Dynamic Processes During the Through-plastic-damper Shock Interaction of Rocket Fairing Separation System Components

• Дата: 2018
• Автори: Zaytsev, Boris F., Asayеnok, Aleksandr V., Protasova, Tatyana V., Klimenko, Dmitriy V., Akimov, Dmitriy V., Sirenko, Vladimir N.
• Формат: Стаття
• Мова: English; Russian
• Опубліковано: Journal of Mechanical Engineering 2018
• Теми: fairing; separation system; impact; stress; contact; damper; plasticity; UDC 539.3; 629.7; обтекатель; система отделения; удар; напряжения; контакт; демпфер; пластичность; УДК 539.3; обтічник; система відділення; напруження; пластичність
• Онлайн доступ: https://journals.uran.ua/jme/article/view/144164
• Назва журналу: Journal of Mechanical Engineering

This article deals with the actual issues of ensuring the dynamic strength of rocketry components using pyrotechnics. It studies the shock interaction of rocket fairing pyrotechnic separation system components during the second phase of the system operation at so-called capturing. The contacting of the system components occurs through a viscoelastic damper. The damper is installed between a movable part and a fixed one to 'attenuate' impact due to plastic deformation. The damper acts as a one-way connector − it limits compression and does not prevent separation. The whole structure is assumed to be elastic, and plastic deformation is concentrated in the damper. The mechanical model is represented as a combination of elastic elements and a nonlinear damper. The technique of taking into account the nonlinearity of a damper is based on the introduction of variable boundary forces on the damper ends. In the case of plastic compressive deformations, boundary forces increase the deformation, restrained by elastic forces, and when the contact disrupts (separation), they completely compensate the stresses in the damper model, nullifying them. A three-dimensional computational model of the fairing assembly composite design is constructed. The damper is presented in the form of a continuous thin ring. The finite element method is used. The calculation of the structural dynamics with respect to time is carried out by the Wilson finite-difference method. Verification of the technique on the test problem with the known wave solution is carried out. Calculation studies of the dynamic stress state at different impact speeds for damper variants with different plastic stiffness are performed: steel elastic (damper without holes, 'rigid', for comparison); initial (damper with holes, plastic, soft) and rational (damper with a selected characteristic of rigidity). It is shown that the initial damper is inefficient due to insufficient rigidity. The characteristics of plastic stiffness are determined, under which dynamic stresses are significantly reduced in relation to the initial structure. The maximum dynamic stresses in the pyrotechnic separation system of the fairing with rational dampers strongly depend on the impact speed. At significant speeds, they exceed the plasticity limit. A more precise formulation of the 'catch-up' task should be carried out taking into account the plasticity in the entire structure.