Two-layered plates of hexagonal and cubic crystals

Рассмотрена задача продольного растяжения двухслойных пластин из гексагональных и кубических кристаллов при различной ориентации слоев. Получены аналитические зависимости модуля Юнга и коэффициентов Пуассона пластин от отношения толщин. Проведен численный анализ изменчивости эффективных характеристик пластин из всех возможных комбинаций гексагональных и кубических кристаллов. Установлено, что существенное нарушение правила смесей для эффективного модуля Юнга двухслойной пластины происходит, если один из двух слоев заполняет ауксетик. Эффективный модуль Юнга может превосходить модули Юнга кристаллов в обоих слоях близкой жесткости. Отношение модулей Юнга кристаллов в обоих слоях оказывает существенное влияние и на эффективный коэффициент Пуассона. The problem of longitudinal tesnsion of two-layered plate of hexagonal and cubic crystals with different orientations of crystallophysic coordinate systems is discussed. Analytical dependences of effective Young’s modulus and Poisson’s ratios on layer thickness ratio are obtained. Numerical analysis of plates from all possible combinations of hexagonal and cubic crystals is performed. It is established that significant deviation of effective Young’s modulus values from predictions by mixture rule takes place in the case when one of the layers is auxetic. Effective Young’s modulus can have greater value than values of Young’s modulus of crystals at both layers. The ratio of Young’s modulus of crystals has great influence on the value of effective Poisson’s ratio.

Sensitivity of Composite Structure with Directional Properties of Annular Three-Layered Plate Mechanically and Thermally Loaded

Paper presents the sensitivity of the three-layered plate structure on the acting of mechanical and thermal loads. The cases of the annular plates, whose individual layers: facings and core have homogeneous building and/or heterogeneous one expressed by the variable material properties in radial direction have been examined. Numerical investigations have been carried out modelling the select examples of plate structure with the use of the finite element method. Plate is loaded in the plane of facings or is subjected to the flat temperature field. The evaluation of the structure sensitivity has been carried out analysing the values of critical loads or critical temperatures and corresponding with them buckling modes. Numerous results presented in diagrams create the image of plate behaviours, show responses of plate structure and indicate on the means of structure designs, which can fulfil the expected conditions of plate work.