Design and Development of Umbrella Using Compliant Mechanism

Lam, Yeap Sheng (2020) Design and Development of Umbrella Using Compliant Mechanism. Past Year Question Paper (Unpublished)

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Abstract

The main objective of this research was to design a compliant stretcher mechanism for the umbrella by replacing the rigid links and joints of a conventional stretcher mechanism. This research also focus on significantly reduce the total number of part count of a conventional stretcher mechanism. Generally, the primary study of this research was focused at the stretcher mechanism which is a part of the frame structure of the conventional umbrella. A reference design for the conventional umbrella was chosen through reviewing different patent designs. The reference design was further modified through reconceptualization of design and a rigid body model was constructed. By referring to the rigid body model, 6 different configurations of the pseudo-rigid-body-model (PRBM) were constructed and the best configuration was chosen. The degree of freedom for both models were compared to determine the validity of the chosen PRBM and kinematic synthesis with function generation was performed for the chosen PRBM using MATLAB. The obtained results from the kinematic synthesis were then used to calculate the dimensions and stresses of the flexural pivots for the compliant stretcher mechanism. Then, the CAD design for the compliant stretcher mechanism was designed using Solidworks for both the actual models and prototype model with stainless steel, aluminium alloy and polyethylene terephthalate (PET) respectively. Non-linear analysis was performed on each of the models through Finite Element Analysis (FEA) simulation and the resultant deflection and flexural pivot stresses were compared with that of the PRBM. This research successfully replace all the rigid joints and links of the stretcher mechanism of the conventional umbrella to form a monolithic structure of compliant stretcher mechanism. The total number of part count for the conventional stretcher mechanism experienced a percentage reduction of 85.71% with the compliant stretcher mechanism. The flexural pivot stresses obtained from the non-linear analysis with Finite Element Analysis (FEA) method were in close agreement with the pseudo-rigid-body-model (PRBM) as the overall percentage error among the three models with different materials are less than 15%. Overall, it was concluded that the design of compliant stretcher mechanism of the umbrella using Rigid Body Replacement approach with PRBM was a success.