International Journal of Materials and Structural Integrity (6 papers in press)

Regular Issues

• Experimental investigation of surface-mounted optical fibre strain sensor using neural network analysis  
  by Ashwarya Sheel Wali, Amit Tyagi 
  Abstract: This study aimed to develop a smart neural network preceptron model for strain prediction using fibre optic sensors signals. Optical parameters corresponding to surface mounted optical fibre are obtained experimentally under static loading conditions. Four variations are used by creating external damage to study strain variations on healthy, single damage and multiple damage beam structures. The strain values are obtained by using phase difference and change in intensities data as input for feed-forward back propagation neural network model. A comparative study of pre-existing analytical solution, conventional strain gauge measurement, and finite element analysis is performed. The neural network model provides more accurate correlation results with strain gauge and FEA analysis compared to analytical analysis.
  Keywords: optical parameters; neural network; finite element analysis; strain.
  
  
• Experimental methods of investigation of contact-fatigue strength of wheel-rail system materials considering the action of electric current  
  by Leonid Novogrudskiy, Valeryi Kharchenko, Yuriy Skrypnyk, Mykola Opravkhata 
  Abstract: The paper illustrates the results of investigations into the influence of electric current pulses on the mechanical properties of rail steel in the initial rail state and after its operation within the electrified railway zone. It is shown that the degree and nature of the variation of strength and plasticity characteristics of M76 rail steel due to the action of the electric current pulses depends on the test temperature, the level of steel operating time, and the operating time of the surfaces of contact rail-wheel interaction. The action of the electric current pulses induces the variation in the stress-strain state of the material in the cross-section of the railhead within the rail-wheel zone. The test facilities developed at the G.S. Pisarenko Institute for Problems of Strength of the NAS of Ukraine are presented. These test facilities are applied for the investigations of contact wheel-rail interaction development considering both differential and integral actions of such operational factors as cyclic loading, rolling and sliding friction, ambient temperatures, electric current, and corrosion (stress and electric) with force parameters in the contact zone, which are consistent with the actual ones in railway transport operation.
  Keywords: wheel-rail contact interaction; mechanical characteristics; operating time; electric current pulse; hardness; temperature; test facilities.
  
  
• Influence of shape of nano-Al2O3 in epoxy adhesive on the critical energy release rate of tapered double cantilever beam steel joints  
  by Sunil Kumar Gupta 
  Abstract: The critical energy release rate (GIC) in mode I of epoxy adhesive reinforced with alumina nanoparticles was determined using tapered double cantilever beam joints. Steel was used as adherend material. Spherical and cylindrical (rod) shapes of nano-Al2O3 were reinforced in adhesive by 0.5, 1.0, 1.5, and 2.0 wt.%. A significant improvement in the GIC of adhesive was obtained at 1.5 wt.% of spherical nano-Al2O3 and 1.0 wt.% of rod nano-Al2O3 over the neat epoxy adhesive. Reinforcement of rod shape of alumina nanoparticles offered a slightly better critical energy release rate of steel joints than the spherical shape of nanoparticles. The mechanisms for improvement in the GIC of adhesive containing spherical and rod alumina nanoparticles are discussed.
  Keywords: epoxy adhesive; critical energy release rate; tapered double cantilever beam; alumina nanoparticles.
  
  
• New cast iron MONICA loses its brittleness with increasing strength  
  by Leonid Sosnovskiy, Sergei Sherbakov 
  Abstract: Modern high-strength cast irons with spherical graphite have strength comparable with that of alloyed steel. However, the replacement of steel by cast iron when manufacturing critical duty products is restrained by the brittleness of cast iron: the higher is strength, the lower is plasticity. Now it is possible to overcome this law: a new material (cast iron) MONICA named after its alloying additives molybdenum (Mo), nickel (Ni) and copper (Cu) was created, which on the contrast loses its brittleness with increasing strength. A new (unexpected) regularity has been established: with the increase in strength of MONICA, its plasticity also increases. This was also confirmed by the results of tests on fracture toughness, rolling and mechanical fatigue. Specific mechanical and service properties of MONICA were analySed in comparison with traditional steels and known high-strength cast irons with spherical graphite (ADI). These properties were confirmed by operational tests of high-loaded full-scale parts: knives of cutting devices of high-performance forage harvesters, heavy railway rails, large gear wheels.
  Keywords: HHgh-strength cast iron; tribo-fatigue; knife; rail; gear wheel; mechanothermodynamics.
  
  
• Mechanical analysis of thick material layers manufactured additively on cylindrical substrates  
  by Dmitry Parshin 
  Abstract: Additive technological processes of layer-by-layer manufacturing viscoelastic ageing material layers of arbitrary thickness on the inner or outer surface of an axisymmetric cylindrical substrate by means of deposition of material plies are investigated. The added plies can undergo preliminary tension/compression in the circumferential direction. The substrate compliance is not taken into account. In course of manufacturing the substrate is rotating around its axis with the variable angular velocity. A quasistatic mechanical model describing the deformation of the formed material layer under the action of centrifugal forces in assumption of small strains is proposed. The model is based on general approaches of mathematical theory of accreted solids. The closed analytical solution of the corresponding nonclassical boundary problem is obtained. By means of this solution the evolvement of the technological stresses in the formed layer during and after the process of its additive manufacturing is reconstructed in quadratures.
  Keywords: mechanical analysis; materials; structural integrity; thick layer; material layer; additive manufacturing; AM; layer-by-layer formation; growth; accretion; material deposition; substance inflow; growth surface; accretion surface; growing solid; accreted solid; cylindrical substrate; cylindrical mould; rotation; centrifugal forces; additional material; additional ply; initial stress; preload; prestressed material; technological stress; residual stress.
  
  
• Comparative study of mechanical and microstructural properties single- and double-sided FSW friction stir welded aluminium alloy AA6062  
  by Vijay Kumar Dwivedi, Dipak Kumar 
  Abstract: The aim of the present examination was to find the strength of friction stir (FS) welds done using two sets of tool rotation speeds and welding speeds, and also to compare between single- and double-sided FS welding process for mechanical strength. Friction stir welding (FSW) is used for welding plates. Afterwards, single and double pass processes were applied to know comparative behaviour and effect of pass on mechanical strength. Furthermore, Scanning Electron Microscopy (SEM) and Optical microscopy (OM) were carried out to characterise the microstructure. The optimised values of mechanical strength as UTS i.e., 339.23 N/mm
  Keywords: friction stir welding; aluminium alloy 6062; microstructure; mechanical strength.