Dynamic stressed-deformed state of a composite dome when separating from a rocket

In this paper, we present a calculated model and the results of computational investigation of the dynamic stressed-deformed state and the motion of the assembled dome during acceleration.A methodical-software based on three-dimensional finite element modeling of the dynamics of structures with curvilinear anisotropy of properties was developed. Unconditionally stable finite-difference schemes for solving the initial problem are used.A computational model for determining the stressed-deformed state of the dome of a composite structure with a metal (cylinder, flange, lining) and composite (shell, filler, heat-insulating layer) elements is provided for acceleration under the action of an impulsive load from the pyrotechnic separation system.The influence of aerodynamic resistance and taking into account the properties anisotropy of the fiberglass shell on the dome stressed-deformed state are considered numerically. The strength of metallic and composite elements is estimated. A problem specific is the absence of fixations, i.e. the dome moves freely along its axis (as a solid), while in it, due to impulse excitation, vibrations occur accompanied by deformation. The results of computational investigations reflect the combination of the motion of the dome as a solid and vibrations associated with deformation.Calculation investigations were carried out for two shell variants: in one case, the shell was considered as a structural element of an isotropic material with averaged characteristics, and in the other case an anisotropic material with characteristics obtained on the basis of data for fiberglass. It is shown that taking into account the anisotropy of properties is more reflected in the stressed-deformed state of the fiberglass shell. The variants were considered separately with and without taking into account the effect of external aerodynamic pressure. It is shown that the effect of aerodynamic drag is insignificant. For the design of the dome, the stress intensity for metal elements, tensile stresses and shear stresses for a fiberglass shell are much lower than the limiting ones.
Построена расчетная модель определения НДС обтекателя составной конструкции с металлическими и композитными элементами при наборе скорости под действием импульсной нагрузки от пиротехнической системы отделения. Использованы МКЭ в трехмерной постановке для среды с криволинейной анизотропией и безусловно устойчивые конечно-разностные схемы решения начальной задачи. Численно рассмотрено влияние на НДС обтекателя аэродинамического сопротивления, учета анизотропии свойств стеклопластиковой обечайки и дана оценка прочности металлических и композитных элементов.