts
(Shahid Chamran University of Ahvaz, 2026-02) Marques Ferreira, Luis Miguel; Sánchez, José Luis; Muñoz-Reja Moreno, María del Mar; Távara Mendoza, Luis Arístides; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; TEP131: Grupo de Elasticidad y Resistencia de Materiales
This work develops and validates finite element models to simulate the anisotropic elasto-plastic behaviour of 3D-printed polymers. Specifically, 3D printed thermo-responsive Shape-Memory Polymer (SMP) coupons tested at room temperature are analysed. The modelling strategy employs built-in constitutive formulations within ABAQUS®, including Hill’s anisotropic plasticity and the Tsai-Hill failure criterion, thereby avoiding the need for user-defined material subroutines. The elastic response is represented through an orthotropic approximation, while plastic hardening is calibrated from reference experimental data. The resulting 3D FE models are able to capture the influence of raster angle on tensile performance, accurately predicting the variations in modulus, strength, and failure strain observed between aligned and off-axis printing orientations. Numerical-experimental correlation demonstrates that the proposed approach reproduces both the stress–strain response and the orientation-dependent failure patterns with satisfactory accuracy. These results confirm the suitability of efficient, commercially available constitutive models for representing the mechanical response of additively manufactured polymers, such as SMPs. The methodology provides a reliable framework for the design and optimisation of anisotropic 3D-printed structures, with potential applications in biomedical, aerospace, and automotive engineering.
Enriched crack-tip element for logarithmic stress singularities of Mode I and Mode II cracks in spring interfaces
(Elsevier, 2026-04) Herrera Garrido, María Ángeles; Távara Mendoza, Luis Arístides; Muñoz-Reja Moreno, María del Mar; Vázquez-Sánchez, Alberto; Mantic, Vladislav; Ingeniería y Ciencia de los Materiales y del Transporte; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Finite element simulations of cracks in Winkler-type spring interfaces encounter numerical difficulties due to logarithmic stress-singularities at the crack tip. These singularities lead to poor convergence of standard FEM and typically require strong mesh refinement, resulting in high computational costs. This work proposes a novel enriched 2D finite element for fracture analysis in mixed Mode I+II, focusing on cracks in interfaces modeled by continuous spring distributions. The new element is triangular with 5 nodes obtained by collapsing a 6-node rectangular element. It incorporates the radial behavior of the asymptotic elastic solutions with logarithmic stress-singularities, improving the accuracy of Energy Release Rate (ERR) calculations compared to standard finite elements. The proposed approach achieves higher accuracy in interface crack growth simulations while substantially reducing computational costs, and demonstrating that this accuracy is maintained when the enriched element is placed along the whole interface, enabling unzipping-type crack propagation without re-meshing. Specifically, for small and moderate values of Lenci’s dimensionless parameter (=1,10 and 100), the error in the displacement value at the crack tip is reduced by a factor of between 2 and 5 when enriched crack-tip elements are used instead of standard elements in Mode I, for both mesh patterns with 2 and 4 crack-tip elements. In Mode II, this error is consistently reduced only for the mesh pattern with 4 crack-tip elements, by a factor of between 2 and 7. Obtained results demonstrate the potential of the proposed enriched element to enhance the efficiency and accuracy of fracture analyses in adhesive joints, making it a promising tool for addressing challenges in interface crack modeling by FEM.
Prediction of failure of hybrid composites with ultra-thin carbon/epoxy layers using the Coupled Criterion
(Elsevier, 2023-03) Aranda Romero, María Teresa; Leguillon, D.; Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
Composites are rapidly increasing in an extensive range of structural applications, but further growth is limited by their lack of ductility. Fiber hybridization is a promising strategy to toughen composite materials. The coupled criterion of the finite fracture mechanics is applied here to describe the sequential damage mechanisms that occur in a hybrid composite under tension. The studied specimens are made of an unidirectional thin layer reinforced with long carbon fibers, embedded between two unidirectional layers reinforced with glass fibers. The first damage is usually translaminar cracking of the carbon/epoxy layer, which can be followed by different mechanisms depending on the stacking lay-up: failure of the glass/epoxy layer, delamination of the interface between carbon/epoxy and glass/epoxy layer, or fragmentation of the carbon/epoxy layer. Once the first translaminar crack has appeared into the carbon/epoxy layer, it impinges on the interface and the crack tips undergo a strong singularity, which plays an important role in predicting the mechanisms that follow. The competition between the different mechanisms is studied here by the novelty of including the principle of maximum dissipation into the Coupled Criterion. The predictions obtained by this approach show a good agreement with the experimental and computational results found in the literature.
