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Student Corner: A Void's Value

| On 03, Sep 2007

By Abram Teplitskiy

A void is “a discontinuity in a substance…an exceptional resource, because it is always available, extremely cheap and can be easily mixed with other resources forming, for example, hollow and porous structures, foam, bubbles, etc.” However odd that may sound, inventors should take note. In TRIZ, you review your available resources. It is easy to overlook an empty space as a resource, but it may be the key to solving your problem.

I recently read about a 4-year-old American girl who, playing with a suction cup discovered that the cup easily could be connected with the polished surface of a box. Once that connection was made, the cup could be used for opening such a box. The wonder of this discovery is that suction cups are easily accessible – Student Corner readers can easily get their own to attempt similar experiments.

For example, press the cup to a vertical polished panel and you get a hook for hanging towels. The secret of how a suction cup works is simple – after pushing the cup to an object’s flat surface, air is pressed out from under the cup. Atmospheric pressure provides enough force to keep the cup connected. A friend once visited a tool shop and found a suction cup, which was developed to lift industrial range weights. Figure 1 shows a mini suction cup with quick release grips that can cling to all smooth surfaces and generates enough suction to pull a 15-pound object.

Figure 1: Mini Lifting Suction Tool

(Courtesy of Alexandro Sarmiento)

A powerful can be force created by atmospheric pressure. In 1654, Otto von Guericke conducted his famous Magdeburg hemispheres experiment, showing that teams of horses could not separate two hemispheres from which the air had been evacuated.

Figure 2: Magdeburg Hemispheres Experiment

(Courtesy of Merle and Kelly Cunningham)

The inventor of the vacuum flask was Sir James Dewar, a Scottish chemist working at the University of Cambridge. In 1893, while working on the properties of very cold materials, he invented a double-walled flask to keep the contents very cold. It was known at the time that a vacuum could provide insulation, but inserting such a layer around a glass vessel (glass being a poor conductor of heat), made a flask’s contents able to stay either cold or hot. The vacuum was created and then sealed by melting the top; the inner wall was coated on both sides with mercury. Dewar flasks, commonly known as a thermos, are now prevalent. These products are the results of the work of a vacuum – a void.

Figure 3: Dewar Flask

U.S. Patent # 872,795

Now, let’s examine how voids work in open space. The Soviet Moon-16 spacecraft, shown in Figure 4, makes soft landings on the Moon. To provide the spacecraft with better vision, a powerful projector was installed on its legs to illuminate the landing area. Lamps, used in Moon-16 experiments, consisted of three main components: a glower, glass flask and a cup.

Figure 4: Lightning System on Moon-16 Spacecraft

During landing experiments, the lamp was switched on but quickly burned out. The problem? The glass bulb developed cracks due to the vibrations of the working engines. The bulb was destroyed and the lamp burned out. The addition of a vacuum layer protected the bulb from vibrations and the spacecraft’s vision was restored.

There are many examples of void-connected technologies used in construction. In the beginning of the 20th century in the Odessa region in Ukraine, close to the coast of the Black Sea, this area included stones that were used to construct buildings. In the 1960s, it was necessary to build a refinery in this area. It was necessary to make the soil denser in order to make the “voided” area suitable to build upon.

For more than 30 years it has been a common practice to structurally isolate a building from expansive soil movements by suspending the interior floor and grade beam above the clays and then transmitting loads to zones of more volumetrically stable soil using different foundations. A necessary part of these structures was different types of voids.

Figure 5: Corrugated Voids Used
for Foundations

Courtesy of Faina Teplitskaya

As shown in Figure 5, the void space beneath the beams allows expansive clays to swell without exerting a load on the beam itself. Void forms are inexpensive, lightweight and easily installed, leading to their general use and acceptance. It is one of safest methods of construction in locations in which expansive soils are spread.

The use of voids can produce humorous examples for their use. I met a construction student and we started to discuss how to make concrete panels lighter. Construction panels usually have voids inside panels to reduce expenditures of all materials – such voids are usually panels filled with air. As a result of our discussion, the student proposed that the panels could be filled with hot air, like smoke, which would decrease the average density of panels. It would, therefore, be easier to transport the panels. The resource for filling the concrete panels with smoke? Collect the smoke produced by smokers during breaks in work, as shown in Figure 6.

Figure 6: Collecting Smoke to Reduce
the Weight of Concrete Panels

Courtesy of Anatoliy Nelidin

Now consider an air balloon, as shown in Figure 7. A vertical shaft is inserted inside the balloon. Because this shaft is actually a tube, air can be pumped through the tube into the balloon, expanding and filling the balloon’s volume from the inside.

Figure 7: Balloon With Vertical Shaft

SU Patent # 1,462,089

Because the balloon is hermetically connected with the tube, when inflated the balloon wall can reach the wall of an underground void – underground emptiness. Stretching data can be transmitted to a surface electronic device, which would register the distance between the wall of emptiness and the tube in the void. By moving this balloon through the void, and taking consecutive “inflating” measurements at different depths, we end up with the volumetric profile of the void.

At the start of my career, I proposed making a heat-insulating concrete material by making porous spheres on a rotating inclined table, keeping them under high temperature. As a result, we had porous spheres. Then, we saturated them with water, put them under pressure left them until we had a high porosity concrete mixture – resulting in a strong, porous concrete. (We applied for a patent, but unfortunately 15 years earlier, another inventor received a patent for taking weeds, mixing them with cement, putting the mixture under press, and then into an oven. During the process, the weeds lost some water, which reacted with cement to make concrete.)

In all of these examples, an important – and often key – resource to solving the problem was taking advantage of “nothing.” The next time you need to create something, do not forget the value of a void.

Happy inventing!