Regularities of Growth of Fatigue Cracks in Hybrid Pumping Rods

Materials Science - We analyze specific features of the fatigue fracture of hybrid pumping rods with carbon-fiber cores and fiberglass shells intended for the oil extraction. It is shown that the...     

玻纤表面动态润湿行为

提出了采用线性回归处理分析玻纤与浸润液体动态润湿的新方法,结合高精度电子天平,表征了玻纤表面动态润湿性能。研究结果表明：在玻纤表面动态润湿过程中,随着润湿速度的增加,动态接触角有增大的趋势,玻纤与去离子水、乙二醇、760E环氧、CYD128环氧的接触角分别由66.04°、42.21°、51.31°、73.90°增加到69.05°、46.95°、74.58°、170.06°,玻纤表面可润湿性能下降。玻纤表面动态润湿过程中,黏度越大,随着润湿速度增加,可润湿性能下降越快,即玻纤与CYD128环氧体系的接触角下降96.16°,而与760E环氧树脂和乙二醇的接触角下降分别为23.27°和4.74°。基于新方法的玻纤表面动态润湿系统中,玻纤所受作用力随三相接触线移动速率和浸润液体黏度的增加而增大。     

Microwave diagnosis of low-density fiberglass composites with resin binder

Dielectric properties of low-density fiberglass composites are studied at microwave frequencies and are related to the resin binder content and state of cure. A completely filled short-circuited waveguide method is used to study the dielectric properties of fresh and slightly cured resin binder (used in the production of low-density fiberglass composite materials) in the frequency range of 4–18 GHz. The preliminary results indicate that the dielectric properties of resin binder may be used to determine its state of cure. The same measurement approach is used to determine the dielectric properties of fiberglass materials containing uncured resin binder, no resin binder, and three different levels of resin binder. It is found that the dielectric properties of these low-permittivity and low-loss materials are very similar. Consequently, to distinguish among real fiberglass products with different resin binder levels, an open-ended rectangular waveguide measurement approach, is used. This technique allows for noncontact and on-line inspection. The standoff distance is utilized as an optimization parameter increasing the sensitivity of detection to slight dielectric property variations. Two microwave images, at 24 and 10 GHz of a panel containing five different fiberglass specimens are presented.     

Microwave Diagnosis of Low-Density Fiberglass Composites with Resin Binder

Abstract

Dielectric properties of low-density fiberglass composites are studied at microwave frequencies and are related to the resin binder content and state of cure. A completely filled short-circuited waveguide method is used to study the dielectric properties of fresh and slightly cured resin binder (used in the production of low-density fiberglass composite materials) in the frequency range of 4–18 GHz. The preliminary results indicate that the dielectric properties of resin binder may be used to determine its state of cure. The same measurement approach is used to determine the dielectric properties of fiberglass materials containing uncured resin binder, no resin binder, and three different levels of resin binder. It is found that the dielectric properties of these low-permittivity and low-loss materials are very similar. Consequently, to distinguish among real fiberglass products with different resin binder levels, an open-ended rectangular waveguide measurement approach is used. This technique allows for noncontact and on-line inspection. The standoff distance is utilized as an optimization parameter increasing the sensitivity of detection to slight dielectric property variations. Two microwave images at 24 and 10 GHz of a panel containing five different fiberglass specimens are presented.     

Plastic compression of long cylinders

The possibility of implementing the method of plastic compression of long cylinders using supporting elements is substantiated. Relationships for calculating the limiting geometric parameters of compressible rods and the supporting pressure required to upset the specimens in a linear stress state are obtained. An example is cited for the calculation of the taper angle of the sectors used in the apparatus as supporting elements. The results of comparison of the compression and tension diagrams suggest sufficient accuracy of experimental data obtained using the indicated apparatus; this enables us to recommend it for investigation of the plastic properties of materials.Translated from Problemy Prochnosti, No. 5, pp. 39–44, May, 1992.     

Thermal conductivity of a fiberglass material with a complex spatial structure

A method is given for calculating the thermal conductivity of a fiberglass material having a complicated spatial structure. This method can be applied up to the onset of pyrolysis.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 35, No. 1, pp. 25–28, July, 1978.     

