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August 20, 2019

2017 – 2018

The 3D printer has come a long way since the introduction in the mid 1980s of the first devices that could print real physical objects using instructions provided by digital files. Today’s models can create anything from toys and common household items to aerospace components and body parts, using materials that include epoxy resins, titanium, steel, wax, wood fibers, polycarbonate, nylon, and a wide range of plastics.

Two men stand in front of a chalkboard with advanced mathematics written on it.

In a project called “Tuning Acoustic Resonance in 3D Printed Components,” Larry Wilen, senior research scientist at the Yale School of Engineering and Applied Science, developed a method for exploring the mechanical properties — such as elasticity and density — of certain materials used in 3D printing processes.  

Wilen, who teaches a course in acoustics and musical instrument design jointly with the Department of Music’s Konrad Kaczmarek, explains that materials possess natural frequencies corresponding to motions such as bending, twisting, and compressing. Resonant ultrasound spectroscopy is an experimental technique used to measure these frequencies. “The measurements we took,” he says, “could provide information about whether a given material would be suitable for various applications. For instance, if the material is used for making musical instruments or instrument parts — like a guitar bridge or a xylophone bar — the measurements would give information critical to tuning the instruments.” 

A man manipulating a device.

Existing acoustic techniques for measuring resonant frequencies tend to be inaccurate at the lower frequencies and therefor unsuited for the types of materials Wilen was testing. His process, which offers greater accuracy, uses inexpensive magnetic stereo phonograph needles to send sound through the material samples and then measure the mechanical responses

While Wilen and Kaczmarek can use the musical applications of this technique in teaching their course, Wilen emphasizes that the information gleaned from resonant ultrasound spectroscopy also has significant engineering applications in fields such as aviation and construction.  When companies such as New York’s Mass Transit Authority explore 3D printing to meet their replacement parts needs, test protocols to verify material quality are an important consideration. The types of measurement work Wilen is pursuing will help build a basis to ensure crucial 3D printed components meet their designed strength and quality parameters.