The Design And Analysis Of Retraction-extension Mechanism For Foldable Garbage Cleaning Catamaran

With the rapid development of China’s coastal and river,the demand for water surface garbage cleaning boat is increasing.It is necessary to develop water surface garbage cleaning boat which can be applied to various waters areas simultaneously.Therefore,this thesis proposes a kind of foldable garbage cleaning catamaran which is lightweight,maneuverable and convenient for storage and transportation,and studies its key technical mechanism,i.e.,retraction-extension mechanism from the aspects of principle,lightweight,kinematics and dynamics.According to the design requirements of the foldable garbage cleaning catamaran,a retraction-extension mechanism is designed,the front and back retraction-extension mechanism is composed of two symmetrical four and five link mechanisms respectively.The degree of freedom of the retraction-extension mechanism is 4,and each group of linkage mechanisms requires a prime mover.The location dimension of the retractable mechanism is optimized.The results show that the optimized size meets the technical indicators,and the maximum deflection angle of the pontoon is reduced by 79.80%.The overall structure design and the main components selection of the retraction-extension mechanism are carried out,and the feasibility of the design scheme is verified through experiments.The lightweight design for retraction-extension mechanism of the foldable garbage cleaning catamaran is carried out.By using ANSYS Workbench software,the stress and displacement contour of the simplified retraction-extension mechanism model are analyzed under four typical working conditions which consist of retraction,full load,braking suddenly and steering quickly of the catamaran.Using ANSYS Workbench software to optimize the section thickness and surface shape of each component of the retraction-extension mechanism.The results show that the overall mass of the retraction-extension mechanism is reduced by79.62% while ensuring the strength requirement.The analysis of the first six-order modes of the retraction-extension mechanism shows that the low-order frequency of the mechanism is in the range of 3～13 Hz,which is greater than the excitation frequency caused by the water surface.The first-order frequency value of the mechanism is 3.3959 Hz,which is located in the excitation frequency range caused by the unbalance of the pontoon.The maximum deformation occurs at the top of the front mechanism and the position of the back mechanism frame,which are 1.2416 mm and0.76653 mm respectively.It has little effect on the vibration of the whole catamaran.The kinematics analysis is performed by analytical method,and the motion characteristic curves of the pontoon and platform under linear drive are obtained;the dynamic analysis is carried out by ADAMS software,and the reaction force characteristic curve of each hinge point of the front and back retraction-extension mechanism under linear drive is obtained.Through comparing the retraction-extension actions derived from the linear and sinusoidal driving functions respectively,it is concluded that the sinusoidal driving function reduces the motion parameters of the pontoon and platform by 40.02% ～ 86.15%,and the reaction force amplitude of each hinged position by 0.67% ～ 30.92%.The sinusoidal driving function has a better effect.