The Experts below are selected from a list of 324 Experts worldwide ranked by ideXlab platform
C Q Chen - One of the best experts on this subject based on the ideXlab platform.
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synthesis of nano micro zinc oxide rods and arrays by thermal evaporation approach on Cylindrical Shape substrate
Journal of Physical Chemistry B, 2005Co-Authors: Yousheng Zhang, Lisheng Wang, C Q ChenAbstract:Nano and micro ZnO rods and arrays have been synthesized by a simple thermal evaporation approach on a Cylindrical Shape substrate. Most of the synthesized ZnO products are single crystalline with a hexagonal structure and grow along the [0001] direction. Individual protrusive ZnO rods and well-aligned arrays are two typical products in our work. The individual protrusive ZnO rods have diameters of 25 nm ∼ 2.1 μm and lengths from several hundred nanometers to 40 μm, while in the well-aligned arrays, the diameter and length of each ZnO rod range from 60 nm to 1.2 μm and from 4 μm to 6 μm, respectively. The heating temperature and deposition position are two key points to control the diameters of the rods. The growth mechanism is discussed and proposed. The perfect crystalline ZnO rods with different scales from nanometer to micrometer are good models for the investigation of the size effect of physical and chemical properties of one-dimensional material.
Yousheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of nano/micro zinc oxide rods and arrays by thermal evaporation approach on Cylindrical Shape substrate.
Journal of Physical Chemistry B, 2005Co-Authors: Yousheng Zhang, Lisheng Wang, Changqiang ChenAbstract:Nano and micro ZnO rods and arrays have been synthesized by a simple thermal evaporation approach on a Cylindrical Shape substrate. Most of the synthesized ZnO products are single crystalline with a hexagonal structure and grow along the [0001] direction. Individual protrusive ZnO rods and well-aligned arrays are two typical products in our work. The individual protrusive ZnO rods have diameters of 25 nm ∼ 2.1 μm and lengths from several hundred nanometers to 40 μm, while in the well-aligned arrays, the diameter and length of each ZnO rod range from 60 nm to 1.2 μm and from 4 μm to 6 μm, respectively. The heating temperature and deposition position are two key points to control the diameters of the rods. The growth mechanism is discussed and proposed. The perfect crystalline ZnO rods with different scales from nanometer to micrometer are good models for the investigation of the size effect of physical and chemical properties of one-dimensional material.
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synthesis of nano micro zinc oxide rods and arrays by thermal evaporation approach on Cylindrical Shape substrate
Journal of Physical Chemistry B, 2005Co-Authors: Yousheng Zhang, Lisheng Wang, C Q ChenAbstract:Nano and micro ZnO rods and arrays have been synthesized by a simple thermal evaporation approach on a Cylindrical Shape substrate. Most of the synthesized ZnO products are single crystalline with a hexagonal structure and grow along the [0001] direction. Individual protrusive ZnO rods and well-aligned arrays are two typical products in our work. The individual protrusive ZnO rods have diameters of 25 nm ∼ 2.1 μm and lengths from several hundred nanometers to 40 μm, while in the well-aligned arrays, the diameter and length of each ZnO rod range from 60 nm to 1.2 μm and from 4 μm to 6 μm, respectively. The heating temperature and deposition position are two key points to control the diameters of the rods. The growth mechanism is discussed and proposed. The perfect crystalline ZnO rods with different scales from nanometer to micrometer are good models for the investigation of the size effect of physical and chemical properties of one-dimensional material.
David W. Lischer - One of the best experts on this subject based on the ideXlab platform.
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quasi static and dynamic buckling of thin Cylindrical Shape memory shells
Journal of Applied Mechanics, 2006Co-Authors: S Nematnasser, Jeom Yong Choi, Jon Isaacs, David W. LischerAbstract:To investigate the buckling behavior of thin and relatively thick Cylindrical Shape-memory shells, uniaxial compression tests are performed at a 295 K initial temperature, using the CEAM/UCSD's modified split Hopkinson bar systems and an Instron hydraulic testing machine. The quasi-static buckling response of the shells is directly observed and recorded using a digital camera with a close-up lens and two back mirrors. To document the dynamic buckling modes, a high-speed Imacon 200 framing camera is used. The Shape-memory shells with an austenite-finish temperature of A f =281 K, buckle gradually and gracefully in quasi-static loading, and fully recover upon unloading, showing a superelastic property, whereas when suitably annealed, the shells do not recover spontaneously upon unloading, but they do so once heated, showing a Shape-memory effect. The thin shells had a common thickness of 0.125 mm a common outer radius of 2.25 mm (i.e., a common radius, R, to thickness, t, ratio, R/t, of 18). A shell with the ratio of length, L, to diameter, D (LID) of 1.5 buckled under a quasi-static load by forming a nonsymmetric chessboard pattern, while with a LID of 1.95 the buckling started with the formation of symmetrical rings which then changed into a nonsymmetric chessboard pattern. A similar buckling mode is also observed under a dynamic loading condition for a shell with LID of 2. However, thicker shells, with 0.5 mm thickness and radius 4 mm (R/t=8), buckled under a dynamic loading condition by the formation of a symmetrical ring pattern. For comparison, we have also tested shells of similar geometry but made of steel and aluminum. In the case of the steel shells with constrained end conditions, the buckling, which consists of nonsymmetric (no rings) folds (chessboard patterns), is sudden and catastrophic, and involves no recovery upon unloading. The gradual buckling of the Shape-memory shells is associated with the stress-induced martensite formation and seems to have a profound effect on the unstable deformations of thin structures made from Shape-memory alloys.
