Applied Mechanics and Materials Vol. 245

Abstract: The current mechanical engineering applications require the use of increasingly larger share precision reducers and special mechatronics units with a high degree of integration. High precision gearboxes is used for such applications with low backlash and high torsional stiffness (harmonic, cycloidal or planetary). Bearing reducers (cycloidal gear) meet the requirements of small built-in space in the implementation a high-precision change of transfers. Bearing reducers TwinSpin from company Spinea accurately fulfil all of these conflicting requirements.

Abstract: The author of the present paper proposes a constructive version, selected on the grounds of dynamic and organological equations, which enables an optimum design and operation of the (MO Sil) orientation module that possesses two degrees of freedom, to which the prehension device is attached, in the mechanical structure of the TRR-type serial modular industrial robot. This paper aims at highlighting the dynamic modelling of the mechanical structure of the TRR-type robot by using Lagrangian formalism, with aspects regarding the MO Sil module’s organological construction as well as with the 3D modelling of the orientation module in the mechanical structure of the robotic arm. Another important issue that this paper deals with is the mathematical-organological algorithm used for the selection of the servomotors actuating the orientation movable system in the mechanical structure of the robot.

Abstract: A framework methodology for multidisciplinary multiobjective optimization and analysis is proposed. It is based on analytical aerothermodynamics and mass-modeling parameters of highly-integrated forebody-inlet configuration and representative hypersonic flight vehicle respectively. A complex configuration for a highly-integrated waverider forebody attached to planar compression ramps and planar sidewalled-inlet system is studied. Optimization and analytical solutions are obtained using SHWAMIDOF-FI design tool. Results show substantial improvement in geometric, performance and flow parameters as compared to baseline configuration.

Abstract: The article deals with a possible way how to monitor and evaluate warranty date. Tools that allow the current development of warranty costs and related indicators to be monitored and evaluated are outlined in the article. The tools proposed are applicable to the continuous (periodical) evaluation of real development and the detection of possible deviations, which can occur when comparing real and predicted development warranty data.

Abstract: Complex mechatronic systems sometimes do work in difficult and adverse environment. Such environment may affect the system’s performance and also dependability characteristics. Since we use complex systems with one shot items we need to know basic characteristics of such a system. The paper deals with advanced mathematical methods used for field data assessment in order to prove presumed impact of mission profile and system real operation profile onto system reliability. Thank to the collected data set it is assumed that operation of the system is actually a kind of time series. The paper presents identification of the time series model, its parameters´ estimation and prediction of system characteristics – like reliability/survivability function of the system for instance. Since the model of the time series has not been known, correlations with other system can be further determined and mission duration estimated. This estimation helps to organize support and operation of the system.

Abstract: Heavy rainfall greatly affects the aerodynamic performance of the aircraft. There are many accidents of aircraft caused by aerodynamic efficiency degradation due to heavy rain. In this paper we have studied the heavy rain effects on the aerodynamic efficiency of NACA 64210 and NACA 0012 airfoils with cruise and landing configuration. For our analysis, CFD method and preprocessing grid generator are used as our main analytical tools, and the simulation of rain is accomplished via two phase flow approach named as Discrete Phase Model (DPM). Raindrops are assumed to be non-interacting, non-deforming, non evaporating and non spinning spheres. Both cruise and landing configurations of airfoils exhibited significant reduction in lift and increase in drag for a given lift condition in simulated rain. Our results are in good agreement with the experimental results. It is expected that the quantitative information gained in this paper will be useful to the operational airline industry and greater effort such as small scale and full scale flight tests should put in this direction to further improve aviation safety.

Abstract: Aeroelasticity is one of the important fields in design of an aircraft or a flying vehicle. It deals with the interaction of aerodynamic, inertial and structural forces. The interaction between these different forces leads to certain aeroelastic phenomena such as divergence, flutter and limit cycle oscillation. Linear aeroelastic analyses of high aspect ratio wings act as basis for nonlinear analysis. Because of large wing deformation nonlinear analyses has to be performed for correct modeling. X-HALE UAV is a test bed exhibiting large structural deformation. Equipped with strain gauges and other measuring sensors, it will provide experimental data which can then be used for nonlinear aeroelastic analyses for other such kind of structures. This papers deals with the linear aeroelastic analysis of this type of aircraft.

Abstract: Electrical Load simulator (ELS) is an important aerodynamics forces/torque loading device which is used for qualification of flight actuation system in ground based experiments. This paper focuses on Backstepping control design with fuzzy logic compensator for extra torque disturbance. To reduce number of fuzzy rules and processing time LuGre model based friction compensation scheme is proposed. Practically fuzzy logic compensation may induce approximation error. A novel PI type tracking performance controller is proposed to compensate tracking error due to parametric uncertainty in the ELS system and LuGre friction model. The tracking performance controller is tuned online based on saturation function based adaptive law derived from the error dynamics between state predictor and actual plant to eliminate chattering from control signal. The validity of control scheme is verified using numerical simulations for desired tracking performance.

Abstract: The characteristics of composite materials are of high importance to engineering applications; therefore the increasing use as a substitute for conventional materials, especially in the field of aircraft and space industries. It is a known fact that researchers use finite element programs for the design and analysis of composite structures, use of symmetrical conditions especially in complicated structures, in the modeling and analysis phase of the design, to reduce processing time, memory size required, and simplifying complicated calculations, as well as considering the response of composite structures to different loading conditions to be identical to that of metallic structures. Finite element methods are a popular method used to analyze composite laminate structures. The design of laminated composite structures includes phases that do not exist in the design of traditional metallic structures, for instance, the choice of possible material combinations is huge and the mechanical properties of a composite structure, which are anisotropic by nature, are created in the design phase with the choice of the appropriate fiber orientations and stacking sequence. The use of finite element programs (conventional analysis usually applied in the case of orthotropic materials) to analysis composite structures especially those manufactured using angle ply laminate techniques or a combination of cross and angle ply techniques, as well considering the loading response of the composite structure to be identical to that of structures made of traditional materials, has made the use of, and the results obtained by using such analysis techniques and conditions questionable. Hence, the main objective of this paper is to highlight and present the results obtained when analyzing and modeling symmetrical conditions as applied to commercial materials and that applied to composite laminates. A comparison case study is carried out using cross-ply and angle-ply laminates which concluded that, if the composition of laminate structure is pure cross-ply, the FEA is well suited for predicting the mechanical response of composite structure using principle of symmetry condition. On the other hand that is not the case for angle-ply or mixed-ply laminate structure.

Abstract: Inertial navigation systems exhibit position errors that tend to grow with time in an unbounded mode. This degradation is due, in part, to errors in the initialization of the inertial measurement unit and inertial sensor imperfections such as accelerometer biases and gyroscope drifts. Mitigation to this growth and bounding the errors is to update the inertial navigation system periodically with external position (and/or velocity, attitude) fixes. The synergistic effect is obtained through external measurements updating the inertial navigation system using Kalman filter algorithm. It is a natural requirement that the inertial data and data from the external aids be combined in an optimal and efficient manner. In this paper an efficient method for integration of Strapdown Inertia Navigation System (SINS), Global Positioning System (GPS) and Doppler radar is presented using a centralized linear Kalman filter by treating vector measurements with uncorrelated errors as scalars. Two main advantages have been obtained with this improved scheme. First is the reduced computation time as the number of arithmetic computation required for processing a vector as successive scalar measurements is significantly less than the corresponding number of operations for vector measurement processing. Second advantage is the improved numerical accuracy as avoiding matrix inversion in the implementation of covariance equations improves the robustness of the covariance computations against round off errors.