July/August_AMP_Digital

A D V A N C E D M A T E R I A L S & P R O C E S S E S | J U L Y / A U G U S T 2 0 2 0 1 1 received funding to build the system for the U.S. Air Force, where it will be primarily dedicated to titanium crys- tallography. CPCI can also characterize other metals, including beryllium, mag- nesium, cobalt, zinc, tin, and zirconium. The company says their technol- ogy could streamline the quality control process for manufacturers working with these metals. With their patented sys- tem, a titanium billet, sheet, or finished part can be placed in front of the sensor to image the surface with an eye-safe laser. Because the sample doesn’t need to be inserted into a small chamber, it doesn’t need to be cut—making the process nondestructive. This technology could potentially characterize titanium while a part is being produced, the company says, and the larger field of view makes it easier for experts and manufacturers to make critical decisions rapidly. It also could be used to analyze aircraft parts in service during maintenance checks. The sensor is portable enough to set up outside an aircraft and provide crystal- lographic images of parts in real time, improving flight safety. sandia.gov. MODELING FLEXIBLE MATERIALS Researchers from McMaster Univer- sity, Canada, developed a new model to better understand how materials used in flexible electronics behave under stress and strain—particularly, how they wrinkle and buckle. Flexible circuits have become a highly desirable commodity in modern technology, with applications in biotechnology, elec- tronics, and monitors. The design of flexible circuits generally involves a thin rigid capping layer—a metallic or poly- meric film—placed upon a thick flex- ible substrate, typically a soft and stretchable elastomer. Compressing this rigid capping layer can lead to local buckling with a sinusoidal wrinkling pattern that allows its excess surface area to be accommodated by the com- pressed substrate. The research team conducted an experiment to determine the geomet- rical parameters that dictate how a free- standing bilayer of film transitions into global or local buckling. The experiment also measured the effect of varying char- acteristics of the capping film and sub- strate layers, such as their relative thick- ness. Using Elastosil sheets, stress was placed on the material biaxially by shift- ing the well-adhered layers in different directions, while leaving the perpendic- ular direction of the material fixed. The result of the team’s experi- ments was a force balance model that allows researchers to better understand the amount and nature of wrinkling and buckling in materials that could form the basis of next-generation electronics. mcmaster.edu. These flexible circuits were created using carbon nanotubes. Courtesy of University of Illinois at Urbana-Champaign.