Artículos (Mecánica de Medios Continuos y Teoría de Estructuras)
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Artículo Acoustic Wave Scattering By Null-thickness Bodies With Complex Geometry(WIT Press, 2024) Romero Ordóñez, Antonio; Velázquez-Mata, Rocío; Tadeu, Antonio; Galvín, Pedro; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Consejería de Economía, Conocimiento, Empresas y Universidad. Junta de Andalucía; Centro Informático Científico de Andalucía (CICA)This paper proposes a general formulation of the BEM based on the Burton–Miller method to study scattering wave propagation by null-thickness bodies with complex geometry. This approach allows the use of arbitrary high order elements and exact boundary geometry. We use the Bézier–Bernstein form of a polynomial as an approximation basis to represent both geometry and field variables. The solution of the element interpolation problem in the Bézier–Bernstein space defines generalised Lagrange interpolation functions that are used as element shape functions. The proposed procedure consists of a new quadrature rule for the accurate evaluation of integral kernels in the sense of the Cauchy principal and the Hadamard finite part by an exclusively numerical procedure.Artículo Experimental and numerical flexural-torsional performance of thin-walled open-ended steel vertical pile foundations subjected to lateral loads(MDPI, 2023-07-10) Pérez, José Antonio; Reyes Rodríguez, Antonio Manuel; Sánchez González, Estíbaliz; Ríos Jiménez, José David; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP972: Mecánica de Materiales y EstructurasThis research investigates the effects of torsional moments on the mechanical behavior of thin-walled open-ended vertical pile foundations subjected to lateral wind loads. The aim of this research is to determine and quantify the errors using traditional design methods and provide more effective alternatives. The warping and torsion effect generated over the piles due to the resultant lateral load impact outside the shear center is analyzed in field tests. Complementarily, a two-dimensional finite element model based on the simple bending stress–strain state, as well as a three-dimensional finite element model considering torsional effects, were implemented and their results analyzed. Finally, a comparative analysis between the in-field lateral loading tests and the finite element model approaches was established by comparing load–displacement curves and using a non-linear Wrinkle model of the soil. Additionally, correlations between the experimental and finite element model errors for the cross-sections pile with a different torsional constant and torsional susceptibility index are shown. From the results, it has been ascertained that the slender thin-walled open-ended pile foundations are particularly sensitive to small load deviations from their center of gravity; this leads to the fact that the slenderer the load and the greater its eccentricity, the more it affects the torsion and warping of the pile. Calculation methodologies usually consider a simple in-plane bending behavior, which leads to errors between 44 and 58% in comparison with the experimental results obtained.Artículo On-the-fly meanfield transition-state theory for diffusive molecular dynamics(Elsevier, 2025-08) Molinos Pérez, Miguel; Ortiz, Michael; Ariza Moreno, María del Pilar; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; California Institute of Technology; Deutsche Forschungsgemeinschaft / German Research Foundation (DFG); Universidad de Sevilla. TEP972: Mecánica de Materiales y EstructurasWe apply transition state theory to derive atomic-level master equations for mass transport from empirical interatomic potentials within the Diffusive Molecular Dynamics (DMD) framework. We show that meanfield approximation provides an exceedingly efficient and accurate means of computing free-energy barriers in arbitrary local atomic configurations, thus enabling long-term DMD ‘on-the-fly’ and on the sole basis of an underlying interatomic potential, without additional modeling assumptions. We apply and validate the resulting meanfield DMD paradigm in simulations of processes of hydrogenation and dehydrogenation of Mg using Angular-Dependent interatomic Potentials (ADP). We show that meanfield DMD correctly predicts hydrogen diffusivities in hcp Mg and vacancy diffusivities in rutile MgH2. We demonstrate the ability of meanfield DMD to predict evolution through calculations concerned with dilute concentrations of hydrogen in hcp Mg, and with dilute concentrations of hydrogen vacancies in rutile MgH2, including off-stoichiometry hydrogen concentrations and temperature effects. Remarkably, the time steps