Effect of rotational forces on the durability of dental materials: implications in biology and anthropology
(The Royal Society, 2026-01) Sánchez González, Estíbaliz; Ríos Jiménez, José David; Guiberteau, Fernando; Berthaume, Michael A.; Hoffman, Mark; Borrero López, Oscar; Mecánica de Medios Continuos y Teoría de Estructuras; TEP972: Mecánica de Materiales y Estructuras
Both natural and synthetic prosthetic teeth undergo mechanical degradation, impacting their durability. Experimental studies typically simulate dental contacts using simple configurations involving normal and lateral forces. While often necessary due to the constraints of apparatus set-ups and mathematical models, these assumptions oversimplify the complex conditions during mastication and ignore poorly understood but potentially important rotational forces, which occur when teeth are compressed into the alveolar bone. We investigate the influence of rotational forces on contact damage/wear in synthetic dental materials using advanced equipment with decoupled biaxial actuators. Cyclic contact loads combining compression (50 N) and rotation (30°) are applied to zirconia (Z), composite (CP), feldspathic (F) and lithium silicate based (ZLS) glass-ceramics. After 105 cycles, Z exhibits the greatest wear resistance (wear volume 4.16 × 10−4 mm3), followed by F (5.83 × 10−3 mm3), CP (9.17 × 10−3 mm3) and ZLS (1.64 × 10−2 mm3), with p-values 0.004 (Z–F), 0.631 (F–CP), 0.012 (F–ZLS) and 0.009 (CP–ZLS). Abrasion is the primary wear mode, with specific mechanisms such as plastic deformation and microfracture varying with material microstructure. Contact mechanics analysis indicates that rotational forces induce lower wear than non-rotational sliding. Potential implications in dentistry, biology and anthropology are discussed, including the design of culturally and behaviourally informed dental prosthetics.
Experimental characterization of Mode I fracture toughness of the undisturbed Guadalquivir Blue Marl: Effect of suction
(Elsevier, 2023-12) Olivares Rodríguez, Pablo; Aranda Romero, María Teresa; Vázquez-Boza, Manuel; Durand Neyra, Percy; Reinoso Cuevas, José Antonio; Estructuras de Edificación e Ingeniería del Terreno; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Junta de Andalucía; Universidad de Sevilla
Fracture Mechanics is an extensively developed discipline for a wide range of materials used in scientific and engineering applications. However, the thorough understanding and characterization of fracture phenomena in many soil and rock-type materials are still under development. This work aims to characterize the suctiondependent fracture response in undisturbed clay soils, which will lead to identifying a ductile–brittle behavior threshold. The undisturbed condition will provide information on the behavior of the soil in its natural state. For this purpose, a new experimental procedure is presented in order to obtain a closed-form relationship between mode I fracture toughness (𝐾Ic) and a suction range (𝛹) for the Guadalquivir blue marl. In order to achieve this objective, an experimental campaign was carried out using a series of semi-circular specimens subjected to the three-point bending test with different suctions. The corresponding loading–displacement curves from the tests are qualitatively analyzed to identify the fracture response of this material, and the linear regression technique is used to finally obtain the desired relationship. Current results show that an increasing value of suction increases both the maximum load and the stiffness, yielding a more brittle behavior associated with an increase in 𝐾Ic. Finally, an alternative expression for the determination 𝐾Ic with respect to that proposed by Kuruppu and coauthors (Kuruppu et al., 2013) is presented, which involves the explicit inclusion of the suction variable for the more brittle behavior, limited by the threshold found. This provides a new perspective on how moisture content affects the fracture mechanics of clays
A unified BEM approach for complex and degenerate geometries based on the Burton–Miller method
(Elsevier, 2026-01) Romero Ordóñez, Antonio; Velázquez-Mata, Rocío; Tadeu, Antonio; Galvín, Pedro; Mecánica de Medios Continuos y Teoría de Estructuras; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
This work presents a general boundary element method formulation for acoustic wave scattering problems involving complex boundary geometries with regions of zero or near-zero thickness. Based on the Burton–Miller method, the formulation adopts the Bézier–Bernstein space, enabling a geometry-independent field approximation. The proposed approach avoids the explicit treatment of singularities, resulting in a simplified, and unified methodology. Integral kernels, including weakly singular, strongly singular, and hypersingular kernels, are evaluated numerically using quadrature rules. The numerical results demonstrate the robustness and accuracy of the proposed method in benchmark and scattering problems, thus validating its feasibility for analyzing thin and degenerate boundary geometries.
