New maps predict strength of composites

The design maps from Rice University researchers show how materials rate in all three categories (stiffness, toughness and strength) and where they overlap.

A Rice University study is said to help scientists and engineers judge the ultimate strength, stiffness and toughness of composite materials for applications such as nanoscale electronics to buildings. The universal maps predict the properties of natural and biomimetic platelet-matrix composites (like nacre, aka mother-of-pearl) and synthetic stacks (or heterostructures) of materials like graphene and boron nitride.

The Rice researchers, Rouzbeh Shahsavari and Navid Sakhavand, said their computer-drawn maps are “dimensionless” and their findings will work as well for materials built with nanoscale blocks as they would for a brick wall, or larger.

The formula relies on four characteristics of the individual materials under consideration for a composite: their length, a ratio based on their respective stiffness, their plasticity and how they overlap.

The researchers’ design maps show how materials rate in all three categories (stiffness, toughness and strength) and where they overlap. Their goal is to help engineers calculate the ultimate qualities of a material and cut down on trial and error.

Rouzbeh Shahsavari said the work is an important milestone toward a better ability to decode and replicate nacre’s architecture for lightweight, high-performance composites. These could benefit the aerospace, automotive and construction industries, he said.

A map of 15 of the materials they tested shows natural ones like nacre tend to be strong and tough while synthetics lean toward strong and stiff. Shahsavari said he hopes materials scientists will use the design maps to give their composites the best possible combination of all three properties.

The Department of Civil and Environmental Engineering at Rice and the National Science Foundation supported the research.