Abstract
This paper is focused on the delamination analysis of a multilayered beam structure loaded in torsion under strain-path control. The beam under consideration has a rectangular cross-section. The layers of the beam are made of different viscoelastic materials which exhibit continuous inhomogeneity in longitudinal direction. Since the delamination is located inside the beam structure, the torsion moments in the two crack arms are obtained by modeling the beam as an internally static undetermined structure. The strain energy stored in the beam is analyzed in order to derive the strain energy release rate (SERR). Since the delamination is located inside the beam, the delamination has two tips. Thus, solutions of the SERR are obtained for both tips. The solutions are verified by analyzing the beam compliance. Delamination analysis with bending-torsion coupling is also performed. The solutions derived are timedependent due to two factors. First, the beam has viscoelastic behavior and, second, the angle of twist of the beam-free end induced by the external torsion moment changes with time according to a law that is fixed in advance.
Abstract
Zeolites are microporous materials that find applications in different fields due to their numerous interesting properties. This research investigated the effect of leaching on unheated Ifon kaolin in dilute hydrochloric acid and sulphuric acid. The hydrothermal method synthesized zeolite-X type, and the resulting sample was characterized using different techniques. The silica/alumina ratio in the synthesized sample was approximately 5.6, while Infrared spectra confirmed that the synthesized material was Zeolite-X. Based on the X-ray diffraction patterns, other phases were also formed in addition to zeolite-X crystals. Thermogravimetry results indicated that the synthesized zeolite was relatively stable below 500oC, so its weight loss was only 13% after heating to about 200oC. A differential thermal analyzer confirmed this amount of weight loss, and endothermic and exothermic reactions were also observed for the samples calcined respectively at 700 and 900oC. Based on Brunauer-Emmett-Teller (BET) analyses, samples at 700oC showed slower adsorption-desorption isotherms, pore volume, and sizes than those at 900oC. These results have shown that leaching and calcination temperature significantly affect the type of zeolite produced.
Key Words
hydrothermal synthesis; Ifon kaolin; metakaolin; processing; zeolite X
Address
Henry E. Mgbemere: Department of Metallurgical and Materials Engineering, University of Lagos, Akoka, Lagos State, Nigeria
Henry Ovri: Experimental Materials Mechanics, Institute of Materials Research, Helmholtz Zentrum Hereon. Max Planck Strasse 1, 21502 Geesthacht Germany
Anna-Lisa Sargent: Department of Nanotechnology, Institute of Materials Research, Helmholtz Zentrum Hereon. Max Planck Strasse 1, 21502 Geesthacht Germany
Abstract
Concrete is the most significant material in the construction industry which is required to construct several facilities like roads, buildings, and bridges etc. which leads to the economic development of a country. But now days, in view of sustainable development and environmental problems, plastic waste management is one of the major environmental issues due to its non-biodegradable nature which allows it to stay in the landfills until they are cleaned up. To overcome all these concerns, plastic waste may be used as a substitute of natural fine and coarse aggregate in concrete and a valuable solution to utilize the plastic items which causes several problems. In order to, present study is focused on the affecting properties of concrete as workability, compressive strength, and tensile strength of concrete with using plastic waste and without using plastic waste. Based on the detailed literature, it was observed that the plastic waste is not affecting the quality and consistency of concrete. However, as the number of PVC particles in the mixture increased, the drying shrinkage values decreased and the inclusion of plastic flakes can mitigate drying shrinkage cracking which leads the higher durability of concrete. Based on the comprehensive literature, it was also observed that the plastic aggregate found to be suitable for low and medium strength concrete. However, the investigation on the application of plastic aggregate in the high strength concrete is found limited. It was concluded that the optimum percentage of the plastic aggregate was found about 20%.
Key Words
compressive strength; concrete; plastic waste; tensile strength; workability
Address
Department of Civil Engineering, Dr. B R Ambedkar National Institute of Technology, G.T. Road, Amritsar Bypass, Jalandhar-144011, Punjab, India
Abstract
This study evaluates the ratio of Toluene di-isocyanate (TDI) functional group isocyanate (NCO) to the binder functional hydroxyl group (OH) in HTPB/AP/Al-based propellants on their mechanical properties, flow rate, and viscosity to determine the limitations of NCO/OH in the composition of solid propellants. The propellants consisted of hydroxyl-terminated polybutadiene (HTPB) polyurethane (PU), aluminum (Al) and tri-modal ammonium perchlorate (AP). The tri-modal AP consisted of 30% of coarse AP, 30% of medium AP, and 8% of fine AP. The ratio of NCO/OH varies from 0.73 to 0.85, with two binder percentages of 10.5% and 12%. An increase in NCO/OH ratio with 10.5% binder provided 20%, 95%, and 8 to 9% increments in UTS, modulus, and hardness, respectively. However, the propellant elongation, density, and flow rate decreased by 170%, 0.2%, and 11-12%, respectively. Viscosity increased 20% based on initial hour reading. The 12% binder provides 27%, 47%, and 5~6% an increment of UTS, modulus and hardness respectively. However, the propellant elongation, density, and flow rate decreased by 47 %, 0.17% and 27%, respectively. The viscosity increased 30% based on initial hour reading. This study suggests the NCO/OH value of 0.77 and 10.5~11% binder content in propellant based on the mechanical properties, flow rate, and viscosity for better processing and pot life.
Abstract
The aim of this work was to determine the behavior of alloy elements and compounds formed during solidification in the manufacturing process of the CuAgZrCr alloy under an oxidizing environment. Bulk and surface analysis techniques, such as Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), Raman and X-ray diffraction (XRD) were used to characterize the phases obtained in the solidification process. In order to focus the analysis on the on grain boundary interface, partial removal of the matrix phase by acid attack was performed. The compositional differences obtained by SEM-EDX, Raman and XPS on post-manufacturing materials allowed us to conclude that the composition of grain boundaries of the alloy is directly influenced by the oxidizing environment of alloy manufacturing.
Key Words
intermetallic phases; microstructure CuAgZrCr cast-alloy; surface chemical analyses
Address
Ernesto G. Maffia: Departamento de Mecánica de la Facultad de Ingeniería, Universidad Nacional de La Plata, Calle 1 y 47 (1900)- La Plata, Buenos Aires, Argentina
Mercedes Muñoz and Pablo A. Fetsis: CINDECA-CCT- CONICET-CIC- Universidad Nacional de La Plata, Calle 47 No 257 (1900)- La Plata, Buenos Aires, Argentina
Carmen I. Cabello: 1) CINDECA-CCT- CONICET-CIC- Universidad Nacional de La Plata, Calle 47 No 257 (1900)- La Plata, Buenos Aires, Argentina, 2) Comisión de Investigaciones Científicas Pcia. Bs.As.CIC PBA Facultad de Ingeniería Universidad Nacional de La Plata, Calle 1 y 47 (1900)- La Plata, Buenos Aires, Argentina
Delia Gazzoli: Dipartimento di Chimica, "Sapienza" Universitá di Roma, Ple. Aldo Moro 5 (00185) Rome, Italy
Aldo A. Rubert: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Calle 64(SN) e/ Bv. 113 y 120, Universidad Nacional de La Plata CONICET, (1900) La Plata, Buenos Aires, Argentina