Assessment of fatigue resistance of concrete: S-N curves to the Paris’ law curves
(Elsevier, 2022-07) Miarka, Petr; Seitl, Stanislav; Bílek, Vlastimil; Cifuentes-Bulté, Héctor; Mecánica de Medios Continuos y Teoría de Estructuras; Czech Science Foundation; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Fatigue behaviour of concrete materials is often investigated on un-notched specimens under the compressive or bending loads. In this experimental study, a notched three-point bending (TPB) specimen is used in high-cycle fatigue experiments to obtain the Wohler’s curve. Based on this approach, a novel, yet relatively simple transition from the traditional Wohler’s curve to the Paris’ law curve is proposed. Such a methodology allows one to obtain the Paris’ law material constants, which are used to determine the fatigue failure of the structure or a component. The constants of the experimentally determined material, measured in four different concrete mixtures, have been verified by recalculating the number of cycles until the fatigue failure Nf by the integration of the Paris’ law equation. The back-calculated number of cycles and the approximation of the S-N curve allowed for a comparison with the experimental data. Furthermore, the initial notch tip was extended in this approximation by the value of the critical distance. Such an extension allowed us to cover a wide range of the experimental data and provided a better prediction of fatigue life. The proposed method was verified on all four studied materials and showed satisfactory results.
Multiscale analysis of carbon microfiber reinforcement on fracture behavior of ultra-high-performance concrete
(Elsevier, 2025-05) Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Ruiz, G.; González, D.C.; Vicente, M.A.; Yu, R.C.; Leiva Fernández, Carlos; Mecánica de Medios Continuos y Teoría de Estructuras; Ingeniería Química y Ambiental; Ministerio de Ciencia e Innovación (MICIN). España
This study delves into the intricate world of ultra-high-performance concrete, specifically how its mechanical integrity and fracture resistance are influenced by the incorporation of carbon microfibers of varying lengths. Employing a suite of multiscale analytical techniques, we link the mechanical attributes of concrete to its microstructural composition, with a keen focus on porosity distribution as revealed by advanced X-ray computed tomography and porosimetry assessments. We uncover how the selection of microfiber type affects the concrete’s internal pore landscape, which in turn dictates the material’s fracture behavior. An innovative use of inverse analysis, based on established fracture mechanics, allows us to formulate cohesive laws for the fracture process zone. Our results uncover a direct correlation between the variability in fracture properties and the specific types and amounts of fibers used, providing mix designers with critical insights for customizing concrete formulations to meet precise performance criteria.
Influence of the chevron notch type on the values of fracture energy evaluated on alkali-activated concrete
(Elsevier, 2020) Miarka, Petr; Pan, Lixia; Bílek, Vlastimil; Seitl, Stanislav; Cifuentes-Bulté, Héctor; Mecánica de Medios Continuos y Teoría de Estructuras; Czech Science Foundation; Ministerio de Economía y Competitividad (MINECO). España
The influence of the notch type on the fracture mechanical parameters (FMP) of alkali-activated concrete (AAC) were presented based on a numerical and experimental study. In the study, the effects of the various notch types on the material’s response, a straight-through and a chevron notch, were analysed. The local fracture process was analysed by the numerically generated stress distribution around the notch tip, while the general material’s response to the applied load was studied by the experimentally recorded load displacement (P-δ) diagrams. It was observed that the differences in the experimentally obtained results for each studied notch type were rather minor. Similarly, the notch type has only a minor influence on the evaluated material’s FMPs, such as the values of the size-independent fracture energy.
