THE INFLUENCE OF SMALL STRENGHTENINGS AND WEAKENINGS ON LOAD CARRYING CAPICITY OF PLATES
Lower quality plates are often manufactured by cutting or stamping sheet metal produced by cold rolling and delivered in rolls. This sheet metal cannot be ideally straightened and its thickenss is often not equal to the nominal thickness. Due to the manufacturing technology and the straightening process, places of unequal thickness can be observed in the direction of rolling, i.e. at right angle to the edge of the roll. The load carrying capacity of a square plate depends on the angle at which it is cut out from such a sheel metal plate or on the direction of strengthening or weakening with respect to the loaded edge. The paper gives an estimation of the influence of small strengthenings and weakenings on the stability of a square plate. Strengthenings and weakenings were studied with respect to the angle they form with the loaded edge. It was found that small strengthenings and weekenings forming a right angle with the loaded edge do not affect its stability. However, strengthenings and weakenings forming any other angle with the loaded edge may importantly lower the buckling stability of the plate.
Buckling of Shear Loading Plates with Strengthenings
The paper treats the influence of either weakening or strengthening of rectangular plates on the critical external buckling load. The plate geometry was chosen so that the buckling process takes place in the elastic range. The simply supported plate is loaded with shear forces per unit length which act on its edges. The results present the buckling coefficient as a junction of the ratio between the thickness of the weakening or strengthening and the initial plate. The buckling coefficient is analyzed as a function of the ratio between the weight of the weakened or strengthened plate and the initial plate weight without weakening or strengthening too.
Plastic buckling of circular cylindrical shells under combined in-plane loads
Abstract A study of plastic buckling of a circular cylindrical shell subject to axial, torsional and circumferential loading stresses is presented. In the deformation model, the transverse shear is taken into account by a first-order theory with a correction factor. For the buckled equilibrium, the contributions of both v (circumferential displacement) and w (normal displacement) to the buckling are included so that a better accuracy can be achieved. J2 deformation theory and J2 flow theory of plasticity are used for the establishment of the constitutive relations for buckling analysis. With the existence of torsional load, the equation of radial equilibrium includes the term of mixed second-order derivative ∂ 2 w/ ∂ x ∂ y and the plastic in-plane stress–strain relations are anisotropic, and therefore a handy form of solution in terms of trigonometric functions is no longer possible. Consequently, the finite difference method is used. To improve the accuracy, a five-point finite difference scheme is employed instead of the conventional central difference. Numerical results of examples show the interactive roles of the in-plane loads in the plastic buckling.