Design, analysis, and manufacturing of a multifunctional parallelogram gangway mechanism

Official URL: https://risc01.sabanciuniv.edu/record=b2486354 _ (Table of Contents)

Gangways are temporary access bridge systems used in sea and air vehicles, that allows passengers to transfer safely between a vehicle and land. Especially in order to provide an aesthetic appearance on yachts, internally mounted and telescopic openable types of gangways are preferred. For this purpose, a gangway is mounted inside a space opened into the hull, particularly at the top of the ladder connecting the decks of the boat. Depending on the distance between the boat and pier in boarding position, the size of the gangway and its mechanism differs. In the case of long gangways, the number of telescopic stages and/or the size of parts and occupation of extra volume of retracting mechanism (for hiding the gangway) are the limiting factors in realizing feasible gangway use on space-limited yachts. This thesis work focuses on improving stacking efficiency and adding functionality to the box type (internally mounted) of gangway prevalent in superyachts. For this purpose, a new multifunctional ergonomic gangway with a parallelogram mechanism was developed and manufactured to remedy the aforementioned problems. This gangway also serves as a ladder between decks, thus retaining functionality when it is not used as a gangway. Furthermore, the gangway stands on the deck and the extension starts from the end of the ladder, whose pieces comprise gangway; thus, the required length of the gangway is managed regardless of limited hull space. At the beginning of the development process of the gangway, the conceptual design of the mechanisms was formed with rigid body links. The detailed working principles of the mechanisms were explained, and degrees-of-freedom (DOF) of each simplified mechanism were calculated. To obtain design parameters such as the length of links, the distance between them and their angles for 3D modeling, the kinematic analysis was studied by the analytic approach, and the equations were solved by MATLAB. Based on the obtained data, the 3D model of the assembly was designed considering the manufacturing process using a computer-aided-design (CAD) program. Then, the static analysis of the gangway was performed with finite element analysis (FEA) using ANSYS Workbench (Static Structural module) software. The final design of the gangway was achieved based on the kinematic and static analyses results considering DNVGL-ST-0358 regulations. Due to the difficulties of accurately calculating required actuator forces in complex assemblies, ANSYS (Rigid Body Dynamics module) was used and the appropriate hydraulic actuators were selected according to the force and kinematic analysis results. Furthermore, the obtained analytical results were validated by comparing them to the results obtained using ANSYS. Finally, the manufacturing of the gangway was completed and applied to the yacht.