Characterization and analysis of the interlaminar behavior of thermoplastic composites considering fiber bridging and R-curve effects

Thermoplastic composites can enable the development of new manufacturing techniques to make the aviation industry more sustainable while at the same time greatly benefit cost-efficient and high-volume production. One of the thermoplastic composite materials that can enable this transition is AS4D/PEKK-FC. In this work, the interlaminar properties of AS4D/PEKK-FC thermoplastic composite are characterized and analyzed by means of Mode I, II and Mixed Mode I/II at 50:50 tests, while considering fiber bridging and R-curve effects. In order to achieve stable crack propagation the test configurations are adjusted to account for the large fracture process zone ahead of the crack tip and an appropriate data reduction method is selected. The experimental data is reduced using an inverse methodology to extract cohesive laws based on only the load–displacement curves. Additionally, the use of this methodology provides new insights into the validity of two different mode II tests and the influence of fiber bridging on the mixed-mode interlaminar behavior. The interlaminar damage mechanisms are investigated by means of scanning electron microscopy. The resulting cohesive laws are implemented in commercial finite element software in tabular form, without the need for user-subroutines. All experimental test configurations are analyzed using a single material card and it is shown that fiber bridging and R-curve effects are well captured

Characterization of Inertial Electrostatic Confinement Fusion Plasma Device

Inetial electrostatic confinment fusion (IECF) device constructed at the Egyptian Atomic Energy Authority (EAEA-IEC), is introduced the characterization of the IEC plasma device. The x-ray and visible light emissions in IEC plasma device were investigated by employing time -resolved detector and measure of the total amount of visible light using lux meter

Accurate simulation of delamination under mixed-mode loading using a multilinear cohesive law

The complex failure mechanisms involved in failure of interfaces requires the use of an accurate description of the cohesive law. In recent years, there have been many developments to determine the full shape of the cohesive law. However, most of the existing cohesive zone models assume a simplified shape, such as bilinear, trapezoidal or exponential, which are usually simple to model. Their accuracy is found to be rather limited, especially in the presence of a large fracture process zone due to either plastic deformation or fibre bridging. In this work, a new cohesive element description is proposed to formulate a general cohesive zone model to overcome these limitations. The benefit of the new approach is that it allows for convenient implementation of any arbitrary shape of the cohesive law obtained experimentally. The authors present a new procedure based on the superposition of n-bilinear cohesive zones to obtain an equivalent multilinear cohesive law that fits any experimental measurement. The new element formulation has been implemented in the commercial finite element software ABAQUS, using user element subroutine. Verification of the methodology is performed at the single element level and the approach is validated for different material systems (adhesives and composites) using the double cantilever beam, end-notched flexure and mixed-mode bending tests. Excellent correlation between all numerical predictions and experimental results is obtained, demonstrating the robustness of the proposed methodology.</p

Characterization and analysis of the interlaminar behavior of thermoplastic composites considering fiber bridging and R-curve effects

Thermoplastic composites can enable the development of new manufacturing techniques to make the aviation industry more sustainable while at the same time greatly benefit cost-efficient and high-volume production. One of the thermoplastic composite materials that can enable this transition is AS4D/PEKK-FC. In this work, the interlaminar properties of AS4D/PEKK-FC thermoplastic composite are characterized and analyzed by means of Mode I, II and Mixed Mode I/II at 50:50 tests, while considering fiber bridging and R-curve effects. In order to achieve stable crack propagation the test configurations are adjusted to account for the large fracture process zone ahead of the crack tip and an appropriate data reduction method is selected. The experimental data is reduced using an inverse methodology to extract cohesive laws based on only the load–displacement curves. Additionally, the use of this methodology provides new insights into the validity of two different mode II tests and the influence of fiber bridging on the mixed-mode interlaminar behavior. The interlaminar damage mechanisms are investigated by means of scanning electron microscopy. The resulting cohesive laws are implemented in commercial finite element software in tabular form, without the need for user-subroutines. All experimental test configurations are analyzed using a single material card and it is shown that fiber bridging and R-curve effects are well captured.Aerospace Structures & Computational Mechanic

Biochemical Isolation and Characterization of Hyaluronidase Enzyme from Venom of Egyptian Honey Bee Apis Mellifera Lamarckii

The hyaluronidase enzyme has been used in many such fields of medicine as ophthalmology, orthopaedia, internal medicine, gynecology, surgery, oncology and dermatology. In this study, the hyaluronidase enzyme was purified and characterized for the first time from Egyptian bee venom homogeneously using DEAE-cellulose and Sephacryl S-300 columns. Bee venom hyaluronidase specific activity was 411.7 units/mg protein with 49.9% yield and 3.23-fold purification. The molecular weight of the purified bee venom hyaluronidase native form was 37 kDa. The purified enzyme was found homogeneous on native PAGE and SDS-PAGE, with two congruent subunits of 18.4 kDa and isoelectric point (pI) of 8.6–8.8. The enzyme was found to be stable over a wide range of temperature (20–60°C) and pH (4.5–6.5), and its optimum activity at 37°C, pH 5.4 and 0.15 M NaCl. Km for bee venom hyaluronidase was 0.029 mg/ml hyaluronic acid and its activity was elevated in presence of MgCl2 and ZnCl2 and lowered in presence of FeCl2. Heparin inhibited the hyaluronidase enzyme noncompetitively with a Ki value of 2.9 units heparin and one binding site on the enzyme molecule

Phospholipase A2 enzyme from the venom of Egyptian honey bee Apis mellifera lamarckii with anti-platelet aggregation and anti-coagulation activities

Abstract Background Honey bee venom contains various enzymes with wide medical and pharmaceutical applications. Results The phospholipase A2 (PLA2) has been apparently purified from the venom of Egyptian honey bee (Apis mellifera lamarckii) 8.9-fold to a very high specific activity of 6033 U/mg protein using DEAE–cellulose and Sephacryl S-300 columns. The purified bee venom PLA2 is monomeric 16 kDa protein and has isoelectric point (pI) of 5.9. The optimal activity of bee venom PLA2 was attained at pH 8 and 45 °C. Cu2+ , Ni2+, Fe2+ , Ca2+, and Co2+ exhibited a complete activating effect on it, while Zn2+, Mn2+, NaN3, PMSF, N-Methylmaleimide, and EDTA have inhibitory effect. Conclusions The purified bee venom PLA2 exhibited anti-platelet aggregation and anti-coagulation activities which makes it promising agent for developing novel anti-clot formation drugs in future