Computational prediction of the lifetime of self-healing CMC structures

Genet, Martin; Marcin, Lionel; Baranger, Emmanuel; Cluzel, Christophe; Ladevèze, Pierre; Mouret, Anne

doi:10.1016/j.compositesa.2011.11.004

Cited by 38 publications

(34 citation statements)

References 39 publications

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“…It is non-monotonic. For an applied stress of 150 MPa, a maximum lifetime can be found around 480 • C, which is in agreement with experimental results on coupons [16].…”

Section: Validation and Mechanisms Analysissupporting

confidence: 90%

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Damage and Lifetime Modeling for Structure Computations

Baranger

Genet

Cluzel

2014

Ceramic Matrix Composites

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INTRODUCTIONCeramic matrix composites (SiC fibers, PyC interphase, and mutistacked Si-B-C matrix in this paper) combine good mechanical properties with the capability of sustaining high temperatures in oxidizing environments. The use of a multilayer self-healing matrix improves the lifetime of ceramic matrix composites (CMCs) considerably [1]. This technology along with the use of SiC fibers paves the way for applications with very long lifetimes (several thousands of hours).Structural applications of CMCs need to answer to the main and critical question that is at the center of this chapter: how to predict, that is, to compute, the lifetime of engineering structures. The answer is a multiphysic macroscopic model able to reproduce couplings between the mechanical and environmental fields. For such materials, confidence in the simulation is related directly to one's understanding of each degradation mechanism and to the introduction of such mechanisms in the model; lifetimes being too large for a purely experimental validation over long lifetimes (tens of thousands of hours).The first part of the chapter deals with the modeling of the different microcracking mechanisms. The key phenomenon is the deflection of the matrix cracks in the fiber matrix interphase [2][3][4]: this mechanical fuse protects the fibers from the cracks and enables the development of multiple cracks in the matrix, giving the composite some level of ductility, even though all of its constituents are brittle. The matrix cracking scenario has already been established for woven CMCs [5]. Since the matrix between the yarns is stiffer, but more brittle, and has larger pores than the yarns themselves, it begins to crack first. For a well-densified composite, the corresponding cracks are oriented by the main loading direction and are orthogonal to the applied stress direction, which is a main modeling difficulty. Then, when this crack network nearly reaches saturation, new cracks mainly appear in the matrix inside the yarns. The corresponding cracks are oriented by the fibers: they are orthogonal to the fibers in the longitudinal yarns, and parallel to the fibers in transverse yarns if the main load direction corresponds to the longitudinal yarns. In summary, there are three types of cracks in the damaged material: (i) inter-yarn cracks, (ii) intra-yarn longitudinal cracks, and (iii) intra-yarn transverse cracks.Among composites, CMCs are the most difficult situation for damage modeling. Rather complex closure effects occur for the damage mechanism associated with microcracks when direction is orthogonal to the loading direction and, therefore, is not known a priori. Here, we are developing our answer with a general anisotropic damage theory including microcracks closure effects [6,7]. In order to differentiate between the crack opening and closing effects, which are very pronounced in CMCs, the strain energy is divided into three parts associated with damage due to pure traction, Ceramic Matrix Composites: Materials, Modeling and Technology, First Ed...

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“…It is non-monotonic. For an applied stress of 150 MPa, a maximum lifetime can be found around 480 • C, which is in agreement with experimental results on coupons [16].…”

Section: Validation and Mechanisms Analysissupporting

confidence: 90%

“…Classical numerical difficulties are displayed and answers are given. To end, the lifetime model is applied to several structural tests [16]. The first test concerns a dog-bone specimen subjected to tension.…”

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confidence: 99%

Damage and Lifetime Modeling for Structure Computations

Baranger

Genet

Cluzel

2014

Ceramic Matrix Composites

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“…Open hole plates computations are presented in [26] as well as the implementation. The definition of the positive and negative parts in Eq.…”

Section: Mechanical Model Reductionmentioning

confidence: 99%

Modeling framework and associated simulation tools for the prediction of damage tolerance of CMC

