Some properties of the polypropylene - aluminum system

The effect of composition on the properties (bulk resistivity, hardness, compressive deformation, density, and microstructure) of polypropylene-aluminum specimens has been investigated. The changes are not additively related with the composition. An explanation of the observations is proposed.Riga Lenin Komsomol Institute of Civil Aviation Engineers. Translated from Mekhanika Polimerov, No. 2, pp. 323–326, March–April, 1971.     

Mechanical properties of henequen fibre/epoxy resin composites

By using surface-treated and untreated henequen fibres and an epoxy resin, composites were made by compression moulding, and their mechanical properties and failure modes were determined experimentally in tension, bending, and impact loading. The results obtained show that the treatment of fibre surface does not improve the bond between the fibres and the resin matrix, and the general mechanical properties of the composites are similar.     

Optimization of sandwich structures with damping properties

Maximum viscoelastic damping characteristics of sandwich structures are designed using finite element and informative planning methods. Two basic design problems were considered: addition of a damping coating to a given homogeneous structure and building a sandwich structure subjected to a given set of constraints. The methods of complex eigenvalues and direct calculation of the frequency characteristics were used. Numerical examples of optimizing sandwich beams are presented for both design problems.Translated from Mekhanika Kompozitnykh Materialov, Vol. 29, No. 5, pp. 653–656, September–October, 1993.     

Investigation of the thermophysical properties of polypropylene

The temperature and pressure dependence of the thermophysical properties of isotactic polypropylene has been investigated. The experimental results are presented and discussed.Mekhanika Polimerov, Vol. 2, No. 5, pp. 793–797, 1966     

Analysis of the anisotropic properties of honeycomb sandwich plates

A mathematical model has been described and an approach proposed to the diagnostics of the anisotropic properties of the relative elasticity constants of three-layer (sandwich) plates with a honeycomb filler. Compact analytical relationships between the anisotropy coefficients and the geometrical dimensions of the cells have been obtained. A practical approach has been proposed for the selection of rational parameters of the honeycomb structure, at which its anisotropic properties would be in the chosen region of the functional space. The conditions have been formulated at which the constructive anisotropy, inherent to honeycomb structures, degenerates to isotropy for some relative elastic constants.Paper to be presented at the Ninth International Conference on the Mechanics of Composite Materials (Riga, October 1995).Translated from Mekhanika Kompozitnykh Materialov, Vol. 31, No. 4, pp. 482–487, July–August, 1995.     

Deformation properties and texture of isotactic polypropylene fibers

The deformation properties of isotactic polypropylene fibers are compared with the fraction of crystallites in thea and c textures and with their orientation.Institute of High-Molecular-Weight Compounds, Academy of Sciences of the USSR, Leningrad. Translated from Mekhanika Polimerov, No. 1, pp. 7–10, January–February, 1971.     

Elastic properties of honeycomb sandwich plates with nontraditional cell forms

A method for correcting the elastic properties of honeycomb sandwich plates by changing the cell shape is described. Compact and convenient analytical expressions (1) are proposed for calculating the reduced elastic parameters of the honeycomb sandwich plates. The acceptable range of changes in the size of the honeycombs is restricted by the cell elongation region [0.5;2] and the region of variation of the angle between cell walls [/6; 5/6]. The results of the calculation experiment showed that the traditional cell shape (=/3, =1) is not effective as an optimum structure (Table 1).Institute of Transport Systems and Technologies (Transmag), National Academy of Sciences of Ukraine, Dnepropetrovsk, Ukraine. Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 2, pp. 187–191, March–April, 1997.     

Electromechanical properties of laminated piezoelectric composites

The general expressions for the effective elastic, piezoelectric, and dielectric coefficients of a laminated piezocomposite composed of laminates in parallel connection are shown. By means of the asymptotic averaging method [12] these effective coefficients are calculated. The effective coefficients as well as physical properties such as electromechanical piezoelectric coupling coefficients, acoustic impedance, and wave velocity for a two-phase composite, where one phase is ceramic and the other one is polymer, are analyzed. A comparison with another results is shown.Presented at the Ninth International Conference on the Mechanics of Composite Materials, Riga, October, 1995.Published in Mekhanika Kompozitnykh Materialov, Vol. 32, No. 3, pp. 410–417, May–June, 1996.     

Experimental characterization of dynamic properties of honeycomb sandwich joints and plates

In lots of lightweight applications, constructions are also made by honeycomb sandwiches but little is known about failure and dynamic behavior of sandwich plate connections. In this research, an experimental and simulation study of the mechanical and failure behavior of honeycomb sandwich plates and joints are performed. In detail, series of tensile test have been conducted under quasi static conditions and failure behavior and resistance of the specimens are investigated. The specimens are made by phenolic resin-impregnated aramid paper as core and two different layers of glass fiber reinforced plastic as face sheets in each side. In addition to the experimental tests, numerical simulation with finite element models are performed in Abaqus. Failure modes are investigated and finally a good agreement between test data and simulation results is achieved. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Elastic-plastic sandwich beams with optimized properties for the impact case

An approach for the design of lightweight sandwich beams with optimal performance under low velocity impact loading is presented. Exemplary for beams with stainless steel faces and aluminium foam cores a procedure is proposed that bases on simulation results using an explicit finite element code. Experimental tests assure the accuracy of numerical analyses and provide data to fit the applied plastic compressible material model. By means of a multicriteria optimization method failure mechanisms are identified which dissipate a maximum of energy and lead to minimal deflections as well as to minimal beam thickness and weight at the same time. Face and core thicknesses are used as design variables. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Optimization of properties of multicomponent isotropic composites

We suggest a method for the calculation of the extremal conductivity of composites under some natural assumptions concerning their microstructure. The method is based on the principle of consecutive assembling of binary mixtures by addition of infinitely small amounts of one of the initial compounds to the already-assembled isotropic composite. This process is assumed to produce an optimal isotropic binary mixture at each step, which is performed by the Hashin-Shtrikman procedure. We are seeking a suitable sequence of compounds to be added to the mixture in order to minimize its resultant conductivity. A solution is given to the corresponding optimization problems for both finite number and infinite number of initial compounds taken in prescribed concentrations. We also describe the microstructure of the optimal composites. The results can be used for the optimal design of elastic and heat-conducting constructions.Dedicated to G. LeitmannThe authors have accepted with pleasure the invitation to participate in the JOTA special issue dedicated to Professor G. Leitmann. The papers by Professor Leitmann are well known in the USSR. They have greatly influenced the formation of the authors' scientific viewpoints. The first author has learned much from Professor Leitmann in the course of his work in translating two books by Professor Leitmann published in the USSR; the second author has also benefited from these translations. Methods of optimization, whose development has been influenced so much by Professor Leitmann's contributions, have penetrated into a number of fields. Here, we apply these methods to a problem in the mechanics of composite materials.