Can the inerter be a successful shock-absorber? The case of a ball-screw inerter with a variable thread lead

• Published in: Journal of the Franklin Institute Vol. 356; no. 14; pp. 7855 - 7872
• Main Authors: Faraj, Rami, Jankowski, Łukasz, Graczykowski, Cezary, Holnicki-Szulc, Jan
• Format: Journal Article
• Language: English
• Published: Elmsford Elsevier Ltd 01.09.2019; Elsevier Science Ltd
• Subjects: Absorption; Active control; Ball screws; Damping; Deceleration; Friction; Impact velocity; Optimization; Shock absorbers; Velocity; Vibration; Vibration control
• ISSN: 0016-0032; 1879-2693; 0016-0032
• DOI: 10.1016/j.jfranklin.2019.04.012

This paper investigates an application of a ball-screw inerter for mitigation of impact loadings. The problem of impact absorption is to provide a minimum reaction force that optimally decelerates and eventually stops an impacting object within the available absorber stroke. It significantly differs from vibration mitigation problems which are typical application of inerters. The paper demonstrates that the optimum absorption can be achieved by fully passive means. For known values of the object mass and inerter parameters, the obtained solution is independent of the impact velocity. The optimum passive absorption is achieved by employing a variable thread lead. As a result, two force components emerge, the typical inertance-related force and a damping-like term, and sum up to provide the optimum constant deceleration force. This result is relatively unique: conventional absorbers do not provide a constant force even with complex active control systems. Finally, an optimization problem is formulated to reduce the influence of process uncertainties (range of possible mass values, unknown friction). The results are verified and analyzed in a numerical example.