Rotor Dynamics Software, Description of some linear and non-linear modeling elements, Dynamics R4

ROTOR DYNAMICS SOFTWARE

Dynamics R4		See also Damper R3.1 here
		Broshure Dynamics R4[pdf]ENG

DESCRIPTION OF SOME LINEAR AND NON-LINEAR MODELING ELEMENTS

Linear Elements

Alford's force element: The element allows computing of aerodynamic cross-coupling forces operating in axial flow compressors and leading to instability of rotor system. It is based on the correlation discovered by J.S. Alford.
Wachel's force element: The element allows computing aerodynamic cross-coupling forces acting in centrifugal compressors and leading to instability of rotors. It is based on J.C. Wachel's empirically derived correlation
Block of code and elements for computation of shaft systems with gearings: This allows computing shaft systems with cylindrical, bevel, helical and hypoid gearings.
Function of import of super elements from FEM systems: The element gives an opportunity to combine solutions obtained in FEM program and in DYNAMICS R4 by means of modal synthesis method. It allows to take into account the complex configuration of separate assembly units, for example, cases and housings.

Non-linear Elements

"Clearance" element ("Elastic Damping Lateral Restraint" element): This element allows to model different cases of full or partial rubbings of rotating and non-rotating structures. This allows you to model most cases of instability in rotating systems with clearances. It takes into account any kinds of contact with external and internal damping, with friction in contact point, weight and circumferential irregularity of clearance. The element is indispensable for educating engineers in fundamental non-linear dynamics.
Journal bearing element: This element allows computing the rotating system with two notable cases of plain bearing: "short" bearing and the "long" bearing. Different kinds of cavitation of fluid film are considered: uncavitated (2-π film) damper and cavitated (π-film) damper. It allows to compute dynamical systems in steady-state and non-steady state conditions.
Squeeze-film damper element: This element models two well-known cases of hydrodynamic damper: the "short" damper and the "long" damper. Combinations of these cases are also possible. Different kinds of fluid film cavitations are considered: uncavitated (2-π film) damper and cavitated (π-film) damper. Fluid inertia effects are also included in squeeze film damper models. It allows to compute dynamical systems in steady-state and non-steady state conditions. Any number of squeeze-film dampers in rotating system. Fast computation.
User-programmable non-linear element: It allows to use the user's own algorithms of nonlinear effects in rotating machinery to program new elements and also to integrate them into DYNAMICS R4 program system. The new element can be of any complexity and it can be used in a rotor model in combination with other non-linear elements of DYNAMICS R4. The language of programming is the script language Python (www.python.org) built-in in DYNAMICS R program system and can be easily mastered by the user. This element is indispensable for engineers and post-graduate students carrying out investigations in the rotor dynamics field. By the user's request the new element which was made in a script language can be adapted and included in program system by DYNAMICS R4 developers (Alfa-Tranzit Co., Ltd). It will make it possible to speed up computation dozen of times.
Rolling bearing element: This element allow to model the main types of rolling bearings - angular-contact (ball) bearing , roller bearing, etc. The Hertz theory is used for computing speed dependent stiffness and bearing forces. Clearances in bearings can also be taken into account. The user has an opportunity to specify bearing linear and nonlinear damping.

Individual options are offered for customers who have purchased the Dynamic R4 program system. Development of the following non-linear elements can be made according to their needs: