Modelling of edge crack formation and propagation in ceramic laminates using the stress–energy coupled criterion

Ševeček, Oldřich; Kotoul, Michal; Leguillon, Dominique; Martín, E.; Bermejo, Raúl

doi:10.1016/j.engfracmech.2016.03.039

Cited by 8 publications

(6 citation statements)

References 46 publications

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“…Even though mainly compressive stresses are thereby introduced in the ceramic material, also tensile stresses can arise at the MoSi 2 surface, as indicated in Figure 6B. Similar “edge cracks” are thereby known from, for example, ceramic multilayer systems, where compressive residual stresses were introduced for damage tolerant design 43,44 …”

Section: Resultsmentioning

confidence: 86%

“…Similar "edge cracks" are thereby known from, for example, ceramic multilayer systems, where compressive residual stresses were introduced for damage tolerant design. 43,44 However, it is remarkable that the crack starts at the surface where the silver is wetting the electrode. This has been investigated deeper within a simulation using the finite element method.…”

Section: Silver Brazingmentioning

confidence: 99%

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Feasibility study on electrically conductive joining of MoSi₂ electrodes for spark plugs

Gruber

Tilz²,

Harrer

et al. 2023

Int J Applied Ceramic Tech

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Despite the often outstanding functional as well as (high temperature-) mechanical properties of ceramics, their usage is often limited due to their inherent brittleness. This also compromises the joining with metals, which is often indispensable for engineering applications. In this context, electrically conductive ceramics like MoSi 2 are promising materials for the application as electrodes where high temperatures in harsh environments are present (e.g., in spark plugs for large gas engines). Due to the difficult joining of the respective materials, long-term experiments are thereby often still pending. In this work, adhesive bonding, brazing, tungsten inert gas-, and resistance welding were performed to evaluate their applicability for generating electrically conductive as well as mechanically reliable joints between MoSi 2 and Inconel 600, aiming to utilize MoSi 2 electrodes in spark plugs. Fractographic analyses are performed to understand cracks associated with the high (thermo-) mechanical stresses. Additionally, a finite element model was set up for a deeper understanding of the observed fracture behavior. While adhesive bonding is acceptable for short-term experiments at low temperatures, brazing and resistance welding may qualify for fast and reliable manufacturing of spark plugs with ceramic electrodes.

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Section: Resultsmentioning

confidence: 86%

Section: Silver Brazingmentioning

confidence: 99%

Feasibility study on electrically conductive joining of MoSi₂ electrodes for spark plugs

Gruber

Tilz²,

Harrer

et al. 2023

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

show abstract

“…5. Such type of plot has been already used by authors in [15] upon the solution of different 2D fracture-mechanics problems, where more details about its interpretation can be found. Besides the determination of the critical applied load leading to initiation of the crack (or in other words to satisfaction of both stress and energy condition) the graph in Fig.…”

Section: D Fe Model and Resultsmentioning

confidence: 99%

“…A promising way for prediction of failure of brittle ceramic materials is an approach based on the theory of Finite Fracture Mechanics (FFM) which utilizes for the definition of the crack onset the coupled (stress-energy) criterion (CC) which has been already used in a number of works -see e.g. [9][10][11]. This criterion states that a crack originates if two conditions (i.e.…”

Section: Failure Criterion Defining the Crack Onsetmentioning

confidence: 99%

Prediction of the Ceramic Foam Structure Failure Using a Detailed Finite Element Model

Ševeček

Hanák

Majer

et al. 2019

KEM

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The contribution deals with modelling and prediction of failure of mechanically loaded open cell ceramic foam structures by using 3D volume FE models constructed from CT scans of real foam specimens. The condition for crack initiation in particular struts comes from the coupled stress-energy criterion which combines two fracture-mechanics parameters of the investigated material – tensile strength and its fracture toughness. By combining of both stress and energy condition one obtains information about the crack initiation length which is later used (together with the tensile strength) for determination of the strut failure in the complex 3D FE model of the ceramic foam structure. The crack onset is considered in the critical location at the moment when the (tensile) principal stress under the strut surface (in a depth corresponding to the crack initiation length) exceeded the tensile strength of the strut. Such approach enables us to define failure also on relatively coarse meshes of the FE models where potential stress concentrations are not described precisely and therefore it is not possible to decide about the failure just based upon the value of tensile stress on the strut surface.

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“…Vibrations and the associated deformation of piezo-ceramics often cause an initiation of unstable crack propagation through the piezo layer and practically immediately result in malfunction of the system [3]. One way to achieve higher fracture toughness of piezo-ceramics (and its higher fracture-mechanics reliability) is to design it as a multilayer structure containing residual stresses [4]. Ceramic laminate systems are typically produced from powders, which are sintered at high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Design Parameters of Fracture Resistant Piezoelectric Vibration Energy Harvester

Majer

Ševeček

Machů

et al. 2018

KEM

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This paper is focused on an analysis of a multilayer ceramic-based piezoelectric vibration energy harvester, which could be excited by ambient vibrations or external forces and thus provide a useful source of electricity for modern electronics. The proposed multilayer concept of the energy harvester enables introduction of tensile / compressive residual stresses inside particular layers. These stresses are intended to be used for enhancement of the harvester ́s fracture resistance and simultaneously for the improvement of the energy gain upon its operation. A crack arrest, by means of compressive residual stresses (in the outer “non-piezo” layer), will be utilized to this end. Primarily, the extended classical laminate theory (taking into account the piezoelectric characteristics of selected layers) will be used to define various designs of particular layers with various levels of residual stresses inside them. The weight function method is subsequently employed to select a design, which is most resistant to propagation of preexisting cracks. Selected laminate configurations are verified by means of FE simulations. Such analysis is essential for development of new energy harvesting systems formed of new smart materials and structures, which could be integrated in future development processes.

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Modelling of edge crack formation and propagation in ceramic laminates using the stress–energy coupled criterion

Cited by 8 publications

References 46 publications

Feasibility study on electrically conductive joining of MoSi₂ electrodes for spark plugs

Feasibility study on electrically conductive joining of MoSi₂ electrodes for spark plugs

Prediction of the Ceramic Foam Structure Failure Using a Detailed Finite Element Model

Optimization of Design Parameters of Fracture Resistant Piezoelectric Vibration Energy Harvester

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Modelling of edge crack formation and propagation in ceramic laminates using the stress–energy coupled criterion

Cited by 8 publications

References 46 publications

Feasibility study on electrically conductive joining of MoSi2 electrodes for spark plugs

Feasibility study on electrically conductive joining of MoSi2 electrodes for spark plugs

Prediction of the Ceramic Foam Structure Failure Using a Detailed Finite Element Model

Optimization of Design Parameters of Fracture Resistant Piezoelectric Vibration Energy Harvester

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Product

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Feasibility study on electrically conductive joining of MoSi₂ electrodes for spark plugs

Feasibility study on electrically conductive joining of MoSi₂ electrodes for spark plugs