Vol 9, No 3-4 (2015)

Optimal structural design of compressor stage of aviation engine is considered. Structural optimization takes into account the blade shape and disk design. Minimization of mismatching between the blade shape in operating position and predefined aerodynamic blade shape and natural frequency detuning problem are discussed. Disk and joint weight minimization under certain constraints is investigated. Optimization criteria, constraints, parameterization and design models, design parameters are discussed. All results were obtained using finite element analysis program connected with the sequential quadratic programming (SQP) optimization procedure.

Investigation of double-circuit geared turbofan engine (GTF) transmission dynamics for flight cycle loads was carried out. Flight cycle loads taking into account overloads at evolutions. Comparative analysis for response of engine models without load reduction device and with load reduction device fracture on fan blade fracture is performed. As basic GTF assembly the assembly presented in most of opensources is taken. For investigation the beam and solid models were developed. Both models contain of fan rotor, gear and low pressure rotor. Special finite element are used in beam model for simulation of stiffness characteristics of complex geometry rotor elements. Stiffness characteristics of beam model are verified with assistance of solid model.

Secondary air system model based on graph theory and one dimentional hydraulic models is discussed. Channel inclination to major axis of integration is taking into account. New hydraulic channel model for smooth transition between “horizontal” and “vertical” flow passages is proposed. Commercial software for 2D and 3D flow modeling were used for one dimentional models verification.

Mathematical model of long journal bearing with incompressible oil flow in field of centrifugal inertia forces acting in lubrication layer of planet wheel journal bearing is developed. Modification of Reynolds equation based on Navier-Stokes equations is received, taking into account centrifugal forces’ impact on fluid film in oil gap of journal bearing. Model was verified by commercial software, which uses full Navier-Stokes equations. Results of verification shows considerable contribution of centrifugal inertia forces on total pressure distribution in journal bearing, carrying force and attitude angle.

The results of using the finite element method to calculate the dynamic stresses in gears are presented. The numerical simulation of meshing gears of different types is obtained a detailed breakdown of contact and bending stresses, rigidity of the mesh stiffness function depending for engagement phase, static and dynamic transmission errors. The behavior of the transmission having defects, namely, incipient cracks at the tooth root is analyzed. The results can be used to develop diagnostic signs transmissions to ensure responsible operation of technical articles.

It was proposed methodology of determining parameters of model of nonisothermal cyclic stress-strain curve. Algorithm of pattern recognition was implemented. It was based on minimization of function of mismatch between experimental results and calculation of three-parameter model curve which depends on Bauchinger’s effect, elastic unloading modulus and scale of transformation of nonlinear part of stress-strain curve. Odkvist’s parameter was used for measure of plastic deformation. Simulation of cyclic stress strain curve was carried out. Results of simulation were compared with experimental data.

Algorithms of solution of big sparse systems of linear algebraic equations based on Cholesky technique is released in program complex of analysis of stress-strain condition under cyclic elastoplastic loading by finite element method. Comparison of memory and computational resource efficiency of algorithms is carried out.