Posted: December 18, 2017

AFRL Materials and Manufacturing Directorate researchers recently took advantage of a unique and rare research opportunity to better understand the behavior of materials used in the additive manufacturing process.

Once a little-known curiosity, the popularity of additive manufacturing, or 3-D printing as it is commonly known, has increased in recent years, both among researchers and home hobbyists. The technology can easily be used to create a wide variety of common and not-so-common objects. It’s no surprise, then, that the military is interested in putting this versatile technology to use for the warfighter. 

The additive manufacturing process involves depositing, or “printing,” thin layers of material on top of each other, following a pattern and slowly building until the layers form a complete solid object. AFRL researchers are interested in using this technology for a variety of purposes, including to quickly and inexpensively produce non-critical replacement parts in the field. 

The technology, however, is not yet mature enough for practical warfighter use. The complication arises in the way printed layers keep their shape when bonding to each other. Material porosity and other factors such as weak blending can result in poor bonding between layers, weakening the overall structure of the additively manufactured component. 

To address this problem, in addition to reinforcement fillers, researchers add nanofillers to the composite medium to act as flow and setting (rheology) modifiers, and to aid in overall structural bonding. In common terms, the resulting behavior can be compared to that of toothpaste, which flows easily under pressure but doesn’t drip or flow when at rest. The precise amount of nanofiller, when added to a reinforcement filler such as carbon fiber, will greatly improve the mechanical properties of a printed part. Therefore, understanding the material properties and dynamics of different mixtures of composites and nanofillers is an important step in making additive manufacturing technology more practical for common use.   


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