Numerical Modelling of Cryomodule Transportation with Nonlinear Wire Rope Isolators

Cryomodules for high-energy physics experiments are complex assemblies based on superconductive cavities aimed at particle beam acceleration. The assemblies are composed of many fragile and weak components, which are assembled in clean room environments and under a vacuum. Thus, a high risk of damage during transportation occurs, leading to huge costs in repairing and re-assembly both from an economical and timing point of view. For this reason, specific fixtures are designed to guarantee the safe transportation of cryomodules, named transportation tooling. These devices act as a mechanical filter, mitigating the vibration coming from road asperities. The key components of the transportation tooling are the wire rope isolators, which are compact and reliable nonlinear springs that provide stiffness and damping to the structure. This paper focuses on the numerical simulation of a cryomodule during transportation by exploiting a finite element and multi-body mixed approach. Two different models for the wire rope isolators are compared: the conventional linear spring-damper model, based on data provided by the manufacturer, and a purposely developed nonlinear model (enhanced Bouc-Wen), based on experimental characterization of the springs.