The Experts below are selected from a list of 142107 Experts worldwide ranked by ideXlab platform
Michael R Wisnom - One of the best experts on this subject based on the ideXlab platform.
-
gradual failure in high performance unidirectional thin ply Carbon glass hybrid composites under bending
Composite Structures, 2021Co-Authors: Guillermo Idarraga, Meisam Jalalvand, Mohamad Fotouhi, J M Meza, Michael R WisnomAbstract:Abstract This paper introduces new composite architectures using Carbon and glass fibre-reinforced epoxy prepregs to achieve gradual failure under bending. The concept is based on a technique developed by the authors to design hybrid composites with gradual failure in tension combined with beam theory to identify and control the failure sequence of the plies in the layups. Two layups are designed based on standard ply thickness S-Glass and hybrid sub-laminates made out of intermediate and high modulus thin-ply Carbon prepregs. The layups are tested under 4-point bending loading where a gradual failure alongside high values of flexural displacement are achieved. No catastrophic failure is observed throughout the whole loading process. The gradual Layer-by-Layer failure of the surface Layers on the tensile side produces a brush-like appearance. Microscopy observations from interrupted tests verified fragmentation of the high-modulus Carbon Layer followed by gradual failure of the intermediate modulus Carbon Layer and delamination on the tensile side, as well as stable shear cracks of the high-modulus Carbon Layer on the compression side.
-
demonstration of pseudo ductility in high performance glass epoxy composites by hybridisation with thin ply Carbon prepreg
Composites Part A-applied Science and Manufacturing, 2013Co-Authors: Gergely Czel, Michael R WisnomAbstract:Abstract A new approach and material architecture is presented in order to overcome the inherent brittleness and unstable failure characteristic of conventional high performance composites. The concept is the use of thin-ply hybrid laminates. Fracture mechanics calculations were carried out to determine the critical Carbon Layer thickness for stable pull-out in a three Layer unidirectional hybrid laminate, which can provide a pseudo-ductile failure. Unidirectional hybrid composites were fabricated by sandwiching various numbers of thin Carbon prepreg plies between standard thickness glass prepreg plies and tested in tension. Specimens with one and two plies of thin Carbon prepreg produced pseudo-ductile failure, whereas ones with three and four plies failed with unstable delamination. An explanation of the different failure modes is given in terms of the different energy release rates for delamination in various specimens. The observed damage characteristics agreed well with the expectations according to the estimated critical Carbon Layer thickness.
Antonio B. Fuertes - One of the best experts on this subject based on the ideXlab platform.
-
Carbon molecular sieve gas separation membranes based on poly vinylidene chloride co vinyl chloride
Carbon, 2000Co-Authors: Teresa A Centeno, Antonio B. FuertesAbstract:The preparation of a composite Carbon membrane from Poly(vinylidene chloride-co-vinyl chloride) is described. The membrane is formed by a thin microporous Carbon Layer (Thickness, 0.8 μm) obtained by pyrolysis of a polymeric film supported over a macroporous Carbon substrate (Pore size, 1 μm; Porosity, 30%). Single gas permeation experiments with pure gases of different molecular size (He, CO2, O2, N2 and CH4) were performed at different temperatures between 25°C and 150°C. It has been observed that the microporous Carbon Layer exhibits molecular sieving properties and it allows the separation of gases depending on their molecular size. The Carbon membrane shows high selectivities for the separation of permanent gases like O2/N2 system (Selectivity≈14 at 25°C). Air preoxidation at 200°C for 6 h improves the permselectivity but a loss in gas permeance is observed.
-
supported Carbon molecular sieve membranes based on a phenolic resin
Journal of Membrane Science, 1999Co-Authors: Teresa A Centeno, Antonio B. FuertesAbstract:Abstract The preparation of a composite Carbon membrane for separation of gas mixtures is described. The membrane is formed by a thin microporous Carbon Layer (thickness, 2 μm) obtained by pyrolysis of a phenolic resin film supported over a macroporous Carbon substrate (pore size, 1 μm; porosity, 30%). The microporous Carbon Layer exhibits molecular sieving properties and it allows the separation of gases depending on their molecular size. The micropore size was estimated to be around 4.2 A. Single and mixed gas permeation experiments were performed at different temperatures between 25°C and 150°C, and pressures between 1 and 3.5 bar. The Carbon membrane shows high selectivities for the separation of permanent gases like O 2 /N 2 system (selectivity≈10 at 25°C). Gas mixtures like CO 2 /N 2 and CO 2 /CH 4 are successfully separated by means of prepared membranes. For example, the membrane prepared by Carbonization at 700°C shows at 25°C the following separation factors: CO 2 /N 2 ≈45 and CO 2 /CH 4 ≈160.
Hongwei Han - One of the best experts on this subject based on the ideXlab platform.
