Stiffness and frequency of slender structures: An experimental study utilizing 3D printing

Abstract

This study analyzes the effect of geometric changes to the stiffness and frequency of slender structures. Geometric changes were made by altering the width and length of the structure as well as adding structural components. 3D printing was utilized to create the slender structures which were tested experimentally. Stiffness was determined by finding the slope of the linear region of the structure's force vs deflection plot. The frequency of the structure was obtained by putting a time series of the structure's oscillations through a Fast Fourier transform which provides a peak signifying the structures in plane frequency. Additionally, several structures were combined to create a springs in parallel system. Results of analysis show that for a structure with constant material properties that increasing/decreasing the length will lead to an decrease/increase in stiffness and frequency while altering the width of the structure will increase stiffness, but have no effect on frequency. It is also shown that additional structural components added to a simple structure increases its stiffness and frequency. Analysis of the springs in parallel system will give a non-linear force vs deflection plot which is made up of linear regions. The slope of the curve changes when the deflection is equal to the spacing between structures. These results are useful for designing structures to fulfill their requirements in the overall system.