required by DMD are up to six orders of magnitude larger than those required by Molecular Dynamics (MD), which demonstrates the overwhelming superiority of the DMD paradigm in simulations of phenomena occurring on the diffusive time scale.Artículo Evaluation of the physical and mechanical behaviour of rammed earth by incorporation of recycled glass(Elsevier, 2025) Canivell, Jacinto; Martín del Río, Juan Jesús; Solís Muñiz, Mario; Rodríguez Mariscal, José Daniel; Flores Alés, Vicente; Pontiga Romero, Francisco de Paula; Universidad de Sevilla. Departamento de Construcciones Arquitectónicas II (ETSIE); Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. Departamento de Física Aplicada II; Universidad de Sevilla. TEP211: Conservación Preventiva del Patrimonio Construido; Universidad de Sevilla. TEP198: Materiales y Construcción; Universidad de Sevilla. FQM253: Electrohidrodinámica y Medios Granulares CohesivosCompacted soil walls provide environmental benefits due to their low impact and embodied energy. Although their mechanical strength is lower than other materials, they meet safety requirements. Current trends promote circular economy solutions, such as waste reuse. This study assesses recycled glass in lime- and cement-stabilized rammed earth as a replacement for natural sand to enhance waste management and soil properties. Ultrasonic inspection confirms increased compressive strength and density, especially in cement-stabilized mixtures. Statistical analysis reveals a direct correlation between crushed glass content and improved properties. The optimal replacement rate is 75% for lime and 100% for cement. The superior performance in cement-stabilized samples is due to a pozzolanic reaction absent in lime mixtures. Both binders show significant reductions in thermal conductivity, improving energy efficiency without compromising structural integrity. Ultrasound proves reliable for predicting compressive strength and stiffness, supporting the viability of this approach. The incorporation of recycled glass in compacted soil offers a sustainable construction alternative, balancing environmental benefits with enhanced mechanical and thermal performance.Artículo Multi-scale toughening of UHPC: synergistic effects of carbon microfibers and nanotubes(MDPI, 2025-04-21) Ruiz Martínez, Jaime Delfino; Ríos Jiménez, José David; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP972: Mecánica de Materiales y Estructuras; Universidad de Sevilla. TEP142: Ingeniería de ResiduosThis study investigates multi-scale reinforcement of Ultra-High-Performance Concrete through targeted modifications of its mechanical and fracture-resistant properties via carbon microfibers and carbon nanotubes. The research employed comprehensive characterization techniques including workability tests, mercury porosimetry for microscale porosity analysis, and X-ray tomography for macro-scale pore evaluation. Mechanical performance was assessed through compression strength, tensile strength, and fracture energy measurements. Results demonstrated significant performance enhancements testing UHPC samples with 6 mm carbon microfibers (9 kg/m3) and varying carbon nanotubes dosages (0.11–0.54 wt%). The addition of carbon microfibres improved compressive strength by 12%, while incorporating 0.54 wt% carbon nanotubes further increased strength by 24%. Remarkably, the combined reinforcement strategy yielded a 313% increase in tensile strength compared to the reference mixture. The synergistic effect of carbon fibers and carbon nanotubes proved particularly effective in enhancing concrete performance. This multi-scale reinforcement approach presents a promising alternative to traditional steel fiber reinforcement, offering superior mechanical properties and potential advantages in corrosive environments.Artículo Influence of the 90/0 ply thickness ratio on the stresses associated with the edge effect phenomenon(Elsevier, 2025-08) Sánchez-Carmona, Serafín; Barroso Caro, Alberto; Correa Montoto, Elena; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla. TEP131: Grupo de Elasticidad y Resistencia de MaterialesThe scale effect phenomenon has shed light on the thermo-mechanical behaviour of ultra-thin plies. These laminas in cross-ply laminates (under certain 90/0 thickness ratios) have given rise to a relevant edge effect phenomenon, causing significant through-the-thickness stress in the weakest ply along its free edge under both thermal and (0-longitudinal tension) mechanical loading. Thus, a biaxial stress state must be considered to analyse what happens along the free edges from experimental samples to structural components, such as drill holes. A parametric numerical analysis is performed taking three