In the fields of aerospace and nuclear power applications, materials and structural parts face extremely high temperature working conditions. Changes in mechanical behavior such as thermal deformation and crack propagation affect the safety and life of the equipment. Digital image correlation (DIC) technology has become a powerful tool for material mechanics research under high temperature conditions due to its advantages of non-contact, full-field measurement, and anti-interference.
Recently, Qianyanlang engineers and R&D personnel of a domestic head equipment company jointly carried out a high-temperature resistant specimen tensile test based on high-temperature DIC technology, verified the stability and accuracy of high-temperature DIC technology, and explored new methods for evaluating the performance of high-temperature materials.
Figure 1 Schematic diagram of high temperature DIC measurement system
The experiment uses the Qianyanlang high-temperature DIC measurement system, and the core configuration is as follows:
1) Image acquisition equipment: Qianyanlang Revealer high-resolution camera 4096×3000 @30fps, equipped with a 50mm large-field industrial lens.
2) Light source system: 450nm band 100W high-power blue light source, equipped with imported filters to suppress high-temperature red light.
3) DIC software: Revealer self-developed RDIC strain measurement and analysis software is used to support real-time full-field strain calculation and displacement tracking.
The experimental platform also includes a vacuum high-temperature furnace (maximum controllable temperature 1900°C), composite specimens, extensometers, etc.
1) Build a DIC measurement system to cover the target field of view of 15×15cm.
2) Spray high-temperature inorganic speckle material to the surface of the specimen.
3) Install a blue light source and filter to reduce exposure time and improve image contrast.
4) Start the high-temperature tensile testing machine, trigger the DIC system synchronously, and collect a total of 1,800 frames of images.
5) Use the Revealer DIC software to measure and analyze the displacement data, and compare and verify it with the extensometer measurement results.
The displacement data of the specimen gauge section measured by the high-temperature DIC system and the traditional extensometer are compared as follows:
1) In the elastic stage, the deviation between the displacement data measured by the high-temperature DIC system and the extensometer is ≤1.2%;
2) In the plastic stage, the deviation between the displacement data measured by the high-temperature DIC and the extensometer is ≤2.8%;
3) In the critical stage before fracture, the maximum deviation is 3.5% due to the local speckle blur caused by the high-temperature white fog.
The standard deviation of the full-field displacement measurement is ≤0.03mm, which verifies the reliability of the non-contact measurement of the high-temperature DIC system.
This experiment verified the high-precision measurement capability of the DIC measurement system under extreme high temperature conditions, solved the problem of speckle material melting and suppression of red light interference under high temperature environment, and provided reliable data support for the performance evaluation of materials under high temperature tensile state. In the future, Qianyanlang will continue to follow the scientific research trends in the field of high temperature mechanics, continue to overcome the difficulties of ultra-high temperature DIC measurement technology, and promote the engineering application of digital image correlation DIC measurement technology under complex conditions.
