A finite element method including transverse stresses for thick laminated plates and shells /
| Main Author: | |
|---|---|
| Other Authors: | , |
| Format: | Thesis Book |
| Language: | English |
| Published: |
1990.
|
| Subjects: | |
| Online Access: | ProQuest, Abstract Link to OAKTrust copy |
| Abstract: | The present work attempts to compute transverse shear and normal stresses in thick laminated composite plates and shells by using shear-deformable finites element formulations. Both plate and solid elements are considered. Quasi-three-dimensional finites element formulations such as those developed by Hamdallah and Engblom1 and Fuehne and Engblom2 are conventional displacement formulations which relax the Kirchhoff hypothesis by independently prescribing three displacements and three rotations at each node. Interpolation functions are chosen with careful attention to obtaining the desired spatial variation in the transverse (inter-laminar) stresses. A fully three-dimensional solid finite element formulation containing three displacements per node with shear-deformable capability is also developed in this research. In-plane stresses are computed using the constitutive equations while the transverse stresses are found by integrating the equilibrium equations, a feature utilized by Engblom and Ochoa3, Hamdallah and Engblom1, and Fuehne and Engblom2. It is the objective of this work to extend the described formulations to include thick geometries by layering plate elements through the thickness and integrating the equilibrium equations through the sets of interfacing elements to obtain the transverse normal and shear stresses. This unique formulation is accomplished by defining displacement constraint equations at common boundaries of the elements and using a penalty function4 to mathematically enforce continuity at those interfaces. In this capacity, the penalty function serves as a very stiff spring between elements, forcing the two elements to act as a continuum. Continuity between the layers is represented by a set of three penalty parameters, which really act like the spring constants of the springs with a very large number representing a very stiff element. Two of these parameters serve to account for the continuity of interlaminar shear stresses across the interface, while the third parameter accounts for the continuity of interlaminar normal stress. Constraint equations for the solid element are simple, since nodes are at the interface. However, the plate element has nodes at the middle surface of the element. Continuity at the interface must account for displacements and rotations at the midsurface of the plate element... |
|---|---|
| Item Description: | Typescript (photocopy). Vita. "Major subject: Mechanincal engineering." |
| Physical Description: | xxi, 145 leaves : illustrations ; 29 cm |
| Bibliography: | Includes bibliographical references. |