Description of the mechanical behaviour of micropolar adhesives

The paper describes the mechanical behavior of two solids—the adherends—adhesively bonded by a thin elastic adhesive considered as a polar material when the parameter associated to the thinness of the adhesive goes to 0. The adherends are considered as elastic nonpolar materials. The limit analysis for a thin adhesive is performed using first an asymptotic expansion of the solution, based on a mixed variational formulation of the equilibrium of the three bodies. The first- and second-order solutions are such that the adhesive behaves as a material surface. The implication of the additional rotational degrees of freedom on the kinematics of the adhesive is then studied. In the second part of the paper, the convergence of the solution of the three-dimensional problem to the limit solution is obtained, using a variational formulation of the equilibrium of the three body system and an epi-convergence argument.     

Antifriction and mechanical properties of polymer compositions based on silicone adhesives

A comparative investigation has been made of the antifriction and mechanical properties of polymer compositions based on K-400 silicone adhesive and fillers in the form of finely dispersed powdered polymers (tetrafluoroethylene, Kapron, polyethylene), graphite, sawdust, B-83 babbitt, and a lubricant^–US-2 grease. The antifriction properties of these materials are not inferior to those of some common nonferrous metals (B-83 babbitt, TsAM9-1.5 zinc alloy, OTsS5-5-5 bronze). The rational range of application of the compositions investigated is indicated.Rostov-on-Don Institute of Railroad Transport Engineers. Translated from Mekhanika Polimerov, No. 5, pp. 937–940, September–October, 1969.     

Influence of nano-particle interactions on the mechanical behavior of colloidal structures in polymeric solutions

Colloidal structures inside solutions are usually considered as rigid bodies or linear springs. However, recent experimental results show a strongly nonlinear mechanical response of large clusters. In this contribution, the nonlinear elastic behavior of the colloidal structures inside polymeric solutions is studied. So far, the influences of initial length and fractal dimension on the elastic response of colloidal structures have mostly been considered by scaling theory. Here, we additionally take into account a deformation induced evolution of the aggregate structure which is mainly influenced by inter-particle interactions. To this end, central and lateral (non-central) inter-particle forces are considered separately. Next, the directional stiffness of the colloidal structure is evaluated by using the concept of a backbone chain. The backbone chain is a unique path between two ends of the colloidal structure that carries the main portion of load. The mechanical response of the backbone chain depends on aggregate geometry, deformation history and moreover, on the nature and the strength of the inter-particle interactions. The aggregate geometry is described by means of the angular averaging concept. The so-obtained model can further be generalized for all types of colloidal structures with central and lateral inter-particle forces. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Influence of the nearest-neighbor connections on shaping weighted evolving network

This paper proposes an extended local-world evolving network model consisting of global strength-driven preferential attachment for one central node, and local weight-driven preferential attachment for nearest neighbors of the central node. Analytical predictions and numerical simulations were executed for network evolutions and distributions. The obtained power-law behaviors display the same exponent functions as the ones in a classic model. More comparisons between these two models were made to investigate the structural differences that the nearest-neighbor connections result in. Compared with the counterpart, the proposed model shows a higher clustering coefficient, the varying average shortest path length and the significant hierarchical organization. our model is generally robustness and yet fragility, and is weaker in synchronizability than the counterpart. All those results are added to our understanding of how the rule of the nearest-neighbor connections affects the characteristics of weighted evolving network.     

Experimental investigations on the mechanical behavior of filled rubber

A lot of experimental results on the elastic as well as on the inelastic behavior of elastomer materials are known. However, so far now systematic examination on defined rubber mixtures has been reported. In this presentation the phenomenology of elastomer materials is characterized on the basis of extension and compression tests performed with dumbbell– and S2–specimen. Stiffness, upturn (stiffness at final deformation), hysteresis and remaining deformation have been analyzed for well defined rubber systems and environmental conditions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Simulation of ice under mechanical and thermal load

The contact physics of the wheel-rail contact of a railway vehicle under presence of water and ice at low temperatures is still not completely understood. For the investigation of the particular process in the contact zone a simulation is required, which is able to calculate the normal and tangential contact, the temperature field and the fluid-structural interaction between wheel and rail at low temperatures under presence of snow and ice. For that purpose the behaviour of ice under wheel-rail contact conditions is an important part. In this paper the thermal dynamic model of TSHIJOV [1], [3] for an adiabatic ice probe is updated by the new IAPWS equations of state for water [5] and ice phase Ih [4]. In a first approximation an ice specimen is loaded by specific wheel-rail contact pressure distributions calculated by the half-space formulation to clarify if phase transitions of ice can exist. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Effect of electron irradiation on the mechanical and thermal properties of some polymer materials

