Articoli di riviste: "Brittle behaviour"

1

Banerjee, Rajat, e Bikas K. Chakrabarti. "Critical fatigue behaviour in brittle glasses". Bulletin of Materials Science 24, n. 2 (aprile 2001): 161–64. http://dx.doi.org/10.1007/bf02710094.

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Vallet, D., e J. C. Charmet. "Mechanical behaviour of brittle cement grains". Journal of Materials Science 30, n. 11 (giugno 1995): 2962–67. http://dx.doi.org/10.1007/bf00349670.

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3

Dlouhý, Ivo, Zdeněk Chlup e Aldo Roberto Boccaccini. "Fracture Behaviour of Brittle (Glass) Matrix Composites". Materials Science Forum 482 (aprile 2005): 115–22. http://dx.doi.org/10.4028/www.scientific.net/msf.482.115.

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A number of examples exist that indicate the potential for increasing the toughness of brittle matrices by dispersing different reinforcements. For further development of these advanced materials the actual material response during mechanical loading under presence of flaws appears to be important. Theoretical and experimental knowledge acquired on different kinds of brittle matrix composites is summarised in the paper. These include glass matrix composites with metallic particles, alumina platelets, continuous SiC (Nicalon®) fibres, and both chopped fibres and ZrO2particles (hybrid composites). The composites were tested in as-received state but also after different forms of thermomechanical loading, e.g. thermal shock, thermal cycling in air, which were investigated according to the envisaged composites application. Chevron notch technique was mainly used for fracture toughness evaluation. Microstructural damage is explained based on identified fracture micromechanisms.

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Xiao, Xiaolan, Jiayun Deng, Qiang Xiong, Qiusheng Yan, Zhengtao Wu e Huatay Lin. "Scratch Behaviour of Bulk Silicon Nitride Ceramics". Micromachines 12, n. 6 (16 giugno 2021): 707. http://dx.doi.org/10.3390/mi12060707.

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Si3N4 ceramic is generally recognized as being difficult to machine due to its hardness and brittleness. It is necessary to control the normal load applied and the machined depth of the abrasive particles in order to eliminate surface/subsurface damage and defects during the grinding or polishing. In this study, scratch experiments were conducted on the polished surface of Si3N4 specimens to investigate the brittle–ductile transformation and the evolution of material removal mechanisms. In addition, the cracking behaviour of Si3N4 ceramic was characterized by indentation tests. The Vickers indentation produced cracks that exhibited good developmental integrity and geometric symmetry. The results indicate that the scratch track can be divided into three stages: the ductile regime, the brittle–ductile coexisting stage, and the brittle fracture regime. The critical loads and the corresponding penetration depths of cracking occurrence in Si3N4 were recorded. The material removal of Si3N4 ceramic was primary attributed to ductile regime removal when the load was less than 9.8 N. Microcrack initiation on the subsurface was observed when the penetration depth of the scratch tip reached 8 μm or the depth of the indentation tip reached 3.2 μm. Microcracks expanded rapidly as the load was further increased, resulting in a brittle fracture of the Si3N4 ceramic.

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Xicheng, Huang, Li Shangkun, Qiang Wei, Chen Gang, Tian Rong e Wang Lixiang. "Numerical Simulation of Crack Initiation and Growth in PBX High Explosive Subject to Compression". EPJ Web of Conferences 183 (2018): 01019. http://dx.doi.org/10.1051/epjconf/201818301019.

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PBX solid high explosive exhibits brittle behaviour in uniaxial tension, quasi-brittle in uniaxial compression, and ductile when subject to high confining pressure. Tension cracking is the primary failure mode of PBX quasi-brittle solid, which is the main effect leading to overall failure of structural integrity. One characteristics of brittle or quasi-brittle solids, such as PBXs, is that when subject to overall compressive loading, the tensile cracks can still initiate inside the material due to existence of imperfection within the materials. In present study the extended finite element method is applied to analyze the cracking failure mechanism in the PBX 9502 platelike specimen with cavity subjected to overall compression. The nonlinear constitutive behaviours and failure of PBX under complex stress states were described by means of stress state dependent strength surface, non-associated flow rule and cohesive model the nonlinear behaviors of PBXs, including failure. Analysis indicates the tensile stress around the cavity arises in the specimen although loaded by overall compression, and this local tensile condition leads to cracking initiation. The comparison between simulation results and the experimental data published by LANL[Liu C, Thompson D G. Crack initiation and growth in PBX 9502 high explosive subject to compression. Journal of Applied Mechanics, 2014, 81(10):212-213] shows that they are in agreement with each other on some aspects of crack behaviours, including overall development of crack history and inflexion, crack initiation moment, crack initial speed, etc.

