The Experts below are selected from a list of 300 Experts worldwide ranked by ideXlab platform
Zhi Li - One of the best experts on this subject based on the ideXlab platform.
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an evaluation of the Failure modes transition and the christensen ductile Brittle Failure theory using molecular dynamics
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2018Co-Authors: Richard N Christensen, Zhi LiAbstract:The Christensen ductile/Brittle Failure theory can be interpreted in terms of the associated Failure modes, those of shear bands and voids nucleation. Their conjunction is then termed as the failur...
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An evaluation of the Failure modes transition and the Christensen ductile/Brittle Failure theory using molecular dynamics
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2018Co-Authors: Richard N Christensen, Zhi LiAbstract:The Christensen ductile/Brittle Failure theory can be interpreted in terms of the associated Failure modes, those of shear bands and voids nucleation. Their conjunction is then termed as the failur...
Richard N Christensen - One of the best experts on this subject based on the ideXlab platform.
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an evaluation of the Failure modes transition and the christensen ductile Brittle Failure theory using molecular dynamics
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2018Co-Authors: Richard N Christensen, Zhi LiAbstract:The Christensen ductile/Brittle Failure theory can be interpreted in terms of the associated Failure modes, those of shear bands and voids nucleation. Their conjunction is then termed as the failur...
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An evaluation of the Failure modes transition and the Christensen ductile/Brittle Failure theory using molecular dynamics
Proceedings of The Royal Society A: Mathematical Physical and Engineering Sciences, 2018Co-Authors: Richard N Christensen, Zhi LiAbstract:The Christensen ductile/Brittle Failure theory can be interpreted in terms of the associated Failure modes, those of shear bands and voids nucleation. Their conjunction is then termed as the failur...
William A Goddard - One of the best experts on this subject based on the ideXlab platform.
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atomistic explanation of Brittle Failure of thermoelectric skutterudite cosb3
Acta Materialia, 2016Co-Authors: Guodong Li, Q An, William A Goddard, Riley Hanus, Pengcheng Zhai, Qingjie Zhang, Jeffrey G SnyderAbstract:CoSb_3 based skutterudite thermoelectric material has superior thermoelectric properties, but the low fracture toughness prevents its widespread commercial application. To determine the origin of its Brittle Failure, we examined the response of shear deformation in CoSb3 along the most plausible slip system (010)/ , using large-scale molecular dynamics simulations. We find that the Brittle Failure of CoSb_3 arises from the formation of shear bands due to the destruction of Sb4-rings and the slippage of Co-octahedraes. This leads to the breakage of Co-octahedraes and cavitation, resulting in the crack opening and mechanical Failure.
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atomistic origin of Brittle Failure of boron carbide from large scale reactive dynamics simulations suggestions toward improved ductility
Physical Review Letters, 2015Co-Authors: Q An, William A GoddardAbstract:Ceramics are strong, but their low fracture toughness prevents extended engineering applications. In particular, boron carbide (B_4C), the third hardest material in nature, has not been incorporated into many commercial applications because it exhibits anomalous Failure when subjected to hypervelocity impact. To determine the atomistic origin of this Brittle Failure, we performed large-scale (∼200 000 atoms/cell) reactive-molecular-dynamics simulations of shear deformations of B_4C, using the quantum-mechanics-derived reactive force field simulation. We examined the (0001)/⟨101¯0⟩ slip system related to deformation twinning and the (011¯1¯)/⟨1¯101⟩ slip system related to amorphous band formation. We find that Brittle Failure in B_4C arises from formation of higher density amorphous bands due to fracture of the icosahedra, a unique feature of these boron based materials. This leads to negative pressure and cavitation resulting in crack opening. Thus, to design ductile materials based on B_4C we propose alloying aimed at promoting shear relaxation through intericosahedral slip that avoids icosahedral fracture.
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boron suboxide and boron subphosphide crystals hard ceramics that shear without Brittle Failure
Chemistry of Materials, 2015Co-Authors: Q An, William A GoddardAbstract:Boron suboxide (B_6O), boron carbide (B_4C), and related materials are superhard. However, they exhibit low fracture toughness, which limits their engineering applications. Here we show the shear deformation mechanism of B_6O using density functional theory along the most plausible slip system (0111)/ . We discovered an unusual phenomenon in which the highly sheared system recovers its original crystal structure, which indicates the possibility of being sheared to a large strain without Failure. We also found a similar structural recovery in boron subphosphide (B_(12)P_2) for shearing along the same slip system. In contrast, for components of B_4C, we found Brittle Failure. These novel deformation mechanisms under high shear deformation conditions suggest that a key element to designing ductile hard materials is to couple the icosahedra via one- or two-atom chains that allow the system to shear by walking the intericosahedral bonds and chain bonds alternately to accommodate large shear without fracturing the icosahedra.
Q An - One of the best experts on this subject based on the ideXlab platform.
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atomistic explanation of Brittle Failure of thermoelectric skutterudite cosb3
Acta Materialia, 2016Co-Authors: Guodong Li, Q An, William A Goddard, Riley Hanus, Pengcheng Zhai, Qingjie Zhang, Jeffrey G SnyderAbstract:CoSb_3 based skutterudite thermoelectric material has superior thermoelectric properties, but the low fracture toughness prevents its widespread commercial application. To determine the origin of its Brittle Failure, we examined the response of shear deformation in CoSb3 along the most plausible slip system (010)/ , using large-scale molecular dynamics simulations. We find that the Brittle Failure of CoSb_3 arises from the formation of shear bands due to the destruction of Sb4-rings and the slippage of Co-octahedraes. This leads to the breakage of Co-octahedraes and cavitation, resulting in the crack opening and mechanical Failure.
