Design and experiment of high load-bearing acrylic connection node for the world's largest acrylic spherical vessel

Abstract

Acrylic is a kind of polymer material and is gradually applied to load-bearing components.The working stress and ultimate bearing capacity of the acrylic structure are the main design indexes. Aiming at the world’s largest acrylic spherical vessel, the structural design, finite element analysis and full-size prototype tensile test of a new acrylic connection node were carried out in this paper.This acrylic node will bear 90 kN tension force for 20 years.According to the viscoelastic characteristics of the material and the working environment, the stress of acrylic should be controlled below 3.5MPa for long term used. At the time, the ultimate bearing capacity should be greater than 6 times the working load.According to the stress-strain curve of acrylic, its tensile strength is about 75MPa. There is no obvious plastic deformation after fracture, showing the material characteristics of brittle fracture.According to the failure analysis of previous acrylic node structures and the characteristics of acrylic, the new acrylic node structure is proposed in this paper. Its performance is improved by reducing the cutting amount of acrylic nodes, optimizing the structure of embedded part and avoiding sharp corners. A 1/4 symmetrical acrylic node model is established FEA software, and the nonlinear problems such as material nonlinearity and friction contact are solved by finite element method. The FEA results show that the maximum principal stress of the node is about 2.9MPa. The relative error between the FEA results and the experimental results is 7.2%, indicating that the FEA results are credible. The ultimate tensile load of the node can reach 1000kN, which is about 11 times the working load. The failure of the node occurs at a sharp corner of the groove, instead of the maximum stress point. Therefore, stress concentration caused by sharp corners should be avoided in the design of acrylic structure.

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“…The acrylic stress of type B can be less than 3.5 MPa and its bearing capacity can be over 900 kN when tested by the prototype. Thanks to its outstanding performances, type B node was finally chosen as the final design [22,23].…”