Neutron diffraction and magnetocaloric effect studies of MnFe 1-x Co x P series of solid solutions

International audienceMnFe 1-x Co x P intermetallic series of solid solutions (0.4<x<0.6) have been studied by means of powder neutron diffraction in 10−320 K temperature range. Rietveld analysis pointed out that Co 2 P-type orthorhombic crystal structure (SG: Pnma) presents for all series. Helicoidal incommensurate antiferromagnetic structure with propagation vector q = [0, 0, q] were evidenced for all compounds at low temperature range. The q value decreases with cobalt content and the second order polynomial q(x) it was evidenced, that is found well correlated with this dependence. Magnetic moments values of µ Mn =3.34 µ B and µ (Fe,Co) =0.06 µ B were determined from neutron diffraction refinements for x=0.4 at 10 K. In addition, magnetic interactions in relations with electronic band structure calculations of MnFe 1-x Co x P were presented and discussed reference to previous published data. Finally, magnetocaloric properties for selected compounds of the MnFe 1-x Co x P and MnFe 0.45 Co 0.45 P 0.9 Ge 0.1 series of compounds are presented

Methods of modern aircraft aeroelastic analyses in the institute of aviation

The aeroelastic phenomena analysis methods used in the Institute of Aviation for aircraft, excluding helicopters, are presented in the article. In industrial practice, a typical approach to those analyses is a linear approach and flutter computation in the frequency domain based on normal modes, including rigid body modes and control system modes. They are determined by means of the finite element method (FEM) model of structure or a result of ground vibration test (GVT). In the GVT case, relatively great vibration amplitudes are applied for a good examination of a not truly linear structure. Instead or apart from the measure of generalized masses, a very theoretical model is used for mode shapes cross orthogonality inspection and improvement. The computed or measured normal mode sets are the basis for flutter analysis by means of several tools and methods, like MSC.Nastran and ZONA commercial software as well as our own low-cost software named JG2 for the flutter analysis of low speed aeroplanes and for a preliminary analyses of other aircraft. The differences between the methods lie in determining normal mode set, unsteady aerodynamic model, flutter equation formulation, time of analysis, costs, etc. Examples with results comparison obtained by means of distinguished methods are presented. Some works in the field of aeroelastic analysis with nonlinear unsteady aerodynamic in the time domain using Tau-code and ANSYS Fluent software were also performed. Aeroelastic properties of deformed structures, like a sailplane with deflected wings, can be also analysed. The simplest way of this analysis is the semi-linear approach in which the deflections modify the aircraft geometry for normal modes determination

A review of the method of calculation analysis of flutter bassed on the I-23 aircraft

Praca zawiera porównanie wykonywanych różnymi metodami, obliczeniowych analiz flatteru czteromiejscowego tłokowego samolotu kompozytowego I-23 w pierwotnej konfiguracji, dla której wykonano badania rezonansowe. Podstawą dopuszczenia samolotu PZL I-23 do badań w locie były obliczenia flatteru wykonane na podstawie wyników pomiarów rezonansowych przeprowadzonych jesienią 1998 r. Niemal dziesięć lat później samolot I-23 został wybrany przez uczestników europejskiego projektu CESAR 2.5 jako jeden z obiektów odniesienia służących do porównania różnych metod obliczeń aeroelastycznych. Celem projektu CESAR było opracowanie efektywnych metod analiz i badań do projektowania, rozwoju i certyfikacji samolotów lekkich. Dane oraz wyniki badań i obliczeń aeroelastycznych samolotu I-23 zostały udostępnione krajowym i zagranicznym partnerom, którzy na tej podstawie wykonywali własne analizy różnymi metodami. Stało się to okazją do podsumowania udziału Instytutu w zadaniu 2.5 projektu CESAR oraz przedstawienia wykorzystywanych metod, ich porównań i wniosków.The flutter calculation results of the origin version (as during GVT) of the PZL I-23 four-seat, piston composite aircraft are presented. The flutter computations were made by several methods, for comparison. Before flight flutter tests the flutter calculation based on GVT results was made (1998). In 2008 the I-23 aircraft was selected in the CESAR European project, Task 2.5. as a demonstrator for comparison of several methods of computational aeroelastic simulation. The goal of CESAR project was a cost effective analysis methods of the small aircraft for design, development and certification. The data and results of GVT and flutter calculations were done for CESAR partners. Based on these, they made their own analysis using several methods. It was an occasion to make a summary of the participation of the Institute of Aviation in the CESAR, Task 2.5, presentation of used methods, comparison of results and conclusions

