Composite Tapes Research Articles

Interlaminar shear fatigue behavior of glass/epoxy and carbon/epoxy composites

Abstract This work addresses a strong need in accurate fatigue properties of glass- and carbon-fiber reinforced polymer–matrix composites. In particular, interlaminar shear fatigue properties of glass/epoxy and carbon/epoxy composite tape material systems used in aircraft fatigue-critical applications are needed. The interlaminar shear fatigue material properties, essential for the development of the analysis methods able to capture fatigue delamination failure onset in composite structures, are presented in this work. S–N curves are generated based on custom short-beam shear (SBS) fatigue tests. The custom SBS test configurations ensure a consistent interlaminar shear failure mode. This work extends the recently developed methodology, published in Composites Science and Technology to characterize nonlinear shear properties of composite materials using digital image correlation (DIC) and finite element analysis, to fatigue loading. Test data sets used to develop the fatigue properties, include approximately 20 glass/epoxy and 30 carbon/epoxy SBS coupons. All tests were run in load control at 0.1 load ratio. To better understand material behavior under cyclic loading, surface shear strain was monitored using the DIC technique. Accurate shear stress approximation resulted in similar S – N curve shapes for the glass-fiber and the carbon-fiber composites.

Radiation resistance and generation of pinning centers in composite HTSC under heavy ion irradiation

AbstractThe effect of irradiation with heavy ions 40Ar8+ (48MeV), 132Xe27+ (167MeV) and 84Kr17+ (107 MeV) on the critical temperature (Tc) and critical current (Ic) of YBCO(123) composite tapes was investigated. It was found that threshold values were 5 × 1012 and 1 × 1013 ion/cm2 for 132Xe27+ and 84Kr17+ irradiation, correspondently. Critical current measured at T = 77 K increased for the lower 40Ar8+ and 84Kr17+ fluencies compared to the initial values.The formation of radiation defects that could be effective pinning centers of Abrikosov vortices resulted in the increase of the critical current. The calculations of track diameters produced by 84Kr17+ ions with energy 1.2 MeV/amu in the composite YBCO tape showed the good agreement with the experimental ones. Transmission electron microscopy (TEM), high resolution TEM and scanning TEM were used to study defects induced by irradiation. The diameter of defects obtained from TEM was in the range from 3 to 5 nm. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Experimental and numerical analysis of quench propagation on MgB2 tapes and pancake coils

In the design and feasibility of electric power applications with MgB2 conductors, thermal conductivity plays an important role. In composite wires and tapes it is mainly determined by the amount of stabilizer (usually copper), while for coils the electric insulation and epoxy binder characteristics are added. In this paper we present results on quench development and propagation on isolated superconducting tapes and small single pancake coils cooled by thermal conduction, for three types of MgB2 tape with different stabilizations. The quench parameters at different temperatures, such as minimum quench energy (MQE), minimum propagation zone (MPZ) and quench propagation velocity (vp), are reported. A complete electrical and thermal characterization of the superconducting tapes and of non-superconducting materials used in the coil manufacture has been made. With these data, numerical computational models using finite element simulations have been performed for isolated wires and single pancake coils, and the results of the relevant quench parameters have been compared with the measured values.

Characterization of the Elastic Properties of Bi2223/Ag/Ag Alloy Composite Tapes by the Generalized Self-Consistent Approach

The characterization of the elastic properties of whole Bi2223/Ag/Ag alloy composite tapes is a very important issue, even when these properties of each constituent are known. In this paper, the generalized self-consistent approach is used for predicting the elastic properties of inner core (Bi2223 filaments combined with Ag matrix), and the mixture rule for those of the whole composite tape (the inner core sheathed with Ag alloy). Compared with the simple estimation of the mixture rule, the prediction of the generalized self-consistent approach is not only physically rational, but also is much more accurate. Further, the theoretical prediction agreed well with the measured data. Hopefully, the generalized self-consistent approach can be adopted to predict the elastic properties of other superconducting composite structures.

A non-local void filling model to describe its dynamics during processing thermoplastic composites

A model is developed to describe the void dynamics within thermoplastic composite tape during the tape placement process. The model relates the volatile pressure in voids, the applied compaction load, fiber bed response and the resin pressure due to squeeze-flow of resin from resin-rich regions to fill void regions. This model relies on some geometric simplifications, but incorporates the relevant physical phenomena.This void consolidation model was implemented in a numerical code which predicts the void development during the process. The initial void geometry can be introduced either manually, using a random generation algorithm or from actual processed tape micrographs.The model predicts that the final void content depends on the original void content but also on the initial void distribution. Presented results analyze the influence of void distribution on tape consolidation. Limitations of the consolidation process rate by the resin squeeze flow pressures are clearly demonstrated.

