抄録
In this experimental study, three PVC shell specimens were formed by thermovacuum process. They were clamped to steel support rings with synthetic resin. The loading was of the constant deflection type. In this theoretical analysis, Marguerre's non-linear differential equations were used. The out-of-plane equilibrium equation was solved by means of Galerkin's method. Concentrated loads were assumed to be the limit state of distributed loads with infinitely small loading area. The good agreement between theoretical and experimental results is obtained. Concentrated loads develop locally large deflection near the loading points. In the case of a single concentrated load, the present results do not indicate the presence of any buckling phenomena for the deflection less than about ten times as large as the shell thickness. The deflection at any load level is larger as the loading point is nearer the apex. In the case of two-point loads, there exists the minimum value of the distance between these two points for which buckling takes place. The large deflection behavior including the buckling phenomenon varies greatly with the symmetrical geometrical initial imperfection. However, for the deflection less than the shell thickness, the effects of the initial imperfection on the load-deflection process are less important. For the shells under concentrated loads, the design by means of deflection limitation as well as allowable stresses may be recommended.
