Physicists Discover Inherent Property of Biological Materials that Explains Mechanical Efficiency of Tendons

Harvey Mudd College physics professor 马克Ilton 和 four of his students are celebrating the publication of their work in the Journal of the Royal Society Interface, which publishes articles of high-quality research at the intersection of the physical 和 life sciences.

Lead author Lucien Tsai ’24 along with Ilton 和 co-authors Paco Navarro ’25, Ingrid Wu ’23 和 Taylor Levinson ’25 performed summer research in Ilton’s 物理 of Soft Matter (PoSM) Lab that resulted in their paper, “Viscoelastic materials are most energy efficient when loaded 和 unloaded at equal rates.” As the paper’s self-explanatory title suggests, the research describes the results of the group’s investigation of the mechanical energy efficiency of biological springs (e.g. 肌腱).

“By underst和ing the properties of these materials,蔡崇信说, “we can extract principles for the design of bio-inspired spring-driven mechanisms. This study examines how the differences between the loading 和 unloading rates of these springs shape their performance.”

研究结果, obtained through innovative mechanical experiments, 和, in collaboration with biologists from the University of California, 欧文, unveil a crucial connection: symmetric rates, characterized by equal loading 和 unloading durations, offer superior mechanical efficiency. “使用数学模型, we find that an inherent property of biological materials is responsible for this rate-dependent effect: their hierarchical structure that imparts a broad range of relaxation times results in an efficient response to symmetric rates,蔡崇信说.

Ilton说Tsai, who worked on the project since its inception in 2021, helped steer the research in a different direction than Ilton had expected. “My original suggestion about how to model the tendon’s response to different loading 和 unloading rates was completely inadequate,伊尔顿说. “I suggested a simplified model with a single characteristic time in the material. It was Lucien who had the idea to take a different approach, 和 he included a range of characteristic times in his model of the tendons. It was this insight that led us to one of the paper’s main findings: the reason why tendons are so mechanically efficient when you load 和 unload them at the same rate is because they have a broad range of characteristic times in their material relaxation.”

“Having your first paper published is an exciting moment!伊尔顿这样评价他的学生. “The students discovered something new, which can be a really addictive experience. Not only does this paper help the students establish their track record as scientists, but they also experienced a rigorous peer review process. I think that having to address critique of your work in a positive way builds skill 和 character, which is something that translates well into life more broadly.”

This project was made possible by donors to the College’s 物理 Summer 研究 Fund 和 a grant from the National Science Foundation.