Innovative Multilayered Structures for a New Generation of Aircraft and Spacecraft

摘要

The main improvements in future aircraft and spacecraft may depend on an increasing use of conventional and unconventional multilayered structures. Some of these configurations have already been in use for over three decades and include: layers made of isotropic alloys such as aluminum and titanium alloys which are widely employed and stacked with other materials in multilayered structures; carbon fiber reinforced laminates where the fiber orientation in each lamina and stacking sequence of the layers can be chosen to achieve the desired strength and stiffness for a specific application; sandwich structures with honeycomb or metallic foams used as core-layers which are lightweight with high bending stiffness; layered ceramic- metallic structures employed as thermal protection systems used, for example, in reentry space capsules. In the near future a variety of new unconventional materials could be used: for example, piezoelectric or iezomagnetic materials, which are commonly used in so-called smart structures as sensor or actuators depending on whether they use the direct piezoelectric/piezomagnetic effect or the converse piezoelectric/ iezomagnetic effect; functionally graded materials, which have a continuous variation of physical properties in a particular direction in order to combine the desirable properties of the constituent hases to obtain a superior performance, avoiding the problem of interfacial stresses typical of classical multilayered configurations; and nanocomposites, which are multiphase materials, where at least one constituent phase has one dimension less than 100 nm, with unique hysical, chemical, thermal and electromechanical properties which allow extensive potential applications. Layers made of such materials can be combined in different ways to obtain structures which are able to fulfill several structural requirements [1,2].