what's the difference between the eiffel towerand the washington monument? both structures soar to impressive heights,and each was the world's tallest building when completed. but the washington monumentis a massive stone structure, while the eiffel tower achieves similar strength using a latticeof steel beams and struts that is mostly open air, gaining its strength from the geometricarrangement of those elements. now engineers at mit and lawrence livermorenational laboratory (llnl) have devised a way to translate that airy, yet remarkablystrong, structure down to the microscale - designing a system that could be fabricated from a varietyof materials, such as metals or polymers, and that may set new records for stiffnessfor a given weight.
the new design is based on the use of microlatticeswith nanoscale features, combining great stiffness and strength with ultralow density.the actual production of such materials is made possible by a high-precision 3-d printingprocess called projection microstereolithography. normally, stiffness and strength declineswith the density of any material; that's why when bone density decreases, fractures becomemore likely. but using the right mathematically determined structures to distribute and directthe loads, the lighter structure can maintain its strength. it is similar to the way eiffeltower gets its strenth by the way of the arrangement of vertical, horizontal, and diagonal beams. this newly invented material is among thelightest in the world.
however, because of its microarchitected layout,it performs with four orders of magnitude higher stiffness than unstructured materials,like aerogels, at a comparable density. these matericals can easily withstand a loadof more than 160,000 times their own weight. so far, the researchers at mit have testedthe process using three engineering materials — metal, ceramic, and polymer — and allshowed the same properties of being stiff at light weight. by using light to imprint features onto polymeror plastic,the researchers disproved the established diffraction limit, and they proved first timethat it is possible to print sub-wavelength features one-hundredth the thickness of ahuman hair. this discovery allows manufacturers
to imprint finer features into items suchas dvds to significantly improve storage capabilities, or to probe the traffic of protein or dna. this approach could be useful anywhere there'sa need for a combination of high stiffness (for load bearing), high strength, and lightweight — such as in structures to be deployed in space, where every bit of weight adds significantlyto the cost of launch. but the researcher says there may also be applications at smallerscale, such as in batteries for portable devices, where reduced weight is also highly desirable.
how much does 3d printing material cost,another property of these materials is thatthey conduct sound and elastic waves very uniformly, meaning they could lead to newacoustic metamaterials, that could help control
how waves bend over a curved surface. as this research was funded by darpa, it couldalso end up on robots and drones.