玻璃纤维增强复合材料抗爆容器的研究进展

综述了国内外树脂基玻璃纤维增强复合材料抗爆容器的主要研究成果,对纤维材料及粘合剂的选取、纤维缠绕方式、壳体的动态响应及失稳抑制、容器的抗爆能力和尺度效应等方面进行了较全面的总结.简要介绍了其在航空航天、工业及国防等领域的应用情况.     

Corrosion resistance tests of strained rods from polymer composite materials

A method of estimating the resistance of samples from composite polymer materials to corrosion damage under load is described. The scheme of tests of this method based on the longitudinal bending of the samples is presented. The comparative results of the tests of samples selected from fiberglass plates in air and in an acid medium are presented.     

Coated photonic crystals: computation of the Green tensor and analysis of the bandgap

A finite-size two-dimensional photonic crystal composed of dielectric rods with holes centered within each rod is considered. The geometry of the rods, as well as the holes, is of arbitrary shape. A boundary-element method is implemented for computing the Green tensor. The semi-analytical solution is used for validating the numerical results in the case of circular geometry. Different types of configurations and geometry shapes are considered in the computation.     

碳纤维复合材料抽油杆研究进展

碳纤维复合材料抽油杆是近几年兴起的一种新型柔性抽油杆,具有轻质、高强度、耐高温、耐腐蚀、耐疲劳及结构功能一体化等优异性能,成为解决传统抽油杆失效问题很有发展前途的重要方法之一。主要综述了3种不同树脂基体的碳纤维复合材料抽油杆,包括:环氧树脂基、乙烯基酯树脂基、酚醛树脂基的制备及应用。由于传统的抽油杆很难满足高腐蚀油井、深井以及超深井的开采要求,对碳纤维复合材料抽油杆的发展方向进行了展望。     

Use of Acoustic Emission to Evaluate Residual Strength in FRP Pipes after Impact Damage

Acoustic Emission (AE) has proven to be a useful tool in the monitoring of fiberglass pressure vessels. The ASME Piping and Pressure Vessel Code (subsection X) implements AE as an approved method for quality control and in service testing of fiberglass pressure vessels, making it an accepted technique for the evaluation of fiber composite structures. This article presents the result of AE monitoring of fiber reinforced plastic (FRP) pipes after impact damage has incurred. The results from these tests indicate that AE can be used as a tool to predict the level of damage incurred in the pipes after impact and during pressurization. The use of the Felicity Ratio as the benchmark for evaluation is presented as the key evaluating value.     

Development of polyurethane elastomer composite materials by addition of milled fiberglass with coupling agent

Polyurethane elastomer composites were developed using milled fiberglass and their mechanical properties were studied. In particular, the organically chemical treatment of the milled fiberglass was investigated in detail. It was demonstrated that both strength and toughness of the resulting elastomer composites were improved considerably with the addition content of fiberglass. Furthermore, it was indicated that the optimal properties can be achieved by the proper addition of milled fiberglass that was chemically treated using coupling agent.     

Morphological features of vanadium dioxide microcrystals grown from the gas phase

A gas-phase synthesis of vanadium dioxide (VO₂) is presented and morphological features of the crystals grown by this method are described. Using the proposed method, VO₂ microcrystals having the shapes of continuous rods and plates, as well as rods with a longitudinal rectangular cavity, can be obtained. The possible mechanisms of growth are considered with allowance for the different crystal shapes and features of the synthesis.     

Decreasing losses in Y1Ba2Cu3O7−δ rods in the superconducting state

A new method is proposed for growing Y₁Ba₂Cu₃O_7?δ (YBCO) rods and special growth regimes are described which provide decreasing losses in these rods in the superconducting state. It is shown that the thermocapillary mechanism of liquid phase transfer during the melting and crystallization of YBCO is responsible for the formation of a nonsuperconducting phase at the boundaries between crystal blocks. Results of the measurement of current-voltage characteristics of YBCO rods in the superconducting state are presented.     

A simple laser speckle dilatometer for thermal expansion measurements

A simple laser speckle method utilizing a 4 mW HeNe laser for thermal expansion measurements is described. The method utilizes the rotation of a probe kept on the sample and reference rods. For 5 cm long sample and reference rods kept 0.5 cm apart, a measurement sensitivity of 5 × 10^?6 for $\text{ΔL}\text{L}$ can easily be obtained.     

