Re-entry systems are subject to the harsh environment during hypersonic atmospheric re-entry phas... more Re-entry systems are subject to the harsh environment during hypersonic atmospheric re-entry phase. In order to withstand the high aerothermal loads, thermal protections systems are necessary to protect the vehicle and hot structures are mandatory for aerodynamic control surfaces. Thermo-structural challenges are quite severe. Indeed, large thermal gradients are induced by the outer surface of the vehicle and the internal environment, including cold structure and avionics as well as at the connections between hot control surfaces and the much cooler actuators inside the vehicle. C/SiC is widely selected as the best option for TPS and hot structure control surface providing the lowest weight and thinnest cross-section, minimal thermal expansion mismatch problems, and a good thermal margin. Different processes are commonly used: Chemical Vapour Infiltration (CVI), Polymer Infiltration and Pyrolysis (PIP) and Liquid Silicon Infiltration (LSI). CIRA has recently set up a research and de...
This paper proposes an effective manufacturing process developed to overcome drawbacks that can o... more This paper proposes an effective manufacturing process developed to overcome drawbacks that can occur using a nanofilled resin as matrix in aeronautical composites. Nanoparticles embedded in epoxy resins impregnating carbon fibers are able to improve a composite with new desired functionalities. As soon as the nanoparticles are dispersed in a resin, the viscosity dizzily rises and usually, the traditional manufacturing processes are not suitable to obtain a good quality of the manufactured panels. An alternative method has been developed starting from the Resin Film Infusion (RFI) process. This method has been firstly tested on several flat panels, and then it has been transferred on a more complex shaped panel with three stringers. In this work, a flame resistant resin based on a tetrafunctional epoxy precursor filled with carbon nanotubes to increase electrical conductivity, has been used for the panel manufacturing.
Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, sp... more Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, spanning from self-repairing of structures to self-deploying of antennas, solar sails, or functional devices (e.g. for grabbing small space debris). In all these cases, it may be essential to have information about their configuration at different stages of shape recovery. In this study, the strain history of a prepreg carbon fibre system, cured with a shape memory polymer (SMP) interlayer, is monitored through a Fibre Bragg Grating (FBG), a fibre optic sensor device. SMPC has been manufactured by using traditional technologies for aerospace. After manufacturing cylindrical shape samples, an external fibre optic system is added to the composite structure; this system is especially suited for high temperatures which are necessary for SMP recovery and composite softening. Sensor functionality is checked before and after each strain history path. Optic fibre arrangement is optimized to avoid unwanted breakings wher...
ABSTRACT This work describes a successful attempt toward the development of CFRCs based on nanofi... more ABSTRACT This work describes a successful attempt toward the development of CFRCs based on nanofilled epoxy resins. The epoxy matrix was prepared by mixing a tetrafunctional epoxy precursor with a reactive diluent which allows to reduce the viscosity of the initial epoxy precursor and facilitate the nanofiller dispersion step. As nanofiller, multiwall carbon nanotubes (MWCNTs) were embedded in the epoxy matrix with the aim of improving the electrical properties of the resin used to manufacture CFRCs. Panels were manufactured by Resin Film Infusion (RFI) using a non-usual technique to infuse a nano-filled resin into a carbon fiber dry preform.
Melt‐spun fibers produced from poly(butylene terephthalate) and containing very small amounts of ... more Melt‐spun fibers produced from poly(butylene terephthalate) and containing very small amounts of multiwall carbon nanotubes (MWNTs) have been investigated. Preliminary studies have been carried out on fibers produced at low draw ratio. The additive contents (≤ 1% by weight) and process conditions for the production of fibers have been optimized to obtain a satisfactory level of MWNTs dispersion for all systems, as confirmed by electron microscopy observations. Structural investigations performed on fibers with varying content and aspect ratio of nanotubes made it possible to relate the observed changes in properties, such as dynamic mechanical behavior and mechanical properties, to the crystalline structure of the polymer in terms of size, main distance between the crystalline lamellae, and orientation. The results have revealed unexpectedly large increase in elongation at break‐in fibres containing MWNTs, even though these exhibited a slight increase in the stiffness of the fibers....