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Maeno, Keiki, Masaki Tanaka, Kenji Higashida, Masahiro Fujikura e Kohsaku Ushioda. "The Brittle-to-Ductile Transition Behaviour in Fe-Al Single Crystalline Alloys". Advanced Materials Research 409 (novembre 2011): 243–48. http://dx.doi.org/10.4028/www.scientific.net/amr.409.243.

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The morphology of deformation twinning, which influences a brittle fracture at low temperatures, was investigated in Fe-8mass%Al. Tensile tests were performed at 129K and room temperature. The specimen tested at room temperature showed yielding and kept deformed by usual slip while the specimen tested at 129K fractured in a brittle manner in an elastic regime with a number of straight markings due to deformation twinning. Detail analysis of those deformation twins suggests that the collision of deformation twinning is the initiation site of the brittle fracture.

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Traidi, Khalil, Véronique Favier, Philippe Lestriez, Karl Debray, Laurent Langlois e Tudor Balan. "Modelling Semi-Solid Behaviour and Brittle Temperature Range". Solid State Phenomena 285 (gennaio 2019): 361–66. http://dx.doi.org/10.4028/www.scientific.net/ssp.285.361.

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In this paper, a new elastic viscoplastic micromechanical modelling is proposed to represent the semi-solid behaviour and predict the ductile-brittle transition of the C38LTT near the solidus. It is based on a viscoplastic modelling previously presented in [1]. The originality of the new model comes from three main enhancements: the transition between the solid state and the semi-solid state was included meaning that the material properties were taken temperature-dependent, the elastic properties was taken into account similarly as [2] and the evolution of the internal variable describing the degree of agglomeration of the solid phase was enhanced. The model was implemented in the commercial software FORGE©. Tensile tests representing the experimental thermal conditions and obtained using a GLEEBLE© machine were simulated. The comparison of the predicted and experimental results shows that, for the first time to our knowledge, the three steps of the load-displacement response and ductile-brittle transition were successfully described.

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Renshaw, Carl E., e Erland M. Schulson. "Universal behaviour in compressive failure of brittle materials". Nature 412, n. 6850 (agosto 2001): 897–900. http://dx.doi.org/10.1038/35091045.

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9

Webster, S. E., e P. H. Bateson. "Significance of local brittle zones to structural behaviour". Materials Science and Technology 9, n. 1 (gennaio 1993): 83–92. http://dx.doi.org/10.1179/mst.1993.9.1.83.

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10

Sieber, Lars, e Richard Stroetmann. "The brittle fracture behaviour of old mild steels". Procedia Structural Integrity 5 (2017): 1019–26. http://dx.doi.org/10.1016/j.prostr.2017.07.160.

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11

Lynch, S. P. "Concerning the anomalous brittle fracture behaviour of iridium". Scripta Materialia 57, n. 2 (luglio 2007): 85–88. http://dx.doi.org/10.1016/j.scriptamat.2007.03.039.

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12

Abraham, Farid F., e Huajian Gao. "Anomalous ductile-brittle fracture behaviour in fcc crystals". Philosophical Magazine Letters 78, n. 4 (ottobre 1998): 307–12. http://dx.doi.org/10.1080/095008398177887.

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13

Roudaut, Ga�lle, Fabienne Poirier, Denise Simatos e Martine Le Meste. "Can dynamical mechanical measurements predict brittle fracture behaviour?" Rheologica Acta 44, n. 1 (25 giugno 2004): 104–11. http://dx.doi.org/10.1007/s00397-004-0392-5.

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14

Kabir, R., Alfred Cornec e Wolfgang Brocks. "Quasi-Brittle Fracture of Lamellar γTiAl: Simulation Using a Cohesive Model with Stochastic Approach". Key Engineering Materials 324-325 (novembre 2006): 1317–20. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.1317.

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Quasi-brittle fracture of fully lamellar two phase (α2+γ)TiAl is investigated both experimentally and numerically. Fracture tests are conducted at room temperature, which fail in a quasi-brittle and unstable manner but exhibit significant variations in crack initiation and propagation prior to unstable failure. Fractographic investigations are performed which elucidate the micromechanical causes of the macroscopic behaviour. The observed deformation and fracture behaviours of the specimens are simulated by a finite element model containing cohesive elements for modelling the material separation. In order to capture the scatter of the macroscopic behaviour, a stochastic approach is chosen, in which local variations of cohesive parameters are taken into account. The model can describe and explain the physical phenomena of the specific material.

