Dr. Keisuke Umezawa and Dr. David Mollenhauer
Dr. Keisuke Umezawa and Dr. David Mollenhauer partner to research usability, capability and needs of research software. (U.S. Air Force photo/Donna Lindner)

Dr. Keisuke Umezawa of the Air Systems Research Center in the Japanese Ministry of Defense (JMoD) recently joined the Air Force Research Laboratory on an engineers and scientists exchange program (ESEP). The JMoD chose Umezawa for the ESEP based on his experience as a stress analysist of polymer matrix composite materials. Also, Umezawa has been heavily involved in the development of the next generation Japanese fighter aircraft, including the development of the test program for prototype PMC structures.

PMC materials consist of strong fibers embedded in a resilient plastic that hold them in place. The Air Force uses PMCs on many parts of an aircraft because they are much lighter and cheaper than other materials.

Umezawa’s primary work focuses on the modeling of damage evolution in PMC materials using an AFRL-developed research software package. This tool, known as BSAM, is a result of many years of research and development led by Dr. David Mollenhauer, a member of AFRL’s Composite Performance Research Team. The stress analysis software simulates damage processes in composite materials. Specifically, damage in PMCs is characterized by complex networks of cracking in the polymer matrix, delamination between layers and fiber fractures.

Umezawa is training on the software and then developing a variety of PMC damage simulations. His primary simulation campaign will focus on simulations of laminated PMCs that have a long, thin saw-cut, mimicking a crack, and observe how damage grows from these “cracks” within the BSAM simulation environment.

As with AFRL, the JMoD has come to the realization that commercial PMC damage codes are lacking in capability. BSAM has limited, but growing exposure in the research and design community. Training Dr. Umezawa in the use of this advanced code is a continuing step in spreading the word about this new useful tool. His efforts aid an ongoing experimental effort that examines damage in PMCs. Additionally, Umezawa brings insight to the U.S. Air Force on composite research and development at the JMOD, especially in relation to the new Japanese fighter program.