Study On Mechanical Properties Of π - Type Structure FRP Honeycomb Plate

Honeycomb sandwich structure has long been popular by virtue of its performances such as high specific strength, high specific stiffness, good acoustic absorption and thermal insulation; different types of honeycomb sandwich structures have been widely applied into wind power generation, aviation and aerospace, shipbuilding and other industries. With the improving of industry requirement, the preparation and performance of honeycomb sandwich structure should be meliorated. So, my research group did a lot of efforts to invent the metal π-structure honeycomb panel. On this basis, the thesis studied the new π-structure honeycomb panel by applying GFRP to π-structure honeycomb sandwich panel. Then, explored the new structure honeycomb panel’s mechanical properties using both experiments and finite element software; measured the fatigue properties and the S-N curves of GFRP honeycomb panel in the apparatus designed by our own lab. This thesis’s results have guiding significance for the optimal design and practical engineering application of honeycomb sandwich structure.1) Measuring the tensile properties of GFRP deck, we can get the modulus of elasticity, poisson ration and longitudinal-transverse shear modulus of GFRP deck, those parameters are equivalent to the nine ontology parameters of the π-structure honeycomb panel(the modulus of elasticity Ex, Ey, Ez, the poisson ration γxy, γyz, γxz and the shear modulus Gxy, Gyz, Gxz);2) Testing the flat pressure performance of the π-structure honeycomb panel and researching the influence of core’s heights, face’s thickness, cell wall’s thickness and number of cores on the flat pressure performance by using experiments and simulations;3) Exploring the three-point bending properties of the π-structure honeycomb panel and studying the effects of core’s orientation and heights on the properties, analyzing stress state and the failure mode, then providing a basis for the fatigue testing by obtaining the displacement-load curves in different core’s heights;4) Designing a fatigue testing device for GFRP honeycomb panel and using this device to obtain the S-N curves. Besides, we surveyed the fatigue damage process and the fatigue damage model of samples.Ultimately, we can draw conclusions that honeycomb’s flat crush resistance has no subject to face plates, while it increased with cell wall’s thickness and numbers of cores, increased with core’s heights at first and decreased at last; the resistance to bending in portrait orientation is better than in landscape orientation; the bending stiffness increased with core’s heights while the shearing rigidity decreased with core’s heights; when the core’s heights is low, the honeycomb’s failure mode is bonding defects between honeycomb’s under-plate and the core, while the core’s heights is high, the bonding occurs between honeycomb’s top-plate and the core, and sometimes the shear failure in core accompanied; the fatigue damage appeared to have two modes:point-debonding mode and linear-debonding mode.