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# Create a 36 page essay paper that discusses Shell Elements: Implementation in Sequentially Linear Analysis.When analyzing more complex problems, an effective approach for inhibiting errors from occurr

Create a 36 page essay paper that discusses Shell Elements: Implementation in Sequentially Linear Analysis.

When analyzing more complex problems, an effective approach for inhibiting errors from occurrence is to use analytical techniques so as to test the Finite Element program over simpler examples. Despite numerous techniques being developed to overcome the convergence problems, however, the sequentially linear analytical (SLA) technique has an edge over the others when modeling cracks or damage of full-scale structures since the SLA technique successfully matches the potentials of total strain fixed crack models. Shell Elements: Implementation in Sequentially Linear Analysis The potential of sequentially linear analysis is stretched to 3-D structures by using the shell elements. Although the analysis with complete three dimensional solid elements can be done, however the shell elements offer an efficient way to model numerous conventional structures. The generalized method for the solution is similar to that in the 2-D structures. Conventionally, the shell elements are used in FE analysis when one direction of the structures is thin, for example: the case in floors, walls, and roofs. The shells offer an efficient way to model the three dimensional structures without the finite elements of the three dimensional solid, consequently to which the analyses get complicated and slow analyses provided that they are not compulsory. The theory of Mindlin-Reissner shell is applied in this formulation, which assumes the stress through the thickness (normal to the centre of the shell-surface) to be equal to zero, whereas the points of the material perpendicular to the central surface of the shell continue to be in a straight line after deformation (despite not requiring to stay normal to the central surface of the shell). In accordance to the Cartesian co-ordinate system, in which the central surface of the shell is aligned with the n-s co-ordinate plane whereas the thickness direction perpendicular to the central surface of the shell is described through the t-coordinate, the correlation of the stress-strain can be given by: _________ (1) Here E- represents the modulus of elasticity, v- represents the Poisson’s ratio, and G-- represents the shear stiffness, in the given directions of n-, s- and t-. In the beginning, prior to the occurrence of any damage, the material is considered to be isotropic that causes: Here the sub-script o represents the initial stage at which the material holds the undamaged properties. By, integrating the above mentioned two equations, we get the conventional stiffness matrix of the shell related to the isotropic materials as given below: In the model, the nonlinear behavior is modeled by applying the damage increment at the critical point of integration. If the cracking occurs at any particular point of integration then the direction of the crack is fixed, and the normal elasticity, En, of the crack is decreased. The stiffness matrix given above in equation (1) is applied at this point instead of the isotropic stiffness matrix that is no longer applicable here. In the ns plane, the Poisson’s ratios decrease with the same rate as that of the relative values of elastic modulus.