Composite Ring Research Articles

Thermal stresses in rings of thermoplastic composites made by automated fiber placement process

AbstractThe automated fiber placement (AFP) of thermoplastic composites has a complex thermal history, which seriously leads to residual stresses in the products. An ANSYS simulation model is proposed to predict thermal history and induced thermal stresses in thermoplastic composite rings. It attempts to simulate closely the AFP process by adding materials incrementally. The processing speed was modeled by incrementally moving the hot air heater along the outer surface of the composite cylinder. The analysis is time-dependent, including two steps of transient heat transfer and induced thermal stress analyses. The heat transfer characteristics and the accumulated thermal effect during processing are investigated. Thermally induced stresses are examined.

Synthesis, crystal structure, and spectra of the trichloromethane solvate of nickel(II) 9(E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazonate

The complex [Ni(L-H)2] · CHCl3 (I), where L-H is the (9E)-phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazone anion (L), was synthesized for the first time. The crystal structure of I was solved. The L-H and L-H′ anions exist as cis- and trans-isomers and are linked to the central Ni2+ atom in a tridentate chelating mode giving rise to two conjugated five-membered metal rings of different composition (NiN3C and NiONC2) at each anion. The Ni2+ coordination polyhedron is a highly distorted octahedron whose axial positions are occupied by N(3) and N(3)′ atoms. The vertices of the tetrahedrally distorted equatorial base of the octahedron are occupied by the N(1) and N(1)′ atoms of the dihydroisoquinoline fragment (A) and the O(1) and O(1)′ atoms of the phenanthrenequinone fragment (B). Complex I occurs as the cis-isomer. The conformations of the L-H anions in I and the L molecules in L · H2O do not differ much. The randomly disordered CHCl3 solvent molecules in I occupy crystal voids between the centrosymmetric dimeric associates. Spectroscopic (IR and UV-Vis) characteristics of I were obtained.

CuO–PAA hybrid films: Chemical synthesis and supercapacitor behavior

We report the synthesis of CuO–Poly (acrylic) acid (PAA) hybrid thin films by a cost-effective spin coating technique for supercapacitor application. Coated films were annealed at 300, 400 and 500°C, to study the annealing effect on the supercapacitor behavior. Further films were characterized by X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform-Raman spectroscopy (FT-Raman) and Fourier transform-Infrared spectroscopy (FT-IR) techniques. Energy dispersive spectroscopy (EDS) shows the formation of amorphous blend of CuO and Cu2O phases at 300°C. Further, films annealed at 400 and 500°C exhibit polycrystalline phase pure CuO with monoclinic structure. The scanning electron microscopy (SEM) micrographs show the transition of island-like structure to CuO crystals surrounded by PAA grafted composite ring with increase in annealing temperature. The possible growth mechanism of PAA and CuO bonding is discussed. Cyclic voltammetry (CV) is employed to calculate the specific capacitance (Csp) in 1M H2SO4 electrolyte. It is observed that the Csp increases from 41 to136Fg−1 with increase in annealing temperature.

A sensitive slope: estimating landscape patterns of forest resilience in a changing climate

Changes in Earth's environment are expected to stimulate changes in the composition and structure of ecosystems, but it is still unclear how the dynamics of these responses will play out over time. In long‐lived forest systems, communities of established individuals may be resistant to respond to directional climate change, but may be highly sensitive to climate effects during the early life stages that follow disturbance. This study combined analyses of pre‐fire and post‐fire tree composition, environmental data, and tree ring analyses to examine landscape patterns of forest recovery after fire in the south‐central Yukon, Canada, a climatically dry region of boreal forest where there is evidence of increasing drought stress. Pre‐fire stand composition and age structures indicated that successional trajectories dominated by white spruce (Picea glauca) with little aspen (Populus tremuloides) comprised most of the study area during the last fire cycle. Although spruce seedling recruitment after the fire was highest at sites near unburned seed sources and where surface organic layers were shallow, spruce seedling densities were often insufficient to regenerate the pre‐fire spruce forests. In particular, sites in the warmer topographic locations of the valley lowland and south‐facing slopes typically had few spruce seedlings and instead were dominated by aspen. The opposite pattern was observed on north‐facing slopes. Age reconstructions of pre‐and post‐fire stands indicate that future canopy composition is driven by initial post‐fire recruitment and thus observed landscape differences in seedling recruitment are likely to be maintained through the next 100–200 years of succession. Observed results support the hypothesis that sites experiencing greater environmental stress show the lowest resilience to disturbance, or greatest compositional changes. Analyses of tree‐ring responses to climate variables across the same landscape indicate that patterns of tree growth prior to a disturbance may be a useful predictor of landscape variations in forest resilience, allowing managers to better anticipate where future changes in forest composition are likely to occur.

