Determining elastic modulus from dynamic mechanical analysis: A general model based on loss modulus data

Abstract

Dynamic mechanical analysis (DMA) method is used to measure viscoelastic properties such as storage and loss moduli of materials. The present work is focused on developing a generalized model that allows transforming the storage and loss moduli obtained from DMA to time domain elastic modulus values. The model is capable of transforming the loss modulus data that may have multiple transition peaks in the test temperature range into elastic modulus over a wide range of temperatures and frequencies. In order to develop the model, the storage modulus is divided into frequency dependent and independent components, which are analyzed separately to build a general transform for strain rate sensitive and insensitive material properties. To test the accuracy of the model, the model is validated with experimental data obtained on ethylene-vinyl acetate (EVA). The secant moduli obtained from tensile tests and loss modulus transform are compared and the average error is found to be 1.1% in the strain rate range of 10−6/s to 10−2/s, which provides validation for the model. The proposed method eliminates the need for conducting numerous tensile tests to obtain modulus over various temperatures and strain rates and replaces them with a single DMA experiment.