Mechanical system modeling and simulation of its dynamic behaviour is a commonly required task in many industrial fields. Fluid transmissions are frequently employed in some applications, and some standard techniques are known to obtain a consistent dynamic model of a fluid line, including the contribution of inertia, compressibility and friction. When fast transient phenomena are to be studied, the full mechanical system including structural and fluid components should be modeled in advance, so that the system designer can avoid a possible critical behaviour. In this work, full fluid piping modeling is first investigated by means of one- and bi-dimensional approaches. It can be shown that a secondary effect, such as laminar flow frequency dependent friction, may consistently improve the accuracy of the simulated line response. The analytical coupling between the discrete model of mechanical substructures, elastically and fluid coupled by a secondary fluid continuous subsystem, is investigated. The formulation of a non standard eigenproblem is proposed to obtain the main full dynamical system properties, such as eigenvalues and shapes. A numerical application example is reported, and results are discussed in detail.
Mode shape analysis of dynamic behaviour of cracked nanobeam on elastic foundation