Crack growth in unidirectional composites using singular finite elements and interactive computer graphics

Graphical simulation of crack growth using singular finite elements and interactive computer graphics is presented. The study consists of two main parts : (i) the formulation and application of an anisotropic singular element (ASE) for analyzing homogeneous anisotropic materials with cracks and, (ii) graphical simulation of crack growth in unidirectional composites. Lekhnitskii’s stress function method is used to formulate the traction-free crack boundary value problem with the stress function expressed in a Laurent series. The geometry of the element is arbitrary. The development of the stiffness matrix for general anisotropic materials is presented and it is shown how the singular element can be incorporated into a conventional displacement based finite element program. The anisotropic singular element (ASE) developed is implemented to analyze cracked anisotropic materials subjected to inplane loading. A 2-D, displacement based linite element code is used and center cracked on- and off-axis coupons under tensile loading are analyzed using the element developed. A general, interactive menu driven program is developed to track crack growth in composite materials. PHIGS (Programmers Hierarchical Interactive Graphics System) is used as the application program interface to integrate the finite element program with interactive graphics. Simulation studies are performed for center cracked on- and off-axis Iaminae using the normal stress ratio theory as the crack propagation criterion. The direction of crack propagation and values of the crack initiation stresses predicted are in reasonable agreement with the experimental values for the cases analyzed.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Mechanics

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1988

Author dc:creator

• Choksi, Gaurang Nalin

Chair dc:contributor.committeechair

• Herakovich, Carl T.

Committee members dc:contributor.committeemember

• Griffin, O.H.
• Johnson, Eric R.
• Reddy, Junuthula N.
• Smith, C.W.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/53931

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/53931