The composition of polynomials by the substitution principle

The necessity to distinguish between polynomials and polynomial maps is recalled. Especially, the incorrectness of a transfer to polynomial maps in order to define a composition of polynomials is demonstrated and a pure composition of polynomials is presented. Furthermore, a composition is defined for n-tuples of polynomials and it is proved that they form a composition ring.

Development of Electromagnetic Composite Ring Expansion as a Fragile Material Test Technique

A method is described for performing the tensile strength of fragile material studies using electromagnetically launched expanding composite ring. The working principle is analyzed, where a fast-discharge capacitor system generates magnetic forces between the solenoid and driving ring, which accelerates radial velocities of the specimen rings. The dynamic measuring methods of instantaneous current and mechanical testing are established for analysis of electrical character and tensile strength of fragile specimen. The current pulse was tested experimentally which was provided by a capacitive discharge with the load solenoid connected in series with the power supply alone. It is shown that experimental results match the theoretical analysis well.

Wide Frequency Range AC Magnetic Properties of Fe-Based Composite Materials

The aim of this work was to analyze the influence of resin content on contribution of the hysteresis, eddy current and anomalous losses to the total losses in the frequency range from DC to 150 kHz. The samples of composite material were prepared in the form of the ring with outer diameter of 25 mm, inner diameter of 17 mm and height approximately 3 mm and in the form of cylinder with diameter of 25 mm and height approximately 3 mm by a compaction of mixture of iron powder ASC100.29 (90 vol.%) and commercial termoset resins. The DC hysteresis losses were obtained by the measurements of DC hysteresis loops and the total power losses in the frequency range 0.4 Hz‐150 kHz from AC hysteresis loops, both at maximum induction 0.05, 0.1 and 0.2 T. The magnetic properties of the composite rings were compared with the properties of the material prepared from the powder supported by Hoganas AB Sweden. By analyzing the frequency dependence of total losses of the Fe-based SMC we found out that hysteresis losses contribute to the total losses as a majority component.

AC Magnetic Properties of Vitroperm Based Composite Materials

The aim of this work was to investigate the influence of resin content on AC magnetic properties of Vitroperm 800-based composite material to extend possibilities for application of this kind of material at higher frequency (up to 100 kHz). The samples of composite material were prepared in the form of the ring with outer diameter of 25 mm, inner diameter of 18 mm and height approximately 3 mm. Powder mixtures were prepared from Vitroperm 800 in partial nanocrystalline state and commercial termoset resins by mechanical mixing. The AC magnetic properties (losses) at maximum induction up to 0.5 T were measured by MATS-2010SA loop tracer in frequency range 1‐100 kHz. The specific resistivity of the material was measured by the van der Pauw method. The magnetic properties of the composite rings were compared with the properties of the material prepared from Fe based powder supported by Hoganas. It was found out that the total losses of the Vitroperm-based soft magnetic composite are more than 10 times lower (at 10 kHz) than that for Fe-based one.

