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... Arunkumar et al. [11] investigated a water driven scissor lift using Autodesk Fusion 360 o . Shi et al. [12] used static analysis data obtained in ANSYS Workbench software to evaluate the reliability of scissor lifting structures with different design criteria by using BP neural network. Rani et al. [13] designed and produced a two scissors lift with lifting height of 1.5 m and load of 1.5 tons using CATIA V5 design software and COMSOL finite element analysis software. ...
In this study, the design of a two scissors greenhouse lift trolley is considered. The maximum height of the platform from the ground is 3500 mm. A program developed in Visual BASIC to automate the design is introduced. The lift is modeled in SolidWorks (SW) and the finite element (FE) modal and static analyses are performed as an initial design first by using graphical user interface (GUI). The lift contains revolute joints and slider joints. A simply supported beam which has two revolute joints and a slider joint is studied to verify how to model the joints. Pim connectors are defined for revolute joints in SW-FE analysis. Spring connectors with very large values are defined between sliding faces in the normal direction for translational joints. The results obtained with solid finite elements in SW are compared with analytical results for the natural frequency and static analyses and it was observed that the results are in good agreement for the simply supported beam. An Excel file where a main sheet contains the list of the bodies and all the geometric values is created after the initial design. The Excel file also contains sheets for each body. Body sheets have all the dimensions in the sketches and features. The dimension values in the cells of the body sheets are defined by formulas related to the geometric values given in the main sheet. Kinematic, kinetic, and revision of the SW model are performed by the design automation program. The FE analyses are done by GUI and the results are evaluated. If the results are not satisfactory, the geometric values are changed in Excel file and the analyses are repeated. The final design is obtained by the iteration easily. The automation program and the procedure developed in this work can be extended other scissors lifts.
Morphing structures with simultaneous deployable and load-bearing characteristics have become the research hotspot due to their practicability. For morphing deployable structures with these requirements, geometrical incompatibility will occur due to the design or the additional loads during the transformation. In order to solve the problem effectively, a novel elastic telescopic rod is designed for suitable axial stiffness and bending deformation capacity. The mechanical behavior is systematically investigated for scissor structures based on the experiments and simulations in this paper. The core parts of the proposed telescopic rods are the springs, constrained sliding tubes and outer steel tube jacket. According to the symmetry of springs and steel tube jackets, three types of elastic telescopic rods are put forward. And their load modes are clarified as the coupling action of axial displacement and concentrated vertical loads. Experiments and simulations are carried out to evaluate their mechanical performance in normal and ultimate use states. The bearing capacity and deformation capacity of the same specimen with different initial axial displacements and different types of specimens are compared. This principle may be able to open a new avenue for the design of morphing scissor structures with load bearing capacity and transformability, and it will unfold their use in architecture and civil engineering.
Tipična rješenja podizača na bazi škarastog mehanizma najčešće su pogonjena hidrauličkim cilindrom, a rjeđe kombinacijom elektromotora i navojnog vretena (električnog cilindra). U radu su analizirane postojeće izvedbe koje uključuju nekoliko rješenja prihvata cilindra na polužje škarastog mehanizma. Analiza poznatih rješenja pokazuje izrazito nelinearni promjenjivi odnos pogonske sile (sile u cilindru) te radne sile (sile na platformi) što rezultira potrebnom za značajno predimenzioniranim cilindrom u odnosu na zahtjev snage. U radu se predlaže realno izvedivo rješenje prijenosa snage s pogonskog cilindra na polužje škarastog mehanizma na principu inverznog škarastog mehanizma koje osigurava konstantni omjer pogonske i radne sile.