different features into account: the thickness of the ply blocks, the cross-ply stacking sequences and the type of fibre, either carbon or glass. The numerical predictions are in accordance with experimental results, which are obtained under a thermal cooldown. The biaxial stress state predictions could be used in future numerical procedures including the presence of components’ free edges.Artículo Damage mechanisms in hybrid composites: experimental characterisation and energy-based numerical analysis(Italian Group of Fracture (IGF), 2025-07) Parente, João M.; Ferreira, Luis Miguel Marques; Reis, Paulo Nobre Balbis; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Fundação para a Ciência e a Tecnologia. Portugal; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla. TEP131: Grupo de Elasticidad y Resistencia de MaterialesThis study analyses the failure mechanisms of bilayer hybrid composites, consisting of carbon and glass fibres embedded in an epoxy matrix, under bending loads. The objective is to evaluate how different hybrid configurations influence failure evolution and mechanical performance. To achieve this, specimens are submitted to 3-point bending tests, and 3D finite element models are developed to simulate the experimental setup. The numerical models incorporate a continuum damage mechanics model to capture intralaminar failure and a surface-based cohesive behaviour for interlaminar damage. The results show that hybrid laminates exhibit intermediate strength and displacement values compared to nonhybrid carbon and glass laminates, with the positioning of glass fibers significantly affecting bending force and displacement. Intralaminar damage is the primary failure mechanism in all configurations, followed by delamination. Additionally, placing glass fibers on the compression side reduces the overall damage, whereas placing them on the tensile side increases intralaminar failure before reaching the peak load. These findings contribute to optimizing the design of hybrid composites for bending applications by providing information about the relationship between material configuration and failure mechanisms, ultimately improving their structural efficiency and durability in engineering applications.Artículo Numerical analysis of the structural performance of adhesive T-joints under bending loads(Elsevier, 2025-08) Ferreira, Luis Miguel Marques; Campilho, R.D.S.G.; Muñoz-Reja Moreno, María del Mar; Reis, Paulo Nobre Balbis; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Fundação para a Ciência e a Tecnologia. Portugal; Ministerio de Ciencia, Innovación y Universidades (MICIU). España; Universidad de Sevilla. TEP131: Grupo de Elasticidad y Resistencia de Materiales; Universidad de Sevilla. TEP963: Ingeniería de Estructuras y MaterialesT-joints are a good alternative to conventional adhesive joints, such as single-lap joints, due to their ability to efficiently transfer bending, compressive, shear, and tensile loads between the T-profile stiffener and the base plate, all while maintaining cost-effectiveness. However, for widespread adoption, a comprehensive understanding of the joint strength and damage mechanisms is essential. Therefore, this study aims to numerically analyse the structural performance of adhesive T-joints subjected to 3-point bending loads using two-dimensional (2D) finite element models, and cohesive zone modelling (CZM) to simulate the behaviour of the adhesive. CZM validation was also accomplished by comparing the joints' behaviour with experimental data. Numerically, peaks of peel stresses at the overlap edges were observed, with sharp gradients toward the inner bond region, as well as shear stresses due to the geometric discontinuity. Adhesives with higher stiffness provide higher peak values of peel and shear stresses, while more ductile ones lead to higher peak loads. The CZM was successfully validated with experiments, and a correlation was observed between energy dissipation and damage propagation, according to a non-symmetrical pattern, and for conditions that minimize the system's functional energy.Artículo Efect of nano silicon nitride on the microstructural characteristics and mechanical properties of ultra‑high‑performance steel fber reinforced concrete(Springer Nature, 2025) Ruiz Martínez, Jaime D.; Ríos Jiménez, José David; Pérez-Soriano, Eva María; Cifuentes-Bulté, Héctor; Leiva Fernández, Carlos; Universidad de Sevilla. Departamento de Ingeniería Química y Ambiental; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. Departamento de Ingeniería y Ciencia de los Materiales y del Transporte; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP142: Ingeniería de Residuos; Universidad de Sevilla. TEP123: Metalurgia