-
efficient hole conductor free fully printable mesoscopic perovskite solar cells with Carbon electrode based on ultrathin graphite
Carbon, 2017Co-Authors: Miao Duan, Yusong Sheng, Yanjun Guan, Yaoguang Rong, Anyi Mei, Hongwei HanAbstract:Ultrathin graphite has been applied in hole-conductor-free, fully printable mesoscopic perovskite solar cells as counter electrode. It was found that ultrathin graphite effectively increased the specific surface area of the Carbon Layer without sacrificing the conductivity. The large specific surface area facilitated the hole collection from the perovskite to Carbon Layer, correspondingly decreased the charge transfer resistance at the perovskite/Carbon interface. Besides, the penetration of perovskite precursor solution in the Carbon Layer was accelerated due to the highly interconnected channels. As a result, the power conversion efficiency of the printable mesoscopic perovskite solar cell was significantly improved from 12.63% to 14.07% by incorporating ultrathin graphite instead of bulk graphite.
-
hole conductor free mesoscopic tio2 ch3nh3pbi3 heterojunction solar cells based on anatase nanosheets and Carbon counter electrodes
Journal of Physical Chemistry Letters, 2014Co-Authors: Yaoguang Rong, Anyi Mei, Tongfa Liu, Hongwei HanAbstract:A hole-conductor-free fully printable mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cell was developed with TiO2 nanosheets containing high levels of exposed (001) facets. The solar cell embodiment employed a double Layer of mesoporous TiO2 and ZrO2 as a scaffold infiltrated by perovskite as a light harvester. No hole conductor or Au reflector was employed. Instead, the back contact was simply a printable Carbon Layer. The perovskite was infiltrated from solution through the porous Carbon Layer. The high reactivity of (001) facets in TiO2 nanosheets improved the interfacial properties between the perovskite and the electron collector. As a result, photoelectric conversion efficiency of up to 10.64% was obtained with the hole-conductor-free fully printable mesoscopic TiO2/CH3NH3PbI3 heterojunction solar cell. The advantages of fully printable technology and the use of low-cost Carbon-materials-based counter electrode and hole-conductor-free structure provide this design a promising prospect to approach low-cost photovoltaic devices.
Guillermo Idarraga - One of the best experts on this subject based on the ideXlab platform.
-
gradual failure in high performance unidirectional thin ply Carbon glass hybrid composites under bending
Composite Structures, 2021Co-Authors: Guillermo Idarraga, Meisam Jalalvand, Mohamad Fotouhi, J M Meza, Michael R WisnomAbstract:Abstract This paper introduces new composite architectures using Carbon and glass fibre-reinforced epoxy prepregs to achieve gradual failure under bending. The concept is based on a technique developed by the authors to design hybrid composites with gradual failure in tension combined with beam theory to identify and control the failure sequence of the plies in the layups. Two layups are designed based on standard ply thickness S-Glass and hybrid sub-laminates made out of intermediate and high modulus thin-ply Carbon prepregs. The layups are tested under 4-point bending loading where a gradual failure alongside high values of flexural displacement are achieved. No catastrophic failure is observed throughout the whole loading process. The gradual Layer-by-Layer failure of the surface Layers on the tensile side produces a brush-like appearance. Microscopy observations from interrupted tests verified fragmentation of the high-modulus Carbon Layer followed by gradual failure of the intermediate modulus Carbon Layer and delamination on the tensile side, as well as stable shear cracks of the high-modulus Carbon Layer on the compression side.
Yusheng Yang - One of the best experts on this subject based on the ideXlab platform.
-
scalable synthesis of core shell structured sio x nitrogen doped Carbon composite as a high performance anode material for lithium ion batteries
Journal of Power Sources, 2016Co-Authors: Lu Shi, Weiku Wang, Anbang Wang, Keguo Yua, Yusheng YangAbstract:Abstract In this work, a novel core-shell structured SiO x /nitrogen-doped Carbon composite has been prepared by simply dispersing the SiO x particles, which are synthesized by a thermal evaporation method from an equimolar mixture of Si and SiO 2 , into the dopamine solution, followed by a Carbonization process. The SiO x core is well covered by the conformal and homogeneous nitrogen-doped Carbon Layer from the pyrolysis of polydopamine. By contrast with the bare SiO x , the electrochemical performance of the as-prepared core-shell structured SiO x /nitrogen-doped Carbon composite has been improved significantly. It delivers a reversible capacity of 1514 mA h g −1 after 100 cycles at a current density of 100 mA g −1 and 933 mA h g −1 at 2 A g −1 , much higher than those of commercial graphite anodes. The nitrogen-doped Carbon Layer ensures the excellent electrochemical performance of the SiO x /C composite. In addition, since dopamine can self-polymerize and coat virtually any surface, this versatile, facile and highly efficient coating process may be widely applicable to obtain various composites with uniform nitrogen-doped Carbon coating Layer.