The effect of electron irradiation on the mechanical properties (deformability) of polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), polyimide (PI), and Fenilon (Fe) films, as well as the thermal properties (heat conductivity and capacity) of PTFE is studied experimentally. The thickness of the films was 40–50 m. Mechanical tests showed that polyimide films were more resistant to radiation than the other films. The investigation of the changes in the thermal properties of PTFE due to electron irradiation revealed that the phase transitions observed at temperatures of 293 and 303 K in unirradiated PTFE were shifted to lower temperature regions.Abai Alma-Ata State University, Kazakhstan. Translated from Mekhanika Kompozitnykh Materialov, Vol. 34, No. 5, pp. 683–689, 1998.     

Finite deformation model for the mechanical behavior of left ventricular wall muscles

The present method of analysis is based on the pressure-volume (p-V) relation of the left ventricle obtained experimentally, differing from the methods with the use of the small specimen dissected from the ventricle. The deformation of the left ventricle is both physically and geometrically nonlinear. The wall thickness is so large that the states of the deformation at endocardial and epicardial surfaces are considerably different. The model considered here is a homogeneous and incompressible thickwall sphere in which the requirements just stated are taken into account. The Valanis-Landel model, which is relatively accurate for the deformation of left ventricles at diastole in comparison with the Laplace, Lamé and Rivlin-Saunders models as discussed by Moriarty (1980), is examined with its validity by using the present model. The advantage of the use of the Valanis-Landel model is that the stress-strain relation and the function W are expressed by simple formulas, but the p-V relationship is considerably complicated compared with that of the present model. The present model can be extended to describe the deformation of the systolic left ventricle when the pressure-time (p-t) relationship is measured at different left ventricular volumes of isovolumic beat. The p-t relation is replaced by the p-V relation for each time t. The model at systole is constructed by regarding the stress due to contraction of the cardiac muscle as an eigen stress.     

On the structure of cross connections and Galois connections

Journal of Applied Mathematics and Computing - We consider partially ordered set as passing from the set of ideals to the set of filters in Cartesian product of partially ordered sets. Lawson...     

Influence of structure on the mechanical properties of block copolymers

The variation of the strength characteristics of three-block butadiene-styrene copolymers with the characteristic viscosity has been investigated for polymers of fixed styrene content, as has its variation with the styrene and butadiene content. Measurements were made in the temperature range 20–60°C, at rates of elongation of 5, 50, 250, 500, and 1000 mm/min. It was shown that the relationship between the breaking strength of the block-copolymers and the rate of elongation is analogous to that found for rubber vulcanizates, but has specific features determined by their structure. Values are tabulated for the parameters A and n in the equation giving the relationship between the strength and the rate of elongation under isothermal conditions.     

Influence of structure on the mechanical properties of block copolymers

The relationship between the breaking strength and the temperature has been studied for butadiene/styrene block copolymers of the three-block configuration styrene-butadiene-styrene. The studies were carried out over the temperature range –20 to 60° at crosshead speeds of 5, 50, 250, 500, and 1000 mm/min. An analysis was carried out on the values of the parameter U in the equation linking the breaking strength with the temperature.For Communication 2 see [3].Voronezh Technological Institute. Translated from Mekhanika Polimerov, No. 3, pp. 392–398, May–June, 1974.     

Effect of the morphology of the organic fibers on the mechanical behavior of composites

Scanning electron microscopy and x-ray diffraction analysis are used to study the morphology of several aramid and polyimide fibers developed in Russia and to determine their strain-strength characteristics. It is shown that the supermolecular structure of the fiber in large part determines the character of its interaction with the matrix and behavior during failure of the fiber composite (FCP). In the case of aramid fibers, composite failure is accompanied by intensive fibrillation leading to lamination on a microscopic scale and a deterioration in the service characteristics of the composite. The stability of the investigated polyimide fibers against fibrillation and microlamination, in combination with good heat resistance, makes them promising as reinforcing materials for FCPs.Submitted for the Tenth International Conference on the Mechanics of Composites (Riga, April 1998).Institute of High-Molecular-Weight Compounds of the Russian Academy of Sciences (St. Petersburg, Russia) and the Khimvolokno Scientific-Industrial Association (Mytishchi, Russia). Translated from Mekhanika Kompozitnykh Materialov, Vol. 33, No. 5, 656–669, September–October, 1997.