Probing the memory of materials

Materials have memories. As they age, their mechanical properties change, including their responses to external strain and stress. Typically, researchers and engineers have used complex models to try to describe these changes so they can better understand how materials in longstanding structures, such as buildings, bridges, aircrafts, and geological formations, will fare over time.

However, these approaches don’t explain the physical origin of aging. Vikash Pandey developed a mathematical model that suggests many aging phenomena arise naturally in a material over time. The relatively simple framework, called jerk-elasticity, links the slow evolution of microscopic interfacial contact regions to the large-scale behavior of materials and can reproduce several of the most common signatures of material aging, including logarithmic stress relaxation and power-law creep.

“Rather than treating aging as a secondary effect, I place it at the heart of the description,” Pandey said. He was surprised to find that the model can connect material aging and friction, which are traditionally separate fields. “The results suggest a common underlying mechanism may be responsible for many slow, time-dependent phenomena observed throughout nature and technology.”

This could be used to better understand natural and engineered materials performing over long timescales, such as structural materials, polymers, and geological systems.

“We hope this work encourages researchers to explore whether aging itself, not just the material’s immediate response, should be treated as a fundamental part of material behavior,” Pandey said. “If so, this could open new ways of studying memory, friction, and long-term deformation across many branches of science and engineering.”

Next, Pandey plans to test this framework against a larger range of experiments and materials, including geophysical systems.

Source: “A linear time-variant rheological model for frictional aging, stress relaxation, and creep,” by Vikash Pandey, Journal of Rheology (2026). The article can be accessed at https://doi.org/10.1122/8.0001179 .