Material Parameter Identification for Acoustic Simulation of Additively Manufactured Structures

Abstract

One possibility in order to manufacture products with very few restrictions in design freedom is additive manufacturing. For advanced acoustic design measures like Acoustic Black Holes (ABH), the layer-wise material deposition allows the continuous alignment of the mechanical impedance by different filling patterns and degrees of filling. In order to explore the full design potential, mechanical models are indispensable. In dependency on process parameters, the resulting homogenized material parameters vary. In previous investigations, especially for ABH structures, a dependency of the material parameters on the structure’s thickness can be observed. In this contribution, beams of different thicknesses are investigated experimentally and numerically in order to identify the material parameters in dependency on the frequency and the thickness. The focused material is polyactic acid (PLA). A parameter fitting is conducted by use of a 3D finite element model and it’s reduced version in a Krylov subspace. The results yield homogenized material parameters for the PLA stack as a function of frequency and thickness. An increasing Young’s modulus with increasing frequency and increasing thickness is observed. This observed effect has considerable influence and has not been considered so far. With the received parameters, more reliable results can be obtained.

Experimental validation of a multi-material Acoustic Black Hole

“…This design could then be produced using multi-material additive manufacture or another suitable material layering procedure. Some investigations have studied ABHs produced through additive manufacturing, 13,14 including those with functionally graded tapers. 15 However, these configurations all utilise the geometric ABH profile.…”

Enhanced absorption with multiple quadratically tapered elastic wedges of different lengths terminating a uniform beam

“…An optimised thickness profile of a circular indentation on a plate, providing significant reduction of the plate vibration, was proposed in [7], which could also be utilised for beam terminations rather than plate indentations. Geometrical variations of the termination power-law taper were considered in [8],…”

Special Issue: “Advances in Structural Mechanics Modeled with FEM”

“…The paper by Rothe et al [11] highlighted the enormous potentialities of additive manufacturing, especially as far as the advanced acoustic design measures like Acoustic Black Holes are concerned. They specified that the continuous alignment of the mechanical impedance could be accomplished by means of the layer-wise material deposition by setting different filling patterns and levels of filling which characterized the technique.…”