Ahmad Anwar
Pharos University In Alexandria, Mechanical Engineering, Faculty Member
The space environment hazards are becoming harsh as they affect both the mechanical and electrical properties of the polymer-based reinforced fiber materials in spacecraft. The structure materials changes by Gamma-irradiation often... more
The space environment hazards are becoming harsh as they affect both the mechanical and electrical properties of the polymer-based reinforced fiber materials in spacecraft. The structure materials changes by Gamma-irradiation often deteriorate the epoxy matrix or the epoxy/nano-composite properties. As a result, the effect of gamma irradiation on the mechanical and electrical properties of the selected materials were evaluated. The mechanical properties and electrical resistivity of nanocomposites were studied by a universal testing system (UTS) and Keithley 2635A System Source Meter respectively. Fourier transform infrared (FTIR) functioned to assess the chemical structural variation due to the gamma-ray exposure. Dynamic Mechanical Analysis (DMA) was conducted to obtain the Tan delta, loss and storage modulus of each sample. The result showed enrichment in both the mechanical properties and the electrical conductivity of Epoxy/MWCNT's nanocomposites.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
In the vacuum deep space, outgassing has contributed to degrade mechanical performance of composite materials used in satellite. In this paper, four composite materials are used. Three types of epoxy based composite materials are tested:... more
In the vacuum deep space, outgassing has contributed to degrade mechanical performance of composite materials used in satellite. In this paper, four composite materials are used. Three types of epoxy based composite materials are tested: Carbon fiber, glass fiber and kevlar, which are used in satellite structure. The tested materials are manufactured by commercial method (hand lay-up method without autoclave curing). The forth material is polyimide which is a commercial sheet used in thermal multilayer insulator. The aim of this paper is to qualify those commercial manufacture materials to be used as Low Earth Orbit satellite structure. This study proves two important results; the use of hand lay-up Kevlar/epoxy in the satellite manufacture is rejected. While, the commercial Polyimide (Artilon ® ) is confirmed as a new material used in space as a layer in the multilayer insulation at the lower temperature side.
Research Interests:
Research Interests:
Environmental space threats are becoming more critical as they affect the optical, thermal, and electrical properties of the reinforced fiber polymeric-based materials in spacecraft. Three different Nano-particles Alumina (Al2,O3),... more
Environmental space threats are becoming more critical as they affect the optical, thermal, and electrical properties of the reinforced fiber polymeric-based materials in spacecraft. Three different Nano-particles Alumina (Al2,O3), Multiwall Carbon Nanotubes (MWCNT), and Reduced Graphene Oxide (RGO) were added to the epoxy matrix and then reinforced by bidirectional carbon fiber plain to form carbon fiber/epoxy by hand lay-up using autoclave curing technique to make three different reinforced materials. In this paper, the electrical, optical, and thermal properties of the carbon fiber/Epoxy Nanocomposite were studied. Fourier transform infrared (FTIR) was performed to evaluate the structural changes in the newly synthesized materials. The optical, thermal, and electrical properties were tested by UV-visible Spectroscopy, Photo-acoustic spectroscopy (PA), and Keithley 2635A respectively. The results showed an enhancement in the electrical, optical, and thermal properties of the epoxy...
Research Interests:
a Space Technology Center, Cairo, Egypt b Polymer Chemistry Department, National Center for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt c Solid State Physics and Accelerators Department, National... more
a Space Technology Center, Cairo, Egypt b Polymer Chemistry Department, National Center for Radiation Research and Technology, Egyptian Atomic Energy Authority, Cairo, Egypt c Solid State Physics and Accelerators Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), Cairo, Egypt d Materials Science and Technology Department, Military Technical College (MTC), Cairo, Egypt
Research Interests:
Despite the harshness of the space radiation on satellite electronic components, some Commercial Of The Shelf (COTS) can sustain such harsh environment. Thus, the low-cost advantage of the COTS can be utilized given that these electronic... more
Despite the harshness of the space radiation on satellite electronic components, some Commercial Of The Shelf (COTS) can sustain such harsh environment. Thus, the low-cost advantage of the COTS can be utilized given that these electronic components meet the technical design requirements of the targeted satellite subsystem. Because of the complexity of microcontrollers and their various integrated functionality, they present a hardness assurance challenge. A careful technique was followed in analyzing the space radiation effects. Then rigorous tests should be conducted to test the performance of the candidate microcontrollers under these effects. This paper presents the predicted dose depth curve and the total ionizing does test results for a commercial ARM microcontroller for Low Earth Orbit (LEO) satellites. Such test results help estimate the effect of space environment on the microcontroller and decide if such microcontroller is an accepted candidate for LEO missions or not.