Baranger

2015

MATEC Web of Conferences

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Abstract.A modeling framework and the associated simulation tools are presented for the prediction of the mechanical behaviour and lifetime of CMC with self-healing matrix. A macroscopic anisotropic damage model enriched with micro information has been developed, identified and validated using experimental information at different levels including reaction kinetics, fiber failure probability or macroscopic mechanical behavior. The computational cost associated to the proposed model being quite expansive, a method has been setup to construct, automatically, reduced numerical constitutive laws. An illustration is given as well as the associated error estimation.With high manufacturing costs and moderated lifetimes at high temperatures, the use of CMC has been limited to military engine application. Nevertheless, recent developments on self-healing matrices have greatly increase their properties for long lifetimes. It is now possible to use them on civil engine applications in order to improve engine temperatures [1].A first family of models have been developped to predict the mechanical behaviour of CMC under static loadings at the macroscopic scale [2][3][4]. For low lifetimes up to 5 000 h, a purely experimental approach allowed, for a high cost, to handle the problem of certification in the military domain. For civil application (expected lifetimes greater than 50 000 h) within the framework of damage tolerance, a direct experimental strategy becomes unaffordable. It becomes necessary to use models in order to anticipate the long term behavior over the whole loading range. A second family of models has been developed at . The aim of these models is to predict the mechanical behavior but also the lifetime of the material. Loading cases accounted for in the model are static or cyclic mechanical loadings has well as thermal and chemical loadings (oxygen and steam pressures). To get robust results under multi-axial and multiphysic loadings, the model should rely on solid foundations. The aim of this paper is to present that kind of model and then how to implement and use them efficiently in a structural computation framework. First of all, note that a large amount of experimental information and models are available at different scales and on different mechanisms for this material [8][9][10]: from lifetimes on fibers to mechanical behavior on composite coupons by oxidation kinetics. a

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“…Genet and co-workers [78,79] developed what they described as a "virtual material" which is a multiscale multi-physics model for lifetime predictions of the constitutive response of CMCs.. The mechanical mechanisms of the virtual material are based on hybrid meso-cells at yarnscale which is subsequently homogenized into a single framework.…”

Section: Compressive Strengthmentioning

confidence: 99%

“…The virtual testing of CMCs, proposed by Genet and co-workers [78,79], was focussed on isolated cracks and their effects on fracture performance of the test material. Lamon [82] continued the study by proffering a stochastic approach to study of effects of multiple cracks for a given CMC.…”

Section: Compressive Strengthmentioning

confidence: 99%

Virtual testing of advanced composites, cellular materials and biomaterials: A review

Okereke

Akpoyomare

Bingley

2014

Composites Part B: Engineering

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Please cite this article as: Okereke, M.I., Akpoyomare, A.I., Bingley, M.S., Virtual testing of advanced composites, cellular materials and biomaterials: a review, Composites: Part B (2014), doi: http://dx.doi.org/10. 1016/ j.compositesb.2014.01.007 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. AbstractThis paper documents the emergence of virtual testing frameworks for prediction of the constitutive responses of engineering materials. A detailed study is presented, of the philosophy underpinning virtual testing schemes: highlighting the structure, challenges and opportunities posed by a virtual testing strategy compared with traditional laboratory experiments. The virtual testing process has been discussed from atomistic to macrostructural lengthscales of analyses. Several implementations of virtual testing frameworks for diverse categories of materials are also presented, with particular emphasis on composites, cellular materials and biomaterials (collectively described as heterogeneous systems, in this context). The robustness of virtual frameworks for prediction of the constitutive behaviour of these materials is discussed. The paper also considers the current thinking on developing virtual laboratories in relation to availability of computational resources as well as the development of multi-scale material model algorithms. In conclusion, the paper highlights the challenges facing developments of future virtual testing frameworks. This review represents a comprehensive documentation of the state of knowledge on virtual testing from microscale to macroscale length scales for heterogeneous materials across constitutive responses from elastic to damage regimes.

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Computational prediction of the lifetime of self-healing CMC structures

Cited by 38 publications

References 39 publications

Damage and Lifetime Modeling for Structure Computations

Damage and Lifetime Modeling for Structure Computations

Modeling framework and associated simulation tools for the prediction of damage tolerance of CMC

Virtual testing of advanced composites, cellular materials and biomaterials: A review

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