The usage of polymer materials for demanding engineering applications is increasing due to better understanding of their temperature- and time-dependant properties. Dynamic properties of polymers known as complex modulus is measured with Dynamic Mechanical Analysis (DMA). The main disadvantage of this method is fixation of the sample, since its stiffness strongly depends on temperature during the measurement. The aim of this master thesis is development of new method for measurements of dynamic properties based on free-free supported sample. The sample is polyamide plate, which is dynamically excited with contactless method using interaction of permanent magnet secured to the plate and a coil. The response of the plate is measured with laser vibrometer. Parameters of measured frequency response functions are used as input parameters of equivalent numerical model. The complex modulus is determined by updating its value untill permissible error between measurement and numerical model is reached. The measurements were carried out at the different temperatures and the results are comparable to the one of standard DMA.
|