Trial design of arch bridge of composite box section with steel web-concrete flange

The concrete arch bridge is a natural and appropriate structural solution, aesthetically pleasing and easily integrated into the environment, especially in mountainous and island areas. However, construction difficulty and cost will increase with heavy self-weight when the span enlarges. A potential solution is to use a composite box arch ring with steel web-concrete flange. Taking Wanzhou Yangtze River Bridge (the longest concrete arch bridge in the world with a main span of 420 m) as a prototype, trial designs of a composite box arch with steel webs (including corrugated steel webs and plain steel webs) and concrete flanges were carried out. Comparison of quantities and structural behaviors of the prototype concrete arch with the two trial designed composite arch was presented. It is shown that the self-weight of the composite arch can reduce about 28% and the structures can meet the design requirements, therefore it is possible to use the two composite arches in long span arch bridges.

Fabrication of 3D Metamaterial Resonators Using Self‐Aligned Membrane Projection Lithography

A new fabrication approach, self-aligned membrane projection lithography, is used to create composite split ring resonators with a resonance near 10 μm. The composite resonators are oriented on the interior face of approximately-spheroidal cavities, and hence represent the first instance of fabrication of micrometer-scale SRRs with out-of-plane current flow.

Ring-type electric current sensor based on ring-shaped magnetoelectric laminate of epoxy-bonded Tb0.3Dy0.7Fe1.92 short-fiber/NdFeB magnet magnetostrictive composite and Pb(Zr, Ti)O3 piezoelectric ceramic

A ring-type electric current sensor operated in vortex magnetic field detection mode is developed based on a ring-shaped magnetoelectric laminate of an axially polarized Pb(Zr, Ti)O3 (PZT) piezoelectric ceramic ring bonded between two circumferentially magnetized epoxy-bonded Tb0.3Dy0.7Fe1.92 (Terfenol-D) short-fiber/NdFeB magnet magnetostrictive composite rings. The electric current sensitivity of the sensor was evaluated, both theoretically and experimentally. The sensor showed a high nonresonance sensitivity of ∼12.6 mV/A over a flat frequency range of 1 Hz–30 kHz and a large resonance sensitivity of 92.2 mV/A at the fundamental shape resonance of 67 kHz, besides an excellent linear relationship between the input electric current and the output magnetoelectrically induced voltage. The power-free, bias-free, high-sensitive, and wide-bandwidth natures of the sensor make it great potential for real-time condition monitoring of engineering systems having electric current-carrying cables or conductors.

Comparison between cartilage–perichondrium composite ‘ring’ graft and temporalis fascia in type one tympanoplasty in children

This study aimed to evaluate the anatomical and audiological outcomes of primary type one tympanoplasty performed with a modified cartilage-perichondrium composite 'ring' graft, and to compare them with results for primary type one tympanoplasty performed with temporalis fascia, in children. Retrospective clinical study. Otolaryngology department, Tanta University Hospital, Egypt. Records were evaluated for 82 children with dry tympanic membrane perforation (any size) and intact ossicular chain, and with no history of previous ear surgery except for tympanostomy. Patients of similar age and middle-ear pathology were selected to make the two groups as homogeneous as possible. An underlay type one tympanoplasty, using either a ring graft or temporalis fascia, was performed: 40 children were included in the ring graft group and 42 in the temporalis fascia group. All procedures were performed by the same surgeon. A successful anatomical outcome was considered to comprise full, intact healing of the graft without perforation, retraction, lateralisation or blunting, for at least one year post-operatively. Patients' post-operative pure tone average air-bone gap and speech reception threshold were compared with pre-operative levels, within and between the two groups. Type one tympanoplasty using a ring graft technique resulted in a significantly greater graft acceptance rate (95 per cent) compared with the temporalis fascia technique (76.2 per cent; p < 0.01). Pure tone average air-bone gap and speech reception threshold levels improved significantly in both the ring graft and fascia groups (p < 0.001). There was no significant difference in audiometric results between the two groups (p > 0.05), although there was a trend towards better post-operative results in the ring group. In our paediatric patients, type one tympanoplasty with a modified cartilage-perichondrium composite ring graft yielded good anatomical and functional results. The anatomical results obtained using this graft (with its unique appearance and stability during and after surgery) were superior to those for temporalis fascia. The ring graft group had equivalent, if not better, post-operative audiometric results, compared with the temporalis fascia group. Thus, the ring graft is believed to be effective in enabling both tympanic membrane closure and rapid hearing improvement, in the paediatric population.

