Study of elastoplastic state of A spherical shell with round unsupported apertures

Conclusions

• 1. The use of miniature foil tensoresistors for measuring large deformations with a base of 1 mm facilitates the study of the deformation state of spherical shells with unsupported apertures.

• 2. The most highly stressed point in the spherical shell with unsupported apertures is the point on the contour of the aperture located on the external surface of the shell.

• 3. In attempts at the theoretical solution of the elastoplastic problem by the terminal difference method, the choice of the step of the independent variable is rationally made by comparing the decision obtained with the accurate solution achieved with the Richardson formula.

• 4. The rate of convergence of the method of sequential approximations depends on the level of the load and the mechanical properties of the shell material. The number of iterations varies in wide limits, from several to 20–24.

• 5. The coefficient of stress concentrations with increase in load diminishes in the elastic region from values equal to 3.5 to 1.3–1.4. The coefficient of deformation concentrations increases to 9–10; and then when the entire shéll is converted into the plastic state, diminishes to 5–9. The theoretical investigations of the elastoplastic state in shells with apertures showed excellent correspondence with the experiment, which indicates the effectiveness of the methods of elastoplastic calculations discussed in [6].