Welcome to the Composites Age

I imagine every new material, when it’s developed, tends to look down its nose at the legacy materials that preceded it. Take the Bronze Age, for example, which started about 4,500 years ago. Bronze, which combines copper with tin and other materials, proved stronger and tougher than the copper it eventually replaced, which allowed bronze to become a highly useful alloy. It was used to make everything from artwork and decorative structures to weapons and farm implements. I’m sure bronze looked down its nose at copper.

Then, along came the Iron Age. Iron, because it was so readily available and did not require alloying to be useful, and because it could be easily smelted, quickly became the metal of choice, supplanting bronze and used to manufacture nails, tools, utensils, agricultural equipment and weapons. Iron definitely looked down its nose at bronze.

We in the composites industry are as guilty as anyone of looking down our noses at legacy materials.

And so it has gone, throughout the history of materials development — steel, aluminum, polymers, composites. Each of these possess strengths and weaknesses, and we seek applications for them that are a good match for the benefits they offer. We usually do this in one of two ways: We look to replace a legacy material that lacks an attribute of the new material, or develop a new application that previously had been out of reach of any material.

It's this replacement strategy that causes all of the looking down of noses. Replacing a legacy material requires that the new material convey value/performance advantages superior to that of the legacy material. In this way, the legacy material becomes inferior.

(By the way, I know this line of thinking ignores the fact that sometimes a superior material loses out to a legacy material because users of the legacy material are familiar with said material and are just plain reluctant to change. That’s a topic for another month.)

We in the composites industry are as guilty as anyone of looking down our noses at legacy materials. Steel is heavy and tends to corrode. Aluminum is susceptible to fatigue. Wood isn’t sustainable. Unreinforced plastics lack strength. Concrete has low tensile strength. And concrete reinforced with steel rebar — don’t get us started. We are justifiably proud of what composites can do.

Very occasionally, an application comes along that is, at once, a conversion opportunity and a new application. An example of this, explored in great depth by CW contributing writer Peggy Malnati in the September issue, is the battery enclosure for electric vehicles (EVs). Peggy’s story is actually Part 2 of a two-part series; you can find Part 1 in the August issue. Peggy explores the battery enclosure landscape thoroughly, reviewing in Part 1 how automotive Tier manufacturers are approaching this application. In Part 2, this month, she looks at how material suppliers — fibers and resins — are meeting the challenges posed by battery enclosures.

And what are the challenges? The initial challenge is the conversion opportunity, and the one most readily met by composites: lightweighting. Battery packs are heavy, thus they need an enclosure that’s lightweight. After that, the demands become increasingly complex and, in many ways, unique, which is the “new” part.

The list of demands is long: Provide torsional, modal and bending stiffness. Protect cells from corrosion, electrical shorts, stone impingement, dust and moisture intrusion and electrolyte leakage. Protect against electrostatic discharge (ESD) and electromagnetic interference/radio-frequency interference (EMI/RFI) from nearby systems, including radar and LiDAR from advanced driver assistance systems (ADAS). In a crash, physically protect the battery system from being crushed, impaled or shorting out due to water/moisture ingress. Keep battery cells within specified thermal operating range during charging/discharging in all weather. In the event of vehicle fire, keep fire out of the battery modules for as long as possible while protecting vehicle occupants from heat and flames that result from thermal runaway events inside the battery packs.

In short, what happens in the battery enclosure stays in the battery enclosure. And what happens outside the battery enclosure stays outside.

Reading Peggy’s articles, it’s difficult not to conclude that, for battery enclosures, composites will be the only material that can do the job cost effectively — thanks mainly to the variety of chemistry, resin and fiber solutions they offer. Does this mean we’re in the Composites Age? Perhaps. But it also makes we wonder which materials in the coming years might be looking down their nose at composites.