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Gesualdo, Antonio, e Michelina Monaco. "Constitutive behaviour of quasi-brittle materials with anisotropic friction". Latin American Journal of Solids and Structures 12, n. 4 (agosto 2015): 695–710. http://dx.doi.org/10.1590/1679-78251345.

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16

Kim, Hyoung Seop, e Ping Ma. "Mode II Fracture Behaviour of PBT Modified Brittle Epoxies". Key Engineering Materials 145-149 (ottobre 1997): 759–64. http://dx.doi.org/10.4028/www.scientific.net/kem.145-149.759.

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17

Hong-zhi, Ding, Zhao Ru-bao e Xing Xiu-san. "The fractal behaviour of crack propagation in brittle materials". Acta Physica Sinica (Overseas Edition) 5, n. 11 (novembre 1996): 801–8. http://dx.doi.org/10.1088/1004-423x/5/11/001.

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18

Pei, Linqing, Cheng Lu, Kiet Tieu, Xing Zhao, Liang Zhang, Kuiyu Cheng e Guillaume Michal. "Brittle versus ductile fracture behaviour in nanotwinned FCC crystals". Materials Letters 152 (agosto 2015): 65–67. http://dx.doi.org/10.1016/j.matlet.2015.03.074.

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19

Shao, J. F. "Poroelastic behaviour of brittle rock materials with anisotropic damage". Mechanics of Materials 30, n. 1 (settembre 1998): 41–53. http://dx.doi.org/10.1016/s0167-6636(98)00025-8.

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20

Taliercio, Alberto, e Roberto Coruzzi. "Mechanical behaviour of brittle matrix composites: a homogenization approach". International Journal of Solids and Structures 36, n. 24 (agosto 1999): 3591–615. http://dx.doi.org/10.1016/s0020-7683(98)00167-x.

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21

Sadowski, Tomasz. "Modelling of semi-brittle MgO ceramic behaviour under compression". Mechanics of Materials 18, n. 1 (maggio 1994): 1–16. http://dx.doi.org/10.1016/0167-6636(94)90002-7.

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22

Roberts, R. J., e R. C. Rowe. "Brittle/ductile behaviour in pharmaceutical materials used in tabletting". International Journal of Pharmaceutics 36, n. 2-3 (maggio 1987): 205–9. http://dx.doi.org/10.1016/0378-5173(87)90157-8.

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23

Zhao, Yishu. "Behaviour and criterion of quasi-brittle fracture of metals". Engineering Fracture Mechanics 39, n. 4 (gennaio 1991): 683–86. http://dx.doi.org/10.1016/0013-7944(91)90218-p.

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24

Li, Chunlin. "Micromechanics modelling for stress-strain behaviour of brittle rocks". International Journal for Numerical and Analytical Methods in Geomechanics 19, n. 5 (maggio 1995): 331–44. http://dx.doi.org/10.1002/nag.1610190503.

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25

Bart, M., J. F. Shao e D. Lydzba. "Poroelastic behaviour of saturated brittle rock with anisotropic damage". International Journal for Numerical and Analytical Methods in Geomechanics 24, n. 15 (2000): 1139–54. http://dx.doi.org/10.1002/1096-9853(20001225)24:15<1139::aid-nag114>3.0.co;2-3.

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26

Christensen, Richard M. "The ductile/brittle transition provides the critical test for materials failure theory". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, n. 2210 (febbraio 2018): 20170817. http://dx.doi.org/10.1098/rspa.2017.0817.

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It is reasoned that any materials failure theory that claims generality must give full account of ductile versus brittle failure behaviour. Any such proposed theory especially must admit the capability to generate the ductile/brittle transition. A derivation of the failure surface orientations from a particular isotropic materials failure theory reveals that uniaxial tension has its ductile/brittle transition at T / C = 1/2, where T and C are the uniaxial strengths. Between this information and the corresponding ductile/brittle transition in uniaxial compression it becomes possible to derive the functional form for the fully three-dimensional ductile/brittle transition. These same general steps of verification must be fulfilled for any other candidate general failure theory.

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27

Woignier, Thierry, A. Hafidi Alaoui, Juan Primera e J. Phalippou. "Mechanical Properties of Aerogels : Brittle or Plastic Solids?" Key Engineering Materials 391 (ottobre 2008): 27–44. http://dx.doi.org/10.4028/www.scientific.net/kem.391.27.