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Experimental observation of high-rate buckling of thin Cylindrical Shape-memory shells
Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, 2005Co-Authors: Sia Nemat-nasser, Jeom Yong Choi, Jon Isaacs, David W. LischerAbstract:We investigate the buckling behavior of thin Cylindrical Shape-memory shells at room temperature, using a modified split Hopkinson bar and an Instron hydraulic testing machine. The quasi-static buckling response is directly observed using a digital camera with a close-up lens and two back mirrors. A high-speed Imacon 200 framing camera is used to record the dynamic buckling modes. The Shape-memory shells with an austenite-finish temperature less than the room temperature, buckle gradually and gracefully in quasi-static loading, and fully recover upon unloading, showing a superelastic property, whereas when suitably annealed, the shells do not recover spontaneously upon unloading, but they do so once heated, showing a Shape-memory effect. The gradual and graceful buckling of the Shape-memory shells is associated with the stress-induced martensite formation and seems to have a profound effect on the unstable deformations of thin structures made from Shape-memory alloys.
Lisheng Wang - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of nano/micro zinc oxide rods and arrays by thermal evaporation approach on Cylindrical Shape substrate.
Journal of Physical Chemistry B, 2005Co-Authors: Yousheng Zhang, Lisheng Wang, Changqiang ChenAbstract:Nano and micro ZnO rods and arrays have been synthesized by a simple thermal evaporation approach on a Cylindrical Shape substrate. Most of the synthesized ZnO products are single crystalline with a hexagonal structure and grow along the [0001] direction. Individual protrusive ZnO rods and well-aligned arrays are two typical products in our work. The individual protrusive ZnO rods have diameters of 25 nm ∼ 2.1 μm and lengths from several hundred nanometers to 40 μm, while in the well-aligned arrays, the diameter and length of each ZnO rod range from 60 nm to 1.2 μm and from 4 μm to 6 μm, respectively. The heating temperature and deposition position are two key points to control the diameters of the rods. The growth mechanism is discussed and proposed. The perfect crystalline ZnO rods with different scales from nanometer to micrometer are good models for the investigation of the size effect of physical and chemical properties of one-dimensional material.
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synthesis of nano micro zinc oxide rods and arrays by thermal evaporation approach on Cylindrical Shape substrate
Journal of Physical Chemistry B, 2005Co-Authors: Yousheng Zhang, Lisheng Wang, C Q ChenAbstract:Nano and micro ZnO rods and arrays have been synthesized by a simple thermal evaporation approach on a Cylindrical Shape substrate. Most of the synthesized ZnO products are single crystalline with a hexagonal structure and grow along the [0001] direction. Individual protrusive ZnO rods and well-aligned arrays are two typical products in our work. The individual protrusive ZnO rods have diameters of 25 nm ∼ 2.1 μm and lengths from several hundred nanometers to 40 μm, while in the well-aligned arrays, the diameter and length of each ZnO rod range from 60 nm to 1.2 μm and from 4 μm to 6 μm, respectively. The heating temperature and deposition position are two key points to control the diameters of the rods. The growth mechanism is discussed and proposed. The perfect crystalline ZnO rods with different scales from nanometer to micrometer are good models for the investigation of the size effect of physical and chemical properties of one-dimensional material.
Sia Nemat-nasser - One of the best experts on this subject based on the ideXlab platform.
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Experimental observation of high-rate buckling of thin Cylindrical Shape-memory shells
Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, 2005Co-Authors: Sia Nemat-nasser, Jeom Yong Choi, Jon Isaacs, David W. LischerAbstract:We investigate the buckling behavior of thin Cylindrical Shape-memory shells at room temperature, using a modified split Hopkinson bar and an Instron hydraulic testing machine. The quasi-static buckling response is directly observed using a digital camera with a close-up lens and two back mirrors. A high-speed Imacon 200 framing camera is used to record the dynamic buckling modes. The Shape-memory shells with an austenite-finish temperature less than the room temperature, buckle gradually and gracefully in quasi-static loading, and fully recover upon unloading, showing a superelastic property, whereas when suitably annealed, the shells do not recover spontaneously upon unloading, but they do so once heated, showing a Shape-memory effect. The gradual and graceful buckling of the Shape-memory shells is associated with the stress-induced martensite formation and seems to have a profound effect on the unstable deformations of thin structures made from Shape-memory alloys.
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Dynamic buckling and recovery of thin Cylindrical Shape memory shells
Smart Structures and Materials 2005: Active Materials: Behavior and Mechanics, 2005Co-Authors: Mahmoud R. Amini, Sia Nemat-nasserAbstract:Shape-memory alloys can sustain relatively large strains and fully recover without noticeable residual strains. This is referred to as superelasticity. We have been studying quasi-static and dynamic buckling of relatively thin circular Cylindrical shells consisting of Shape-memory alloys in order to understand the response when used as the core of the sandwich structures. The work consists of experimental characterization of the buckling process, as well as numerical simulation. For comparison, we have also studied both dynamic and quasi-static buckling of aluminum tubes of similar dimensions. This presentation will focus on numerical simulation of dynamic buckling of these tubes and correlation with experimental observations.