Hysteresis loops of MgB2 + Co composite tapes

The (MgB2)1−xCox composite tapes fabricated by the ex situ PIT method were investigated. The structural and magnetic properties were characterized. Only MgB2 and Co phases were observed in the composites while x ≤ 0.2. A superconducting transition temperature was stable for these samples. Enhancement of the critical current density is found for x = 0.1.

Selection Criteria of High ${\rm T}_{\rm c}$ Superconducting Tapes for Superconducting Fault Current Limiter Applications

To establish a selection criterion of high temperature superconducting (HTS) tapes for their possible application in superconducting fault current limiters (SFCLs), it is required to have high critical current density, high `n' value, high normal state resistance, low AC losses, large heat transfer area, high thermal diffusivity and quick recovery against thermal instabilities for the HTS tapes. At present HTS tapes are categorized into two types namely Bi2223 based 1st generation (1G) HTS tape and YBCO based 2nd generation (2G) coated conductors (CCs). These 1G and 2G tapes are composite tapes. Hence, it is required to know their averaged material properties that can affect the performance of the SFCL during normal state operation. This paper deals with these issues along with DC characterization results to establish selection criteria of HTS tapes for SFCL applications.

Thermomechanical Analysis of Shape-Memory Composite Tape Spring

Intelligent materials and structures have been extensively applied for satellite designs in order to minimize the mass and reduce the cost in the launch of the spacecraft. Elastic memory composites (EMCs) have the ability of high-strain packaging and shape-memory effect, but increase the parts and total weight due to the additional heating system. Shape-memory sandwich structures Li and Wang (J. Intell. Mater. Syst. Struct. 22(14), 1605–1612, 2011) can overcome such disadvantage by using the metal skin acting as the heating element. However, the high strain in the micro-buckled metal skin decreases the deployment efficiency. This paper aims to present an insight into the folding and deployment behaviors of shape-memory composite (SMC) tape springs. A thermomechanical process was analyzed, including the packaging deformation at an elevated temperature, shape frozen at the low temperature and shape recovery after reheating. The result shows that SMC tape springs can significantly decrease the strain concentration in the metal skin, as well as exhibiting excellent shape frozen and recovery behaviors. Additionally, possible failure modes of SMC tape springs were also analyzed.

Lubrication of poly(vinyl alcohol) chain orientation by carbon nano‐chips in composite tapes

AbstractThe extraordinary structural properties of graphene and carbon nanotube materials motivate the development of practical methods for their use in fabricating continuous, strong, and tough composite fibers. Poly(vinyl alcohol) (PVA)/carbon nano‐chip fiber (CNCF) composite tapes with 0.5 wt % loading show that Young's modulus, tensile strength, and toughness are increased by 585%, 653%, and 20%, respectively as compared to the control (PVA) tapes. Nano‐chips exfoliated from the CNCF during processing, lubricate polymer chain alignment, and orientation during drawing, where composite tapes could be drawn to higher draw ratios compared with the control tapes. As a result, the Herman's orientation factor (f) increased from 0.5 (control tape) to 0.8 (composite tape). Theoretical analysis shows ∼ 16 vol % of the composite tapes consists of fully oriented PVA chains, which contributes to its exceptional mechanical performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Analysis of the correlation between n-value and critical current in bent multifilamentary Bi2223 composite tape based on a damage evolution model

The change in n-value and critical current with bending strain and the relation of n-value to critical current of bending-damaged Bi2223 composite tape were studied experimentally and analytically. The n-value of the bending-damaged Bi2223 filamentary composite tape decreased very slightly with increasing bending strain and with decreasing critical current, in comparison with that of tension-damaged tape. To describe the experimental result for bending-damaged tape, a damage evolution model was applied in which the steep tensile-strain variation in the thickness direction, the shape of the core into which the superconducting filaments are bundled and the damage strain parameters obtained from the analysis of the tensile stress–strain curve were incorporated. The measured change in n-value and critical current with bending strain and the relation of n-value to critical current under applied bending strain were described satisfactorily by the present approach.

