Why are buildings made into "potato chips"? Not to tempt you, but because they are strong...

01 Potato Chips. What shape are you?

In fact, the potato chips sold on the market are roughly divided into two shapes, namely the parabolic shape represented by Lay's and Pringles potato chips and the saddle shape. (As shown below)

(Lays potato chips on the left | Pringles potato chips on the right)

There was a debate on the Internet about which of the two was less fragile, known as the potato chip dispute.

Which side won the argument? Let's analyze it.

02 Magical Saddle Noodles

The saddle surface, also known as the hyperbolic paraboloid, is named after its shape similar to a saddle. The structure of the saddle surface is formed by a concave parabola moving on another convex parabola. The horizontal contour line of the surface is a hyperbola, and the perpendicular to the contour line is a parabola, so it is called a hyperbolic paraboloid. Its function analytical expression is:

(The red and white lines are parabolas of two surfaces respectively)

The geometric characteristics of the hyperbolic paraboloid allow the entire surface to be viewed as two parts: one is a cable parallel to the high corner point, and the other is an arch parallel to the low corner point. The two are orthogonal to each other to form a spatial force system, which gives full play to the compression of the arch and the tension of the cable. That is, when squeezed by external force, the concave arch structure bears pressure, and when pulled by external force, the convex cable structure can withstand greater tension, making this structure more stable than other types of structures.

The hyperbolic paraboloid shape therefore cannot form stress lines, so even if cracks appear on the potato chips, the entire piece will not break, at most only the edges and corners will be bumped.

03 The slightly inferior parabolic cylinder

By carefully observing the two different types of potato chips in the picture above, you will find that the shape of Lay's potato chips is not a hyperbolic parabola, but a parabolic cylinder (as shown below)

Its function expression is:

Its generatrix is ​​parallel to the Z axis, and its geometric features make it easy for stress lines to form at the generatrix, causing it to break. If you observe carefully, you will find that most Lays potato chips break in half.

04Comparison: The Winner Is Determined

Due to the difference in geometric characteristics between the two, Pringles potato chips cannot form stress lines compared to Lays potato chips, and can withstand higher degrees of compression and stretching, so Pringles potato chips win the potato chip competition.

In addition to being more stable and less prone to breaking, saddle-shaped chips have another advantage: they are easier to stack during transportation, saving space and fitting perfectly. Even…

You can build a ring out of potato chips with a hyperbolic paraboloid! (amazing)

05Interesting “Potato Chip Building”

(Left: 2012 London Olympic Velodrome, right: Scotiabank Saddledome)

Do the two buildings in the picture above look like two huge potato chips? This is also the result of the saddle surface structure’s stable performance characteristics that are not easily deformed when subjected to tension and pulling forces. This greatly increases the force limit of the support system. The process is simple, safe and reliable, and it can use less building materials and a shorter construction period to build a more stable building.

Contributors: Southwest University Popular Science Space Station, Chongqing Physics Society, Beibei District Science and Technology Association

Audit expert: Zhang Qiaoming

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