@inproceedings{ChristovPetrova2000,
  author    = {Christov, Christo T. and Petrova, Lyllia B.},
  title     = {COMPARISON OF SOME VARIANTS OF THE FINITE STRIP METHOD FOR ANALYSIS OF COMPLEX SHELL STRUCTURES},
  doi       = {10.25643/bauhaus-universitaet.576},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-5760},
  year      = {2000},
  abstract  = {The subject of this paper is to explore and evaluate the semi-analytical, analytical and numerical versions of the finite strip method (FSM) for static, dynamic and stability analyses of complex thin-walled structures. Many of bridge superstructures, some roof and floor structures, reservoirs, channels, tunnels, subways, layered shells and plates etc. can be analysed by this method. In both semi-analytical and analytical variants beam eigenvalue vibration or stability functions, orthogonal polynomials, products of these functions are used as longitudinal functions of the unknowns. In the numerical FSM spline longitudinal displacement functions are implemented. In the semi-analytical and numerical FSM conventional transverse shape functions for displacements are used. In the analytical FSM the accurate function of the strip normal displacement and the plane stress function are applied. These three basic variants of the FSM are compared in quality and quantity in view to the following: basic ideas, modelling, unknowns, DOF, a kind and order of the strips, longitudinal and transverse displacement and stress functions, compatibility requirements, boundary conditions, ways for obtaining of the strip stiffness and load matrices, a kind and size of the structure stiffness matrix and its band width, mesh density, necessary number of terms in length, accuracy and convergence of the stresses and displacements, approaches for refining results, input and output data, computer resources used, application area, closeness to other methods, options for future development. Numerical example is presented. Advantages and shortcomings are pointed. Conclusions are given.},
  subject      = {Schale},
  language  = {en}
}
@inproceedings{ChristovPetkov2000,
  author    = {Christov, Christo T. and Petkov, Zdravko B.},
  title     = {DETERMINATION OF THE DYNAMIC STRESS INTENSITY FACTOR USING ADVANCED ENERGY RELEASE EVALUATION},
  doi       = {10.25643/bauhaus-universitaet.577},
  url       = {http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20111215-5770},
  year      = {2000},
  abstract  = {In this study a simple effective procedure practically based upon the FEM for determination of the dynamic stress intensity factor (DSIF) depending on the input frequency and using an advanced strain energy release evaluation by the simultaneous release of a set of fictitious nodal spring links near the crack tip is developed and applied. The DSIF is expressed in terms of the released energy per unit crack length. The formulations of the linear fracture mechanics are accepted. This technique is theoretically based upon the eigenvalue problem for assessment of the spring stiffnesses and on the modal decomposition of the crack shape. The inertial effects are included into the released energy. A linear elastic material, time-dependent loading of sine type and steady state response of the structure are assumed. The procedure allows the opening, sliding and mixed modes of the structure fracture to be studied. This rational and powerful technique requires a mesh refinement near the crack tip. A numerical test example of a square notched steel plate under tension is given. Opening mode of fracture is studied only. The DSIF is calculated using a coarse mesh and a single node release for the released energy computation as well a fine mesh and simultaneous release of four links for more accurate values. The results are analyzed. Comparisons with the known exact results from a static loading are presented. Conclusions are derived. The values of the DSIF are significantly larger than the values of the corresponding static SIF. Significant peaks of the DSIF are observed near the natural frequences. This approach is general, practicable, reliable and versatile.},
  subject      = {Bruchmechanik},
  language  = {en}
}