Artículos (Mecánica de Medios Continuos y Teoría de Estructuras)

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

Examinar

Mostrando 1 - 5 de 5

An extended invariant approach to laminate failure of fibre-reinforced polymer structures
(Cambridge University Press, 2022) Corrado, G.; Arteiro, Albertino; Marques, A.T.; Reinoso Cuevas, José Antonio; Daoud, F.; Glock, F.; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; Universidad de Sevilla. TEP-131: Elasticidad y resistencia de materiales.
This paper presents the extension and validation of omni-failure envelopes for first-ply failure (FPF) and last-ply failure (LPF) analysis of advanced composite materials under general three-dimensional (3D) stress states. Phenomenological failure criteria based on invariant structural tensors are implemented to address failure events in multidirectional laminates using the “omni strain failure envelope” concept. This concept enables the generation of safe predictions of FPF and LPF of composite laminates, providing reliable and fast laminate failure indications that can be particularly useful as a design tool for conceptual and preliminary design of composite structures. The proposed extended omni strain failure envelopes allow not only identification of the controlling plies for FPF and LPF, but also of the controlling failure modes. FPF/LPF surfaces for general 3D stress states can be obtained using only the material properties extracted from the unidirectional (UD) material, and can predict membrane FPF or LPF of any laminate independently of lay-up, while considering the effect of out-of-plane stresses. The predictions of the LPF envelopes and surfaces are compared with experimental data on multidirectional laminates from the first and second World-Wide Failure Exercise (WWFE), showing a satisfactory agreement and validating the conservative character of omni-failure envelopes also in the presence of high levels of triaxiality.
Effect of tailored fiber deposition in 3D printed composites: application of an anisotropic phase field model
(Elsevier, 2023-10) Sangaletti, Simone; Mitrou, Anatoli; García García, Israel; Arteiro, Albertino; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 861061; Spanish Ministry of Science and Innovation Project PID2020-117001 GB-I00; Universidad de Sevilla. TEP131: Elasticidad y Resistencia de Materiales
Continuous Fiber 3D printing is a relatively new technology which can allow for tailored reinforcement of critical regions in structural components, i.e., stress concentrations, following principal stress lines. The influence the fiber deposition path has on the mechanical and failure behavior of such components is assessed using an anisotropic phase field model. A comparison with experimental results for notched unidirectional composite plates, available in the literature, demonstrates the ability of the method to produce satisfactory predictions for unidirectional reinforcement paths. The analysis is then extended to Open-Hole and Double Edge-Notched tension coupons of both unidirectional and variable stiffness reinforcement patterns. It is observed that the strength obtained for the components made with a reinforcement pattern that follows the principal stress lines is markedly higher than that for the equivalent unidirectionally reinforced ones. It is highlighted that the improvement in strength deriving from the tailored fiber deposition cannot be deduced solely by the analysis of the stress concentration factor but an analysis taking damage into account is necessary. In addition, the effect of the reinforcement strategy on the size effect was also explored, highlighting how the tailored fiber path leads to an increase in the failure load attainable by the specimens for all the dimensions analyzed.
Effect of the level of anisotropy on the macroscopic failure of notched thin-ply laminates
(Elsevier, 2024-11) Mitrou, Anatoli; Arteiro, Albertino; Reinoso Cuevas, José Antonio; Camanho, Pedro P.; 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 Materiales
This work presents a detailed experimental study conducted for a range of different lay-ups using thin-ply carbon fiber reinforced polymer (CFRP) laminates. The selection of the laminates was performed relying on their level of anisotropy. The laminates vary from a quasi-isotropic (QI) laminate, which is weakly anisotropic, to a cross-ply (CP) laminate, which is strongly anisotropic. The laminates were tested in on-axis and off-axis open hole tension (OHT). The main objective was to observe the effect of the level of anisotropy of the laminate on the macroscopic failure and observed failure patterns. It is shown that, contrary to most existing observations so far, depending on the lay-up and consequently its level of anisotropy, open-hole, quasi-homogeneous thin-ply laminates do not necessarily exhibit a fiber dominated failure mode, but could develop sub-critical damage mechanisms in a large extent prior to ultimate failure, reminiscent of what is observed for standard-ply CFRP laminates.