The damage resistance of quasi-isotropic carbon/epoxy composite tape laminates impacted by high velocity ice

Transverse impact from hail ice can create internal damage to composite structures that is not visually detectable and is therefore a damage tolerance concern. This paper focuses on the experimental characterization of the damage resistance of laminates made from T800/3900-2 carbon/epoxy tape material to impact by high velocity ice spheres, i.e., simulated hail ice (SHI). The failure threshold energy (FTE) defining the onset of damage was found for three panel thicknesses (1.59, 3.11, and 4.66mm), each impacted by three ice diameters (38.1, 50.8, and 61.0mm). Non-destructive investigation techniques were used to detect, map, and characterize the delaminated area. A regression analysis was used to quantitatively determine the FTE of the tape laminates, which was found to closely match previous woven carbon/epoxy FTE data. Both data sets were found to exhibit a linear and common relationship to the ratio of panel thickness to ice diameter (H/D). The resulting delamination patterns of the current and previous panels were found to be similar at damage initiation, but to differ for higher damage states.

Modeling of the bending strain dependence of the critical current in Bi2223/Ag composite tapes based on the damage stress of the superconducting filament

An analysis model of the bending strain dependence of the critical current in multifilamentary Bi2223/Ag composite tapes is presented. To investigate the effect of the mechanical properties of the Bi2223 superconducting filament, the actual part for carrying current, its damage stress and elastic modulus are introduced. The calculated result of the variation of the critical current with the bending strain is well agreed with the experimental one. The further studies find that the mechanical properties of the filament have a remarkable effect on the bending strain dependence of the critical current. Specifically, the larger the damage stress and elastic modulus of the filament are, the higher the critical current is, when the bending strain increases to a larger value beyond the critical one.

Relation of n-value to critical current in bent-damaged Bi2223 composite tape

The relation of n -value to critical current of bent-damaged (Bi,Pb)2Sr2Ca2Cu3O10+δ (Bi2223) composite tape was studied experimentally and analytically. The experimental results showed that, under bending strain, the n -value decreased rather slightly with decreasing critical current in comparison with the data obtained under applied tensile strain. The experimentally observed slight decrease in n -value with critical current under bending strain, and the measured changes in critical current and n -value with increasing bending strain, were described satisfactorily by the presented damage evolution model that correlates the extent of damage to variation of bending strain-induced tensile strain in the core along the thickness direction.

Relation of Shunting Current at Cracked Part to Critical Current and <i>n</i>-Value in Multifilamentary Bi2223 Composite Tape

Relation of transport current and n-value to collective crack-induced current shunting in BSCCO (Bi2223) multi-filamentary composite tape pulled in tension was studied experimentally and analytically. For analysis, the partial crack-current shunting model of Fang et al. was used by placing the collective crack as the partial one. It was shown that (a) collective crack-induced shunting current increases with increasing current (and voltage) and with increasing collective crack size, (b) the transport current normalized with respect to the transport current in noncracked state is described with the modified ratio of non-cracked area to overall cross-sectional area of superconducting filaments at low voltage where shunting current is low, while it deviates upward from the modified ratio at high voltage where the shunting current is enhanced, and (c) the enhanced shunting current acts to reduce n-value at high voltage. These features were similar to those of cracked coated conductor.

A Composite Athletic Tape With Hyperelastic Material Properties Improves and Maintains Ankle Support During Exercise

Controlled laboratory testing using a single-group, prospective, repeated-measures design. To compare the material properties of a hyperelastic athletic tape to a conventional tape and to compare the passive ankle support of these tapes before and after exercise. The near-linear material properties of conventional athletic tape may interfere with ankle motion, resulting in reduced athletic performance. Conventional athletic tape is also known to lose much of its initial support during exercise. It was assumed that a tape constructed of Kevlar fibers embedded in a silicon matrix would possess hyperelastic material properties that would improve ankle support. A tensile testing machine was used to determine the tensile material properties of 11 samples of conventional and hyperelastic tape. The ankles of 11 young, healthy athletes were taped, one ankle with conventional tape and the other ankle with hyperelastic tape. The passive ankle support of each tape was measured with an instrumented linkage (the ankle flexibility tester) before and after 30 minutes of exercise. The composite tape had a significantly higher load to failure than the conventional tape. It had significantly lower initial stiffness and higher late stiffness than conventional tape, thus demonstrating highly hyperelastic behavior. The hyperelastic tape maintained a significantly higher portion of its support during the 30 minutes of exercise than the conventional tape. Composite athletic tape with highly hyperelastic properties can be constructed and maintains a larger portion of its support during short-duration exercises (less than 30 minutes) than conventional athletic tape.