AC Magnetic Properties of Fe-Based Composite Materials

We investigated the influence of resin content on ac magnetic properties of Fe-based composite material to extend possibilities for application of this kind of material at higher frequency. The samples of composite material with different content of phenol-formaldehyde resin acting as insulator were prepared by conventional powder metallurgy. The samples in the form of the ring were used for ac magnetic measurements and in the form of cylinder for specific resistivity measurements. The ac magnetic properties (sample in the form of ring) were measured at maximum flux density up to 0.4 T by MATS-2010SA loop tracer in a frequency range 1-150 kHz and obtained total power losses. The dc hysteresis loops were measured by a fluxmeter-based hysteresisgraph. The values of the specific resistivity measured by the van der Pauw method (sample in the form of cylinder) were used for calculation of eddy current losses. All magnetic properties of the composite rings were compared with the properties of the material prepared from the powder provided by Hoganas AB Sweden by the technology usually used by the producer.

In situ fabrication of Al&lt;SUB align=right&gt;3Ti-Al functionally graded composites by centrifugal casting

In situ Al3Ti-Al functionally graded composite rings were fabricated by centrifugal casting. The effects of processing parameters on the microstructures and hardness of the rings were mainly investigated. Simultaneously, the corrosion characteristics of the composites were discussed. The results indicated that not only the Al3Ti platelet concentration distributed with a gradient along the radial direction of the rings, but also their size appeared in a gradient distribution. The presence of Al3Ti platelets decreased the corrosion resistance of Al and the corrosion resistance of the rings also appeared in a graded manner.

Performability Analysis of Token Ring Networks using Hierarchical Modeling

It is important for communication networks to possess the capability to overcome failures and provide survivable services. We address modeling and analysis of performability affected by both performance and availability of system components for a token ring network under failure and repair conditions. Stochastic reward nets (SRN) is an extension of stochastic Petri nets and provides compact modeling facilities for system analysis. In this paper, hierarchical SRN modeling techniques are used to overcome state largeness problem. The upper level model is used to compute availability and the lower level model captures the performance. And Normalized Throughput Loss (NTL) is obtained for the composite ring network for each node failures occurrence as a performability measure. One of the key contributions of this paper constitutes the Petri nets modeling techniques instead of complicate numerical analysis of Markov chains and easy way of performability analysis for a token ring network under SRN reward concepts.

Vibration and critical speeds of composite-ring disks for data storage

A new concept for data storage disks is proposed to increase operating speed with minimum changes in the geometry and design of conventional data storage disks. The disk—named a composite-ring disk—is composed of a storage material inside and a thin composite ring outside. Stress distributions are found for the rotating disk composed of two annular disks, of which the inside is made of isotropic material and the outside is made of orthotropic material. The dynamic equation for a composite-ring disk in rotation is formulated to calculate its natural frequencies and critical speeds. For the solution of transverse vibration, a rotational symmetry condition is applied in the circumferential direction and a finite element interpolation with Hermite polynomials is performed in the radial direction. The results show that reinforcing a disk at the rim increases critical speeds drastically, and can cause buckling in mode (0,0) which occurs above the lowest critical speed.

The crystal structure of tedhadleyite, Hg2+Hg101+O4l2(Cl,Br)2, from the Clear Creek Claim, San Benito County, California

