A 3D p-version LSFEF for laminated composites incorporating laminate physics

Conference · Thu Dec 31 04:00:00 EST 1998

OSTI ID:357773

Nayak, H V; Surana, K S ^[1]

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1. Univ. of Kansas, Lawrence, KS (United States). Dept. of Mechanical Engineering

This paper presents a 3D p-version least square finite element formulation (LSFEF) for laminated composites incorporating the physics of interlamina behavior. At the interlaminar boundary of two laminas consisting of dissimilar materials, the laminate physics requires continuity of u, v, w, {var_epsilon}{sub xx}, {var_epsilon}{sub yy}, {gamma}{sub xy}, {sigma}{sub zz}, {tau}{sub yz}, and {tau}{sub xz}, and discontinuity of {var_epsilon}{sub zz} {gamma}{sub yz}, {gamma}{sub xz}, {sigma}{sub xx}, {sigma}{sub yx} and {tau}{sub xy}. In traditional Galerkin finite element formulation (in which u, v, w, are interpolated) and more recent least square finite formulation (in which u, v, w, and all stresses are interpolated) interlamina discontinuities of the quantities constitute singularity thus requiring mesh refinements and high p-levels in the vicinity of each interface. In the formulation presented, 3D equations of elasticity are recast in an appropriate form involving u, v, w, {var_epsilon}{sub xx}, {var_epsilon}{sub yy}, {gamma}{sub xy}, {sigma}{sub zz} {tau}{sub yz}, and {tau}{sub xz} for which a p-version least squares finite element formulation is constructed using equal order C{sup 0} interpolation for each of the three displacements, strains and stresses ensuring interlamina continuity of these. Interlamina discontinuities of {var_epsilon}{sub zz}, {gamma}{sub yz}, {gamma}{sub xz}, {sigma}{sub xx}, {sigma}{sub yy} and {tau}{sub xy} are automatically generated due to different material properties of the mating laminas. In the formulation, precise behavior of laminate physics is incorporated in the finite element formulation, that is the displacements, strains, stresses exhibiting interlamina continuity are interpolated while discontinuous strains and stresses are generated as a consequence of dissimilar material properties of the mating laminas, hence they do not constitute singularities. Thus, when using the present formulation, mesh refinements and high p-levels are not required near the interlamina boundaries.

• OSTI ID: 357773
• Report Number(s): CONF-980213--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
FINITE ELEMENT METHOD
INTERFACES
LAYERS
STRAINS
STRESS ANALYSIS
STRESSES
THREE-DIMENSIONAL CALCULATIONS