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Different sets of silica aerogels (classical aerogels, partially dense aerogels, composite aerogels) have been studied in the objective to understand the mechanical behaviour of these extremely porous solids. The mechanical behaviour of xerogels and aerogels is generally described in terms of brittle and elastic materials, like glasses or ceramics. The main difference compared to silica glass is the order of magnitude of the elastic and rupture modulus which are 104 times lower. However, if this analogy is pertinent when gels are under a tension stress (bending test) they exhibit a more complicated response when the structure is submitted to a compressive stress. The network is linearly elastic under small strains, then exhibits yield followed by densification and plastic hardening. As a consequence of the plastic shrinkage it is possible to compact and stiffen the gel at room temperature. These opposite behaviours (brittle and plastic) are surprisingly related to the same kinds of gel features: pore volume silanol content and the pore size. Both elastic modulus and plastic shrinkage depend strongly on the volume fraction of pores and on the condensation reaction between silanols. On the mechanical point of view (rupture modulus and toughness), it is shown that pores size plays likely an important role. Pores can be considered as flaws in the terms of fracture mechanics and the flaw size, calculated from rupture strength and toughness is related to the pore size distribution.

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Teixeira, Pedro, Dulce Maria Rodrigues e Altino Loureiro. "Modelling Local Brittle Zones in Welds Using the Finite Element Method". Materials Science Forum 514-516 (maggio 2006): 1419–23. http://dx.doi.org/10.4028/www.scientific.net/msf.514-516.1419.

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This paper reports the results of a numerical study concerning the influence of local brittle zones intersecting the crack front on the fracture behaviour of welded joints. This work was performed using the numerical simulation of the three point bending test of weld samples with different amount of brittle structures at the crack front. Using 3D finite element discretization it was possible to simulate welded samples with very small fractions of brittle zone at the crack front, such as 5 %. Comparing the results of samples with increasing proportion of brittle zone it was observed a significant decrease in the crack growth resistance with increasing amounts of brittle material. This decrease in crack growth resistance was obtained even for samples with very small amounts of brittle material at the crack front.

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Gardner, R., S. Piazolo e N. Daczko. "Pinch and swell structures: evidence for brittle-viscous behaviour in the middle crust". Solid Earth Discussions 7, n. 2 (24 aprile 2015): 1517–54. http://dx.doi.org/10.5194/sed-7-1517-2015.

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Abstract. The flow properties of middle to lower crustal rocks are commonly represented by viscous flow. However, examples of pinch and swell structures found in a mid-crustal high strain zone at St. Anne Point (Fiordland, New Zealand) suggest pinch and swell structures are initiated by brittle failure of the more competent layer in conjunction with material softening. On this basis we develop a flexible numerical model using brittle-viscous flow where Mohr–Coulomb failure is utilised to initiate pinch and swell structure development. Results show that pinch and swell structures develop in a competent layer in both Newtonian and non-Newtonian flow provided the competent layer has enough viscosity contrast and initially fails brittlely. The degree of material softening after initial failure is shown to impact pinch and swell characteristics with high rates of material softening causing the formation of thick necks between swells by limiting the successful localisation of strain. The flow regime and yielding characteristics of the matrix do not impact pinch and swell structure formation itself, so long as the matrix is less competent. To aid analysis of the structures and help derive the flow properties of rocks in the field, we define three stages of pinch and swell development and offer suggestions for measurements to be made in the field. Our study suggests that Mohr–Coulomb behaviour combined with viscous flow is an appropriate way to represent the heterogeneous rocks of the middle to lower crust. This type of mid-crustal rheological behaviour has significant influence on the localization of strain at all scales. For example, inclusion of Mohr–Coulomb brittle failure with viscous flow in just some mid-crustal layers within a crustal scale model will result in strain localisation throughout the whole crustal section allowing the development of through-going high strain structures from the upper crust into the middle and lower crust. This localization then has a significant effect on developing near-surface structures.

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Khandavilli, Udaya B. Rao, Aoife M. Buckley, Anita R. Maguire, Mangalampalli S. R. N. Kiran, Upadrasta Ramamurty e Simon E. Lawrence. "Epimers with distinct mechanical behaviours". CrystEngComm 23, n. 34 (2021): 5848–55. http://dx.doi.org/10.1039/d0ce01723j.

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Ray, Purusattam. "Statistical physics perspective of fracture in brittle and quasi-brittle materials". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 377, n. 2136 (26 novembre 2018): 20170396. http://dx.doi.org/10.1098/rsta.2017.0396.

