Principle of stiffness variation based on matching composite structures with fibers

Stiffness adjustment is essential to enhance the environment adaptability of many machines and soft robots. In this paper, a principle for stiffness variation based on fiber-reinforced structure matching (meshing) was proposed. By this proposed method, a flexible flat structure can change its stiffness more readily compared to existing approaches. The basic principle is that two soft laminates made of fibrous composites have complementary shapes that can interlock with each other in a controlled way; the resulting structure will be soft when the two laminates separate, but rigid when the two laminates interlock with each other. Therefore, the stiffness of a structure can be adjusted by altering between the separated and matched states. The principle was validated by a matching structure composed of two commercial toothed belts, which can change its stiffness up to 40 times just by a small vacuum pressure of 0.4 atm.