China's independent research and development of testing instruments breaks the technological monopoly of Europe and the United States
in China's ceramic manufacturing process, the soft clay will become fine ceramics with high hardness after firing at high temperature; In daily life, if you use a plastic spoon to fry vegetables, the plastic will slowly soften when encountering high temperature. This may be our simplest understanding that temperature will affect the mechanical properties of materials, but we still don't know what kind of materials will change at what temperature and strength
in the eyes of Li Weiguo, a professor at the school of aerospace and aeronautics of Chongqing University, the evolution of mechanical behavior of these materials with temperature can be predicted by theoretical models. His latest research achievement is that the mechanical behavior and strength properties of relevant materials can be predicted when the single variable of temperature is clear. His achievement is considered by domestic and foreign scholars as a major breakthrough in this field, and has made contributions to further promoting the development of high-tech fields such as aerospace, energy and nuclear industry in China
creatively put forward the "temperature correlation theoretical model" without fitting parameters.
with the rapid development of modern science and technology, the demand for expanding service conditions is becoming stronger and stronger, and the performance of materials under abnormal conditions has become a hot and difficult research topic. Take the aerospace field for example. The temperature of the aircraft can reach more than 3000 degrees Celsius when it is running at high speed. Under such a high temperature, 3. Under the condition that the oil return pipe should be inserted below the oil level of the oil tank, what kind of material can meet such harsh service requirements, and what changes will happen to its mechanical behavior? These problems have been puzzling researchers and restricting the development of related fields in China
Li Weiguo has been engaged in the research on the mechanical behavior and strength theory of solids under extreme conditions of ultra-high temperature since he worked as a postdoctoral researcher at Tsinghua University in 2005. "At that time, China had not established a quantitative relationship between material properties and related temperatures. To test at what temperature a material will fracture or deform, we can only rely on experiments." Li Weiguo said that the experiment is not only time-consuming and labor-intensive, but also the most critical is the high cost. After that, the establishment of theoretical prediction model of high temperature strength based on physical mechanism has become Li Weiguo's biggest topic
in order to overcome this problem, Li Weiguo collected and collated all kinds of experimental data, and classified and analyzed the data day and night. Through unremitting efforts, he creatively proposed the idea of temperature dependent modeling of material properties, broke through the restriction of temperature on the existing strength theoretical model, and established a temperature dependent fracture strength theoretical characterization model without any fitting parameters for ultra-high temperature ceramic materials for the first time
what does it mean to have no fitting parameters? Lev Davidovich Landau, the Nobel Laureate in physics, said: "the value of a model decreases exponentially with the number of fitting parameters it contains.". This makes it easier to recycle the model proposed by Professor Li Weiguo than the corresponding multi-layer packaging, without any fitting parameters, breaking through the requirements of the original high-temperature theoretical model for fitting "Holtzberg from composite castings Co., Ltd. in West Palm Beach, Florida, said the parameters, greatly reducing the experimental difficulty of studying high-temperature mechanical behavior, and improving the accuracy of the experimental results
independent research and development of testing instruments to break the technological monopoly of Europe and the United States
speaking of the world's aerospace industry, we can never ignore the great and pathetic space shuttle Columbia. The first launch in 1981 opened a new page in the world aerospace history. On February 1st, 2003, when the space shuttle Columbia passed through the atmosphere, it produced hot air as high as 1400 degrees Celsius, causing cracks in the wings. If it was found to be loose, ultra-high temperature gas entered the body, and finally exploded and disintegrated in the air, killing all seven astronauts. The thermal protection materials used by the space shuttle Columbia are made of ceramic materials
in recent years, the research on the strength of aircraft thermal protection materials in China has never stopped, but there are still many problems to be solved. "Especially the technological monopoly in Europe and the United States and other countries makes us more eager to have our own technology in this field." To this end, Li Weiguo began a long "learning road"
in fields such as aerospace and energy exploration, the ultra long environment experienced by materials is complex and changeable, which may be high temperature, extremely cold temperature, oxygen rich or oxygen thin. In view of this, on the basis of the "temperature correlation intensity model" previously proposed, Li Weiguo developed a test instrument to simulate the impact of complex hot stamping environment on materials by establishing three different environmental modules and allowing the specimen to switch between different environmental modules
now, with the efforts of Li Weiguo's team, the test version of the instrument has been completed. "Next, we will improve the equipment through experiments, hoping to develop instruments that can test various complex environments and help the development of China's aerospace industry." Li Weiguo said that the development of this equipment will be widely used in the performance testing of thermal barrier materials and environmental barrier coatings, which is equivalent to adding another guarantee for the application of high-temperature materials. "Real gold is not afraid of fire". After such a high standard test and detection, high-temperature materials that can maintain their original properties can withstand the test of the real complex impact environment and provide safety assurance for key areas such as national aerospace
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