Titles and Abstracts from Issue 2 of 2008:
Insights in Filament Winding for High Quality Composites
David Fullwood and Brent Strong
Abstract:While filament winding is a well established technology, the goal of consistent high-quality products which retain the cost benefits of a largely automated process can be elusive. This article reviews some of the myriad of factors involved in filament winding, while providing specific insights for high quality winding with thermoset resins. As more parameters in the process are identified and controlled, the production of high-quality components will become routine.
Characterization and Processing of Carbon Fiber Reinforced PETI-RFI
Richard Buckley, D.W. Radford, and Rudy Stanglmaier
Abstract - PETI-RFI is a variant of the polymer PETI-5 developed by NASA and viscosity modified for resin transfer molding. The polymer has characteristics of a thermoplastic at low temperature, and high temperature processing results in cross-linking. The cured polymer retains its strength and does not degrade at high-temperature (400°C). Previous work with PETI-RFI has focused on compression molding and vacuum assisted compression molding of simple shapes. This paper details the development of a resin-transfer molding process for carbon-fiber reinforced PETI-RFI and the process parameters for removing voids, including injection parameters such as temperature and pressure. Results of Differential Scanning Calorimetry (DSC), Thermo-Gravimetric Analysis (TGA) and optical microscopy are presented. Several processing options for resin-transfer molding are recommended which lead to reduced void content.
Manufacturing and Properties of the Fibrous/Aluminum Foil Thermal Insulation Composite
C.W. Lou, Y.C. Lee, I.J. Tsai, C.H. Lei, J.M. Chen, and J.H. Lin
Abstract - Heat energy is essential in human life, and it is an important resource in economical and social development. In this study, the fire-retardant fibrous materials (FR-FTI) were prepared using fire-retardant polyester fibers (FRPF) and low melting point polyester fibers (low-Tm fibers). The linear-density of the FRPF, (the layers of the loose nonwoven and the low-Tm fiber content) were changed in the preparation of the FR-FTI. The thermal conductivity of the FR-FTI, tensile strength and the limiting oxygen index (LOI) were evaluated to study the processing parameters on the properties of the FR-FTI. Besides, the aluminum foils were placed between the loose nonwoven FR-FTI to prepare the FR-FTI/A. The thermal conductivity of the FR-FTI was estimated to study the influence of the addition of the aluminum foils on the thermal transfer ability of the composites. The results showed that the effect of the low-Tm fiber content was interacted with the effect of the layer number of the loose nonwoven on the thermal conductivity of the FR-FTI.
A New Spectroscopic Method for the Non-Destructive Characterization of Weathering Damage in Plastics
Andrew R. George and A. Brent Strong
Abstract - The weathering of plastics and composites is a problem because of the loss of both physical and mechanical properties. Surface erosion can be confirmed by scanning electron microscope (SEM) surface studies and other visual detection methods. But the weathering effect has been difficult, and in some cases, impossible to quantitatively characterize without destroying the sample. Clearly a rapid, reliable, and non-destructive test for the extent of the weathering damage is critically needed. Such a test, a new spectroscopic method of analysis, was developed and has been applied across a wide range of plastic materials. The chemical theory upon which this solution rests is also confirmed.
Free Vibrations of Antisymmetric Angle-Ply Laminated Thin Square Composite Plates
Metin Aydogdu and Taner Timarci
Abstract - Accurate numerical results are presented for vibration frequencies of anti-symmetric angle-ply laminated thin square composite plates having different boundary conditions. Boundary conditions are chosen as two adjacent free edges and the remaining edges either simply supported, clamped or free. The Ritz method, along with the displacement assumed in the form of simple polynomials, is applied to solve the problems. Convergence studies are presented to demonstrate the accuracy of the results. The effects of various parameters such as fiber orientation, number of layers and boundary conditions upon the natural frequencies are studied.
Scarf Repair Lay-up Orientation Study
Sophie W.Y.C. Wong Kai and Rikard B. Heslehurst
Abstract - The two principal composite scarf repair configurations have evolved separately from the aviation and marine industries. The aviation scarf repair configuration has the smallest repair ply laid up first over the damaged area, with gradual build-up of the ply size. The marine scarf repair configuration has the largest ply is laid up first followed by the smaller plies. Which should be the preferred repair patch lay-up configuration? This paper has statistically proven that the aviation scarf repair configuration not only provides a small increase in repair strength but with a smaller scatter band has a significantly higher B-Basis design allowable strength. As a result, the aviation scarf repair configuration should be the preferred repair patch lay-up scheme.
Abnormal Form Patch Winding
Fu Hongya, Wang Xianfeng, and Han Zhenyu
Abstract - The theory of composite material patch winding is proposed to determine the winding trajectory by a meshed data model. Two different conditions are considered in this work. One is bridge condition on the concave surface and the other is slip line condition in the process of patch winding. This paper puts forward the judgmental principles and corresponsive solutions by applying differential geometry theory and space geometry theory. To validate the feasibility of the patch winding method, the winding control code is programmed. Furthermore, rocket engine crust experiment and vane winding experiment are carried out.