How do you model a material with modulus vs. strain data for two points?
You should be able to approximate this material behavior with a simple two-term Yeoh hyperelastic material model. With two data points, you can use the formula on slide 29 of attached training material to convert Young's modulus to shear modulus (mu), assuming Poisson's ratio=0.50. The Cio coefficients are related to shear modulus via the equation on slide 10.
It is best to get a full complement of test data in tension, shear, and compression to fully characterize the material.
For more details, please refer to the document below.