Engineers and designers are always looking for new materials that combine high strength and low weight. These kinds of materials are useful in many areas, from aircraft to sports equipment to mobile devices. But what exactly makes something strong, lightweight, or both? There are a few key factors that contribute to these important material properties.
Atomic Structure
At the smallest scale, a material’s strength and weight depend on its atomic structure. Metals tend to be strong because they contain atoms arranged in rigid crystalline lattices. The orderly alignments of metal atoms resist being pushed out of shape. Woods derive strength from long strands of cellulose molecules bundled together in fibers. The long molecules become interlocked, giving solidity to the overall material. Hard plastics are formed of long hydrocarbon chains linked together into networks and matrices. The connections between chains create resistance to stress and impact.
Materials with such ordered internal structures have high strength. Nevertheless, they are also heavy or dense. Lighter materials have more space and gaps between their components. Foams contain pockets of gas between their solid parts. Honeycomb structures have open spaces surrounded by thin walls. These spacings decrease density and weight, but they also reduce strength by interrupting the continuity of the material. The goal is to use spacing judiciously to lower weight while retaining as much strength as possible.
Reinforcing Fibers
An effective way to boost the strength and minimize the weight of a material is to embed reinforcing fibers within a lightweight matrix. This takes advantage of strong, slender fibers such as carbon, glass, boron, silicon carbide, polyethylene and aramid to improve resistance to tension. The fibers provide stiffness and tensile strength to reinforce the matrix material surrounding them.
Using high-performance fibers, very strong, rigid composites can be made even with low-density matrices like epoxy, polyester resin or aluminum. Reinforcing fibers running in multiple directions prevent cracks and fractures from spreading through the material. And slender fibers with high length versus width ratios give tremendous strengthening effects with little added mass. Fiber reinforcement makes composites like fiberglass, carbon fiber and Kevlar much lighter and stronger than bulk materials of similar composition. This enables EPS manufacturers like Epsilyte to create foam insulation board with tough fiber-reinforced skins.
Geometry and Structure
Material dimensions, physical size, complexity, and consistency also determine relative strength and mass. Given equal mass and substance, a large object with thick walls tends to be stronger than a small thin-walled one. Fixed amounts of material flowing around corners and contours leave fewer molecules spanning vulnerable cross sections. But excess material bulk adds useless weight. Thus, shape optimization balances sufficient sizes against unnecessary extras.
Structurally solid designs endure stresses more easily than fragmented shapes prone to cracking at joints and interfaces. Unbroken geometries spread loads gradually through greater regions of material. However, bulky sizes raise weight while complicating manufacturing and transportation. Engineers refine computer models and physical prototypes, searching for lightweight structures that resist buckling, twisting and fracturing at stress points. Evolving 3D printing processes permit new forms not possible with older machining methods. Calculating load factors and safety margins for each application allows designers to select physical configurations able to withstand expected forces without failure.
Conclusion
Seeking the ideal balance of low weight and high strength continues motivating materials science innovation. Customized metallic alloys, reinforced polymers, active composites with dynamic properties, hybrid mixes merging distinct material classes; all aspire towards previously unattainable optimization. Future lightweight structures could adjust to reshape themselves, report on integrity issues, self-diagnose damage or failures, and self-repair deteriorated sections. Pursuing such possibilities and pushing boundaries ever further inspires the ceaseless quest for stronger, lighter, ever more incredible material creations.
