Dynamic analysis of block offloading using self-propelled modular transporters

A self-propelled modular transporter (SPMT) is a platform vehicle with a large array of wheels that is used for transporting outsized objects. In a shipyard, a number of connected SPMTs are used to move outsized blocks transported from abroad to the floating dock to increase the productivity and reduce the operation time. This operation is called offloading. This study proposes a method of analyzing the offloading operation dynamically. To develop this method, multibody dynamics was used to analyze the motion of the transportation barge, and a floating dock connected by hinge joints was adopted. The modeling of the mechanical parts of the SPMT was also proposed, taking into consideration the axle compensation mechanism to maintain the level of the platform when the SPMT drives over an uneven roadway by lifting up the wheel. Furthermore, a non-interpenetration constraint method between a plane and the cylinder was derived for the collision between the wheels of the SPMT and the decks of the transportation barge and floating dock. The non-interpenetration constraint method was successfully applied to the dynamic analysis of block offloading using SPMTs. From the dynamic analysis, the safety criteria according to the given wave conditions were evaluated. •This study presents the method for analyzing dynamically offloading operation using SPMTs.•The method includes the multibody formulation and axle compensation mechanism for the SPMT.•Safety criteria are evaluated to check the feasibility of the operation under the given environmental conditions.•This study could find safe environmental conditions for offloading operation using SPMTs.