Three-Dimensional Finite-Element Analysis of Chevron-Notched Fracture Specimens


Book Description

Stress-intensity factors and load-line displacements were calculated for chevron-notched bar and rod fracture specimens using a three-dimensional finite-element analysis. Both specimens were subjected to simulated wedge loading (either uniform applied displacement or uniform applied load). The chevron-notch sides and crack front were assumed to be straight. Crack-length-to-specimen width ratios (a/w) ranged from 0.4 to 0.7. The width-to-thickness ratio (w/B) was 1.45 or 2. The bar specimens had a height-to-width ratio of 0.435 or 0.5. Finite-element models were composed of singularity elements around the crack front and 8-noded isoparametric elements elsewhere. The models had about 11,000 degrees of freedom. Stress-intensity factors were calculated by using a nodal-force method for distribution along the crack front and by using a compliance method for average values. The stress intensity factors and load-line displacements are presented and compared with experimental solutions from the literature. The stress intensity factors and load-line displacements were about 2.5 and 5 percent lower than the reported experimental values, respectively. Raju, I. S. and Newman, J. C., Jr. Langley Research Center NASA-TM-85798, NAS 1.15:85798 RTOP 505-33-23-02...







Three-Dimensional Elastic-Plastic Finite Element Analysis of Three-Point Bend Specimens


Book Description

Elastic-plastic finite element analyses of the three-point bend specimen geometry were performed as part of an investigation to study the application of the crack tip opening displacement (CTOD) fracture parameter to flawed pressure vessels. The elastic-plastic fracture mechanics (EPFM) parameters, CTOD and J, were determined from the results of two- and three-dimensional finite element analyses. Three sizes of the preferred specimen geometry (thickness, t, by depth, 2t, by span, 8t) and five steels with varying stress-strain characteristics were considered. To obtain experimental results for comparison, tests were conducted in accordance with the procedure outlined in British Standard BS 5762:1979, "Methods for Crack Opening Displacement Testing.".







The Finite Element Method for Three-Dimensional Thermomechanical Applications


Book Description

Though many 'finite element' books exist, this book provides a unique focus on developing the method for three-dimensional, industrial problems. This is significant as many methods which work well for small applications fail for large scale problems, which generally: are not so well posed introduce stringent computer time conditions require robust solution techniques. Starting from sound continuum mechanics principles, derivation in this book focuses only on proven methods. Coverage of all different aspects of linear and nonlinear thermal mechanical problems in solids are described, thereby avoiding distracting the reader with extraneous solutions paths. Emphasis is put on consistent representation and includes the examination of topics which are not frequently found in other texts, such as cyclic symmetry, rigid body motion and nonlinear multiple point constraints. Advanced material formulations include anisotropic hyperelasticity, large strain multiplicative viscoplasticity and single crystal viscoplasticity. Finally, the methods described in the book are implemented in the finite element software CalculiX, which is freely available (www.calculix.de; the GNU General Public License applies). Suited to industry practitioners and academic researchers alike, The Finite Element Method for Three-Dimensional Thermomechanical Applications expertly bridges the gap between continuum mechanics and the finite element method.




NASA Technical Note


Book Description