Volume 2 Issue 2
Authors: M. Jayabalan; G. T.Finosh; Medha Murali
Abstract: Biodegradable polymeric bone plates suffer from warping, hollowing or substantial erosion inherent with the process of degradation. In order to solve the problem of warping and insufficient mechanical strength, forging of curable sheet molding polyester compound has been attempted. Polymeric nanocomposite was prepared by forging using compression molding with a sheet molding compound (SMC) consisting inorganically modified hydroxy terminated poly (propylene fumarate) (HT-PPF). Hydroxyapatite nanopowder (100-250nm sintered) and polyol modified-polymeric diphenyl methane diisocyanate (Empeyonate PM-35, NCO Content 27%) were used for modification of HT-PPF to get the SMC. The DTA studies on SMC mixed with methyl methacrylate reveal exothermic peak at 94.9oC for the curing of SMC though crosslinking of HT-PPF with methyl methacrylate. SEM microphotographs (fractography) of as-prepared compression molded polymeric nanocomposite reveal serrated structure reflecting higher mechanical strength and good dispersion of hydroxyapatite in the polymer matrix and good interfacial bonding between the polymer and hydroxyapatite nanocrystals.The surface studies revealed the hydrophilicity of the composite. The in-vitro degradation of the nanocomposite was found to be more in Ringer solution than PBS which is due to the slow degradation by the buffering effect of the PBS and hydroxyapatite. The nanocomposite is nonhemolytic, noncytotoxic and blood compatible.
Keywords: Sheet Molding Compound; Inorganically Modified Hydroxy Terminated Poly (Propylene Fumarate); Polymeric Nanocomposite; Interfacial Bonding; Blood Compatibility
Authors: V. V. Somonov; S. Böhm; M. Geyer; S. Bertelsbeck
Abstract: This work is devoted to the research of hot spots generated by induction heating to prevent hot cracks during laser welding of aluminum samples. Plates were used, which were made from aluminum alloys AA6082Т4 and AA5754Н22 with a thickness of 2 mm. This article shows the results of numerical modeling of temperature fields and stress fields formed during the process of induction heating. The results of experimental validation of the simulation are also demonstrated.
Keywords: Modeling; Sysweld; Induction Heating; Aluminum Alloys; Thermal Stress; Hot Crack
Authors: Brahim Attaf
Abstract: Structural adhesives used to bond composite blade parts have to fulfil sustainability requirements and REACH regulation in addition to quality design requirements in terms of specific stiffness, specific strength, fatigue and weathering characteristics. To appreciate the impacts involved in the bonding process (e.g., harmful substances, amount of VOC emissions, toxic chemicals, carcinogens, odours, ...), designers and users should have more knowledge and better innovation policies on how to integrate health and environmental aspects into the bonding procedures to enable a sustainable production coupled with green manufacturing practices. With this argument as an objective, the aim of the present paper is to innovate and develop a new approach providing high performance of adhesively-bonded composite blade half-shells in terms of Quality-Health-Environment interrelated issues. Alternative solutions leading to new generation of environmentally-friendly adhesives can be achieved through the integration of a new eco-factor, λa, into the classical bonding formulations. Further to that, shear stress eco-ratio, Λ, versus adhesive lap ratio, Φ, for different values of λa were plotted and some conclusions were drawn.
Keywords: Ecodesign; Blades; Composite Materials; Eco-coefficients; Sustainable Development; REACH
Authors: D. V. Vlasov; L. A. Apresyan
Abstract: A new cascade model of polymer composite materials giant current fluctuations is developed on the basis of published representable set of experimental data. This qualitative model describes the “anomalous” features of the conduction of polymer nanocomposites, in particular, conduction many orders of magnitude self-switching to the conducting state in polymer films including relatively thick up to tens of microns or more. The development is achieved by combining well known model of hopping conduction mechanism with experimental data of soft reversible electric breakdown. With much simplification the instability can be explained as follows: dividing the distance between electrodes on conducting islands (with constant potential with zero electric field) and insulating gaps (where electric field is higher than average level). In such a system we obtain “instability” - type correlation of electric field in the adjacent insulating gaps: one gap microbreakdown increases the field strength in the adjacent gaps.
Keywords: Polymer Films; Conductivity Switching; Fluctuations
Authors: Yoshihiro Ootao; Masayuki Ishihara
Abstract: This paper presents the theoretical analysis of a laminated hollow cylinder constructed of isotropic elastic and magneto-electro-thermoelastic materials under unsteady and uniform surface heating. We obtain the exact solution of the transient thermoelastic problem of the laminated hollow cylinder in the plane strain state. As an illustration, we perform numerical calculations of a three-layered composite hollow cylinder made of isotropic elastic, piezoelectric and magnetostrictive materials and investigate the numerical results for temperature change, displacement, stress, and electric and magnetic potential distributions in the transient state.
Keywords: Thermoelastic Problem; Magneto-Electro-Thermoelastic; Laminated Hollow Cylinder; Plane Strain Problem; Transient State
Authors: Amir Kari; Mehdi Ghassemieh
Abstract: This study presents the utilization of the shape memory alloys in the steel structures for retrofitting purposes and brings them to the state of the current specifications. Shape memory alloys with the super-elastic behavior exploited in order to operate as a suitable passive seismic control device in the structural systems. In this article, the results of a numerical investigation in which the improvement of a damaged moment resisting steel frame due to seismic loadings is presented. Super-elastic model of shape memory alloys and plasticity model of steel are incorporated into the nonlinear finite element program particularly developed for this research. Also to compare the behavior of the proposed energy dissipation system, the behavior of the steel frame with shape memory alloy braces are compared with the behavior of the buckling restrained bracing, considered to be the forefront lateral systems among the existing systems. Results proved that using shape memory alloy braces for the retrofitting purposes is preferred in comparison with buckling restrained braces; particularly in high levels of seismic damage.
Keywords: Shape Memory Alloys; Super-Elastic; Energy Dissipation; Steel Structure; Finite Element Method; Seismic Control