Browsing by Author "Dittmer, Colin Thomas"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Open Access
    An incremental, non-linear displacement method for the elastic analysis of space trusses and plane frames
    (1975) Dittmer, Colin Thomas; Martin, JB
    An incremental displacement method which takes account of finite deflections is developed for the elastic non-linear analysis of space trusses. In the incremental loading procedure the elastic critical load of a structure is determined by establishing the load at which the determinant of the stiffness matrix passes through zero. Chord shortening due to bowing of truss compression members which have an initial imperfection in straightness is included in the analysis by modifying the member axial stiffness term. Numerical examples of truss analyses are presented and comparisons made with published results. An incremental non-linear displacement method is then developed for plane frame analysis taking account of finite deflections and the effect of axial force on flexural stiffness, but ignoring member chord shortening due to flexure. Numerical examples of plane frame analyses are presented and comparisons made with published results.
  • Thumbnail Image
    Item
    Open Access
    A programming approach to the numerical analysis of elasto-plastic continua
    (1978) Dittmer, Colin Thomas; Martin, J B
    The application of a kinematic minimum principle involving a continuous functional subject to inequality constraints is described for the incremental analysis of elasto-plastic continua. A simple algorithm is used for solution of the resulting mathematical programming problem. The formulation is presented for problems in plane stress, plane strain or axial symmetry, using triangular constant strain finite elements, and is extended to the use of cubic quadrilateral isoparametric elements for which a numerical integration technique is employed to account for elasto-plastic interfaces within elements. The material is assumed to obey the von Mises yield condition, and be either elastic-perfectly plastic or linear kinematic hardening. Computational details and solution techniques are described, and numerical examples compared with experimental and numerical results in the literature. Some assessment is made of the relative computational efficiency of the method.