TRIZ Physical Contradictions & Skis
Editor | On 01, Mar 2010
By Pentti Soderlin
Editor’s note: This article is an update to a previous piece titled “Ski – A Perfect Example for TRIZ.” The following offers physical contradictions with the Theory of Inventive Problem Solving (TRIZ) using the example of skis. Tools used include separating in time, space and structure, using phase transition and moving from current levels to sub or super levels. Skis are used to illustrate how to proceed in deep snow (a poorly functioning system).
Skis as a Tool
Some of the oldest tools made by man included inventions such as the axe, fire and skis. When exploring marshes for energy use (peat) archeologists found the remains of ancient skis preserved by water. Skis were extremely important for man during the winter when large amounts of snow hindered free motion in the woods. Without skis man would sink deep into the snow.
Sami woman on skis, adapted from Olaus Magnus, 18831
The first skis were made of wood. The size and forms developed over time were two different sizes of skis. Long skis were used to slide; short skis were used to push for speed. A stick or lance in the hands was used to push for speed to hunt game.
The following is a system drawing from a problem into a working system:
Tar was a natural material used to protect skis over the years. Tar is a derivative of wood. Without tar the skis would rot or decay in open air as would any wooden object without protective coating such as paint. A solution is to add a substance or a modification of a substance. Tar, therefore, is made of wood, preferably from pine by tar burning or dry distillation.
The Physical Contradiction
Tar was also useful for providing a sliding effect and grip. Tar was elementary wax, which possessed two mutually contradictory properties:
Neither, however, was good enough, so tallow was invented to use for sliding. Tallow was spread under the longer ski; shorter (original) skis were tarred without any tallow. Also, skis were flat (only the front was turned upwards to help keep afloat). Modern cross country skis are made of plastic and of equal length and curved in the middle plus they are designed with a turned-up toe.
Skiing techniques and skis are combined to provide two functions:
- Pushing (for additional speed and to proceed)
There is a clear physical contradiction:
- The wax should slide
- The wax should not slide, but grip
The tar or wax should have two mutually exclusive properties: to slide and to grip (to have both A and anti-A).The solution for the physical contradiction is separation in time (operational times, OT1 and OT2), separation in space (operational zones, OZ1 and OZ2) and separation in structure (the form of the skis).
There are two operational times (OT) and operational zones (OZ):
- In the former case of sliding, the OT1 and the OZ1 will be the fore and tail of the skis.
- In the latter of pushing for more speed, the OT2 and the OZ2 is in the middle of the skis. For sliding purposes a sliding wax is spread over the OZ1. To provide grip or friction during OT2, a special grip wax is applied on the middle or OZ2.
Note: A further separation in structure is in the form of the skis.
The form of the skis (structural solution) requires some additional information. When selecting skis an individual must choose a pair that curve in the middle and do not touch the ground. This applies when standing with weight equally distributed on both skis. This is important for the sliding phase. On the other hand, the skis should go flat and the wax should grip the track when moving weight on the other ski and simultaneously pushing downwards and backwards for speed. Next, test them and make turns, left, right, left, right.
Skiing is also a good example of phase transition. For example, when ice skating the ice below the skates melts for a fraction of a second, therefore, enabling the skates to slide. The same idea is valid for skiing. The snow crystals under the skis will melt and form a layer of microscopic water droplets underneath the skis.
From Macro to Micro Solution (Sub Level)
There is a possibility to move from macro to micro. There have been numerous attempts to use macro scale design modifications with various bottom structures at the middle of skis. There is either a threshold type or zig zag groove solution placed at the bottom of the skis. In TRIZ a micro solution is preferred instead of a macro solution.
The NanogripTM: A Finnish Innovation
The Nanogrip is used to cover the bottom of skis with a nano coating or structure.1
Components of the Nanogrip:4
- A synthetic liquid material that is applied onto the whole length of a ski base.
- A glide wax and a grip wax at the same time that is applied onto the ski already at the factory.
- Suitable for all recreational skiers. Compared to a waxed ski, its gliding properties are slightly weaker (measured on glide tests as negative five percent to negative ten percent, offers shorter gliding distances).
- Has a wider range of conditions with its range from plus ten degrees Celsius to negative 20 degrees Celsius, an all-round grip system.
- The ski’s grip and glide are provided and assured by the Nanogrip’s ability to control the amount of water in between a ski and the snow.
- The ski should be selected a bit softer than normally used. A dealer can help with selecting the right pair.
- The grip is optimal right from the start.
A patent survey reveals that there are several patents on various nanostructure applications. The inventions relate to structural and sliding coating for winter sports equipment, in particular for skis and snowboards.
The sliding coating may be easily extruded, however, anyone familiar with fiberglass or reinforced plastic structures knows how difficult it is to make a flat and smooth surface. For this problem the TRIZ solution to use is principle # 25, self service.
After a few kilometers the snow crystals have grinded down to a reasonable flat and smooth surface. This principle is used in numerous contexts such as in car engines when an individual should avoid extreme power or speed during the first 1000 to 1500 kilometers in order to let the piston rings hone to the cylinder’s surface.
The Nanogrip is based on the nano scale reactions. The innovation was developed through numerous trials and errors by Matti Jarvinen.2 Jarvinen claims that the nano coating of the surface of the skis is manifold, the effectual surface is tenfold or “several square meters.” The nano is a method to further extend the slide and grip functions. The difference between the static friction and sliding can be maximized, says Jarvinen.3
When sliding, skis are moving on a water layer surface. The drier the snow is, the lower the temperature is, the thinner the water layer. In wet conditions the water layer might be so thick that it causes suction. This will be broken by the nano coating. When pushing the skis forward the water bed is broken by the pressure causing friction.2 Jarvinen is cautious and reluctant to give the exact details of the invention and the composites of the nano coating.
In recreational skiing as well as in competitions the most important piece with the wax is to find a suitable grip wax for various conditions. Different waxes are used for different temperatures, especially temperatures that near freezing point are problematic. A poor choice of wax makes skiing a nightmare instead of a pleasure. There is no need for wax, but the nano coating both slides on snow and grips. This provides the ideal final result.
Ideal final result: The coating both slides and grips. The nano coating works better on wet snow. The structural change is no longer required, the ski might be flat.4
Super Level Solution
A super level solution is found because the method of skiing has changed from one style to more than one style. In major competitions there are different races for conventional skiing and for freestyle skiing or skating, which is a faster technique, but also considered more exhaustive (700 kcal/h compared with only 400 kcal/h in conventional style skiing). It also requires better conditions and a wider track.
The conventional style was used in the wilderness where no track existed or for recreational skiers on a track narrower than one used for skating. The conventional method is suitable, especially on deep new snow, which is smoother and less bearing. In springtime the snow might melt during the daytime and freeze during the night, when the surface of snow becomes icy and more bearing and more slippery, thus making it easier to skate, but worse for the conventional technique.
This article applies only to conventional cross country style skiing. The new freestyle uses skis, which are shorter and both use only sliding wax. The technique is called skating creating the effect of skating on ice.