Distortion in the similitude of soil-machine systems

This paper contains an appraisal of the current knowledge concerning sources of distortion in similitude studies and techniques used to deal with it. The general philosophy and basic principles that relate the concepts of similitude and studies of soil-machine systems have been discussed in detail in the paper, Similitude Studies of Soil-Machine Systems by Freitag et al. Some of that material is repeated to help define the condition referred to as distortion and to establish the effects of distorted models in the application of similitude to the analysis of soil-machine systems.     

Prediction of vibration characteristics of blisks using similitude models

This study investigates the determination approach of distorted scaling laws for predicting the dynamic characteristic of an aero engine’s blisk. Based on the dynamic scaling laws of typical thin-walled structures, an assumption of geometrically complete scaling laws is firstly proposed and numerically validated. For distorted models of disk thickness, in order to simplify the design procedure, a simplification condition is proposed and applied to the first 10 orders’ distorted scaling laws (blade-dominated vibrations) by combining sensitivity analysis. Next, the 11th–14th orders’ distorted scaling laws are determined for disk-dominated vibrations. Numerical validation demonstrates that distorted scaling laws possess a good accuracy. Finally, the applicability of these new scaling laws is validated by the experimental data. The results indicate that, by using the new scaling laws, the simple models can predict vibration characteristics of blisk by employing similitude models.     

On the applicability of some approximate similitude laws in hypersonic aerodynamics

The range of applicability of some similitude laws for heat transfer, friction and drag coefficients is discussed on the basis of numerical solutions of the complete viscous shock layer equations describing hypersonic flow past blunt bodies. Moscow. Translated from Izvestiya Rossiiskoi Akademii Nauk, Mekhanika Zhidkosti i Gaza, No.2, pp. 121–130, March–April, 1994.     

Application of conservation laws to Dirichlet problem for elliptic quasilinear systems

In the present work we show the possibility of using of conservation laws to solve the Dirichlet problem for elliptic quasilinear systems. As a result the integral representation of solution is obtained. For the system of filtration of aerated fluid in porous medium and for system of elastic–plastic torsion of prismatic rods corresponding conservation laws are calculated in explicit form and the Dirichlet problems are solved.     

Application of a fourth-order relaxation scheme to hyperbolic systems of conservation laws

A fourth-order relaxation scheme is derived and applied to hyperbolic systems of conservation laws in one and two space dimensions. The scheme is based on a fourth-order central weighted essentially nonoscillatory (CWENO) reconstruction for one-dimensional cases, which is generalized to two-dimensional cases by the dimension-by-dimension approach. The large stability domain Runge-Kutta-type solver ROCK4 is used for time integration. The resulting method requires neither the use of Riemann solvers nor the computation of Jacobians and therefore it enjoys the main advantage of the relaxation schemes. The high accuracy and high-resolution properties of the present method are demonstrated in one- and two-dimensional numerical experiments. The project supported by the National Natural Science Foundation of China (60134010) The English text was polished by Yunming Chen.     

Structural response of stiffened plates in similitude under a turbulent boundary layer excitation

In structural dynamics, similitude laws usually deal with simple configurations as thin flat plates with point forces. Only recently, few papers have analyzed stiffened shells or stochastic pressure loads.This research activity extends the applicability of some similitude laws, developed for thin flat plates under a turbulent boundary layer load, to ribbed plates forced by the same wall pressure fluctuations.The work addresses the problem of designing a scaled experimental test-article and, successively, of re-modulating the measured data in order to get the structural response of an original (unscaled) configuration.Due to the complexity of the structural domain, the design of a scaled configuration leads to a distorted similitude. Then, a simple approach, to circumvent the distortion effects, is proposed.     

Application of modal analysis methods to the design of wireless power transfer systems

Meccanica - Wireless recharge of electric vehicles is an important field of research. Design of inductive power transfer systems involves the optimization of resonant coils coupled through mutually...     

Application of an augmented Lagrangian approach to multibody systems with equality motion constraints

Nonlinear Dynamics - The focus of this work is on dynamics of multibody systems subject to bilateral motion constraints. First, a new set of equations of motion is employed, expressed as a coupled...     

Experimental and simulation studies on similitude design method for shock responses of beam-plate coupled structure

The similitude theory helps to understand the physical behaviors of large structures through scaled models. Several papers have studied the similitude of shock issues. However, the dynamic similitude for shock responses of coupled structures is rarely incorporated in open studies. In this paper, scaling laws are derived for the shock responses and spectra of coupled structures. In the presented scaling laws, the geometric distortion and energy loss are considered. The ability of the proposed sca...     

Application of local co-ordinate systems to the solution of integral equations referred to plane fluid flow problems

Two-dimensional fluid flow problems expressed in terms of velocity potentials or stream functions are often summarized as boundary-value problems for the Laplace or Poisson equations, or the homogeneous or non-homogeneous biharmonic equations. Simple local co-ordinate systems have been applied to the solution of integral equations associated with these boundary-value problems. This procedure has been shown to be an efficient technique in the numerical solution of fluid flow problems.     

Integration of topological modification within the modeling of multi-physics systems: Application to a Pogo-stick

The present work tackles the modeling of multi-physics systems applying a topological approach while proceeding with a new methodology using a topological modification to the structure of systems. Then the comparison with the Magos' methodology is made. Their common ground is the use of connectivity within systems. The comparison and analysis of the different types of modeling show the importance of the topological methodology through the integration of the topological modification to the topological structure of a multi-physics system. In order to validate this methodology, the case of Pogo-stick is studied. The first step consists in generating a topological graph of the system. Then the connectivity step takes into account the contact with the ground. During the last step of this research; the MGS language (Modeling of General System) is used to model the system through equations. Finally, the results are compared to those obtained by MODELICA. Therefore, this proposed methodology may be generalized to model multi-physics systems that can be considered as a set of local elements.