Micro-mechanical analysis of composite materials using Phase-Field models of brittle fracture
(Elsevier, 2023-12) Macías, Juan; Arteiro, Albertino; Otero Gruer, Fermín; Camanho, Pedro P.; Reinoso Cuevas, José Antonio; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union’s H2020-MSCA-ITN-2019 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 861061 – Project NEWFRAC “New strategies for multifield fracture problems across scales in heterogeneous systems for Energy, Health and Transport”; Universidad de Sevilla. TEP131: Elasticidad y Resistencia de Materiales
Failure in fiber-reinforced composites is a complex phenomenon where different damage mechanisms interact and evolve through various scales. Micro-mechanical analysis using the finite element method has become an important alternative to study such failure phenomena and their interactions, by modeling explicitly the fiber, matrix, and fiber–matrix interface. In this work, the predictive capabilities of the finite element method together with the Phase-Field (PF) method for fracture has been assessed. The study compares different PF formulations, energy splits and numerical parameters, using Representative Volume Elements (RVEs) of different sizes, fiber distributions and with different Boundary Conditions (BCs). It is found that even though good approximations can be obtained and meso-scale failure envelopes for transverse loading generated, these are highly dependent on the modeling assumptions and PF parameters. The AT2 formulation combined with Amor’s energy split provides the best predictions when compared with an analytical failure surface. The best fit is found for transverse shear-dominated loading, while larger differences are found for compressive loading, whose strength predictions are strongly affected by the PF formulations and energy splits. It is demonstrated that meso-scale strength is conditioned by interface properties as interface damage is the dominant failure initiation mechanism under tensile-dominated loading. On the other hand, PF parameters have a stronger influence on compressive-dominated loading. Finally, it is shown that assuming a perfect fiber–matrix interface has a strong effect on the expected meso-scale strength, as failure is markedly delayed. Accordingly, based on the present results, especial care should be taken in properly assessing all the variables involved in the modeling methodology to draw conclusions from computational micro-mechanical analyses based on the PF approach.
Modeling fracture of multidirectional thin-ply laminates using an anisotropic phase field formulation at the macro-scale
(Elsevier, 2023-06) Mitrou, Anatoli; Arteiro, Albertino; Reinoso Cuevas, José Antonio; Camanho, Pedro P.; Universidad de Sevilla. Departamento de Mecánica de Medios Continuos y Teoría de Estructuras; European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 861061 – Project NEWFRAC; Consejería de Economía y Conocimiento, Junta de Andalucía, and European Regional Development Fund Project P20-00595; Ministerio de Ciencia e Innovación of Spain Project TED2021-131649B-I00; Universidad de Sevilla. TEP131: Elasticidad y Resistencia de Materiales
An equivalent single layer approach to model fracture events of multidirectional balanced thin-ply laminates via the use of the Phase Field method is explored. The inherent anisotropic nature of a multidirectional laminate is taken into account through the use of a structural tensor, defined from scaled directional vectors, which can account for the variation in fracture toughness of the laminates in varying directions. The scaling constants are defined using the lay-up of the laminate and the intra-laminar fracture toughness of the lamina, minimizing the number of input parameters required while also alleviating the structural tensor of a pure numerical and geometric meaning. They have a significant effect in the solution, and are here related to materials properties, not only providing a new perspective on their definition but also allowing the reduction of the number of numerical parameters used to calibrate the anisotropic PF model. The numerical implementation of the proposed formulation is performed using a simple and robust thermal analogy in Abaqus by exploiting the use of an anisotropic conductivity matrix that plays the role of the structural tensor in the anisotropic phase field formulation, which reduces the complexity of the simulations. Experimental results, based on open-hole tension and double edge-notched tension, are reproduced via simulation validating the model for size effects and for the response to off-axis loading. Successful prediction of notch size effects in multidirectional composite laminates is achieved by means of an equivalent single layer approach, incl. the off-axis open-hole tension strengths of a directional thin-ply laminate. All numerical strength predictions were well within acceptable errors of the respective experimental values.

Examinar

Examinando Artículos (Mecánica de Medios Continuos y Teoría de Estructuras) por Autor "Arteiro, Albertino"