e Ingeniería de los Materiales; Universidad de Sevilla. TEP972: Mecánica de Materiales y EstructurasThis study investigates the incorporation of an innovative nano-reinforcement, nano silicon nitride (NSIN), to enhance the workability and mechanical performance of ultra-high-performance fber reinforced concrete. The addition of NSIN at dosages of 0.25, 0.5, 0.75, and 1.5 wt% of cement was analyzed to evaluate its impact on the distribution and interaction between steel fbers and the cementitious matrix. Experimental analyses, including thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), were conducted to establish a relationship between the microstructural modifcations, fber-matrix interactions, and the resulting mechanical behavior. The fndings revealed that NSIN increased workability and extended setting time, enabling improved steel fber dispersion and interactionArtículo Wear and subsurface stress evolution in tractive rolling contact(Elsevier, 2025-05-15) Juliá Lerma, Javier Miguel; Rodríguez de Tembleque Solano, Luis; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Ciencia e Innovación (MICIN). España; European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER); Universidad de Sevilla. TEP245: Ingeniería de las EstructurasWear phenomenon is inherent to tractive rolling contact problems e.g., in rolling bearings or in rail–wheel interaction. It takes place in the sliding regions of the rolling contact area, and it accumulates as particles from the rolling bodies cross the contact region. Wear modifies the solids’ surface, the contact tractions, the subsurface stresses, and the tangential forces transmitted between the rolling solids, which are fundamental contact variables in sectors such as rolling fatigue or vehicle system dynamics. Thus, ignoring wear in tractive rolling contact analysis could lead to underestimations of bearing fatigue lives or inaccurate lateral guiding forces in multibody vehicle models. This work presents a robust SAM-based formulation on rolling contact to study how wear, contact tractions, resultant rolling contact-forces, and surface and subsurface stresses evolve with the number of revolutions. For the first time, subsurface stress distributions are computed as a function of revolutions under orthotropic friction and wear conditions, highlighting the influence of tribological axes orientation and wear evolution on stress and force reactions. After validating the proposed formulation, several numerical examples are presented to show how considering orthotropic friction and wear laws impacts stress distributions and resultant rolling contact forces. These findings could provide important insights into the role of wear in tractive rolling contact for applications in engineering and industrial design.Artículo Review of the matched asymptotic approach of the coupled criterion(Académie des Sciences, 2025) Jiménez Alfaro, Sara; García García, Israel; Doitrand, Aurélien; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union (UE). H2020; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP131: Grupo de Elasticidad y Resistencia de MaterialesMatched Asymptotics is a powerful mathematical technique with broad applicability in various engineering fields. One of its key uses is in Fracture Mechanics, where it provides accurate approximations in the vicinity of the crack tip with low computational complexity. This method can be seamlessly integrated with the Coupled Criterion (CC), which enables the prediction of crack nucleation and propagation in brittle materials. Hence, this paper deeply explains how the MA technique can be applied together with the CC in the context of Fracture Mechanics, providing a detailed literature review of the advances made in the last decade.Artículo A dialogue between Finite Fracture Mechanics and Phase Field approaches to fracture for predicting crack nucleation at the microscale(Springer, 2025-01-20) Jiménez Alfaro, Sara; Leguillon, Dominique; Maurini, Corrado; Reinoso Cuevas, José Antonio; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union (UE). H2020; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP963: Ingeniería de Estructuras y MaterialesUnraveling the material behavior at the microscale is one of the challenges of this century, demanding progress in experimental and computational strategies. Among the latter, two approaches are commonly applied for predicting crack nucleation. The Coupled Criterion (CC) and the Phase Field (PF) model, both depending on a material length parameter. In brittle materials at the macroscale, this parameter is significantly smaller than the specimen size. However, when the scale decreases, this material length might approach the structural