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We discuss the physics of fracture in terms of the statistical physics associated with the failure of elastic media under applied stresses in presence of quenched disorder. We show that the development and the propagation of fracture are largely determined by the strength of the disorder and the stress field around them. Disorder acts as nucleation centres for fracture. We discuss Griffith's law for a single crack-like defect as a source for fracture nucleation and subsequently consider two situations: (i) low disorder concentration of the defects, where the failure is determined by the extreme value statistics of the most vulnerable defect (nucleation regime) and (ii) high disorder concentration of the defects, where the scaling theory near percolation transition is applicable. In this regime, the development of fracture takes place through avalanches of a large number of tiny microfractures with universal statistical features. We discuss the transition from brittle to quasi-brittle behaviour of fracture with the strength of disorder in the mean-field fibre bundle model. We also discuss how the nucleation or percolation mode of growth of fracture depends on the stress distribution range around a defect. We discuss the corresponding numerical simulation results on random resistor and spring networks. This article is part of the theme issue ‘Statistical physics of fracture and earthquakes’.

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Herrmann, Christoph, Daniel Schneider, Ephraim Schoof, Felix Schwab e Britta Nestler. "Phase-Field Model for the Simulation of Brittle-Anisotropic and Ductile Crack Propagation in Composite Materials". Materials 14, n. 17 (30 agosto 2021): 4956. http://dx.doi.org/10.3390/ma14174956.

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In this work, a small-strain phase-field model is presented, which is able to predict crack propagation in systems with anisotropic brittle and ductile constituents. To model the anisotropic brittle crack propagation, an anisotropic critical energy release rate is used. The brittle constituents behave linear-elastically in a transversely isotropic manner. Ductile crack growth is realised by a special crack degradation function, depending on the accumulated plastic strain, which is calculated by following the J2-plasticity theory. The mechanical jump conditions are applied in solid-solid phase transition regions. The influence of the relevant model parameters on a crack propagating through a planar brittle-ductile interface, and furthermore a crack developing in a domain with a single anisotropic brittle ellipsoid, embedded in a ductile matrix, is investigated. We demonstrate that important properties concerning the mechanical behaviour of grey cast iron, such as the favoured growth of cracks along the graphite lamellae and the tension–compression load asymmetry of the stress–strain response, are covered by the model. The behaviour is analysed on the basis of a simulation domain consisting of three differently oriented elliptical inclusions, embedded in a ductile matrix, which is subjected to tensile and compressive load. The material parameters used correspond to graphite lamellae and pearlite.

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De Almeida, Olivier, Jean-François Ferrero, Laurent Escalé e Gérard Bernhart. "Charpy test investigation of the influence of fabric weave and fibre nature on impact properties of PEEK-reinforced composites". Journal of Thermoplastic Composite Materials 32, n. 6 (4 giugno 2018): 729–45. http://dx.doi.org/10.1177/0892705718778744.

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The aim of the work is to use Charpy impact test for quick evaluations of different Polyether-ether-ketone (PEEK)-reinforced composites to be used for impact protection. In the first part, the influence of weave pattern was first analysed by comparing the impact behaviour of three PEEK composites reinforced with plies of unidirectional (UD) tapes, 5H satin fabrics and 2 × 2 twill fabrics made of high-strength carbon fibres. In the second part, the influence of fibre nature was investigated for the same weave pattern. The impact behaviour of five 2 × 2 twill fabrics made from inorganic fibre (carbon, glass and basalt) and organic fibre (aramid and poly(p-phenylene-2,6-benzobisoxazole) (PBO)) has been compared. Two main types of failure modes were identified: a brittle behaviour mode with high failure strength and a highly deformable behaviour mode in which energy absorption is more important. The balance between brittle behaviour and highly deformable behaviour results from competition between the yarn crimp, weave pattern and fibre properties of the composite. Slight yarn crimp and small ply thickness increase the stiffness of the composite and induce brittle behaviour characterized by fibre failure in tension and a steep peak on the loading curves. This behaviour is observed in UD and 5H satin carbon-reinforced composites or 2 × 2 twill glass and basalt fabric-reinforced composites. In contrast, aramid and PBO 2 × 2 twill fabric composites exhibit high shear strength. The highly deformable behaviour of the specimens during the Charpy impact led, in the case of organic fibres, to a non-breakage of the fibres and consequently to a high level of energy absorption. This behaviour is necessarily interesting in armour applications.

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Forquin, Pascal. "Brittle materials at high-loading rates: an open area of research". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, n. 2085 (28 gennaio 2017): 20160436. http://dx.doi.org/10.1098/rsta.2016.0436.

