Material Parameter Identification for Acoustic Simulation of Additively Manufactured Structures.

Sebastian Rothe,Thomas Vietor,Christopher Blech,Sabine C Langer,Hagen Watschke

doi:10.3390/ma14010168

Sebastian Rothe, Thomas Vietor + Show 3 more

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https://doi.org/10.3390/ma14010168

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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.

Highlights

The development of new measures to reduce noise in our environment is an important contribution to comfort and from a health point of view
In Equation (1), vi are the velocities of each surface point i and Fi the exciting force. These parameters are frequency-dependent, which results in a h2 value dependent on frequency f
The identified frequency-dependent material parameters by Section 4.2 are applied to each beam specimen and solved with ∆ f = 20 Hz

Summary

Introduction

The development of new measures to reduce noise in our environment is an important contribution to comfort and from a health point of view. New advanced design measures are needed to achieve these objectives. This is accompanies the challenge of using unconventional manufacturing processes and providing mechanical models for reliable simulations. The possibilities of integrating acoustic measures and other properties are often limited due to the given manufacturing constraints of conventional processes. With the help of additive manufacturing (AM), completely new possibilities open up. In this contribution, the additive manufacturing process material extrusion (MEX) is focused upon. If AM is used to produce structures with integrated acoustic measures or functions, design restrictions are significantly reduced. Due to the layer-wise build-up of the parts, AM allows almost every design, even a fully integrated measure. The step-wise build-up leads to anisotropies and inhomogeneities, which have to be considered depending on the individual task

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