Dynamical analysis of fluid lines coupled to mechanical systems taking into account fluid frequency-dependent damping and non-conventional constitutive models: part 1 – Modeling fluid lines

•Transient 2-dimensional flow modeled with fractional derivative constitutive laws.•Continuous and discretized (by modal decomposition) models of a fluid line.•Fast and accurate computation method of time and frequency response functions.

The design of hydraulic transmission systems for control and actuation requires accurate knowledge of their dynamic response: some standard techniques are known to obtain a consistent dynamic model of a fluid line, including the contribution of inertia, compressibility and friction. In this paper an efficient procedure is developed for simulating the dynamic response of a fluid line in both the frequency and time domains, focusing the attention on the modal analysis of a discretized model, in view of coupling with mechanical systems. A bi-dimensional approach is adopted, and the laminar flow frequency-dependent friction is modeled using non-integer order differential laws, which may improve the accuracy of the simulated responses in comparison with more traditional Newtonian models.