Nav: Home

The secret strength of gnashing teeth

September 10, 2019

The strength of teeth is told on the scale of millimeters. Porcelain smiles are kind of like ceramics -- except that while china plates shatter when smashed against each other, our teeth don't, and it's because they are full of defects.

Those defects are what inspired research led by Susanta Ghosh, assistant professor in the Department of Mechanical Engineering-Engineering Mechanics at Michigan Technological University. The work came out recently in the journal Mechanics of Materials. Along with a team of dedicated graduate students -- Upendra Yadav, Mark Coldren and Praveen Bulusu -- and fellow mechanical engineer Trisha Sain, Ghosh examined what's called the microarchitecture of brittle materials like glass and ceramics.

"Since the time of alchemists people have tried to create new materials," Ghosh said. "What they did was at the chemical level and we work at the microscale. Changing the geometries -- the microarchitecture -- of a material is a new paradigm and opens up many new possibilities because we're working with well-known materials."

Glass is one such material. Making stronger glass brings us back to teeth -- and seashells. On the micro level, the primary hard and brittle components of teeth and shells have weak interfaces or defects. These interfaces are filled with soft polymers. As teeth gnash and shells bump, the soft spots cushion the hard plates, letting them slide past one another. Under further deformation, they get interlocked like hook-and-loop fasteners or Velcro, thus carrying huge loads. But while chewing, no one would be able to see the shape of a tooth change with the naked eye. The shifting microarchitecture happens on the scale of microns, and its interlocking structure rebounds until a sticky caramel or rogue popcorn kernel pushes the sliding plates to the breaking point.

That breaking point is what Ghosh studies. Researchers in the field have found in experiments that adding small defects to glass can increase the strength of the material 200 times over. That means that the soft defects slow down the failure, guiding the propagation of cracks, and increases the energy absorption in the brittle material.

"The failure process is irreversible and complicated because the architectures that trap the crack through a predetermined path can be curved and complex," Ghosh said. "The models we work with try to describe fracture propagation and the contact mechanics at the interface between two hard-brittle building blocks."

Ghosh's team developed two models. The first uses finite element modeling (FEM) and is detailed and highly accurate, but expensive. The second is surprisingly accurate, though less so than FEM techniques, and is much cheaper to calculate.

FEM is a numerical model that takes apart a complex whole by evaluating separate pieces -- called finite elements -- then puts everything back together again using the calculus of variations. Humpty Dumpty and all the king's men would have liked FEM, but it's no quick roadside trick. To run such complex calculations requires a supercomputer, like Superior at Michigan Tech, and ensuring that the right inputs get plugged in takes diligence, patience and a keen eye for coding detail. Using FEM for super strong glass means modeling all the possible interactions between the material's hard plates and soft spots. Analytical modeling offers an alternative.

"We wanted a simple, approximate model to describe the material," Ghosh said, explaining the team used more basic math equations than the FEM calculations to outline and describe the shapes within the material and how they might interact. "Of course, an experiment is the ultimate test, but more efficient modeling helps us speed up the development process and save money by focusing on materials that work well in the models."

Both the FEM and analytical microarchitecture modeling from Ghosh's lab can help make ceramics, biomedical implants and the glass in buildings as tough as our teeth.
-end-


Michigan Technological University

Related Glass Articles:

Glass tables can cause life-threatening injuries
Faulty glass in tables can cause life-threatening injuries, according to a Rutgers study, which provides evidence that stricter federal regulations are needed to protect consumers.
The nature of glass-forming liquids is more clear
Researchers from The University of Tokyo have found that attractive and repulsive interactions between particles are both essential to form structural order that controls the dynamics of glass-forming liquids.
Experimental study of how 'metallic glass' forms challenges paradigm in glass research
Unlike in a crystal, the atoms in a metallic glass are not ordered when the liquid solidifies.
On-demand glass is right around the corner
A research group coordinated by physicists of the University of Trento was able to probe internal stress in colloidal glasses, a crucial step to control the mechanical properties of glasses.
Glass from a 3D printer
ETH researchers used a 3D printing process to produce complex and highly porous glass objects.
Making glass more clear
Northwestern University researchers have developed an algorithm that makes it possible to design glassy materials with dynamic properties and predict their continually changing behaviors.
Researchers use 3D printer to print glass
For the first time, researchers have successfully 3D printed chalcogenide glass, a unique material used to make optical components that operate at mid-infrared wavelengths.
New family of glass good for lenses
A new composition of germanosilicate glass created by adding zinc oxide has properties good for lens applications, according to Penn State researchers.
In-depth insights into glass corrosion
Silicate glass has many applications, including the use as a nuclear waste form to immobilize radioactive elements from spent fuel.
New research questions the 'Glass Cliff' and corroborates the persistent 'Glass Ceiling'
Are women more likely to be appointed to leadership positions in crisis situations when companies are struggling with declining profits?
More Glass News and Glass Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.