Design and Structural Analysis of a Lifting Platform for Hydrotherapy Pool

Abstract Hydrotherapy is a supervised exercise session conducted in a specially designed swimming pool to induce healing health conditions against arthritis, inflammation and other ailments. Hydropool is a pool intended for such aquatic therapy whereby the users are seated in special-chairs on top of a platform that will be slowly submerged into the pool. However, existing platform structure and hoisting mechanism of hydropools are mostly physically strenuous for disabled people. Besides that, the cost of the lifting systems is often high owing to the sophisticated hydraulic or pneumatic apparatus and materials used. Thus, it is essential to design and analyze a hydropool platform and lifting mechanism to overcome these limitations. This study presents the numerical analysis of a 1200 mm (width) by 1015 mm (length) platform structure, and a scissor mechanism to lift the platform from a 1750-mm deep pool. The structure comprises nine individual components including base, scissor links, supporting and connecting links, leadscrew, platform, fence, bolts and nuts. The design objective is to minimize mass at optimum load carrying capacity with a reasonable safety factor. A few design options are considered to achieve this objective. A virtual model of the selected design is created using SolidWorks®. Finite element analysis (FEA) on the model is conducted using the ANSYS® workbench in static structural mode to evaluate the von Mises stresses and total deformations of the platform when a maximum load of 2943 N is applied vertically on the structure. The structure is made of SS316, which has a yield strength at 0.2% offset of 205 MPa as per the ASTM A276/A276M standard. The FEA results showed that the maximum von Mises stress of 67.9 MPa is obtained at the scissor link component of the structure. The corresponding maximum total deformation is 1.33 mm. The safety factor is found to be equivalent to 33.1% of the yield strength of SS316 at the maximum applied load. These observations indicate that the platform structure and scissor-lifting mechanism are safe under the loading conditions used in the simulation.