Non-linear structures

Non-linearity is a frequent occurrence in engineering structures including spacecraft structures. It can take different forms, and it is at the origin of various dynamical phenomena with no linear counterpart. These phenomena include jumps, harmonics, bifurcation and non-unicity of the solutions. Even when they are local, non-linearities can affect the global dynamical behaviour of a structure and have a substantial impact on spacecraft loads. What makes non-linear dynamics challenging to analyse and model is the well-known result that the principle of linear superposition does not (generally) apply to non-linear systems. Even if linearisation may suffice in some cases, the rigorous analysis of non-linear structures requires adequate and dedicated numerical and experimental methodologies. The main objective of this chapter is to describe how to handle non-linearities for an accurate estimation of loads in spacecraft structures. Specifically, guidelines for both modeling and testing are provided.