MSC NASTRAN, ZONA ZAERO and ANSYS/Fluent flutter computation of rectangular wing with control surface - comparison with wind tunnel flutter tests results

Do oceny właściwości aeroelastycznych obiektów latających powszechnie wykorzystywane są analizy obliczeniowe w dziedzinie częstości. W niniejszej pracy do sprawdzenia wiarygodności takich obliczeń wykorzystano wyniki badań prostego obiektu (skrzydła ze sterem) przeprowadzonych przed kilku laty w tunelu Instytutu Lotnictwa. W tym celu zbudowano model obliczeniowy badanego obiektu w systemie MSC Nastran. Spośród wielu wyników, do obecnych porównań wybrano najciekawszą konfigurację, dla której w tunelu występował flatter przy prędkości 17,7 m/s, natomiast w obliczeniach w systemie MSC Nastran flatteru nie wykryto. Dla tych danych za pomocą MSC Nastran wykonano metodą PK obliczenia flatteru z wykorzystaniem modeli aerodynamicznych Doublet Lattice i pasowego. Obliczenia flatteru wykonano także za pomocą dwu wersji programu ZAERO firmy ZONA: z marca 2005 r. i z sierpnia 2011 r. We wszystkich przypadkach, do uzyskania w obliczeniach zmierzonej prędkości krytycznej flatteru była konieczna korekta modelu aerodynamicznego. Zastosowano korektę sił aerodynamicznych za pomocą współczynników WTFACT oraz poprzez zmianę zadanego do obliczeń podziału skrzydło/ster. Ten drugi sposób okazał się bardziej skuteczny. Do uzyskania zgodności wyników obliczeń z eksperymentem najmniejszej korekty wymagało zastosowanie nowego programu ZAERO, nieco większej – MSC Nastranu a największej – starszej wersji programu ZAERO. Dla porównania podano także wyniki analiz flatteru tego samego obiektu i tej samej jego reprezentacji modalnej, wykonane w dziedzinie czasu za pomocą systemu ANSYS/Fluent.A computational analysis in time domain are commonly used for the aeroelastic properties evaluation. In this paper, the credibility of this analysis is proven, based on wind tunnel flutter tests of a simple object – a wing with control surface - provided a few years ago. For this purpose the MSC Nastran computational model was prepared. In order to make the comparison and to obtain a more detailed analysis in time domain, the most interesting test object configuration was selected. For this configuration, on one hand, in the wind tunnel flutter occurs at 17,7 m/s, but on the other hand, by the MSC Nastran typical aerodynamic flutter computation no flutter was detected. For this model the flutter computation using MSC Nastran with PK method and Doublet Lattice a well as strip aerodynamic models, and two versions: March 2005 and August 2011 of the ZAERO software of ZONA Technologies, Inc. were provided. In each case, an aerodynamic model correction for the consistency with test results was necessary. The correction by WTFACT factors or by, for computation done, wing/control surface dividing line change was used. The second idea turned out to be more effective. In order to get good consistency, the new ZAERO software needs the smallest correction of dividing line localization, MSC Nastran needs a middle correction and the old ZAERO software needs the greatest correction. However, in the case of using in MSC Nastran the strip aerodynamic theory, the good consistency appeared. For comparison, there are also presented flutter analyses in time domain concerning the same object, and the same its modal representation, but using ANSYS/Fluent system