Determination of dynamic elastic modulus of materials under a state of simple stresses by using electrodynamic actuators in beam-type mechanical elements

Abstract

The dynamic elastic modulus is an important parameter for the study of solid mechanical elements. Even though there exist several well-established standardized methods that allow determining this parameter under a state of simple stresses, some of these may require sophisticated laboratory equipment or involve the use of multiple devices (impulser, sensor transducer…). The main purpose of this work is to propose an alternative approach that uses a single electrodynamic actuator both as an impulse exciter and vibration sensor simultaneously. By generating a random signal excitation and measuring the electrical input impedance of the actuator when coupled to a beam-type cylindrical element, the fundamental flexural mode of vibration of the latter can be identified and the dynamic elastic modulus of its material determined in a simple and straightforward manner. Preliminary experiments were performed over different size beams with rectangular cross-sections made of natural stone, marble, wood, and aluminium. Results were compared to those obtained using the standardized procedure described in the ASTM E1876 for the same specimens, these showing a good agreement in terms of dynamic elastic modulus.