Methods of reduction of honeycomb structures’ displacements in manufacturing the polymeric composite structures
PJSC “Sukhoi Company”, 23A, Polikarpova str., Moscow, 125284, Russia
The honeycomb structure forming’s technologies often result the displacements of the honeycomb elements. The deviation of the structure’s form from the structural norm reduce the quality of composite structures and result the rejection of the defective structural elements. The deviation of the form may be detected wore often after the sandwich structure’s disassembling and cannot be eliminated.
The solution of the mentioned problem requires the analysis of the main causes of the displacement of honeycomb cores, the analysis of existing models allowing the theoretical investigation as well as the practical methods of elimination of honeycomb cores’ deviations, and the optimal design solutions increasing the technological efficiency of honeycomb structures of high structural depth and bias angle 45°.
The deviation of honeycomb’s forms during the forming are caused by the following reasons:
— the insufficient stiffness of the block subjected to the horizontal static loads being result of the molding pressure;
— the insufficient adhesion between honeycombs and covering layers.
The preliminary analysis shows that the main cause of the displacement of honeycombs is the horizontal loading during the forming. Therefore, taking into account the various methods of the honeycomb displacement elimination, the specimens for the experimental study were constructed.
One of the main methods of elimination of honeycombs’ deviation is the arising of the adhesion conditional factor on the groundwork of the technology of the prepreg fixation at the matching attachment by use of supplementary materials such as abrasive grids or perforated steel foil.
To estimate both the longitudinal and lateral stiffness of honeycomb cores the tests are implemented using the special test attachment. It must be noted that the longitudinal and lateral forces of bearing are three times different values. The computation based on the results of the mentioned tests has shown that the re-orientation of the honeycomb core in the skew area allows one the efficient resistance to the forces resulting the structure deviation.
Thus, the design solutions and the technology of elimination of honeycomb core structures during the forming of polymer sandwich composites are proposed and their efficiency is shown.
Keywords:Polymer composite materials, honeycomb structures, stiffness, contact retention force, horizontal component of pressure molding vector
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