dimensions. In this context, a comprehensive comparison between the two models is conducted, changing the ratio between the material length parameter and the dimensions of the specimen. Results indicate that when this ratio is sufficiently small predictions from both models coincide, otherwise both the CC and the PF model predict different results. Despite their differences, an agreement with experiments reported in the literature have been observed.Artículo Phase field modeling of anisotropic silicon crystalline cracking in 3D thin-walled photovoltaic laminates(Springer, 2025-01) Liu, Zeng; Lenarda, Pietro; Reinoso Cuevas, José Antonio; Paggi, Marco; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla; European Union (UE). H2020; Ministerio de Ciencia e Innovación (MICIN). EspañaA novel computational framework integrating the phase field approach with the solid shell formulation at finite deformation is proposed to model the anisotropic fracture of silicon solar cells in the thin-walled photovoltaic laminates. To alleviate the locking effects, both the enhanced assumed strain and assumed natural strain methods are incorporated in the solid shell element formulation. Aiming at tackling the poor convergence performance of standard Newton schemes, the efficient and robust quasi-Newton scheme is adopted for the solution of phase field modeling with enhanced shell formulation in a monolithic manner. Due to fracture anisotropy of the brittle silicon solar cells, the second-order structural tensor that is defined by the normal of preferential crack plane is introduced into the crack energy density function in the phase field modeling. On the other hand, to efficiently predict the crack growth of silicon solar cells, a global–local approach in the 3D setting proposed in the previous work is adopted here for the fracture modeling. In this approach, both mechanical deformation and phase field fracture are accounted for at the local model, while only mechanical deformation is addressed at the global level. At each time step, the solution of the global model is used to drive the local model, which corresponds to the one-way coupling in line with experimental evidence that the silicon cell cracking has negligible influence on the stiffness of photovoltaic modules. The capability of the modeling framework is demonstrated through numerical simulation of silicon solar cell cracking in the photovoltaic modules when subjected to different loading cases.Artículo The influence of thermo-electromechanical coupling on the performance of lead-free BNT-PDMS piezoelectric composites(IOP Publishing, 2024) Akshayveer; Buroni Cuneo, Federico Carlos; Melnik, Roderick; Rodríguez de Tembleque Solano, Luis; Sáez Pérez, Andrés; Singh, Sundeep; Universidad de Sevilla. Departamento de Ingeniería Mecánica y Fabricación; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP245: Ingeniería de las EstructurasIn recent times, there have been notable advancements in haptic technology, particularly in screens found on mobile phones, laptops, light-emitting diode (LED) screens, and control panels. However, it is essential to note that the progress in high-temperature haptic applications is still in the developmental phase. Due to their complex phase and domain structures, lead-free piezoelectric materials such as Bi0.5Na0.5TiO3 (BNT)-based haptic technology behave differently at high temperatures than in ambient conditions. Therefore, it is essential to investigate the aspects of thermal management and thermal stability, as temperature plays a vital role in the phase and domain transition of BNT material. A two-dimensional thermo-electromechanical model has been proposed in this study to analyze the thermal stability of the BNT-PDMS composite by analyzing the impact of temperature on effective electromechanical properties and mechanical and electric field parameters. However, the thermo-electromechanical modelling of the BNT-PDMS composite examines the macroscopic effects of the applied thermal field on mechanical and electric field parameters, as phase change and microdomain dynamics are not considered in this model. This study analyzes the impact of thermo-electromechanical coupling on the performance of the BNT-PDMS composite compared to conventional electromechanical coupling. The results predicted a significant improvement in piezoelectric response compared to electromechanical coupling due to the increased thermoelectric effect in the absence of phase change and microdomain switching for temperature boundary conditions below depolarization temperature (Td ∼ 200◦C for pure BNT material).Artículo On the (lack of) representativeness of quasi-static variational fracture models for unstable crack