Wyniki wyszukiwania - BazTech

1

Time integration of stochastic generalized equations of motion using SSFEM

Poński Mariusz

Journal of Theoretical and Applied Mechanics

|

2019

|

Vol. 57 nr 1

37--48

EN

The paper develops an integration approach to stochastic nonlinear partial differential equations (SPDE’s) with parameters to be random fields. The methodology is based upon assumption that random fields are from a special class of functions, and can be described as a product of two functions with dependent and independent random variables. Such an approach allows one to use Karhunen-Lo`eve expansion directly, and the modified stochastic spectral finite element method (SSFEM). It is assumed that a random field is stationary and Gaussian while the autocovariance function is known. A numerical example of onedimensional heat waves analysis is shown.

2

State-of-the-art time integration methods in the ADINA program

Walczak J.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

|

2017

|

z. 64, nr 2/I

239--246

EN

This paper presents state-of-the-art solution methods available in the ADINA program for dynamic, direct time integration analysis of time-dependent problems. For implicit direct dynamic solutions, a two-step Bathe method is presented. Advantages of the Bathe method over the widely used Newmark method are shown in small sample problems. Solutions of complex dynamic problems using the Bathe method will be presented at the Conference. For direct explicit dynamic solutions, the Noh-Bathe method is presented and compared with the central difference method and here again, advantages of the Noh-Bathe method are shown in small sample problems.

PL

W pracy zaprezentowano metody do bezpośredniego całkowania równań ruchu schematem niejawnym (metoda Bathe’go) i jawnym (metoda Noh-Bathe). W przypadku niejawnego schematu rozwiazywania równań ruchu, porównano rezultaty otrzymane metodami Bathe’go i Newmarka dla prostych przykładów uwypuklając przewagę metody Bathe’go. W przypadku jawnego schematu rozwiazywania równań ruchu, porównano wyniki otrzymane przy pomocy metody Noh- Bate i metody różnic centralnych. Wyniki rozwiązań dla kompleksowych konstrukcji będą przedstawione w czasie Konferencji.

3

An advanced aeroelastic model for horizontal axis wind turbines

Dumitrescu H., Dumitrache A., Cardos V., Frunzulica A.

International Journal of Applied Mechanics and Engineering

|

2009

|

Vol. 14, no 3

683-702

EN

In this paper, an advanced aeroelastic numerical tool for horizontal axis wind turbines (HAWT) is presented. The tool is created by coupling an unsteady aerodynamic model based on the lifting-line approximation with an elastodynamic model based on the beam approximation. The coupling is non-linear in the sense that at every time step the two models interact through data transfer from the one to the other. Two interfaces assure a constant communication between the two parts of the complete model. The aero-to-elastic interface defines the loads exercised on the structure, whereas the elastic-to-aero interface transmits the rates of deformations. The aeroelastic model is evaluated through comparisons of its predictions with experimental data as well as with predictions obtained by simpler models.

4

Moving inertial load and numerical modelling

Bajer C., Dyniewicz B.

Vibrations in Physical Systems

|

2008

|

Vol. 23

65--70

EN

The paper presents the numerical approach to the moving mass prob¬lem. We consider the string and beam discrete element carrying a mass particle. In the literature efficient computational methods can not be found. The same disadvantage can be observed in commercial codes for dynamic simulations. Classical finite element solution fails. The space-time finite element approach is the only method which now results in convergent solutions and can be successfully applied in practice. Characteristic matrices and resulting solution scheme are briefly described. Examples prove the efficiency of the approach.

5

Aeroelastic computation using the beddoes-leishman dynamic stall model

Dumitrescu H., Frunzulica F.

International Journal of Applied Mechanics and Engineering

|

2008

|

Vol. 13, no 1

63-73

EN

The application of the semi-empirical dynamic stall model by Beddoes and Leishman (B-L) on aeroelastic conditions is described. The approach is to couple the structural model to the nonlinear Beddoes-Leishman model and integrate through time. The nonlinear aerodynamic effects are included in the B-L model and thus, the behavior of the unstable system can be investigated after flutter has occurred, i.e., periodicity (limit cycle oscillations), chaos, etc., can be analyzed. The B-L time integration approach is applied to quickly decide test cases for the unsteady CFO computations, which are much more time consuming. Computations using a NavierStokes solver are compared to the present results.