The capacity of twin cable. II
Equations (14), (15) and (16) are Michell's conditions which are thus seen to be the natural boundary conditions of the variational problem for the stress function. The manner in which these equations are used in determining <f> is obvious. Let 0o, 0i. 02, 03 be the biharmonic functions defined by the following boundary conditions: 1) 0o and d<j>o/dn have the prescribed boundary values on the loaded boundary curve Ci and vanish on the other boundary curve C2; 2) cf>i=d<j>i/dn = 0 on Ci, 4>i=xi and d<t>\/dn = n\ on C2; 3) 02=d02/dw=O on Ci, (£2 ="£2 and dfa/dn =tii on C2; 4) 03=d03/d» = O on Ci, 4>s = 1 and d<j>,/dn = 0 on C2. Substituting 4> = <j> 0 + 0101 + 0202 + b<t>3