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atomistic origin of Brittle Failure of boron carbide from large scale reactive dynamics simulations suggestions toward improved ductility
Physical Review Letters, 2015Co-Authors: Q An, William A GoddardAbstract:Ceramics are strong, but their low fracture toughness prevents extended engineering applications. In particular, boron carbide (B_4C), the third hardest material in nature, has not been incorporated into many commercial applications because it exhibits anomalous Failure when subjected to hypervelocity impact. To determine the atomistic origin of this Brittle Failure, we performed large-scale (∼200 000 atoms/cell) reactive-molecular-dynamics simulations of shear deformations of B_4C, using the quantum-mechanics-derived reactive force field simulation. We examined the (0001)/⟨101¯0⟩ slip system related to deformation twinning and the (011¯1¯)/⟨1¯101⟩ slip system related to amorphous band formation. We find that Brittle Failure in B_4C arises from formation of higher density amorphous bands due to fracture of the icosahedra, a unique feature of these boron based materials. This leads to negative pressure and cavitation resulting in crack opening. Thus, to design ductile materials based on B_4C we propose alloying aimed at promoting shear relaxation through intericosahedral slip that avoids icosahedral fracture.
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boron suboxide and boron subphosphide crystals hard ceramics that shear without Brittle Failure
Chemistry of Materials, 2015Co-Authors: Q An, William A GoddardAbstract:Boron suboxide (B_6O), boron carbide (B_4C), and related materials are superhard. However, they exhibit low fracture toughness, which limits their engineering applications. Here we show the shear deformation mechanism of B_6O using density functional theory along the most plausible slip system (0111)/ . We discovered an unusual phenomenon in which the highly sheared system recovers its original crystal structure, which indicates the possibility of being sheared to a large strain without Failure. We also found a similar structural recovery in boron subphosphide (B_(12)P_2) for shearing along the same slip system. In contrast, for components of B_4C, we found Brittle Failure. These novel deformation mechanisms under high shear deformation conditions suggest that a key element to designing ductile hard materials is to couple the icosahedra via one- or two-atom chains that allow the system to shear by walking the intericosahedral bonds and chain bonds alternately to accommodate large shear without fracturing the icosahedra.
Miguel Yurrita - One of the best experts on this subject based on the ideXlab platform.
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Brittle Failure in the parallel-to-grain direction of multiple shear softwood timber connections with slotted-in steel plates and dowel-type fasteners
Construction and Building Materials, 2019Co-Authors: Miguel Yurrita, J.m. Cabrero, Pierre QuennevilleAbstract:Abstract The multiple shear connection with slotted-in steel plates and dowel-type fasteners is a very efficient timber joint for large timber cross sections. It is used in practice, mainly due to its high capacity and its better performance under fire. However, when the number of inner plates is increased, instead of a ductile mechanism, Brittle Failure may govern its capacity. No standard deals explicitly with this kind of joint. A set of tests has been performed in order to study the Brittle Failure of this kind of connections. The test results are then compared with the available prediction models that study both ductile and Brittle Failure modes to assess their prediction accuracy. An improved model for the assessment of the Brittle Failure mode for the multiple shear connections with slotted-in steel plates and dowel-type fasteners is then proposed.
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A probabilistic study of Brittle Failure in dowel-type timber connections with steel plates loaded parallel to the grain
Wood Material Science and Engineering, 2019Co-Authors: J.m. Cabrero, Daniel Honfi, Robert Jockwer, Miguel YurritaAbstract:Dowel-type connections in timber structures should be typically designed in a way that, if the load bearing capacity is exceeded, desirable ductile Failure should likely occur, i.e. yielding of the metal dowel or embedment of the timber. However, the probability of Brittle Failures cannot be completely avoided in many cases. If the connection is loaded parallel to the grain direction, splitting, row-shear, plug/block shear and tensile Failure are examples of such Brittle Failure modes. To ensure a beneficial structural performance locally and sufficient structural robustness globally, the probability of such Brittle Failures should be kept at a sufficiently low level. However, in the current version of EN1995, the probability of such Failure is not considered explicitly. The final aim of the presented research study is to develop a rational approach for the consideration of Brittle Failure in timber connections with dowel-type fasteners and steel plates loaded parallel to the grain, consistently with the partial factor method. As a first step, a probabilistic model has been used to study the susceptibility to Brittle Failure and provide a rational basis for the calibration of a “Brittle overstrength factor”. The results of this study are reported in the current contribution.
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Performance assessment of existing models to predict Brittle Failure modes of steel-to-timber connections loaded parallel-to-grain with dowel-type fasteners
Engineering Structures, 2018Co-Authors: J.m. Cabrero, Miguel YurritaAbstract:Abstract For safety reasons, ductile Failure in timber connections with dowel-type fasteners is always recommended. It has usually been assumed that it can be achieved by fulfilling minimum spacing requirements between fasteners. However, recent works address the need to account for Brittle Failure modes (namely splitting, row-shear, and block and plug-shear) in connections loaded parallel-to-the-grain in an explicit manner, in order to evaluate them and achieve the desired ductility. This article describes the Brittle Failure modes and reviews the existing calculation models proposed by several authors – some of them included in standards. Finally, the performance of these models is assessed against an extensive database of tests gathered from the literature following a comprehensive methodology.
