A New Map for Composite Design and Testing

Researchers at Rice University in Houston are hoping their new theory on composite properties may help the oil and gas industry reduce the time it takes to develop and test new materials.

By comparing properties of composite structures using a new design map, Rice University researchers Rouzbeh Shahsavari, left, and Navid Sakhavand say engineers can better predict the strength, stiffness, and toughness of composite materials.
Photo courtesy of Jeff Fitlow, Rice University.

Researchers at Rice University in Houston are hoping their new theory on composite properties may help the oil and gas industry reduce the time it takes to develop and test new materials.

After 3 years of work, the researchers have created a design map that predicts strength, stiffness, and toughness of different materials when they are layered onto one another. Applications for this theoretical map may include pipes, downhole tools, and marine drilling risers, and especially those that are exposed to high-pressure/high-temperature environments.

To develop the map, the research team looked to nature. Rouzbeh Shahsavari, an assistant professor in the Department of Civil and Environmental Engineering at Rice, said that designing composites that are strong, tough, and lightweight is a big challenge for the materials science world.

Copper, for example, is tough and hard to break. But copper does not have the strength of ceramics, which can be engineered to be strong enough to stop bullets. Conversely, ceramics are not considered tough because when they are pushed to their limit, they tend to shatter or break into pieces. “But nature, on the other hand, has come up with a series of techniques to overcome these challenges,” he said.

Shahsavari said the everyday composites found in nature, such as bones and seashells, have been optimized through billions of years’ worth of evolution. The soft material in bones is responsible for ductility and toughness, while the harder materials give them strength. “That is why when you touch a bone, it is quite hard to break it, it is quite light, and once you break the bone, along the fracture you see several tough fibers coming out of it,” he said.

The trick to applying what nature has accomplished with something manmade is finding the right composition of materials and applying them in the right way. The map seeks to address this problem and can be used to design composite materials of any size, from the nanoscale to the very large.

The new theory about how to make composites may also help speed the development and qualification of new composite materials. This is something that has been a challenge for the oil and gas industry. While testing standards for steel and other metals exist, it has been much more difficult to establish them for composite materials and hybrid composites that incorporate steel.

Rouzbeh said he hopes that engineers can use the map to design a new material and then make a low-cost sample with a 3D printer. This is a fast evolving technology sometimes called additive manufacturing. The advantage of 3D printing is that it has a high level of accuracy, down to the micrometer, which allows it to make composites in the laboratory. Going this route provides technology developers with a shortcut.

Rather than make 10 or more large-scale composite systems to find the best ones, the 3D printer can be used to select the best two or three candidates to scale up for further testing. “Instead of doing trial and error strategies to make composites and test to see if they are going to fail or resist the load, first use a handy map to make the right composite for the right strength and right toughness,” Rouzbeh said.

The next step of the work at Rice is to develop the map for more complex structures and composite materials. The research team is also looking to collaborate with different industries, including oil and gas, to commercialize some of the technology involved.