The thesis for a candidate of technical science degree in the specialty 05.02.09 – dynamics and strength of machines.– National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Ministry of Education and Science of Ukraine, Kyiv, 2018.
The dissertation work deals with scientific justification and development of the methods to create thermo-dimensionally stable (TDS) load-bearing structures of spacecraft (SC) and high-resolution optical scanners (HROS) for Earth remote sensing spacecraft, with specified technical characteristics in respect of ensuring their sufficient dimensional stability (DS, stiffness) and strength under dynamic loads in orbital injection phase, at minimal weight.
The topicality of this investigation arise from adoption of the National Space Programs of Ukraine whose priority task was determined to be creation of Earth remote sensing space systems, particularly, in optical range. The prime executor of these programs was assigned to be Yuzhnoye SDO. In the process of programs fulfilling, it was found that achievement of the purpose in view is impossible without transition to thermo-dimensionally stable structures both of spacecraft itself and of high-resolution scanners.
It was determined that as the priority objective is to obtain TDS load-bearing structures of SC and HROS, it is required to realize the following cause-effect sequence: at first – ensuring TDS, then DS and only after that – strength and endurance. All these characteristics are interrelated and therefore they should be considered in package.
The basis of load-bearing TDS SC structures is the panel, shell or frame structure, with equipment attachment points, holes, etc. Each SC after manufacturing must pass the test cycle. As the space launches are not made in the territory of Ukraine, SC transportation to great distances is inevitable. During launch vehicle (LV) launch in the first seconds both LV and SC with payload experience high acceleration, considerable vibration and acoustic loads. And a consequence of SC motion in Erath orbit with its entering into Earth shadow and leaving it to under the effects of solar radiation are thermal cycles that cause temperature deformations. Therefore a number of requirements are imposed on the SC and HROS load-bearing structures.
The problem of obtaining TDS load-bearing structures was solved through the use of shells and plates made of PCM (layered composite materials with carbon band filler and polymer base) and honeycomb panels (combination of PCM plates with honeycomb intermediate layer made of aluminium foil). The required, even negative, value of linear thermal expansion coefficient (LTEC) in main direction was obtained through combining the layers with different angles of carbon fiber winding due to the great divergence in LTEC values of each separate PCM layer in different directions and due to Poisson effect. This theoretical basis is built in the developed analytical designing method, which was used in practice during creation of TDS load-bearing structures of Sich-2M class SC.
From the PCM designed by such method, the test samples of structural elements are created. In particular, to design the composite TDS case of optical HRS (of shell type); in this process, the created engineering procedure is used for calculation of future indices of that case. Besides, such plates made of PCM are used in honeycomb composite panels whose middle layer is made of thin aluminum foil.
The full-scale thermostatic tests of obtained load-bearing structures test samples showed that their characteristics meet the technical specification requirements in respect of TDS, DS (stiffness) and weight.
The stiffness and strength characteristics of manufactured SC load-bearing structures made on the basis of PCM and honeycomb composite panels were analyzed by numerical calculations of simulating computer models with the use of finite element method (FEM).
The theoretical developments confirmed by calculation results and full-scale tests allowed formulating the documents (methodological recommendations, procedures) which are general guidelines for making well-founded design decisions and conducting checking calculations of SC load-bearing structures based on PCM and honeycomb panels.
These procedures are universal for analogous space hardware.
The results of investigations were put into practice and are used at Yuzhnoye State Design Office (Dnipro city).
Keywords: polymer composite materials, multi-layer carbon plastic plates, honeycomb panels, optical Earth scanner, harmonic vibrations, random vibrations, finite-element modeling, elastic characteristics, deflected mode, strength.
