Thermal compensation design and implementation method for a near-net-shape (nns) molding of thermoset composite part based on temperature field and curing degree field

A thermal compensation design and implementation method for a near-net-shape (NNS) molding of a thermoset composite part based on a temperature field and a curing degree field, the thermoset composite part being made of a thermoset composite comprising a thermoset resin matrix and a fiber-reinforced phase;

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• the thermal compensation design and implementation method comprising:
• (S1) establishing a minimum symmetric unit model based on a size of the thermoset composite part, a size of a mold of the thermoset composite part, and an ambient temperature;
• (S2) performing, by a differential scanning calorimeter, a non-isothermal testing on the thermoset resin matrix;
• establishing a reaction rate-temperature relationship of the thermoset resin matrix during a curing process according to a change in heat flowrate;
• and establishing a curing kinetic model based on the reaction rate-temperature relationship;
• (S3) measuring parameters required for a heat transfer analysis to establish a heat transfer model during the NNS molding process;
• (S4) writing a molding temperature curve into a subprogram, wherein in a first calculation process, the molding temperature curve is a molding temperature curve of the thermoset resin matrix, and in a subsequent thermal compensation design, the molding temperature curve is a corrected molding temperature curve of the thermoset resin matrix, wherein the corrected molding temperature curve considers a thermal compensation introduced to a first thermal compensation region of the thermoset composite;
• (S5) performing a thermo-chemical coupled analysis on the thermoset composite to obtain a temperature field distribution procedure and a curing degree field distribution procedure of the thermoset composite during the NNS molding process;
• (S6) based on the temperature field distribution procedure and the curing degree field distribution procedure obtained in step (S5), performing a simulated thermal compensation on the first thermal compensation region during the NNS molding process, wherein a temperature of the first thermal compensation region is lower than a molding temperature with a temperature difference greater than or equal to 5% of the molding temperature;
• repeating steps (S4) and (S5) based on the corrected molding temperature curve of the thermoset resin matrix until a difference between temperatures of all regions and a current molding temperature is lower than 5% of the current molding temperature, so as to satisfy design requirements of a temperature field distribution and obtain a simulated thermal compensation design program;
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• if a curing degree of a certain area of the thermoset composite during the NNS molding process in the simulated thermal compensation design program is less than or equal to 0.9, regarding the area as a second thermal compensation region of the thermoset composite and optimizing the simulated thermal compensation design program based on a curing degree field by increasing a temperature of the second thermal compensation region to enhance the curing degree of the thermoset composite until the curing degree is greater than 0.9, so that a simulated thermal compensation design scheme that satisfies the design requirements of the temperature field distribution and design requirements of the curing degree field at the same time is obtained;
• (S7) assembling a thermal compensation device based on the simulated thermal compensation design scheme obtained in step (S6);
• and measuring a temperature evolution procedure of the first thermal compensation region and the second thermal compensation region during the NNS molding process through a buried temperature sensor;
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• (S8) when a difference between a measured temperature value and a simulated temperature value obtained from the simulated thermal compensation design scheme is greater than or equal to 5% of the simulated temperature value, optimizing the thermal compensation device until the difference between the measured temperature value and the simulated temperature value is less than 5% of the measured temperature value, so as to arrive at a desired thermal compensation design scheme and implementation method.