Center for Composite Materials
Center for Composite Materials
Tian H.,Tsinghua University |
Varada Rajulu A.,Center for Composite Materials
Polymer Composites | Year: 2017
In this work, the surface coated silicon carbide (SiC) obtained by dispersing it in silane coupling agent/ethanol solutions of different concentrations was used as a filler in poly (vinyl alcohol)(PVA) and the composites of (PVA)/SiC were prepared by melt process. The structure and properties of PVA/SiC composites were studied by Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM), mechanical and wear resistance tests in detail. The silane coupling agent was hydrolyzed under acidic conditions, and as a result, large number of hydroxyl and amino groups were generated, which could form hydrogen bonds with hydroxyl groups of the PVA molecular chains, this effect subsequently improved the interactions between the filler and matrix. The surface modified SiC particles dispersed well in PVA matrix resulting a good compatibility with the matrix. For the PVA/SiC composites with the same content of SiC filler, both tensile strength and elongation at break improved with the increase of silane coupling agent concentration. In addition, a good improvement in the wear resistance of the PVA/SiC composites was also achieved compared with the neat PVA/SiC composite. © 2017 Society of Plastics Engineers.
Leng J.,Center for Composite Materials |
Liu L.,Center for Composite Materials |
Liu V.,China Institute of Technology
JEC Composites Magazine | Year: 2012
The applications for shape -memory polymers and composites in aerospace have been widely studied since the 1980. As shown in this paper, these promising smart materials are being particularly developed and qualified for space deployabes struc-tures morphieoptical reflectors, smart textiles and fabrics.
Liu H.,Center for Composite Materials |
Liu K.,Center for Composite Materials |
Mardirossian A.,Center for Composite Materials |
Heider D.,Center for Composite Materials |
And 3 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017
In fiber reinforced composite materials, the modes of damage accumulation, ranging from microlevel to macro-level (matrix cracks development, fiber breakage, fiber-matrix de-bonding, delamination, etc.), are complex and hard to be detected through conventional non-destructive evaluation methods. Therefore, in order to assure the outstanding structural performance and high durability of the composites, there has been an urgent need for the design and fabrication smart composites with self-damage sensing capabilities. In recent years, the macroscopic forms of carbon nanotube materials have been maturely investigated, which provides the opportunity for structural health monitoring based on the carbon nanotubes that are integrated in the inter-laminar areas of advanced fiber composites. Here in this research, advanced fiber composites embedded with laminated carbon nanotube layers are manufactured for damage detection due to the relevant spatial electrical property changes once damage occurs. The mechanical-electrical coupling response is recorded and analyzed during impact test. The design and manufacturing of integrating the carbon nanotubes intensely affect the detecting sensitivity and repeatability of the integrated multifunctional sensors. The ultimate goal of the reported work is to develop a novel structural health monitoring method with the capability of reporting information on the damage state in a real-time way. © 2017 SPIE.
He Y.-R.,Harbin Institute of Technology |
Wang X.-Z.,Harbin Institute of Technology |
Han J.-C.,Harbin Institute of Technology |
Han J.-C.,Center for Composite Materials |
And 3 more authors.
Journal of Propulsion and Power | Year: 2014
One of the greatest challenges of hypersonic vehicles is their thermal protection and, more specifically, the cooling of their engine. To simulate the behavior of a complete actively cooled thermal protection system, a computational fluid dynamics and finite element analysis coupling method is applied to calculate the fluid/thermal/stress distributions for steady-state flight conditions. Work has been done on four different Ni-based alloys and three different panel structures. Temperature and stress profiles at the outlet cross section show that the maximum temperature and stress happen on the side that is close to the combustion chamber, and so this is the section on which the active cooling system should focus. It is better to have small rounded chamfers in the panels to decrease the stress concentration at the corners. Failure maps are presented for four Ni-based alloys showing the comparison of their thermostructural performance, which will be helpful for the selection of the materials in an active cooling system. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc.