Re-entry systems are subject to the harsh environment during hypersonic atmospheric re-entry phas... more Re-entry systems are subject to the harsh environment during hypersonic atmospheric re-entry phase. In order to withstand the high aerothermal loads, thermal protections systems are necessary to protect the vehicle and hot structures are mandatory for aerodynamic control surfaces. Thermo-structural challenges are quite severe. Indeed, large thermal gradients are induced by the outer surface of the vehicle and the internal environment, including cold structure and avionics as well as at the connections between hot control surfaces and the much cooler actuators inside the vehicle. C/SiC is widely selected as the best option for TPS and hot structure control surface providing the lowest weight and thinnest cross-section, minimal thermal expansion mismatch problems, and a good thermal margin. Different processes are commonly used: Chemical Vapour Infiltration (CVI), Polymer Infiltration and Pyrolysis (PIP) and Liquid Silicon Infiltration (LSI). CIRA has recently set up a research and de...
This paper proposes an effective manufacturing process developed to overcome drawbacks that can o... more This paper proposes an effective manufacturing process developed to overcome drawbacks that can occur using a nanofilled resin as matrix in aeronautical composites. Nanoparticles embedded in epoxy resins impregnating carbon fibers are able to improve a composite with new desired functionalities. As soon as the nanoparticles are dispersed in a resin, the viscosity dizzily rises and usually, the traditional manufacturing processes are not suitable to obtain a good quality of the manufactured panels. An alternative method has been developed starting from the Resin Film Infusion (RFI) process. This method has been firstly tested on several flat panels, and then it has been transferred on a more complex shaped panel with three stringers. In this work, a flame resistant resin based on a tetrafunctional epoxy precursor filled with carbon nanotubes to increase electrical conductivity, has been used for the panel manufacturing.
Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, sp... more Shape memory polymer composites (SMPCs) have the potential for many applications in aerospace, spanning from self-repairing of structures to self-deploying of antennas, solar sails, or functional devices (e.g. for grabbing small space debris). In all these cases, it may be essential to have information about their configuration at different stages of shape recovery. In this study, the strain history of a prepreg carbon fibre system, cured with a shape memory polymer (SMP) interlayer, is monitored through a Fibre Bragg Grating (FBG), a fibre optic sensor device. SMPC has been manufactured by using traditional technologies for aerospace. After manufacturing cylindrical shape samples, an external fibre optic system is added to the composite structure; this system is especially suited for high temperatures which are necessary for SMP recovery and composite softening. Sensor functionality is checked before and after each strain history path. Optic fibre arrangement is optimized to avoid unwanted breakings wher...
ABSTRACT This work describes a successful attempt toward the development of CFRCs based on nanofi... more ABSTRACT This work describes a successful attempt toward the development of CFRCs based on nanofilled epoxy resins. The epoxy matrix was prepared by mixing a tetrafunctional epoxy precursor with a reactive diluent which allows to reduce the viscosity of the initial epoxy precursor and facilitate the nanofiller dispersion step. As nanofiller, multiwall carbon nanotubes (MWCNTs) were embedded in the epoxy matrix with the aim of improving the electrical properties of the resin used to manufacture CFRCs. Panels were manufactured by Resin Film Infusion (RFI) using a non-usual technique to infuse a nano-filled resin into a carbon fiber dry preform.
Melt‐spun fibers produced from poly(butylene terephthalate) and containing very small amounts of ... more Melt‐spun fibers produced from poly(butylene terephthalate) and containing very small amounts of multiwall carbon nanotubes (MWNTs) have been investigated. Preliminary studies have been carried out on fibers produced at low draw ratio. The additive contents (≤ 1% by weight) and process conditions for the production of fibers have been optimized to obtain a satisfactory level of MWNTs dispersion for all systems, as confirmed by electron microscopy observations. Structural investigations performed on fibers with varying content and aspect ratio of nanotubes made it possible to relate the observed changes in properties, such as dynamic mechanical behavior and mechanical properties, to the crystalline structure of the polymer in terms of size, main distance between the crystalline lamellae, and orientation. The results have revealed unexpectedly large increase in elongation at break‐in fibres containing MWNTs, even though these exhibited a slight increase in the stiffness of the fibers....
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Papers by Paola Spena