Research Interests:
Materials developed for space application to sustain both of Mechanical loads and space environmental threats. The Electron Beam (EB) was selected to represent one of the most hazardous space environment parameters subjected to the... more
Materials developed for space application to sustain both of
Mechanical loads and space environmental threats. The Electron
Beam (EB) was selected to represent one of the most hazardous
space environment parameters subjected to the Spacecraft (SC)
components; the charged particle flux which predicted according
to the space mission and its orbit parameters. The candidate
materials for this study based on the carbon fiber/epoxy which
was enhanced by adding Reduced Graphene Oxide (RGO) and
investigate its resistance to EB. RGO addition was varies in three
different compounds with different preparation methods; (RGO-24N,
RGO-33C and RGO-G270). The RGO additives were dispersed in
the epoxy matrix. Each sample was subjected to Integrated Current
Transformer (ICT) electron beam at a constant dose of 100 kGy.
The mechanical properties of Nano composites were tested by a
Universal Testing System (UTS) and were correlated to the variation
of their constituent molecular structure obtained by Fourier
Transform Infrared (FTIR) spectroscopy, Dynamic Mechanical
Analysis (DMA) and Electric Resistivity (ER). The results revealed
an enhancement in the mechanical properties of epoxy mthe atrix after
the addition of RGO except for (RGO-33C) and preservation of the
Mechanical properties even after irradiation.
Mechanical loads and space environmental threats. The Electron
Beam (EB) was selected to represent one of the most hazardous
space environment parameters subjected to the Spacecraft (SC)
components; the charged particle flux which predicted according
to the space mission and its orbit parameters. The candidate
materials for this study based on the carbon fiber/epoxy which
was enhanced by adding Reduced Graphene Oxide (RGO) and
investigate its resistance to EB. RGO addition was varies in three
different compounds with different preparation methods; (RGO-24N,
RGO-33C and RGO-G270). The RGO additives were dispersed in
the epoxy matrix. Each sample was subjected to Integrated Current
Transformer (ICT) electron beam at a constant dose of 100 kGy.
The mechanical properties of Nano composites were tested by a
Universal Testing System (UTS) and were correlated to the variation
of their constituent molecular structure obtained by Fourier
Transform Infrared (FTIR) spectroscopy, Dynamic Mechanical
Analysis (DMA) and Electric Resistivity (ER). The results revealed
an enhancement in the mechanical properties of epoxy mthe atrix after
the addition of RGO except for (RGO-33C) and preservation of the
Mechanical properties even after irradiation.
Research Interests:
In this study, we add MWCNTs to enhance the properties of the epoxy as a resin matrix for a nanocomposite material. Thermal properties are enhanced by improving the matrix properties. An investigation was performed to find the relation... more
In this study, we add MWCNTs to enhance the properties of the epoxy as a resin matrix for a nanocomposite material. Thermal properties are enhanced by improving the matrix properties. An investigation was performed to find the relation between the thermos-physical properties and the MWCNTs percentage in epoxy matrix. A various weight percentage of MWCNTs was dispersed in epoxy matrix to be examined these were (0.1, 0.25, 0.5, 1.0) %. The samples were prepared with the sonication technique for about an hour and cured in an open mold in autoclave at 80°C for about four hours and made into (6x6) mm square with (1.0) mm thickness. The thermal conductivity (k) was obtained by measuring the thermal diffusivity (α) and thermal effusivity (e) using the photoacoustic (PA) technique. The composites exhibit about (180) % improvement in k at (1.0) wt. %. A micromechanical models were evaluated to predict throughthickness thermal conductivity of the manufactured sample, and then compared with the experimental results. A Finite Element Model (FEM) was developed to reveal heat transport mechanisms of the resultant nanocomposites. The nanocomposite design for finite element analysis (FEA) provided close predictions and performed better than the micromechanical models.
Research Interests:
Research Interests:
Abstract The effect of gamma irradiation on the optical and electrical properties of the reinforced fiber polymeric based materials became an important issue. Fiberglass/epoxy and Kevlar fiber/epoxy were selected as investigated samples... more
Abstract The effect of gamma irradiation on the optical and electrical properties of the reinforced fiber polymeric based materials became an important issue. Fiberglass/epoxy and Kevlar fiber/epoxy were selected as investigated samples manufactured with hand lay-up without autoclave curing technique. The selected technique is simple and low cost while being rarely used in space materials production. The electric conductivity and dielectric constant for those samples were measured with increasing the gamma radiation dose. Moreover, the absorptivity, band gap and color change were determined. Fourier transform infrared (FTIR) was performed to each of the material's constituent to evaluate the change in the investigated materials due to radiation exposure dose. In this study, the change of electrical properties for both investigated materials showed a slight variation of the test parameters with respect to the gamma dose increase; this variation is placed in the insulators rang. The tested samples showed an insulator stable behavior during the test period. The change of optical properties for both composite specimens showed the maximum absorptivity at the gamma dose 750 kGy. These materials are suitable for structure materials and thermal control for orbital life less than 7 years. In addition, the transparency of epoxy matrix was degraded. However, there is no color change for either Kevlar fiber or fiberglass.