This paper was developed in support of a workshop delivered at the 2020 NAFEMS Americas & DE CAASE Conference.

Summary

Digital Twin applications that integrate in-situ load measurements with periodically updated simulations of remaining fatigue life hold great promise for creating huge value in maintenance and logistical operations. In this work, the author simplement two commercially available, off-the-shelf solutions to create a closed loop pogo stick digital twin that tracks damage accumulation due to actual loads experienced. A pogo stick was chosen because it experiences highly non-linear loading. The system records 12 strain gauges on the pogo stick frame at 1000 Hz. Strain gauges were placed using the True-Load load reconstruction. The True-Load process automatically creates strain correlation plots comparing measured strain to the strains in the FEA model simulated by the reconstructed loads. It also converts the strain gauge signals into 3 mutually perpendicular load channels that then are fed to a simulation of the pogo stick’s rubber tip. After each “operating” session, load history from the pogo stick is downloaded and accumulated as fatigue damage in a digital twin that tracks the remaining life of the rubber tip of the pogo stick. In order to accelerate loads processing to real-time speeds, the Endurica EIE interpolation engine has been used. EIE uses pre-computed finite element solutions of the rubber tip of the pogo stick under a series of load cases to rapidly convert input load history into strain tensor component history for each finite element. The Endurica DT incremental fatigue solver is then used to accumulate damage in all finite elements of the model, for each operating session. The result is a continually updated account of remaining life left in the pogo stick tip due to actual loads experienced. Whether you are developing a new product, or operating a digital twin, combining real-time high accuracy structural loads with real-time fatigue evaluation software will propel you leaps and bounds towards a digital twin for durability.