Iwona Adamiec-Wójcik

Vibration Analysis of Collecting Electrodes by means of the Hybrid Finite Element Method

The paper presents a hybrid finite element method of shell modeling in order to model collecting electrodes of electrostatic precipitators. The method uses the finite element method to reflect elastic features and the rigid finite element method in order to model mass features of the body. A model of dust removal systems of an electrostatic precipitator is presented. The system consists of two beams which are modeled by means of the rigid finite element method and a system of collecting shells modeled by means of the hybrid finite element method. The paper discusses both the procedure of deriving the equations of motion and the results of numerical simulations carried out in order to analyze vibrations of the whole system. Experimental verification of the model is also presented.

Artificial neural networks to control braking moments on wheels of an articulated vehicle

The paper presents an application of artificial neural networks to control braking moments on wheels of an articulated vehicle in a critical situation. The trajectory of the articulated vehicle was calculated for given braking moments by means of the 3D computational model. Dynamic optimization was performed in order to use appropriate values of braking moments for each wheel of the vehicle. Solutions of the optimization tasks for different inputs formed a set of optimal values. In the next step the set of optimal values was used for training an artificial neural network. Results of the calculations with the Nelder-Mead method and for the MLP and RBF neural networks are presented.

APPLICATION OF THE FINITE STRIP METHOD TO MODELING OF VIBRATIONS OF COLLECTING ELECTRODES

The paper presents an application of the finite strip method to modeling of vibrations of the collecting electrodes, which are shells with large length (up to 16 m), width of 0.5 m and thickness of 0.002 m. The models and computer programs have been worked out and validated. Comparison of results obtained from numerical simulations and experimental measurements are presented and discussed. The equations of motion have been solved using methods for solution of sparse algebraic equations and Newmark method. The strip method has proved to be numerically effective. The programs enable us to carry out calculations for a system with several hundred thousands of degrees of freedom with time of analysis requiring thousand integration steps during less than 90 min on a PC computer. High numerical efficiency enables the geometrical parameters of the collecting electrodes to be selected in order to ensure large accelerations caused by a beater to be spread evenly over the surface of the electrodes. Conclusions concerning the influence of length of the collecting electrodes on the normal and tangentz accelerations are formulated.

Distributed Neural Network Used in Control of Brake Torque Distribution

The paper presents implementation application of a feed-forward multi-layer neural network for a distributed system. A modified distributed topology with a changeable number of blocks is proposed. This enables us not to carry out parallel calculations on single processors. The distributed network is used to solve an optimization task in order to find such a distribution of braking torques applied to car wheels which assure a stable motion in difficult situation on a road. The model of the car, optimization task and results of calculations are presented. The use of distributed neural network considerably shortens the calculation time.

A New Approach to the Rigid Finite Element Method in Modeling Spatial Slender Systems

The static and dynamic analysis of slender systems, which in this paper comprise lines and flexible links of manipulators, requires large deformations to be taken into consideration. This paper presents a modification of the rigid finite element method which enables modeling of such systems to include bending, torsional and longitudinal flexibility. In the formulation used, the elements into which the link is divided have seven DOFs. These describe the position of a chosen point, the extension of the element, and its orientation by means of the Euler angles Z′Y′X′. Elements are connected by means of geometrical constraint equations. A compact algorithm for formulating and integrating the equations of motion is given. Models and programs are verified by comparing the results to those obtained by analytical solution and those from the finite element method. Finally, they are used to solve a benchmark problem encountered in nonlinear dynamic analysis of multibody systems.

Application of the Rigid Finite Element Method to Static Analysis of Lattice-Boom Cranes

Abstract In the paper a nonlinear model of a lattice-boom crane with lifting capacity up to 700mT for static analysis is presented. The rigid finite element method is used for discretisation of the lattice-boom and the mast. Flexibility of rope systems for vertical movement and for lifting a load is also taken into account. The computer programme developed enables forces and stress as well as displacements of the boom to be calculated. The model is validated by comparison of the authors’ own results with those obtained using professional ROBOT software. Good compatibility of results has been obtained.

Numerical Effectiveness of Different Formulations of the Rigid Finite Element Method

Abstract The paper presents an application of different formulations of the rigid finite element method (RFEM) to dynamic analysis of flexible beams. We discuss numerical effectiveness of the classical RFEM and an alternative approach in which continuity of displacements is preserved by means of constraint equations. The analysis is carried out for a benchmark problem of the spin-up motion in planar and spatial cases. Torsion is omitted for numerical simulations and two cases of the new approach are considered. The results obtained by means of these methods are compared with the results obtained using a nonlinear two-node superelement

Developing mathematical and computer models for car dynamics using joint co-ordinates and homogenous transformations

In modelling vehicle dynamics absolute coordinates are mostly used. This approach allows the equations of motion to be obtained by means of independent generalized coordinates which describe the motion of each body in the kinematic chain. Then the equations of motion are completed with constraint equations. The absolute coordinates are used for modelling multibody system dynamics in ADAMS and DADS packages.