To solve the problems such as too much trial-and-error, limited material being involved in the graphs and calculation results being obviously influenced by artificial factors and errors of the graphs in the design of external pressure vessel according to current standard ASME Ⅷ-1, GB150 and EN13445, the mathematic expression of the graphic charts is examined, and a set of analytical equations and algorithms for the linear and nonlinear instability of external pressure vessel are established. The equation was applied to calculate the ultimate buckling pressure of cylinder and spherical shells. The algorithm here provided can not only avoid the shortages of current graphic analysis methods, but also be convenient for technicians to calculate, which could enrich and consummate the graphic charts in the current standards and be useful to the design of external pressure vessels to be made of new materials.

A non-contact Fourier-domain optical coherence creep tomography (OCCT) is developed and employed in real-time non-contact creep measurement. Experiments on thermal deformation were carried out by using the self-developed OCCT to measure a high-temperature structure. In the OCCT system, a high-performance spectrometer, and a thermal light are, respectively, employed as the detector and the light source. Due to the broadband of the spectrometer and light source, the system provided high robust performance with an excellent deformation measurement resolution of sub-millimeter scale. Due to the energy leakage effect of FFT, a spectrum correction technique was employed to enhance the resolution of the OCCT system. From the experimental results, the self-developed OCCT has great potential applications in non-contact real-time creep measurement of high-temperature structures.