Stress singularity at the vertex of homogeneous and composite cones for different boundary conditions

A method of constructing singular solutions for conical bodies is proposed and versions of its numerical realization based on the finite-elements methods are considered. The results of numerical experiments illustrating the effectiveness and reliability of the proposed method are presented, as well as the results of a calculation of the eigenvalues, which define the form of the stress singularity for homogeneous and composite circular and non-circular cones for different boundary conditions.     

Study of narrow resonances of coherent radiation in time separated fields in SF6

The present paper reports for the first time application of coherent radiation in time separated fields (CRTSF) for high resolution spectroscopy in gases. Experimentally the high resolution spectrum of SF₆ has been obtained by the time delay averaging of the CRTSF signals.     

The dynamic behaviour of elastic coaxial cylindrical shells conveying fluid

The dynamic behaviour of elastic coaxial cylindrica shells, which interact with a flow of compressible fluid in the inner shell or in the annular gap between the shells when both flows are present, is investigated by the finite element method. A number of test problems is considered in the case of cantilevered coaxial shells. The effect on the stability limit of the gap between the two shells is investigated for different values of the stiffness parameters of the outer shell and the fluid flow. An important difference is found with existing solutions in cases when the loss of stability of the coaxial shells occurs at higher oscillation modes. It is established that, for a certain value of the gap between the shells, the elasticity of the outer shell may have a stabilizing effect. It is shown that the presence of internal and annular flows simultaneously has a considerable stabilizing effect, while a loss of stability when the flow rates increase occurs at extremely high oscillation modes.     

Effect of poly (lactic acid)‐graft‐glycidyl methacrylate as a compatibilizer on properties of poly (lactic acid)/banana fiber biocomposites

The main aim of this study was to synthesis of poly (lactic acid) (PLA)‐graft‐glycidyl methacrylate (GMA) as well as its influence on the properties of PLA/banana fiber biocomposites. PLA‐graft‐GMA graft copolymer (GC) was synthesized by melt blending PLA with GMA using benzoyl peroxide and dicumyl peroxide as initiators. Graft copolymerization was confirmed by FTIR and ¹H‐NMR spectroscopic studies. PLA/silane treated banana fiber (SiB) biocomposites with various GC concentrations were prepared by melt blending followed by injection molding techniques. The influence of GC content on the mechanical, thermal and moisture resistance properties of the composite was investigated. The addition of 15 wt% GC content in the biocomposite provided optimum tensile and flexural strength, which is attributed to the greater compatibility between fiber and PLA matrix. The thermal properties of biocomposites have been evaluated using thermogravimetric analysis which provided evidence of improved interfacial adhesion between SiB and PLA by the addition of GC. Additionally, GC enhanced the moisture absorption resistance of biocomposites. These results indicated that GC is indeed a good candidate as a compatibilizing agent to improve the compatibility in PLA/fiber biocomposites. Copyright © 2015 John Wiley & Sons, Ltd.     

The Influence of Substances Reducing the Surface Energy of Naphthalene Single Crystals on Plastic Flow

The effect of surface active substances on plastic flow of naphthalene single crystals is considered. The role of normal and shear stresses is revealed. Rates of single crystals flow in different glide systems under constant stress are compared. The stress of plastic flow in single crystals can be decreased in active media by as much as 50%.