AbstractThe crystal structure of tedhadleyite, ideally Hg2+Hg101+O4l2(Cl,Br)2,triclinic, AĪ, a 7.0147(5), b 11.8508(7), c 12.5985(8) Å, α 115.583(5), β 82.575(2), γ 100.619(2)º, V 927.0(2) Å3, Z = 2,was solved by direct methods and refined to an R1 index of 4.5% for 2677 unique reflections. There are six symmetrically distinct Hg sites in tedhadleyite: Hg(1) is occupied by Hg2+ and Hg(2–6) are occupied by Hg+ that forms three [Hg–Hg]2+ dimers with Hg–Hg separations between 2.527 and 2.556 Å. These [Hg–Hg]2+ dimers have strong covalent bonds to O atoms,forming pseudo-linear O–Hg–Hg–O arrangements,and weak bonds to halogen and O atoms at high angles to the dimer axis. The [O–Hg–Hg-O] groups share anions to form four-membered square rings of composition [Hg8O4] that link along [100] via [O–Hg–Hg-O] groups and along [001] via [O–Hg–O] groups, forming rectangular rings of composition [Hg14O8]. The rings form a corrugated layer that interweaves with a symmetrically related layer whereby the [O–Hg(6)–Hg(6)–O] linking groups of one layer pass through the centres of the square [Hg8O4] rings of the other layer to form [Hg11O4] complex slabs parallel to (010) that link through Hg-I and Hg-Br,Cl bonds.

Carbon fiber/epoxy composite ring–disk electrode: Fabrication, characterization and application to electrochemical detection in capillary high performance liquid chromatography

Carbon fiber/epoxy composite materials, which are manufactured using the pultrusion process, are commercially available in various shapes and sizes at very low cost. Here we demonstrate the application of such a material as an electrochemical detector in a flow system. Cyclic voltammetry shows that the material’s electrochemical behavior resembles that of glassy carbon. Using tube and rod composites, we successfully fabricated a ring–disk electrode with a 20 μm gap between the ring and the disk. The narrow gap is favorable for mass transfer in the generator–collector experiment. This composite ring–disk electrode is assembled in a thin-layer radial-flow cell and used as an electrochemical detector. The disk electrode, placed directly opposite to the flow inlet, is operated as a generator electrode with the ring electrode being a collector. The high collection efficiency on the ring electrode (0.8 for a chemically reversible species) enhances the detection selectivity.

Stress relaxation testing of pre-compression ring mock-up for the ITER magnet system

The ITER pre-compression ring system is based on two sets of 3 rings made in fibreglass-epoxy composite and is located on top and bottom of the inner straight leg region. These rings will provide a radial force of about 70 MN/coil (35 MN at the top and 35 MN at the bottom) under cryogenic conditions, pulling the TF coils into contact, reducing the gap between the poloidal shear keys and their keyways during operation and also reducing the toroidal tension in the four outer intercoil structures bands. The paper describes the stress relaxation test performed in ENEA Frascati laboratories on a reduced scale glass fibre-epoxy composite ring. The ring was manufactured with a diameter of 1 m (1/5 of the real scale one) by winding S2 glass fibres then impregnated with epoxy. The volumetric glass content was of 69% and no significant presence of defects was verified by an X-ray survey. The test has been carried out following as close as possible the ASTM standard E 328-86. The ring has been inserted into a dedicated hydraulic testing machine consisting of 18 radial pulling actuators and then loaded up to a ring membrane hoop stress of 800 MPa. The deformation has been maintained constant during the test by inserting a solid steel disk in the machine centre restraining the machine radial motion. Average hoop stress has been daily monitored measuring the force required to lift the ring just free of the constraints during the test period. The ring performed 125 testing days showing no significant stress relaxation and a small reduction of the ring stiffness that appeared mainly in the first days of the test.

Analysis and Design of High-Speed Flywheel on Satellite Energy Storage/Attitude Control System

Flywheel rotor structure is one of essential assemblies of the flywheel system used in IPACS. It is significant to ensure the safety of metallic hub and the composite rim under high centrifugal loading induced by the rotation field and the surface pressure produced by the interface misfits. In this paper a 3-D stress analysis model of the flywheel rotor is presented with the finite element analysis software ANSYS and the failure criteria of the materials are discussed to assess the structural strength. Moreover, the key design parameters are investigated briefly to disclose their influences on the stress distribution of rotor structure. At last, an optimum mathematics model with the outer radius of metallic hub, the thickness of each composite ring and the interface misfits as the design variables is presented. Based on the optimum design platform, the series of flywheel rotor structures can be designed systematically.