Ceramic Matrix Composites, Ultra-High Temperature Ceramics, Additive Manufacturing

My research area if focused on the mechanical behavior of structural metal alloys and specifically on fatigue and creep. For the past three years my group has been involved in using ultrasonic fatigue to examine the very high cycle fatigue behavior of magnesium, aluminum, titanium alloys and nickel-base superalloys. Our goals are to understand the mechanisms of fatigue crack initiation and crack growth where fatigue lifetimes may be as long as 109 cycles and to understand how microstructural variability can be incorporated into probabilistic models for fatigue life prediction. My research group is also investigating the influence of composition and microstructure on creep behavior in magnesium alloys. Here the emphasis is on understanding the role of microstructural stability during creep in die cast magnesium alloys intend for elevated temperature applications. These research efforts are funded by NSF, AFOSR, DARPA, Ford Motor Company and USAMP.

Dr. Mansfield's research focused on the application of advanced microscopy techniques to the chemical, morphological, and crystallographic characterization ofa wide variety ofmaterials. He served as the laboratory manager of the University of Michigan Electron Microbeam Analysis Laboratory (EMAL) from 1987-2005, then as the laboratory manager and associate laboratory director from 2005-15. In 2015, when EMAL was renamed as the Michigan Center for Materials Characterization ((MC)²), Dr. Mansfield was promoted to director ofeducation and engagement, a position that he held until his retirement.
In his position in the EMAL/(MC)², Dr. Mansfield taught, mentored, and collaborated with over 6,110 undergraduate students, graduate students, and post-doctoral researchers in the field of nanoscale materials characterization. He taught the introductory electron microscopy course MSE562, over a dozen different techniques seminars for new users to EMALI/(MC)², modules of the College of Engineering's Responsible Conduct for Research and Scholarship, and numerous guest lectures in electron microscopy techniques across campus. His efforts were always focused on student success and have ensured that graduate practitioners in advanced materials characterization are among the most proficient in the field, both nationally and internationally.
In addition, his numerous contributions to the university have included ensuring that external funding was secured to maintain the EMAL/(MC)² as a world-class facility for materials science research.

Current research interests range from the molecular dynamics of mechanical relaxation of polymers to the high-speed, low-cost manufacturing of fiber composite structures and includes fracture processes in polymers and composites and failure analysis. Related to mechanical relaxation is the physical aging of polymer glasses. The nature of molecular motion in polymer glasses and the parameters that control the kinetics of physical aging are being studied. The goal is to be able to predict aging rates at normal service temperatures where experimental measurements would take too long. Current study of fracture processes ranges from fundamental studies of the mechanisms of crack propagation in brittle materials to the use of fracture in fiber composite structures for crash energy absorption.

Research into high-speed, low-cost fiber composite structure manufacturing involves several problems of the "liquid molding" process, in which liquid resin is injected into a closed mold containing a fiber preform. The problems being studied are the design and manufacture of the fiber preform and the displacement of air and the wetting of the fibers by the injected resin. A related problem being studied is the repair of such composite structures after damage.

Research activities focus on various aspects of the physical and mechanical behavior of polymer-based materials. The emphasis is on understanding the fundamental mechanisms governing their behavior, with the ultimate goal of modifying polymers on microscopic and macroscopic levels to enhance performance.

A new area of investigation relates to polymers for electronic devices and MEMS: low-K dielectrics, packaging, and thin films. Other current work includes investigations into the nature of cooperative molecular motions in glassy polymers and the effect of changes in the molecular architecture on these motions. These motions influence the diffusion, viscoelastic, and fracture behavior of polymers. Another group of projects studies the deformation and fracture mechanisms of multi-phase polymers. Methods of investigation include various mechanical characterization techniques, optical and electron microscopy, positron annihilation spectroscopy (in some cases utilizing a monoenergetic low energy positron beam), chemical synthesis, and numerical simulation.