News Article | December 18, 2015
TPI Composites Inc has been awarded a US$3 million program by the U.S. Department of Energy’s Office of Energy Efficiency & Renewable Energy (EERE) to design, develop, and demonstrate a lightweight hybrid composite door. TPI will be leading a team of industry and academic participants with knowledge in vehicle design and composite materials, including Creative Foam Corporation, Hexion Inc., KraussMaffei, SAERTEX USA, LLC, Center for Composite Materials at the University of Delaware, and a global automotive OEM. ‘We are excited about the opportunity to design, develop and validate the materials and manufacturing technologies that can transition lightweight structural composites into the high volume automotive mainstream,’ said Steve Lockard CEO & President TPI Composites. Part of the challenge of widespread composite adoption in automotive applications is the ability for composite structures to achieve cost targets and high volume production rates. The composite door program will focus on meeting all structural, safety and noise, vibration, and harshness performance goals while addressing cycle time and cost constraints. This story is reprinted from material from TPI Composites, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
Lopatnikov S.L.,University of Delaware |
Lopatnikov S.L.,Center for Composite Materials |
Gillespie Jr. J.W.,University of Delaware
Transport in Porous Media | Year: 2010
We present here the approach to the theory of fluid-filled poroelastics based on consideration of poroelastics as a continuum of "macropoints" (representative elementary volumes), which "internal" states can be described by as a set of internal parameters, such as local relative velocity of fluid and solid, density of fluid, internal strain tensor, specific area, and position of the center of mass of porous space. We use the generalized Cauchy-Born hypothesis and suggest that there is a system of (structural) relationships between external parameters, describing the deformation of the continuum and internal parameters, characterizing the state of representative elementary volumes. We show that in nonhomogenous (and, particularly, nonlinear) poroelastics, an interaction force between solid and fluid appears. Because this force is proportional to the gradient of porosity, absent in homogeneous poroelastics, and one can neglect with dynamics of internal degrees of freedom, this force is equivalent to the interaction force, introduced earlier by Nikolaevskiy from phenomenological reasons. At last, we show that developed theory naturally incorporates three mechanisms of energy absorption: visco-inertial Darcy mechanism, "squirt flow" attenuation, and skeleton attenuation. © 2010 Springer Science+Business Media B.V.
Cender T.A.,Center for Composite Materials |
Gangloff J.J.,Center for Composite Materials |
Simacek P.,Center for Composite Materials |
Advani S.G.,Center for Composite Materials
International SAMPE Technical Conference | Year: 2014
Out-of-Autoclave (OOA) thermoset prepreg manufacturing of aerospace quality parts is now being explored to reduce costs. Low pressure processing and ability to introduce automation and improve reliability makes this process very attractive. However, this process has a higher propensity for voids than its contemporary autoclave processing, because higher pressures are not available to arrest void growth. Hence, it is important to understand the fundamental phenomena and identify the parameters that cause voids to reduce or eliminate them. This presentation discusses the mechanisms of void formation, growth, and transport during processing. This includes insufficient resin impregnation into the dry fibers due to very low transverse permeability of the prepreg, and the management of the vacuum driven air pathway network. It is shown how the air pathway network is essential for sufficient removal of air from the laminate before consolidation to allow complete resin saturation of the fibers. Models are formulated to characterize dual scale prepreg permeability. Experiments are conducted to demonstrate the fundamental mechanisms and validate the formulated models which should prove useful in guiding the process optimization of OOA thermoset prepreg composite structures. Copyright 2013 by Suresh G. Advani.
Sun Y.,Center for Composite Materials |
Chen Y.,Center for Composite Materials |
Lin X.,Center for Composite Materials |
Su H.,Center for Composite Materials |
He X.,Center for Composite Materials
Materials Research Innovations | Year: 2014
The Fe based oxide dispersion strengthened alloy has become the preferred material for future nuclear reactor fuel cladding because of its neutron radiation stabilisation and mechanical properties caused by specific composition and microstructure at high temperature. This paper investigated the microstructure characteristics and the tensile properties at room temperature and high temperature of the as deposited test samples of Y2O3 strengthened FeCrAl alloy foils fabricated by electron beam physical vapour deposition technique, as well as the annealed state, the cold rolled/recrystallisation-annealed state and cold forged/recrystallisation-annealed state samples. The results indicated that there was a fine crystal zone near the substrate of the as deposited samples, and the rest, >95% of the sample, had obvious columnar crystal structure feature. The long axis of the columnar crystals was parallel to the normal of foil surface. Annealing technology and cold deformation (including cold rolling and cold forging technology)/recrystallisation-annealing technology have been studied to eliminate this microstructure, which goes against bearing stress, and to improve the tensile properties at high temperature. The results showed that these follow-up densification treatments studied in this paper could significantly improve the microstructure of these alloy foils. The effect of annealing could completely eliminate the rectangular pyramid grain characteristics as the strength was improved. It was observed obviously that the grain arrangement of the foil surface became more compact, and the size of the grains became smaller after cold deformation/recrystallisation-annealing. The strength at high temperature improved substantially compared with the as deposited foils. © W. S. Maney & Son Ltd. 2014.