Low noise measurement system for determination of the critical currents in superconducting tapes by a pulse method

Steady state measurements of the high critical currents in superconducting composite wires and tapes might be burdened with some errors. The origin of the errors is mainly associated with the Joule heat generated at current leads contacts, which at high transport currents can considerably increase temperature of an investigated sample wire. To avoid this unwanted heating phenomenon pulsed current methods are widely used. A waveform of the current pulse is usually shaped by means of a series RLC circuit with the subcritical dumping condition. Measurement results (i.e., a value of current peak, its time derivative, and a voltage drop along a superconducting sample) are recorded by means of a 4-channels, 12-bit resolution, 50 ns sampling time, digital recorder. Very low noise, broadband, voltage preamplifiers, based on rf bipolar transistors, were designed and fabricated. From the data, current-voltage characteristics are plotted and then the critical currents of investigated tapes are determined. Presented in the work our home-made, low noise, measurement setup allows to obtain a current pulse of about 4000 A at duration time of several milliseconds.

Analysis of distribution of critical current of bent-damaged Bi2223 composite tape

Distributions of critical current of damaged Bi2223 tape specimens bent by 0.6, 0.8 and 1.0% were investigated analytically with a modelling approach based on the correlation of damage evolution to distribution of critical current. It was revealed that the distribution of critical current is described by three parameter Weibull distribution function through the distribution of the tensile damage strain of Bi2223 filaments that determines the damage front in bent-composite tape. Also it was shown that the measured distribution of critical current values can be reproduced successfully by a Monte Carlo simulation using the distributions of tensile damage strain of filaments and original critical current.

Role of friction on the thermal development in ultrasonically consolidated aluminum foils and composites

Ultrasonic consolidation is a solid-state bonding process capable of producing metal and metal matrix composite parts. In this work a friction-based heat generation model is proposed to characterize the thermal development of ultrasonically consolidated aluminum foils and continuous fiber alumina reinforced aluminum metal matrix composite tape as a function of process control parameters. The friction coefficient between mating surfaces is determined experimentally, and the credibility of using both a constant friction coefficient and a process dependent friction coefficient is assessed. In most cases a constant friction coefficient is capable of producing results that are within 15% error; while a process dependent friction coefficient achieves an average error of 7%.

Dependences of HTS tape critical parameters on fluences under irradiation with heavy ions and high energy electrons

Experimental data on the study of modifications of two types of the YBCO(123)-based composite tape under irradiation with electrons with the energy of 23 MeV and 132Xe27+ (167 MeV), 84Kr17+ (107 MeV), and 40Ar8+ (48 MeV) ions in a wide range of irradiation doses are presented. It is shown that no changes in the HTS transition temperature and critical current occurred under electron irradiation up to the dose D ≈ 10−4 disp/a (displacements per atom). The threshold dose of irradiation with 132Xe27+ ions, at which superconductivity disappears, is determined. In comparison with the initial value, the critical current of 40Ar8+ ions is found to increase by ≈18% in the zero magnetic field at T = 77 K. This effect can be explained by the pinning centers for Abrikosov vortices induced by relatively small ion irradiation doses. High doses of heavy ions lead to partial or complete amorphization of a superconductor, which results first in a decrease in the critical current and transition temperature and then in a total disappearance of superconductivity. X-ray diffraction is used to study the changes in the crystal structure of the YBCO(123) superconductor under ion irradiation.

A Monte Carlo simulation on critical current distribution of bent-damaged multifilamentary Bi2223 composite tape

It was attempted to reproduce the measured critical current (Ic) distributions of the Bi2223 composite tape bent by 0–0.833% by simulation. Simulation was carried out with a Monte Carlo method in combination with a model that correlates the critical current to damage evolution. Two variables that differ from specimen to specimen were input in the simulation. One was the damage strain parameter, with which the difference in extent of damage among specimens was expressed. Another was the original critical current (Ic0) values at zero bending strain. With the present simulation approach, the measured distributions of critical current at various bending strains, and the measured variations of average and coefficient of variation of critical current values with increasing bending strain were reproduced well.