Straw characterization method for Mullines effect parameters

Abstract

The invention discloses a straw characterization method for Mullines effect parameters. The method comprises the following steps: firstly, a dimensionless function is introduced into a straw experiment to establish the relation between physical quantities in the straw experiment, then display expression of the dimensionless function is obtained through calculation according to a finite element model containing the Mullines effect, and then the straw experiment is carried out to obtain a loading and unloading load-displacement curve of an actual material; and then the initial shear modulus andthe hyperelastic mechanical parameters of the material are obtained according to the display expression of the dimensionless function and the loading load-displacement curve inversion of the straw experiment, and finally the Mullines effect parameters of the material are obtained according to the display expression of the dimensionless function and the unloading load-displacement curve inversion of the straw experiment. The stress softening mechanical property of the rubber material can be rapidly and locally characterized in situ in a multi-scale mode, the complexity of a traditional tensilecompression experiment is reduced and the accuracy of the obtained Mullines effect parameters is improved.

Description

technical field [0001] The invention belongs to the technical field of straw experiments, and in particular relates to a Mullins effect characterization method for high molecular polymer materials. Background technique [0002] Straw experiment is an effective method to characterize the local mechanical properties of soft materials, especially polymer materials such as rubber. Because polymer materials such as rubber have low modulus and are highly sensitive to external stimuli, straw experiments often involve material, geometry, boundary highly nonlinear and large deformation. Therefore, it is difficult to obtain an analytical expression between the experimental response and material parameters. Many studies assume that there is a linear relationship between the pressure and the suction height in the straw experiment in order to extract the elastic or viscoelastic properties of the material. Verify this hypothesis. Under the framework of continuum mechanics, polymer mater...

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Problems solved by technology

Most of the above characterizations are conventional methods such as tension and compression. In the test, samples of specific size and shape need to be prepared, and the apparent stress softening effect of the material is likely to be affected during the machining process of the sample.

In contrast, the indentation method is easier to measure, and it is easier to achieve in-situ, multi-scale and local characterization measurements, but the current work of using the indentation method to characterize the Mullins effect is relatively rare

Although the constitutive model of the Mullins effect has already been embedded in ABAQUS, there are few works that specifically use the straw method to characterize its constitutive parameters

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