A 2.5D BEM-based approach in the Bézier–Bernstein space for railway noise prediction and acoustic barrier assessment
(Elsevier, 2026-01) Velázquez-Mata, Rocío; Knuth, Christopher; Romero Ordóñez, Antonio; Squicciarini, Giacomo; Tadeu, Antonio; Thompson, David J.; Galvín, Pedro; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España
Noise pollution from railway traffic, primarily caused by rolling noise resulting from the vibrations of the track and wheels, is a major public health concern. While traditional acoustic barriers are effective, they are often visually intrusive, particularly in urban settings. This has led to growing interest in more integrated solutions, such as low, close barriers, which require accurate noise prediction tools. This paper presents a two-and-a-half-dimensional BEM for predicting and mitigating railway noise. The method uses Bézier–Bernstein space to accurately model complex geometries, enhancing noise prediction across different rail profiles. Several rail configurations are compared to evaluate their impact on noise emissions and to support the design of more effective and adaptable barrier solutions. The method is then applied to evaluate the performance of a specific low-height barrier configuration, considering the presence of the vehicle to assess its impact on noise reduction. Numerical predictions are validated through comparison with experimental data and other numerical approaches. Results highlight the importance of accurate source modelling for barrier design and demonstrate the potential of the proposed method as a flexible tool for developing noise mitigation solutions that utilize the barrier’s geometry to improve acoustic performance and support visual integration in urban environments.
Flexural fatigue behaviour of a heated ultra-high-performance fibre-reinforced concrete
(Elsevier, 2021-03) Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Blasón, Sergio; López-Aenlle, Manuel; Martínez de la Concha, Antonio; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Economía y Competitividad (MINECO). España; TEP972: Mecánica de Materiales y Estructuras
A comprehensive experimental campaign was carried out to assess the flexural fatigue behaviour of an ultra-high-performance fibre-reinforced concrete. Several concrete mixes were submitted to room temperature, 100 °C, 200 °C, and 300 °C. Two types of reinforcement were explored: steel fibres and a combination of steel and polypropylene fibres. The influence of the addition of fibres and the temperatures in the microstructure were analysed through X-ray CT scans. In addition, the mechanical and fracture properties of the concrete were determined with monotonic tests and a connection between macroscopic and microscopic results was established to explain the fatigue behaviour. The beneficial effect of the fibres was observed essentially at a low cyclic fatigue regime. In heated concretes, the reduction of matrix porosity due to the presence of steel fibres led to significant damage after being exposed to 300 °C by spalling failure. By contrast, the concrete reinforced with polypropylene fibres maintained remarkably similar fatigue behaviour at room temperature and 300 °C.
Extracting residual stresses from experiments through inverse methods
(Elsevier, 2026) Sanz Herrera, José Antonio; Goriely, Alain; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; TEP245: Ingeniería de las Estructuras
Residual stresses are stresses present in a body in the absence of loads. They are found universally in biological systems and play a key role in many industrial applications as they alter a body’s effective material properties. Typically, in biomechanics, they are the result of growth, remodeling, or other active processes. In industry, they are the consequence of manufacturing processes such as welding, cooling, or quenching. To study the response of materials with residual stresses, their initial values must be known, and neglecting their contribution may lead to wrong predictions, even at the qualitative level. It is therefore crucial to estimate them. Residual stresses can be obtained by simulating the underlying physics using numerical methods, or using experimental setups. The former approach is limited by the amount of constitutive models and associated phenomenological parameters needed in the simulation. In the latter approach, residual stress quantification is restricted to a certain region and its accuracy is affected by noisy measurements. In this paper we propose an inverse approach to reconstruct residual stress fields using domain displacements as an input. This displacement field is measured during the motion of the sample when it is sectioned (divided) into different regions through cutting experiments that partially relieve stresses. We demonstrate through various examples that residual stress recovery is possible both for linear and nonlinear solids while the formulation is independent of the physics of the residual stress source. Our findings show accurate reconstructions of residual stress when sufficiently many cuts have been performed, with errors below 10% and 20% for the linear and nonlinear examples, respectively, even for high input errors in the strain field (40%). This unique mixed numerical-experimental approach is also valid to improve the quantification of residual stress fields in existing experimental methods.