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Brittle materials are extensively used in many civil and military applications involving high-strain-rate loadings such as: blasting or percussive drilling of rocks, ballistic impact against ceramic armour or transparent windshields, plastic explosives used to damage or destroy concrete structures, soft or hard impacts against concrete structures and so on. With all of these applications, brittle materials are subjected to intense loadings characterized by medium to extremely high strain rates (few tens to several tens of thousands per second) leading to extreme and/or specific damage modes such as multiple fragmentation, dynamic cracking, pore collapse, shearing, mode II fracturing and/or microplasticity mechanisms in the material. Additionally, brittle materials exhibit complex features such as a strong strain-rate sensitivity and confining pressure sensitivity that justify expending greater research efforts to understand these complex features. Currently, the most popular dynamic testing techniques used for this are based on the use of split Hopkinson pressure bar methodologies and/or plate-impact testing methods. However, these methods do have some critical limitations and drawbacks when used to investigate the behaviour of brittle materials at high loading rates. The present theme issue of Philosophical Transactions A provides an overview of the latest experimental methods and numerical tools that are currently being developed to investigate the behaviour of brittle materials at high loading rates. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’.

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Zhang, X. B., J. Li e S. E. Boukha. "Modelling the failure behaviour of brittle or quasi-brittle materials by analysing the growth of micro-cracks". International Journal of Fracture 160, n. 1 (9 ottobre 2009): 73–83. http://dx.doi.org/10.1007/s10704-009-9412-x.

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Heard, P. J., e Peter E. J. Flewitt. "Study of Reticulated Vitreous Carbon Foam as a Quasi-Brittle Material". Key Engineering Materials 665 (settembre 2015): 229–32. http://dx.doi.org/10.4028/www.scientific.net/kem.665.229.

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Quasi-brittle materials are those where the addition of specific microstructural features such as porosity can lead to departure from linear elastic behaviour prior to maximum force, followed by graceful failure. A simple example of a quasi-brittle material is reticulated vitreous carbon foam; an open-cell structure consisting of brittle ligaments connected in a three-dimensional array. Tensile testing measurements have been made on foams with various pore and ligament dimensions; force - displacement combined with acoustic monitoring together with the evaluation of the associated elastic moduli and fracture strengths. These tests give insights into the mechanisms of quasi-brittle failure, and the results are explored using simple considerations of elastic energy storage throughout process zones.

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Atutis, Mantas, e Juozas Valivonis. "REINFORCEMENT CHARACTERISTICS OF PRESTRESSED CONCRETE BEAMS WITH FIBER-REINFORCED POLYMER (FRP) TENDONS". Engineering Structures and Technologies 2, n. 2 (30 giugno 2010): 71–78. http://dx.doi.org/10.3846/skt.2010.10.

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The basic advantages of fiber-reinforced polymer (FRP) reinforcement are reviewed. FRP tendons exhibit linear elastic response to rupture without yielding and thus failure is expected to be brittle. Structural beahaviour of beams prestressed with FRP tendons is different from that of beams with traditional steel reinforcement. Strength design approach for prestressed beams with FRP tendons is based on the concept of brittle ratio, reinforcement ratio at which concrete fails in compression at the same time as FRP tendon ruptures. Depending on reinforcement ratio, the flexural behaviour of the beam can be devided into several groups. If reinfrocement ratio is equal to brittle ratio, beams fail by rupture of tendons and crushing of concrete simultaneously. Beams with reinforcement ratio, less than brittle ratio, are under-reinforced and will fail by rupture of tendons. When reinforcement ratio is greater than brittle ratio, concrete fails in compresion prior to rupture of tendons. Brittle ratio was calculated by different expressions proposed in scietific literature, and particular results were given. It has been shown, that brittle ratio is influenced by the mechanical properties of FRP and concrete.

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Kiehas, Florian, Anna Kalteis, Michael Jerabek e Zoltán Major. "EXPERIMENTAL INVESTIGATION OF THE FAILURE BEHAVIOUR OF POLYPROPYLENE COMPOUNDS FOR INSTRUMENTED PUNCTURE TESTS". Acta Polytechnica CTU Proceedings 18 (23 ottobre 2018): 66. http://dx.doi.org/10.14311/app.2018.18.0066.

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Instrumented puncture tests according to ISO 6603-2 and ASTMD3763 were executed for five different Polypropylene compounds (talcum-, glass fibre- and elastomer modified) with specimen thicknesses ranging from 1mm to 4 mm. Over 1500 puncture tests were executed at the Impact & Long-term Behaviour laboratory of the company Borealisr in Linz. This serves as strong foundation for statistical evaluations of the ductile/brittle transition temperature. For different materials and ductile/brittle transition determination methods, similar trends have been observed, which were characterized by introducing shift factors.

