Sound Absorption and Transmission Loss Properties of Open-Celled Aluminum Foams

Sound Absorption and Transmission Loss Properties of Open-Celled Aluminum Foams


Sparks, NV – ERG Aerospace is excited to announce the article Sound absorption and transmission loss properties of open-celled aluminum foams with stepwise relative density gradients has been published in volume 193 (May 2022) of ScienceDirect. ERG supported Wichita State University’s project, with funding from NASA. This article is the first publication in support of the ongoing project; with over the rotor testing at University of Notre Dame planned to be completed this summer.

ERG’s Design Engineer Jake Puppo, and Director of Engineering Denver Schaffarzick (co-author) are honored to have worked with Bhisham Sharma and the team in support of this project to further the understanding of acoustic properties of open-celled metal foam.

The team used open cell foam to research acoustical properties of compressed and uncompressed open-cell aluminum metal foams.

Foams were compressed to different ratios. Static airflows, acoustical, and other properties were measured with scanning electron microscopy and microphone impedance tubes.

Different ratio foams were then stacked and tests repeated to examine optimum performance of the foams.

The results showed that “open-celled metal foams with stepwise relative density gradients can be designed to provide tailored acoustic absorption performance while reducing the overall weight of the noise reduction package.”

Highlights from the article include:

  • Compressing open-celled foams distorts their struts and reduces the effective open porosity.
  • Cellular distortion increases the airflow resistivity and relative density of the foam.
  • Stepwise relative density gradients improve absorption at low- and mid-frequency ranges.
  • Transfer matrix method is used to tailor the absorption properties of gradient foams.
  • Stepwise gradients can allow design of lightweight foams with high absorption.

The study used open-celled Aluminum foams sold by ERG Aerospace Corporation under the commercial name Duocel®. This patented light-weight material is available only from ERG.

The article may be found here:

About ERG Aerospace:

ERG Aerospace has been in business since 1967 and is the sole manufacturer of Duocel®, a strong, light weight, rigid foam material with solid ligaments and a variety of uses. Duocel® foam is found in a variety of products including air/oil separators, heat sinks, energy absorbers, flame arrestors, electrodes and more. The company has components on the space shuttle, the international space station, and commercial aircraft around the world. ERG specializes in solutions of all sizes and has the capacity to manufacture custom components in house. The company holds several patents for their open-cell foam products.

More information about Duocel® may be found on ERG’s website:

Contact Information:
ERG Aerospace Corp.
55 Greg Street
Sparks, NV 89431