A collaborative machine learning-optimization algorithm to improve the finite element model updating of civil engineering structures
(Elsevier, 2020-12) Naranjo Pérez, Javier; Infantes, María; Jiménez Alonso, Javier Fernando; Sáez Pérez, Andrés; Mecánica de Medios Continuos y Teoría de Estructuras; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Ministerio de Economía y Competitividad (MINECO). España
Finite element model updating has become a key tool to improve the numerical modelling of existing civil engineering structures, by adjusting the numerical response to the observed experimental behaviour of the structure. At present, model updating is mostly conducted using the maximum likelihood method. Following this approach, the updating problem can be transformed into a multi-objective optimization problem. Due to the complex nonlinear behaviour of the resulting objective functions, metaheuristic optimization algorithms are normally employed to solve such optimization problem. However, and although this is nowadays a well-established technique, there are still two main drawbacks that need to be addressed for practical engineering applications, namely: (i) the high simulation time required to compute the problem; and (ii) the uncertainty associated with the selection of the best updated model among all the Pareto optimal solutions. In order to overcome these limitations, a new collaborative algorithm is proposed herein, which takes advantage of the collaborative coupling among two optimization algorithms (harmony search and active-set algorithms), a machine learning technique (artificial neural networks) and a statistical tool (principal component analysis). The implementation details of our proposal are discussed in detail throughout the paper and its performance is illustrated with a case study addressing the model updating of a real steel footbridge. Two are the main advantages of the newly proposed algorithm: (i) it leads to a clear reduction of the simulation time; and (ii) it further permits a robust selection of the best updated model.
A numerical analysis on the behavior of CFRP laminates under biaxial loads
(Taylor & Francis, 2024-11) Zumaquero Bernal, Patricia Lucía; Correa Montoto, Elena; París Carballo, Federico; Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; TEP131: Grupo de Elasticidad y Resistencia de Materiales
The study of the failure mechanisms of a composite material is essential for the efficient design of structures. The analysis of the effect of transverse biaxial loads, both at micromechanical and macromechanical level, is required for an integral vision of the whole mechanism of damage. In a previous work by the authors a transverse biaxial testing campaign was performed on cruciform specimens; in the present work a FEM model that successfully reproduces the coupons elastic state is presented in order to understand the failure occurrence and to make failure predictions avoiding the complexity of the experimental process.
Evaluation of the incremental ERR in interface cracks with frictional contact and its application in the coupled criterion of finite fracture mechanics
(Académie des Sciences, 2025) Graciani Díaz, Enrique; Mantic, Vladislav; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Agencia Estatal de Investigación. España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)
A crack located in a straight and perfectly bonded interface between dissimilar isotropic linear elastic materials with a frictional contact zone adjacent to the crack tip is considered under plane strain conditions. Assuming the Coulombfrictionlaw, thecrack-tip stress singularity in such a crack is weaker than the classical square-root singularity. The main difficulty in predicting propagation of such an interface crack is that the Energy Release Rate (ERR) is zero, which is a direct consequence of this weak stress singularity at the crack tip. Therefore, the Griffith fracture criterion, which assumes infinitesimal crack advances, cannot be applied in this case. To overcome this problem a new approach to predict the propagation of an interface crack with a frictional contact zone at the crack tip, based on the Coupled stress and energy Criterion (CC) of Finite Fracture Mechanics (FFM), is proposed and analyzed. In contrast to previous approaches, the critical f inite crack advance ∆ac is determined by the CC as a structural parameter given by the overall problem configuration. Two methods for calculating the incremental ERR GII(∆a) are considered which differ in the treatment of the frictional energy dissipated along the crack advance ∆a. Closed-form expressions for GII(∆a) are derived for sufficiently large interface cracks when the most singular term of the asymptotic expansion of the elastic solution at the crack tip is dominant along the path of crack advance ∆a before the crack propagation occurs. In this case, closed-form expressions for the critical crack advance ∆ac and the critical stress intensity factor KIIc are derived.
