Stress variability in multilayer composite hydraulic cylinder

The focus of this research is to evaluate the variability of the stress state in hydraulic cylinder, due to the deviation respect to the nominal values for both the geometrical and the material properties. The element is composed by a multilayer in which the inner layer is made by means of a thin tubular aluminum part, while the coating is made of composite material. The analytical work developed is based on the theory of axial symmetric elements and finds its application in a real hydraulic cylinder made for heavy duty i.e. for an earth moving machine (internal pressure 350 bar). The research is also developed by considering and comparing the results obtained by designing a component made of a single aluminum layer. From the results, it is clear that the multilayer solution has a variability, much higher than the component made by a single layer. This result, therefore, requires at least a complete revision of the safety coefficient evaluated and imposed by standards.