Zhao, H (2015) Experimental and Numerical Modelling of Gasket Materials and Property Correlation. Doctoral thesis, Liverpool John Moores University.

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Abstract

In this work, a detailed combined numerical-experimental program has been developed to study the shore hardness testing of rubber materials principally used for gasket applications. The correlation between shore hardness and linear elastic and hyperelastic properties has been systematically investigated. A detailed FE model of the shore A hardness test has been developed with re-meshing functions in order to cope with the large deformation during simulation of shore hardness tests over a range of E values. The model is used in modelling shore A hardness on samples with standard thickness (over 6mm) and the result is validated against published experimental data. FE indentation models of thin samples are then developed and successfully used to predict the shore hardness of thinner samples over a property range relevant to gasket applications. A chart linking shore hardness, Young’s modulus and samples thickness is established and used to analyse shore hardness of three cases including silicone rubber made in the lab with different thicknesses, thin silicone rubber gasket and an EPDM (Ethylene Propylene Diene Monomer) gasket for plate heat exchangers. In all of the cases, the estimated E values based on shore hardness tests are able to predict the deformation of the material under different loading conditions including tensile and compression tests on samples of different shapes. In shore OO hardness modelling, the numerical results show a good agreement with analytical solution for spherical indenters. The shore hardness, thickness and E value chart predicted is used to evaluate the properties (Young’s modulus) of a soft silicone rubber and a latex rubber, in both cases, the E values predicted from hardness tests are able to predict the deformation of the material under tension and compression. In the case of latex rubber, the results also agree with hyperelastic properties from combined tensile and planar tests.

Based on the FE model developed, extensive data over a larger spectrum of material properties are developed and used in developing an Artificial Neural Network (ANN) program for inverse estimation of material properties from shore hardness and direct prediction of shore hardness for the cases when the material properties are known. The results show that the E values can be predicted from shore hardness tests with accuracy within 10% for both shore A and shore OO hardness tests. In the direct analysis, the ANN is able to predict the shore hardness values accurately from the linear elastic properties and sample thickness or a combination of hyperelastic parameters and sample thickness. The effect of indenter shape, testing condition, and choice of linear or hyperelastic material models on shore hardness tests are established and discussed, which would provide a detailed understanding to further enhance the use of shore hardness tests as a quick and effective way to test rubber materials.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Shore hardness, Rubber gasket, FE modelling, Indentation test, Elastic and Hyperelastic materials, Artificial Neural Network (ANN)
Subjects:	T Technology > TJ Mechanical engineering and machinery
Divisions:	Maritime & Mechanical Engineering (merged with Engineering 10 Aug 20)
Date Deposited:	27 Oct 2016 09:28
Last Modified:	03 Sep 2021 23:27
DOI or ID number:	10.24377/LJMU.t.00004555
Supervisors:	Ren, XJ and Allanson, DR
URI:	https://researchonline.ljmu.ac.uk/id/eprint/4555

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