Phase-field fracture in elastic–plastic polycrystals, analysis of FEM and FFT implementations
(Elsevier, 2026-02) Aranda Acuña, Pedro Miguel; Valverde González, Ángel de Jesús; Reinoso Cuevas, José Antonio; Segurado Escudero, Javier; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; TEP963: Ingeniería de Estructuras y Materiales
A simulation framework is proposed for the elastoplastic fracture of polycrystals at the mesoscale based on the simulation of representative volume elements of polycrystals by means of the phase-field fracture (PFF) model and crystal plasticity. The method is implemented in two boundary value problem solvers, the Finite Element Method (FEM) and a Fast Fourier Transform based solver (FFT), using in both cases identical periodic boundary conditions and a staggered-based solution scheme. The framework is able to reproduce the basic features of elastoplastic fracture at this scale, showing localized plasticity at the crack tip and crack path changes during propagation from grain to grain. The results obtained using the two different solvers are convergent with the discretization, but their results using coarser discretizations present clear differences both in the macroscopic mechanical response and in the crack paths developed. It is found that the origin of the discrepancies is the representation of the initial crack as a row of elements/voxels with negligible stiffness, which enhances different energy localization around its tip. These differences are appreciated in elastic polycrystals but become more important when the elastoplastic response is considered. A phase-field crack-tip enrichment technique in FFT has been proposed to reduce the difference between both numerical approaches.
An inf-sup stable phase-field formulation for fracture of thermo-responsive hydrogels: Isotropic and transversely isotropic material models
(Elsevier, 2026-02-01) Valverde González, Ángel de Jesús; Olivares Rodríguez, Pablo; Reinoso Cuevas, José Antonio; Dortdivanlioglu, Berkin; Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; National Science Foundation (NSF). United States; TEP963: Ingeniería de Estructuras y Materiales
This investigation presents a comprehensive phase-field formulation for fracture analysis of thermo-responsive hydrogels, encompassing both isotropic and transversely isotropic material models within an integrated thermo-chemo-mechanical framework. The proposed numerical approach addresses computational challenges through a mixed variational formulation that ensures inf-sup stability while maintaining robust fracture simulation capabilities. The finite element implementation employs quadratic interpolation functions for the displacement field and linear shape functions for the chemical potential (fluid pressure), temperature, and fracture fields. This formulation is implemented as a user-element subroutine UEL in ABAQUS, utilizing a Q2Q1Q1Q1 finite element formulation. The validation strategy comprises two key investigations. First, a comparative analysis against the foundational work of Böger et al. (2017), pinpoints the capacity of the current formulation to achieve numerical stability while accurately capturing fracture limit states across varying temperature conditions. Second, the methodology is applied to simulate complex material behavior through the analysis of pre-notched specimens under combined swelling and mechanical loading conditions. This thorough assessment provides valuable insights into the coupled chemical and mechanical responses of thermo-responsive hydrogels, demonstrating the ability of the proposed formulation in simulating these advanced materials.
Multiscale analysis and lifetime prediction of adhesive lap joints in contact with aggressive environments
(Springer, 2025) Ariza Moreno, María del Pilar; Ortiz, M.; Mecánica de Medios Continuos y Teoría de Estructuras; Office of Naval Research (ONR). United States
We formulate a multiscale model of adhesive layers undergoing impurity-dependent cohesive fracture. The model contemplates three scales: i) at the atomic scale, fracture is controlled by interatomic separation and the thermodynamics of separation depends on temperature and impurity concentration; ii) the mesoscale is characterized by the collective response of a large number of interatomic planes across the adhesive layer, resulting in a thickness-dependence strength; in addition, impurities are uptaken from the environment and diffuse through the adhesive layer; and iii) at the macroscale, we focus on lap joints under the action of static loads and aggressive environments. Within this scenario, we obtain closed form analytical solutions for: the dependence of the adhesive layer strength on thickness; the length of the edge cracks, if any, as a function of time; the lifetime of the joint; and the dependence of the strength of the joint on time of preexposure to the environment. Overall, the theory is found to capture well the experimentally observed trends. Finally, we discuss how the model can be characterized on the basis of atomistic calculations, which opens the way for the systematic exploration of new material specifications.

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