propagation(Elsevier, 2024-05) Chao Correas, Arturo; Reinoso Cuevas, José Antonio; Cornetti, Pietro; Corrado, Mauro; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union (UE). H2020; Ministerio de Ciencia e Innovación (MICIN). España; Universidad de Sevilla. TEP963: Ingeniería de Estructuras y MaterialesThe present work is devoted to prove that unstable crack propagation events do not comply with quasi-static hypotheses and thus should be modelled by dynamic approaches. Comprehensive supporting evidence is provided on the basis of three different analyses conducted on multi-ligament unstable fracture conditions, including a simplified Spring-Mass model, detailed quasi-static and dynamic Phase Field fracture models, and bespoke experiments with 3D printed specimens. The obtained results unequivocally show that neglecting the inertial effects can lead to unsafe predictions in the presence of energetic barriers for the development of fracture. Likewise, quasi-static Phase Field fracture models are proven to yield crack patterns that disagree with the experimental evidence because they overlook the progressive diffusion of the mechanical information within the continuum. Moreover, the inability of quasi-static approaches to follow unstable crack propagation is shown to weaken the crucial irreversibility condition of fracture. Overall, these experimentally backed insights should be gravely reckoned with, for they are not exclusive to Phase Field fracture models but common to (almost) any variational approach to fracture, inter alia Cohesive Zone Models or Continuum Damage Mechanics.Artículo Evaluating failure modes through energy dissipation mechanisms in hybrid composites under bending loads(Elsevier, 2025-03) Parente, João M. ; Ferreira, Luis Miguel Marques; Reis, Paulo Nobre Balbis; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Fundação para a Ciência e a Tecnologia. Portugal; Ministerio de Ciencia, Innovación y Universidades (MICINN). España; Universidad de Sevilla. TEP131: Grupo de Elasticidad y Resistencia de MaterialesUnderstanding the bending behaviour of composite materials is essential for effective design, particularly with the increasing use of complex components with multiple bends. Carbon fibres are often preferred in such applications due to their superior tensile properties; however, given their limited compressive performance, hybridization with glass fibres is commonly used. In this context, this study analyses the energy contributions of intralaminar and interlaminar damage mechanisms leading to failure in hybrid carbon/glass fabric-reinforced laminates under bending loads. Different hybridization ratios and configurations, specifically the positioning of glass and carbon fabric reinforcements relative to the load application, are evaluated experimentally and numerically. The experimental results show that the bending performance of hybrid laminates falls between those of non-hybrid carbon (8C) and glass (8G) laminates, with a clear dependence on the hybridisation ratio. When glass fibres are positioned in the compression region, the hybrid laminates exhibit slightly higher force and displacement values. Notably, the 3G/5C configuration (glass on the compression side) achieves a force and a displacement of 255.1 N and 4.23 mm, respectively, representing increases of approximately 5.9% and 13.1% compared to the 5C/3G configuration, which reaches 240.9 N and 3.74 mm. Numerical models show a good agreement with the experimental data, with force errors predominantly within ±5.3% and displacement errors within ±6.8%. Non-hybrid configurations demonstrate a more predictable damage progression, whereas hybrid laminates introduce variability due to differences in fiber type and placement, influencing overall energy dissipation and structural performance. Additionally, the energy analysis reveals that intralaminar damage is the dominant energy dissipation mechanism, followed by delamination and friction.Artículo Effect of 3D-Printed Hexagonal Honeycomb Core Density of PLAWood Based Subjected to Low-Velocity Impact(Society of Sugar Palm Development and Industry Malaysia, 2024-12) Ainin, F. Nur; Azaman, M.D.; Majid, M.S. Abdul; Ridzuan, M.J.M.; Ferreira, Luis Miguel Marques; Coelho, Carlos A.C.P.; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de EstructurasAdditive manufacturing (AM) technology has become the preferred method for fabricating lightweight sandwich composite structures, due to its ability to produce complex designs rapidly. However, these structures are susceptible to performance decline and potential damage, especially under impact loading in engineering applications. This study investigates the low-velocity impact characteristics of 