Experiment § Photoelastic experiment
The biweekly report 196 and 197 reported that the stress of the test piece was observed with a polarizing stress meter. Figure 1 shows that the test piece has no stress at high temperatures. Slowly lower the temperature of the test piece to room temperature, and the photoelastic phenomenon of stress appears in the inner ring and outer ring (Figure 2). If the test piece quickly cooled from a high temperature into the water, which means a lot of stress has occurred (Figure 3). Put the video of Fig.3 at 20℃, the stress will be completely eliminated and return to the state of Fig.1. Slow cooling will get the characteristics of Fig.2. This experiment shows that stress is related to the cooling process, and the stress can also be eliminated by heating. Use a large iron ring as the outer frame, a small iron ring simulates internal parts, and the middle part is filled with resin (Figure 4). Because the two iron rings inside and outside limit the expansion and contraction of the resin, the entire test piece has a color in the stress meter, and the pattern after slow cooling is regular (Figure 5). The lines after rapid cooling are dense and chaotic (Figure 6). If put the test piece in Figure 6 at a high temperature and then slowly cool down to get the state in Figure5. This experiment shows the result of thermal shock, rapid cooling has great stress, and the subsequent high temperature will relieve the stress. The failure of the part is the result of repeated stress.
—Author: Mr. Zhan-Zu, Chen
Activity § This year’s exhibition information
We arrange different exhibitions at home and abroad every year. In addition to the just-concluded Munich Shanghai Electronic Manufacturing Equipment Exhibition, you can also see us at the following exhibitions: Taipei International Auto Electronics Show from April 11th to April 14th、Shanghai International New Energy Vehicle Battery Motor Electronic Control Exhibition from July 11th to July 13th、Smart Car Exhibition from August 29h to August 31st、China International Optoelectronic Expo from September 5th to September 8th and Japan Display Manufacturing and High-Performance Material Exhibition from December 5th to December 7th. What is especially noticed is that the Smart Car Optoelectronics Exhibition to be held at the end of August will be held together with the Taipei International Optoelectronics Week. We will definitely look forward to seeing you at the exhibition.
Knowledge § What is the F grade? What is the H grade?
The International Electrotechnical Commission classifies the maximum temperature that the insulation of motors, transformers, etc. is effective for a long time. Y grade means the highest operating temperature is 90℃，Agrade，Egrade，Bgradeare 105℃，120℃，130℃，Fgradeis155℃ and H grade is 180℃. ICE recommends suitable insulator materials for different classifications based on past experience. For example, Y grade electrical products can use paper or cotton as the insulating materials, E grade can use epoxy resin, phenolic resin, PET film, etc., F grade can use mica flakes, glass fiber cloth soaked with vanity water, epoxy resin, Alkyd resin, etc., inorganic materials are recommended to be used most frequently above grade H, and silica gel is recommended for adhesives. Although there are different recommended materials for different classifications, due to the continuous updating of materials, the early experience is no longer used, so ICE proposes experimental methods to determine the effectiveness of materials for insulation at long-term high temperatures.
Living § Different India
Indian culture is relatively foreign to us. There are poor and rich, different religions, caste systems, and hundreds of languages and a population of over one billion constitute a unique country. This time on a business trip to India to see the exhibition (PAINTINDIA), what impressed me most was the local food and transportation. The staple food of Indians is actually made up of various cakes and spices (Masala) with curry paste. Spices can indeed boost appetite in hot weather and it seems that all food in India is curry flavor! The streets of India are quite chaotic, 80% of the time the driver is honking the horn. All kinds of cars are crowded on the endless street, the road is bumpy and there are no rules, but they continue to move forward. If the atmosphere in the street is very active, the Thousands of People Laundry will show a sad side: the laundry workers are all from lower castes, and they or their children will do this kind of work for a lifetime, can only earn less than one hundred Taiwan dollars a day. No matter how hard you work, you cannot make a difference because of your status. Even so, they still work hard. I want to tell my children: You who grew up in a free and prosperous country are really happy!
—Author: Mr.Zheng-Kuan, Yao
