The stressed-deformed state model of curvilinear composite beam
Deformable body mechanics
Аuthors1*, 2**, 2***
1. Bauman Moscow State Technical University, MSTU, 5, bldg. 1, 2-nd Baumanskaya str., Moscow, 105005, Russia
2. Mechanical Engineering Research Institute of the Russian Academy of Sciences, 4, M. Khariton'evskii per., Moscow, 101990, Russia
Polymer composite materials are applied in a wide range of aviation and space technology products. A lot of such products’ components are curvilinear beams that work on bending. However, in connection with pronounced property anisotropy, composed materials’ behavior in such components differs significantly fr om metals.
While developing design technique, information is required on material’s working in these or that conditions. For this purpose, samples with shapes close to typical structural elements are tested, in which course the stressed-deformed state of these elements is studied. Classical tensile, compression and shear tests cannot fully demonstrate the behavior of multilayered composite materials. Bending tests can provide additional information that fully describes the behavior of the material.
ASTM D6415 Standard describes the samples testing of a typical structural element. The radial stresses in the sample are determined at the end of the test. Based on the experimental data listed in the ASTM Standards, a conclusion can be made that the destruction occurs in the curved zone of the sample due to delamination.
While composite structures designing, the interlaminar stresses should be taken into account, since the contact zone between the layers has a low strength and destruction can be caused by the delamination of the material. Thus, determination of internal stresses caused by interlaminar interactions during stretching and compression of layers is an important task.
The model determining the stress state in a layered curvilinear composite beam is suggested. The model correctness is verified by comparing the calculated stress values and the results obtained by finite element modeling. It is shown that the discrepancy between the results does not exceed 5%.
Calculations for curvilinear beams with cylindrical anisotropy of properties and for layered beams were performed. It is shown that maximum stress values are determined by the bending moment and geometric parameters of the beam. The most effective stress reduction can be achieved by reducing the curvature of the laminated beam.
It was determined that the central part of a composite beam, wh ere delamination is most possible, was the most dangerous zone. Optimum relationship of the beam’ material strength in circumferential and radial directions was determined.
Recommendations to increase the bearing capacity of curved beams were elaborated.
Keywords:bending, polymeric composite material, stressed-deformed state, curvilinear beam
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