Engineers working on the Netherlands’ Wilhelmina Canal back in June 2016 had the privilege of installing the world’s largest composite locks. The lock gates were needed to accommodate a deepening and widening of the canal along with ships that just keep getting bigger. A year-and-a-half later, the locks are still a source of awe and wonder.
So why did engineers choose composites over wood and steel? There are a number of reasons, as outlined in a June 2016 article in Composites Today. Below you will find each of the reasons along with a basic explanation. Suffice it to say that what was done in the Netherlands is likely to be repeated on future canal projects of similar or larger size. Composites seem to be the best way to go right now.
1. Structural Demands
Numerous lock projects of smaller size and scale have already utilized composite materials. But the Wilhelmina installation pushed the envelope. Each gate in the lock system measures 20.3′ x 42.3′, which is demanding even for steel and wood.
Engineers needed a material that would exhibit exceptional tensile strength and rigidity, resist water pressure and continual contact, and stand up to routine ship impact. Moreover, the material has to last for at least eight decades. Composite materials meet all those requirements.
2. Low Weight
Another thing engineers were looking for was a material with a relatively low weight. The composite gates weigh roughly 24 metric tons each, which is 50% less than steel and 25% less than wood. The lower weight made installing the gates a lot easier. Builders were not required to bring in specialized equipment capable of handling much heavier steel or wood doors. Instead, much lighter cranes placed the composite gates in place without incident.
3. Mechanical Stress
Lastly, lock designers knew all too well how much stress steel and wood gates put on internal lock mechanics. Not only do motors and gears have to work to move the weight of the gates, but they’re also working against the weight and pressure of the water. Composite gates reduce the stress on mechanics significantly. The weight and pressure of the water does not change, but now motors and gears are having to work less to move the weight of the gates themselves.
Composite Gates a Perfect Fit
Workers who stood by and witnessed the installation of the composite gates might possibly say they were a perfect fit. That’s true in more ways than one. Not only did the gates slide right into place, but time has revealed that composite materials were perfect for their construction.
One of the big draws of composites like carbon fiber is tensile strength. Rock West Composites, a Utah company specializing in carbon fiber, explains that tensile strength is measured by the amount of force necessary to break an object. Composites exhibit a very high strength-to-weight ratio that allows engineers to use it in a long list of applications that aren’t suitable for steel, aluminum, and other materials.
The high-strength-to-weight ratio is just what engineers in the Netherlands needed for their lock gates. Not only will the gates withstand water pressure and routine impact with ships, but they will not develop the kind of impact damage steel and wood gates endure over time. That means less stress on the gates and, quite likely, longer life as well.
Engineers in the Netherlands chose composite lock gates for their project because these made the most sense. Like so many other industries, lock engineers are discovering that the benefits of composite materials far outweigh the few downsides that exist.