§ 12-2 Basic Equations Solving sheet bending problem in terms of displacement Choose the sheet bending w as the basic unknown quantity and express the other physical quantities with w (1) Geometric Function Fetch a small rectangle ABCD on the middle plane, as shown in fig. Its side B lengths are dx and dy. Under action of the load, the rectangle is bent to flexural z plane ABCdo suppose the bending atD point a is w, the obliquities of stretch flexural plane along direction x and y are and ow 1313 § 12－2 Basic Equations Solving sheet bending problem in terms of displacement. Choose the sheet bending as the basic unknown quantity， and express the other physical quantities with . w w （1）Geometric Function Fetch a small rectangle ABCD on the middle plane, as shown in fig.. Its side lengths are dx and dy. Under action of the load, the rectangle is bent to flexural plane A ’B ’C’D’。suppose the bending at point A is ,the obliquities of stretch flexural plane along direction x and y are and . w y w x w     dx x w   y w   dy y z D C A B  A B x D C