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Indexed by:Journal Papers

Date of Publication:2020-05-15

Journal:ENGINEERING STRUCTURES

Included Journals:SCIE

Volume:211

ISSN No.:0141-0296

Key Words:Nuclear polar crane; Non-smooth; Linear complementarity problem; Frictional unilateral constraints; Model smoothing method; Flexible multibody system

Abstract:This paper numerically analyzes the seismic response of a polar crane operating at a nuclear plant, with derailment considered. In this case, the wheels and rails can no longer be treated as being bonded, and thus traditional methods in structural dynamics (e.g. response spectrum method) are no longer suitable for transient contact analysis. On the other hand, contact-impact analysis of flexible multibody systems will often face great difficulties attributed to the complexity of modeling and low computational efficiency. To overcome these problems, the wheel-rail interactions are modeled as multiple frictional unilateral constraints, and the resulting contact-impact problem is formulated as a linear complementarity problem (LCP). Later, a novel smoothing method is applied to smooth the LCP formulation by replacing the normal gap with the time-averaged normal gap over a short time period. A model smoothing method is then combined with modal synthesis to derive the equations of motion without high frequency components. Finally, the validity and feasibility of the proposed method are demonstrated through several numerical examples. The results show the different contact states during the seismic process, including smooth contact, detachment and re-contact.