Polyethylene windproof net guards the “cloud top”

On February 18, in the freestyle skiing women’s U-shaped field final, Gu Ailing scored an average of over 90 points in the previous two jumps, locking the championship ahead of time and winning the eighth gold medal for the Chinese sports delegation. In the Genting Ski Complex, nine snow-white towers of different sizes and eight white “curtains” printed with the Winter Olympics logo were erected beside the tracks for aerial skills and U-shaped field skills. These white “curtains” are actually windproof nets made of high-density polyethylene materials, not only for beautiful decoration, but also to provide a safety barrier for athletes to perform wonderful high-altitude tricks.
The windproof net protecting the Yunding ski resort complex was independently developed by the team of Professor Liu Qingkuan, director of the Wind Engineering Research Center of Shijiazhuang Railway University. The windbreak net has not only been unanimously recognized and highly praised by experts such as the International Snow Federation, but also received many praises from participating athletes during the official competition.

“The windscreen is amazing, it protects us from the wind,” said men’s snowboarder and three-time Winter Olympic champion Sean White. “The trackside net is amazing,” said American freestyle skier Megan Nick. The windbreak helps us a lot and keeps us stable even when the wind is blowing.” Freestyle skier Winter Winecki also said: “In many competition venues, athletes have to compete with the wind. But here, the windscreen is designed to keep us safe and allow us to play more tricks in the air.”
According to Liu Qingkuan, the Yunding stadium group in Zhangjiakou competition area is responsible for most of the freestyle skiing and snowboard competitions. Some skiing competitions have very strict requirements on the wind, especially in the two events of aerial skills and U-shaped field skills, where athletes take off The height is large, and many difficult movements are to be performed in the air. Under the influence of strong winds, the skills may be deformed and the performance will be affected, and the balance will be lost in the air and injured. In the previous Winter Olympics, World Championships and other important competitions, there have been many accidents in which athletes lost their balance in the air due to strong winds and suffered injuries. Therefore, FIS recommends that the wind speed of the track should be controlled below 3.5 m/s during the competition.
Previously, the windproof nets for the skiing competition venues of the Winter Olympics were all produced and installed by European companies. The artificial materials were expensive, the quotations were relatively high, and the construction period was time-consuming. Moreover, the foreign epidemic also caused certain difficulties in supply. Therefore, the current Winter Olympics tried to use domestic products. Windscreen. However, there is no windscreen design and manufacturer in China that can meet the requirements of FIS. In the end, the team of Liu Qingkuan took on the task of developing the windbreak net.
According to Liu Qingkuan, the International Snow Federation has strict requirements on a number of indicators of the windbreak net for ski competitions, and the design must be based on wind shielding efficiency, light transmission, color, strength and other aspects. The project team first collected various parameters of the wind speed during the same period of the Winter Olympics in recent years, and then carried out meteorological analysis, terrain tests, and wind tunnel tests to obtain data such as the corresponding relationship between the existing meteorological stations and the wind speed and direction of each point on the athletes’ trajectory, and then Taking the site 3.5 m/s as the target, computer numerical calculations and wind tunnel tests were repeatedly carried out, and finally it was decided to use the high-density polyethylene material with strong flexibility, and the specific parameters of the high-density polyethylene windproof net were determined.
After solving the parameter problem, the visual effect of the windbreak net becomes a problem again. The permeability of the windproof net is inversely proportional to the wind blocking effect. They repeatedly weighed and found a manufacturer of windproof net weaving equipment in the south. Using the 12-needle weaving technology, we compiled a three-dimensional structure windproof that meets both the wind blocking effect and the light transmission requirements. network.
Liu Qingkuan said that the high-density polyethylene windproof net is about 4 mm thick, and the internal three-dimensional space structure is complex. The combination of holes just meets the needs of the dual performance of windproof and light transmission, as well as the tensile performance under strong wind. The windproof net can withstand a pressure of 1.2 tons per meter of width, 80% of the wind downstream of the neighboring net can be blocked, and the wind speed of more than 10 m/s can be reduced to 3.5 m/s or even lower, which greatly ensures the safety and movement of athletes of completion. It has good low temperature resistance. After repeated freezing and thawing at -40°C, it can still not be hard or brittle, and always maintain flexibility and strength. It also has flame retardancy and UV resistance at the same time, the cost is not high, and the economic indicators are good. When in use, the windproof net can be opened and retracted into the tower within 6 to 8 minutes according to the needs of the site, which can be used repeatedly.
In addition, in order to ensure the low temperature resistance of the tensioning power system, the driving device is also equipped with a rapid low temperature heating device to ensure that the tensioning and recycling operations can be quickly started at low temperature.
On the aerial skills track of Genting Ski Resort, Xu Mengtao and Qi Guangpu contributed two gold medals to China respectively, and the mixed team of Xu Mengtao, Qi Guangpu and Jia Zongyang won a silver medal; in the U-shaped skill competition, Gu Ailing won a gold medal. The achievement of these excellent results is inseparable from the efforts of the athletes and the guarantee of the windbreak net team during the game. “During routine training and pre-competition venues, our team is always on duty on site, monitoring wind speed, snow surface maintenance parameters, opening and recovery of windbreak nets, passing of referees and snowmaking vehicles, etc. It is worthwhile to see the excellent results of Chinese players, no matter how hard the process is,” said Liu Qingkuan proudly.

Original author: Dong Xinqi China Chemical Industry News