The general approaches to creation of parametrical models of aviation designs taking into account a multiplication on a theoretical contour
Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia
AbstractThe use of parametric geometrical models for aviation constructions design is investigated. The parameterization of geometrical models is considered for groups of constructively and geometrically similar details containing the curvilinear surfaces of aircraft theoretical contour. The parametric model of such detail allows one to construct the models of remaining details by use of the simple change of required parameters and will reduce the input data for digital models of the considered group’s details in direct ratio to number of details.
The geometrical element of auxiliary geometry forming the sized basis for geometrical model of a detail is called a "binding". To secure full model’s parameterization and to eliminate geometry failures the determination of the bindings must be independent from the model position so that allows one to conserve all geometrical reconstructions at ever change of the position. This specificity requires avoiding the bindings’ changeover if the model position in construction changes.
To eliminate the mentioned changeover of binding planes and surfaces the continuous determination of axial elements used as bindings is necessary instead of the discrete one. The use of the revealed regularities of determination of axes of the constructive and force diagram (CFD) is proposed as a continuous determination method. This approach is based on the known fact that the discretely located axes can be defined by parallel shift with a certain step with respect to its initial position. The use as bindings of the elements forming the sized bases for CFD axes is proposed contrary to the use of the force set axes. The term "basic bindings" is for this kind of bindings introduced.
On the basis of the described approach and the use of available basic bindings the remaining bindings can be determined “in model” instead of their import from the master geometry. Such bindings’ determination avoids their changeover at ever change of the model position and requires only the new values of parameters defining the binding’s position with respect to the rather basic bindings. The proposed above bindings’ determination avoids also failures of evolution of geometrical elements at changes of model’s position in aggregate construction. On the other hand the model spatial position of the model can be parameterized together with the model’s form.
A new method of construction of parametric models for aviation constructions that takes into account the multiplication on theoretical contours can be developed on the basis of the proposed continuous bindings’ determination aproach.
Keywords:aviation designs, theoretical contour, parametrical model
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