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Sadowski, T., L. Marsavina, E. Craciun e D. Pietras. "Description of Brittle Behaviour of Alumina/Zirconia 2 Phase Ceramics". IOP Conference Series: Materials Science and Engineering 416 (26 ottobre 2018): 012059. http://dx.doi.org/10.1088/1757-899x/416/1/012059.

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40

Xu, Tao, Chun-an Tang, Jian Zhao, Lianchong Li e M. J. Heap. "Modelling the time-dependent rheological behaviour of heterogeneous brittle rocks". Geophysical Journal International 189, n. 3 (23 aprile 2012): 1781–96. http://dx.doi.org/10.1111/j.1365-246x.2012.05460.x.

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41

Donzé, Frédéric, e Sophie-Adélaide Magnier. "Formulation of a 3-D numerical model of brittle behaviour". Geophysical Journal International 122, n. 3 (dicembre 1995): 790–802. http://dx.doi.org/10.1111/j.1365-246x.1995.tb06838.x.

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42

Ebrahem, Firaz, Franz Bamer e Bernd Markert. "Vitreous 2D silica under tension: From brittle to ductile behaviour". Materials Science and Engineering: A 780 (aprile 2020): 139189. http://dx.doi.org/10.1016/j.msea.2020.139189.

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43

Bansal, P., P. H. Shipway e S. B. Leen. "Finite element modelling of the fracture behaviour of brittle coatings". Surface and Coatings Technology 200, n. 18-19 (maggio 2006): 5318–27. http://dx.doi.org/10.1016/j.surfcoat.2005.06.015.

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44

Michot, Gérard, e M. A Loyola de Oliveira. "Plastic Relaxation at Crack Tip: from Brittle to Ductile Behaviour". MATERIALS TRANSACTIONS 42, n. 1 (2001): 14–19. http://dx.doi.org/10.2320/matertrans.42.14.

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45

Liang, Chen, e Yu Yuan Zhao. "Quasi-Static and Impact Response of Graded Aluminium Matrix Syntactic Foams". Materials Science Forum 933 (ottobre 2018): 246–55. http://dx.doi.org/10.4028/www.scientific.net/msf.933.246.

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Abstract (sommario):

The behaviour of aluminium matrix syntactic foams (AMSFs) with homogeneous and graded structures have been studied under quasi-static compression and impact. Particle size of ceramic microspheres and impact velocity had significant effects on the static and impact responses. Smaller microspheres led to higher strength but lower toughness. The compressive yield stress, plateau stress and specific energy absorption of the graded AMSF specimens were approximately the averages of the constituent layers, following the rule of mixture, although the order of the layers had some influence on the compressive behaviour. The syntactic foams were brittle under impact, no matter whether they were brittle or ductile in quasi-static compression. They had higher peak stresses and absorbed more energy in impact than in quasi-static compression. The location of the most brittle layer of the small ceramic microspheres had a significant effect on the impact failure pattern and sequence of the three-layer graded AMSFs.

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46

Sheng, C. H., M. Nagentrau e N. H. Ibrahim. "Prediction of brittle fracture propagation behaviour of hydroxyapatite (HAp) coating in artificial femoral stem component". Archives of Materials Science and Engineering 114, n. 1 (1 marzo 2022): 34–41. http://dx.doi.org/10.5604/01.3001.0015.9851.

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Purpose: This study addresses the brittle fracture propagation behaviour modelling of hydroxyapatite (HAp) coating in artificial femoral stem component. Design/methodology/approach: A simple two dimensional flat-on-flat contact configuration finite element model consisting contact pad (bone), Ti-6Al-4V substrate and HAp coating is employed in static simulation. The HAp coating is modelled as elastic layer with pre-microcrack which assumed to be initiated due to stress singularity. Findings: The study revealed that reducing coating thickness, pre-microcrack length and artificial femoral stem elastic modulus along with increasing bone elastic modulus will result in significant stress intensity factor (SIF) to promote brittle fracture propagation behaviour. Research limitations/implications: The influence of coating thickness, pre-microcrack length, bone and artificial femoral stem elastic modulus on fracture behaviour is examined under different stress ratio using J-integral analysis approach. Practical implications: The proposed finite element model can be easily accommodating different Hap coating thickness, pre-microcrack length, bone and artificial femoral stem elastic modulus to perform detailed parametric studies with minimal costly experimental works. Originality/value: Limited research focussing on brittle fracture propagation behaviour of HAp coating in artificial femoral stem component. Thus, present study analysed the influence of coating thickness, pre-microcrack length, bone and artificial femoral stem elastic modulus on stress intensity factor (SIF) of HAp coating.

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47

Gunawan, Gunawan, e Amir Arifin. "INTERGRANULAR CORROSION AND DUCTILE-BRITTLE TRANSITION BEHAVIOUR IN MARTENSITIC STAINLESS STEEL". Indonesian Journal of Engineering and Science 2, n. 3 (8 settembre 2021): 031–41. http://dx.doi.org/10.51630/ijes.v2i3.23.

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Material mechanical behavior is critical for both safety and economic considerations. Because engineering items are manufactured using appropriate grade materials, mechanical approval of the materials used must be completed before assembly. Petrochemicals, marine, and biomaterials are just a few of the industries that use stainless steel. Despite its extensive use, structural failure is still frequently caused by inadequate stainless steel type selection. As a result, dangerous conditions, resulting in personal harm or financial loss. Dangerous conditions is might result in accidents, resulting in personal injury or financial loss. Martensite stainless steel is a type of stainless steel with a high strength value but is brittle, necessitating careful handling. Intergranular corrosion, sensitization, tempering heat treatment, and the Ductile to Brittle Transition Temperature (DBTT) are topics still working on Martensite stainless steel for researchers.

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48

Jackson, G. A., Wei Sun e D. Graham McCartney. "The Application of the Small Punch Tensile Test to Evaluate the Ductile to Brittle Transition of a Thermally Sprayed CoNiCrAlY Coating". Key Engineering Materials 734 (aprile 2017): 144–55. http://dx.doi.org/10.4028/www.scientific.net/kem.734.144.

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Thermally sprayed MCrAlY bond coats are important elements of thermal barrier coating (TBC) systems which are applied to the surface of gas turbine components to protect them in high temperature environments. Knowledge of their mechanical properties is essential in preventing TBC failure which can have catastrophic consequences. However, limited data on modulus, strength and ductility are available for such coatings. In this work, the ductile to brittle transition behaviour of a CoNiCrAlY coating has been investigated via the small punch tensile test (SPTT). Displacement controlled tests were carried out on free standing coatings at room temperature (RT) and between 400-750 °C at a rate of 1 μms-1. At low temperatures there was evidence of elastic-brittle behaviour and at high temperatures there was clear evidence of yielding and plastic deformation. The ductile to brittle transition temperature was found to be between 500-750 °C. The yield stress ranged from 1000-1500 MPa below 600 °C to less than 500 MPa above 650 °C. The elastic modulus was found to be approximately 200-230 GPa at 500 °C and 55 GPa above 700 °C. At room temperature the fracture surface showed flat, smooth features indicating brittle failure whereas at 700 °C there was evidence of ductile tearing.

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49

Zhao, Gen Tian. "Seismic Behaviour on Composite Strengthening for Existing Reinforced Concrete Short Columns". Advanced Materials Research 194-196 (febbraio 2011): 1986–89. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1986.

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In order to develop an effective seismic shear strengthening method for improving the earthquake behavior of existing R/C short columns, experimental studies are conducted by using four beam-column sub assemblage specimens with a short column. Three short columns of these specimens are strengthening by steel plates and concrete, while other one is without any steel plate strengthening. All the specimens are tested under a constant gravity load and alternately repeated lateral forces. Test results demonstrate that, if the short column is strengthened by a welded square tube and concrete, then brittle shear failure does not occur and the column can develop its ultimate flexural moment capacity. It is also shown by tests that the proposed strengthening method using steel plates and concrete is applicable to repair and rehabilitate the damaged short columns failed in the brittle shear mode.

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50

Zhao, De Shen, Tao Xu, Chun An Tang, Hou Quan Zhang e Zheng Zhao Liang. "Avalanche Behaviour in Microfracturing Process of 3-D Brittle Disordered Material". Key Engineering Materials 297-300 (novembre 2005): 2567–72. http://dx.doi.org/10.4028/www.scientific.net/kem.297-300.2567.

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Using a newly-developed Material Failure Process Analysis code (MFPA3D), the micro-fracturing process and the avalanche behavior characterization of brittle disordered materials such as rock or concrete is numerically studied under uniaxial compression and tension. It is found that, due to the heterogeneity of the disordered material, there is an avalanche behavior in the microcrack coalescence process. Meanwhile, a hierarchy of avalanche events also numerically observed though a study of numerically obtained acoustic emissions or seismic events. Numerical simulations indicate that macro-crack nucleation starts well before the peak stress is reached and the crack propagation and coalescence can be traced, which can be taken as a precursory to predict the macro-fracture of the brittle disordered materials. In addition, the numerically obtained results also reveal the presence of residual strength in the post-peak region and the resemblance in the stress-strain curves between uniaxial compression and tension.

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