Variable Transient Input Motion Influence on Shake Table Operational Conditions: Electrodynamic Shaker Applications

Transient time history motions are environmentally induced dynamic phenomena relevant to many engineering fields, such as mechanical, civil, and aerospace engineering. Particularly in structural dynamics applications, transient time history motions are widely used to simulate specific environmental loading conditions such as earthquakes, impacts, blasts, or spacecraft launches. The presented experimental study uses a suite of transient motions to investigate the motion replication of a 20 kN electrodynamic shaker that includes payloads with variable stiffness. When shaking a rigid and flexible structure in three orthogonal directions, the measurements focus on the achieved transient time history motion amplitude. The experiments are designed to test the impact of the motion characteristics and variable loading conditions on the motion replication. Specifically, the impact of shortening/decreasing the motion time duration and increasing the transient motion amplitude is investigated to identify the limit of the shaker performance. Further, the role of the motion type, e.g., single-frequency sine beats, triangle beats, or random bursts, to alter the achievable performance range of the shaker is investigated. This will inform best practices for motion selection and modifications for future studies experiencing the limit of their shake table performance.