Simulation of transport properties in Nb3Sn strand under bending

Superconducting performance of a large-scale Nb₃Sn cable-in-conduit conductor (CICC) is degraded by periodic bending of strands subjected to a distributed transverse electromagnetic force during operation. The current transport in a single strand depends mainly on the bending strain and transverse resistivity. In particular, in the case of high-level strain and/or crack occurring among the filaments in the strain-sensitive Nb₃Sn strand, these two parameters are required for better understanding of the critical current I_c degradation of a single strand. We use finite element method to simulate transport properties of a single Nb₃Sn strand under bending. The simulation allows treating a wider range of transverse resistivity of strand, compared with our previous analytical method (Cryogenic, 58, 2013). Also, the present simulation incorporates the change of the area of strand cross section due to filament fracture into the boundary of the current transport, rather than simply imposes the condition of vanishing current on the filament fracture region as in the previous analytical method. We show the current/field profiles in the strand for various bending loads and transverse resistivities, as well as the I_c degradation of several types of strands under bending.     

Modeling of continuous ultrasonic impregnation and consolidation of thermoplastic matrix composites

Ultrasonic propagation was used to provide heat and pressure in order to perform impregnation and consolidation during production of thermoplastic matrix composites. For this purpose, a new experimental set-up, integrating a laboratory filament winding machine with a horn and a compaction roller, was developed.The heat transfer phenomena occurring during continuous impregnation and consolidation were simulated solving by finite element (FE) analysis the energy balance equations in 2D accounting for the heat generated by ultrasonic waves, the melting characteristics of the matrix and the movement of the thermoplastic commingled roving.The temperature distribution in the composite, predicted by the numerical simulations, was validated by temperature measurements during the production of E-glass/polypropylene cylinders, with the optimized parameters obtained by the FE analysis. The ultrasonic consolidated composite cylinders were characterized by low void content and a shear modulus comparable with that obtained by the micromechanical analysis.     

Research on a precision tension control system with a magnetic particle clutch as the actuator

The open-loop tension control system, with an industrial control computer as the core and a magnetic particle clutch as the actuator, equipped with three compensation techniques, is researched and manufactured. It has been verified by experiment that the principle of the precise tension control system designed is right and that its properties are reliable. It can ensure tension control stability of the yarn in the filament winding process and increase the response velocity and the stability of the control precision of the whole system.     

某星载天线复合材料骨架的动态特性

本文介绍了纤维缠绕复合材料壳体的刚度的计算方法，采用有限元工程分析软件ANSYS对某星载雷达碳纤维缠绕复合材料天线骨架结构的动态特性进行了分析和计算，所得结果为天线结构设计提供了参考依据。     

On the pressure drop modeling of monofilament-woven fabrics

Pressure drop of monofilament-woven fabrics is often calculated via the so-called orifice model in which a discharge coefficient is assigned to the weave's unit cell. In all previous models of woven fabrics, the filaments were assumed to have circular cross-sections—an assumption which is not entirely accurate especially when there is a considerable tension in the warps and wefts. Following the methodology developed by Lu et al. [1996. Fluid flow through basic weaves of monofilament filter cloth. Textile Research Journal 66 (5), 311-323], a new set of expressions are derived for calculating the most constricted open area, and so the discharge coefficient, of plain-woven monofilament fabrics having filaments with elliptical cross-sections. Conducting numerical simulations for computing the pressure drop of such fabrics, we observed a logarithmic relationship between the discharge coefficient and the Reynolds number. It was also shown that the discharge coefficient decreases by increasing the aspect ratio of the filaments’ cross-section.     

Twaron长丝的上浆工艺探索及试织

优化Twaron对位芳纶纤维的上浆及织造工艺参数.通过分析Twaron长丝的断裂强力及断裂伸长率受水温及浸渍时间的影响,确定了浆料配方及上浆工艺参数,并测试了浆膜性能指标、上浆前后及退浆后的Twaron长丝的断裂强力和断裂伸长率,认为可通过上浆工艺实现Twaron长丝机织物的批量生产;在剑杆织机上织造顺利,织造效率可达到90%,布面平整光洁.     

Buckling of filament-wound composite cylinders subjected to hydrostatic pressure for underwater vehicle applications

The buckling and failure characteristics of moderately thick-walled filament-wound carbon–epoxy composite cylinders under external hydrostatic pressure were investigated through finite element analysis and testing for underwater vehicle applications. The winding angles were [±30/90]_FW, [±45/90]_FW and [±60/90]_FW. ACOS, an in-house finite element program, successfully predicted the buckling pressure of filament-wound composite cylinders with 2 ∼ 23% deviation from the test results. The analysis and test results showed that the cylinders do not recover the initial buckling pressure after buckling and that this leads directly to the collapse. Major failure modes in the test were dominated by the helical winding angles.     

Modal analysis for filament wound pressure vessels filled with fluid

Filament wound pressure vessels have been extensively used in many engineering fields, especially aerospace industry. Vibration-based damage detection methods have the potential to be employed to monitor the health status of the structures based on the fact that damage occurred in a structure would result in changes in its structural dynamic characteristics. However the presence of fluid will affect the dynamic response of this type of vessel structures. Due to the liquid mass decrease during its service, the whole system is considered a time-variant system in terms of its dynamic response even the structure itself remains free of damage, which cause problems for vibration-based damage detection method that utilized dynamic response change to identify damage. Therefore it is critical to understand how the change of the liquid height level influences the dynamic response of the coupled fluid–structure system. This work describes the FEM analysis and an experimental study on the dynamic response of filament wound pressure vessels filled with liquid of different heights and provides the primary information that can be used for vibration-based damage detection.     

Morphology and degradation properties of PCL/HYAFF11® composite scaffolds with multi-scale degradation rate

The analysis of scaffold degradation is a promising strategy for understanding the dynamic changes in texture and pore morphology which accompany polymer resorption, and for collecting same fundamental indicators regarding the potential fate of the scaffold in the biological environment. In this study, we investigate the morphology and degradation properties of three composite scaffolds based on poly(ε-caprolactone) (PCL) embedded with benzyl ester of hyaluronic acid (HYAFF11®) phases, and, in turn, different reinforcement systems – i.e., calcium phosphate particles or continuous poly(lactic acid) (PLA) fibres. Scanning electron microscopy (SEM) and μ-tomography supported by digital image analysis enabled a not invasive investigation of the scaffold morphology, providing a quantitative assessment of porosity (which ranged from 63.1 to 82.8), pore sizes (which varied from 170.5 to 230.4 μm) and pore interconnectivity. Thermal analyses (DSC and TGA) and Raman spectroscopy demonstrated the multi-scale degradation of the composite with highly tailoring degradation kinetics depending on the component material phases and scaffold architecture changes, due to their conditioning in simulated in vivo environment (i.e., SBF solution). These results demonstrate that the judicious mixing of materials with faster (i.e., HYAFF11) and slower (i.e., PLA and PCL) degradation kinetics, different size and shape (i.e., domains, particles or long fibres), certainly concurs to design a smart composite scaffold with time-controlled degradation which can support the regeneration of a large variety of tissues, from the cartilage to the bone.