3D-printed hexagonal honeycomb cores made from wood-filled polylactic acid (PLA) with unit cell sizes of 6, 8, and 10 mm. Energy absorption and failure mechanisms were assessed through drop-weight impact testing at an energy level of 11 J, with results analyzed using a stereo microscope. The findings demonstrate that unit cell size significantly impacts the performance of sandwich composite structures. Smaller unit cells increase core density, leading to enhanced energy absorption capabilities. The medium-density 8 mm unit cell is identified as the optimal structure for lightweight materials, offering efficient energy absorption and intermediate failure modes. While lighter than the high-density 6 mm unit cell, the 8 mm unit cell absorbs a comparable amount of energy (8 mm: 9.22 J, 6 mm: 9.61 J). Furthermore, this medium-density cell outperforms the low-density 10 mm unit cell, which absorbs only 7.44 J, due to its intermediate stiffness that better resists substantial deformation compared to the lower-density structure.Artículo Effect of moderate temperatures on compressive strength of ultra-high-performance concrete: A microstructural analysis(Elsevier, 2021-02) Suescum-Morales, David; Ríos Jiménez, José David; Martínez de la Concha, Antonio; Cifuentes-Bulté, Héctor; Jiménez Romero, José Ramón; Fernández Rodríguez, José María; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Junta de Andalucía; Ministerio de Educación, Cultura y Deporte (MECD). España; Ministerio de Economía y Competitividad (MINECO). España; Universidad de Sevilla. TEP972: Mecánica de materiales y estructurasConcrete with two types of steel fibres and a polypropylene fibre prevented spalling and preserved the compressive strength at 300 °C, which makes these concretes suitable for long-term applications up to 300 °C, such as for steam collectors or thermal energy storage systems. The compressive strength behaviour of three types of ultra-high-performance fibre-reinforced concrete manufactured with the same matrix was investigated. For this purpose, a complete characterisation of all the raw materials and the three types of fibres used was performed. The morphology of all concrete mixtures at room temperature was analysed using scanning electron microscopy–energy-dispersive X-ray spectroscopy. From the results, it was ascertained that the steel fibres and coarse siliceous aggregates were not in contact (being separated by ≥3.41 μm) and were surrounded by the binder (of ≥1 μm in thickness) for all the mixtures studied. Rosenhahnite and/or quartz Dauphiné-twinned phases improved the compressive strength (as determined by X-ray diffraction).
Artículo Longitudinal fibre/matrix debonds in CFRP ultra-thin plies: T-T cyclic testing and numerical prediction(Elsevier, 2025-03) Sánchez-Carmona, Serafín; Sandino de Benito, Carlos; Correa Montoto, Elena; Velasco López, María Luisa; Barroso Caro, Alberto; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla; Junta de Andalucía; Ministerio de Ciencia, Innovación y Universidades (MICINN). EspañaThe edge effect phenomenon in cross-ply laminates made of ultra-thin (UT) 90º plies produces a relevant stress component through the laminate thickness that could lead to the generation of longitudinal debonds (parallel to the loading direction) in the 90° ply block. In this study, specimens from a carbon-epoxy laminate made of conventional 0º and UT 90º ply blocks are inspected after the curing process in order to find longitudinal debonds. The debonds growth is also monitored during a later T-T cyclic testing campaign. The experimental results are compared with the predictions obtained from a BEM model showing a good agreement. Finally, the use of an inverse procedure combining both experimental and numerical analyses leads to the estimation of GIc of the fibre/matrix interface.Artículo Interaction between fibres in the transverse damage in composites(Elsevier, 2020-11) Velasco López, María Luisa; Correa Montoto, Elena; París Carballo, Federico; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Ministerio de Educación, Cultura y Deporte (MECD). EspañaA micromechanical study is carried out taking the initial expected damage that is manifested in a composite laminate by the debonding between the fibres and matrix in the 90° lamina as a reference. Questions such as the influence in the appearance of damage of the inter-fibre distance and the orientation of the fibres with respect to the loading direction are studied. Additionally, the effect of the presence of damage at a secondary fibre in the subsequent appearance of further debonding is also analysed. Finally, the conclusions reached are supported by experimental evidence obtained by testing [0,90n]S laminates.