High Temperature Moire Interferometry And Its Applications

First of all, the fundamental theory of Moire Interferometry was elaborated. The various experimental methods and techniques of Moire Interferometry applied in high temperature mechanics measurements were discussed in detail. The application areas, research history, and current research of high temperature Moire Interferometry were also introduced.Based on the related research of the world, a high temperature Moire Interferometry measurement system was developed, which was successfully used to measure deformations under high temperature in real-time. This system included a high temperature moire oven, a four-beam moire interferometer, and high temperature gratings. A computer was used to collect and analyse the moire fringe patterns. The principles and functions of this system were discussed in detail.The above system was used to the measurement of the high temperature elastic constants and the study of creep deformations of several alloy materials used in aerial engines. The elastic constants of the materials including elastic modulus, Poisson ratio and shear modulus, under the conditions from room temperature to 1000℃, were successfully obtained. The experimental results showed that the elastic modulus and shear modulus decreased with the increasing of temperature in general. However, they kept constant even increased with the increasing of temperature in a certain temperature range. The experiment also found that some materials were not uniform and the mechanical properties of all materials varied with the different crystallizing directions of the materials.The high temperature Moire Interferometry was used with high speed photography to measure the dynamic deformation of aluminium plates with a central hole under tensile loading condition and heated by a strong current. Transient full-field fringe patterns were first successfully acquired in real-time during the heating process. Transient temperature of the specimen was simultaneously recorded by a temperature measurement system. The experimental results showed that dynamic moire fringe patterns can be measured during high heating rate conditions using highspeed photography.The high temperature Moire Interferometry was first applied to study the deformation and damage process of tensile aluminium plates radiated by high power laser. The full displacement fields around the laser radiation area on the aluminium plates' surfaces were measured in real-time during the laser radiation. Transient temperatures at the radiation center on the plates' surfaces were simultaneously recorded by a temperature measurement system. The experimental results showed that the damage forms of aluminium plates were different with the plates' widths. Both the load exerted on the plate and the plate width influenced the time of damage occurring. Finally, a brief theoretical analysis was made for the obtained results.