Study On Stress Analysis Method Of Film-based Structural Based On Stress-optical Law

The film-based structure has unique optical,mechanical and electromagnetic properties,and thus has a wide application prospect in the fields of heavy industry,light industry,military,petrochemical,etc.It is of great significance for stress analysis.Based on the stress-optical law,a new method for stress analysis of film-based structures has been developed.The main work is as follows:Based on the stress-optical law,an experimental system for stress analysis of film-based structures was established.The traditional Mach-Zehnder interference optical path has been improved to produce polarized light in different directions.A micro-loading device that applies a tensile load to the film-based structure is designed.The digital image correlation technique is used to measure the strain,thereby calculating the stress,and calculating the refractive index change amount of the material by analyzing the phase change of the interference fringe.Carry out relevant experiments and analyze the random error of the experimental system.Stress analysis experiments were carried out on single-layer structures.The theoretical model of the phase delay caused by the Poisson effect and the stress optical effect of the single-layer structure is established.The stress optical coefficient and stress measurement principle of the single-layer structure are analyzed.The stress optical coefficient of polycarbonate(PC)was measured to verify the reliability of the experimental system and measurement theory.The design experiments measured the stress optical coefficients A and B of the polyimide film.The stress of the edge of the porous polyimide film at the edge of the hole and the distal end of the hole under the tensile load was measured by the experimental system.The stress ratio was basically consistent with the finite element calculation.The experimental results show that the experimental system can perform stress analysis on single-layer structures.Stress analysis experiments were carried out on the film-based structure.The theoretical model of phase delay caused by Poisson effect and stress optical effect is established.The principle of stress optical coefficient measurement of film material and the principle of film-based structural stress measurement in film-based structure are analyzed.The design experiment measured the stress optical coefficients A and B of the nano-scale copper film.The stress distribution of the porous polyimide substrate/nanoscale metal copper film structure under tensile load was measured by the experimental system.The stress at the edge of the hole and the stress at the distal end of the hole were measured to be about 1.5 times,which is basically consistent with the finite element calculation.The experimental results show that the experimental system can perform stress analysis on the film-based structure.The above work shows that the stress analysis system designed in this paper can measure the internal stress of the film-based structure,which provides a feasible method for the non-destructive testing of the stress of the film-based structure and the residual stress measurement of the film-based structure.