According to Penn Engineering, researchers have discovered that introducing controlled disorder into 3D printed mechanical metamaterials can make them over twice as resistant to cracking. This breakthrough could significantly enhance the durability of these materials without altering their base composition.
Mechanical metamaterials, produced using digital manufacturing techniques like 3D printing and laser cutting, offer unique properties such as enhanced strength and stiffness. However, their fragility has been a major limitation. By tweaking the internal geometry rather than the material itself, researchers found that toughness could be increased by 2.6x.
Nature often employs structural disorder for durability – examples include bone, nacre (the iridescent layer inside seashells), and mussel byssus threads. Inspired by these natural materials, the researchers tested different levels of disorder in their designs. They started with a triangular lattice structure and systematically varied the positioning of the nodes where the triangles meet. Through thousands of computer simulations and physical tests, they identified an optimal level of disorder that maximized toughness without compromising strength.
The key discovery was that cracks in optimally disordered structures do not travel in straight lines – requiring more energy to propagate. This finding was visually confirmed using a technique that tracked how stress distributes within the material. Compared to ordered structures, disordered ones distributed damage over a larger area – making them much more resistant to fracture.
Despite its advantages, designing and manufacturing disordered structures is more complex than using regular repeating patterns like honeycombs. To achieve the desired precision, the researchers collaborated with specialists at Aarhus University, using an advanced laser cutter to fabricate the structures accurately.
This Penn Engineering study paves the way for broader adoption of mechanical metamaterials in industries where toughness is crucial, such as aerospace. By applying principles from natural materials, engineers could design more resilient structures with enhanced performance. The researchers hope their findings will encourage further exploration of disordered patterns in material science – ultimately leading to stronger and more adaptable materials for real-world applications.