Design of a phase/doppler light-scattering system for measurement of small-diameter glass fibers during fiberglass manufacturing

We present fundamental studies examining the design of a phase/Doppler laser light-scattering system applicable to on-line measurements of small-diameter (<15 mum) fibers during fiberglass manufacturing. We first discuss off-line diameter measurement techniques currently used in the fiberglass industry and outline the limitations and problems associated with these methods. For the phase/Doppler design study we have developed a theoretical computer model for the response of the measurement system to cylindrical fibers, which is based on electromagnetic scattering theory. The model, valid for arbitrary fiber diameters and hardware configurations, generates simulated detector output as a function of time for a finite absorbing, cylindrical fiber oriented perpendicular to the two incident laser beams. Results of experimental measurements are presented, confirming predictions of the theoretical model. Parametric studies have also been conducted using the computer model to identify experimental arrangements that provide linear phase-diameter relationships for small-diameter fibers, within the measurement constraints imposed by the fiberglass production environment. The effect of variations in optical properties of the glass as well as fiber orientation effects are discussed. Through this research we have identified phase/Doppler arrangements that we expect to have future applications in the fiberglass industry for on-line diameter monitoring and process control.     

电推力器电磁辐射测试透波副舱性能评价

为了获得电推力器工作时的电磁辐射干扰（EMI）数据,通过试验对电推力器的电磁辐射开展测试,测试时推力器必须工作在具有良好透波性的真空副舱内,根据此需求研制了一种集成于现有不锈钢真空室主舱的玻璃纤维透波副舱,针对研制的透波副舱设计指标,提出了从透波率、工作热特性和系统极限真空等方面开展透波副舱综合性能评价的方法。通过测试获得的透波副舱工作特性以及分析评价结果,为透波副舱用于推力器产品电磁辐射试验提供了可靠依据。     

Preform permeability variation with porosity of fiberglass and carbon mats

An experimental investigation on fiber bed permeability variation with porosity for three types of reinforcement mats is performed. The reinforcements consist of plain-weave carbon, plain-weave fiberglass, and chopped fiberglass mats. Resin flow experiments are performed in a rectangular cavity with different fiber volume fractions. RL 440 epoxy resin is used as the working fluid in the experiments. Several layers of mats are laid inside the mold in each experiment and resin is injected at a constant pressure. The effects of reinforcement type and porosity on fiber bed permeability are investigated. Fiber mat permeability of woven mats show large degrees of anisotropy. Resin flow in chopped fiberglass mats is circular, suggesting an isotropic permeability tensor. In all the three cases, preform permeability increases with fiber bed porosity in a non-linear fashion. The results of this investigation could be employed in optimization of liquid composite molding manufacturing processes.     

Nondestructive Evaluation of Fiberglass Wrapped Concrete Bridge Columns

Many in-service concrete bridge decks and columns built before the advent of epoxy coated bars show cracking and spalling of the concrete due to corrosion of the steel reinforcement. In cold regions, the corrosion rate of concrete bridge decks and columns is accelerated by the use of deicing solutions in winter. The corrosion of the steel rebars causes cracking, delamination, and spalling of reinforced concrete structures and increases the cost of rehabilitation and maintenance operations. In Wisconsin (USA), fiberglass wrapping has been used for corrosion protection of reinforced concrete columns. In this methodology, a fiberglass wrap is placed as a barrier between the concrete surface and the surrounding environment and is expected to reduce the detrimental effect of traffic splashing of deicing solutions. This paper describes a study aimed at evaluating the effectiveness of fiberglass wrapping in controlling and reducing the rate of corrosion in bridge concrete columns. Field tests included nondestructive wave propagation and half-cell potential methods. Nondestructive evaluation results were examined and compared to chloride ion (Cl⁻) intrusion measurements. The data show that fiberglass wrapping helps in arresting the chloride ion ingress to the columns, however, it does not help reduce corrosion rates in chloride contaminated concrete columns.     

多层绝热的间隔材料有效低温热导率测试研究

叙述了多层绝热的间隔材料玻璃纤维布、隔热纸的有效低温热导率测试方法,为薄层材料的有效低温热导率测试提供了一种方法,并对测试结果和影响因素,如叠层密度和层密度等进行了讨论分析。