A hp-adaptive discontinuous Galerkin finite element method for accurate configurational force brittle crack propagation

Engineers require accurate determination of the configurational force at the crack tip for fracture fatigue analysis and accurate crack propagation. However, obtain- ing highly accurate crack tip configuration force values is challenging with numer- ical methods requiring knowledge of the stress field around the crack tip a priori. In this thesis, the symmetric interior penalty discontinuous Galerkin finite element method is combined with a residual based a posteriori error estimator which drives a hp-adaptive mesh refinement scheme to determine accurate solutions of the stress field about about the crack. This facilitates the development of a novel method to calculate the crack tip configurational force that is accurate, requires no a priori knowledge of the stress field about the crack tip with, its error bound by an error estimator which is calculated a posteriori. Benchmark values of the crack tip con- figurational force are presented for problems containing multiple mixed mode cracks in both isotropic and anisotropic materials. Additionally, the hp-adaptivity is com- bined with a mathematical analysis of the stress field at the crack tip to critique the convergence and limitations of other methods in the literature to calculate the crack tip configurational force. Two methods for staggered quasi-static crack prop- agation are also presented. An rp-adaptive method which is simple to implement and computationally inexpensive, element edges aligned with the crack propagation path with the exploitation of the discontinuous Galerkin edge sti↵ness terms exist- ing along element interfaces to propagate a crack. The second method is denoted the hpr-adaptive method which combines the accurate computation of the crack tip configuration force with r-adaptivity to produce a computationally expensive but accurate method to propagate multiple cracks simultaneously. Further, for indeter- minate systems, an average boundary condition that restrains rigid body motion and rotation is introduced to make the system determinate

A Family Affair: The Pre-Kansas Saga of James Henry Lane

Historian Craig Miner suggests that territorial Kansas between 1854 and 1861 was a nursery of weird and manic figures. Foremost among the weird and manic figures of Kansas history stands James Henry Lane, formerly a U.S. congressman from Indiana, and destined to become one of Kansas\u27 first pair of senators. Writing at the midpoint of the twentieth century, Albert Castel pronounced Jim Lane the most colorful and fascinating personality in the history of Kansas, adding that Very likely, too, he was mentally unbalanced and paranoid. Yet, James H. Lane never set foot on Kansas soil until he was well into his fortieth year of life. Thus, the individual who by 1860 earned a national reputation as the Grim Chieftain of Kansas hardly sprang full-blown from the prairies of his adopted state. He was, rather, haunted by a tragic past that has been largely overlooked by historians. So traumatic were the events that predated Jim Lane\u27s arrival in Kansas that they arguably determined his behavior after he settled in the territory, and ultimately became part of the mix of variables that led to his suicide shortly after the Civil War. In 1854, Lane\u27s mother, Mary Foote Howse Lane, warned her son, What a man is at forty, he will continue to be through the remainder of his life. The present study aspires to shed light on what made Jim Lane the man he was as he celebrated his fortieth birthday, just under a year before he immigrated to Kansas. Lane biographer Ian Spugeon recently noted the habit of historians to focus almost solely on Lane in Kansas, as well as a need to interpret Lane\u27s actions in the broader context of the collapse of the second-party system and the sectional conflict. Aspiring to help fill that gap, the present study suggests that a leitmotif of the Lane story involves the inception, as much as the collapse, of America\u27s second two-party system. Moreover, the saga of Jim Lane before Kansas was essentially a family affair. Enablers so far largely neglected by historians inspired and helped him along the way

Leucocyte depletion of blood components - guidelines of the blood transfusion services of South Africa

No Abstract. South African Medical Journal Vol. 96(5) 2006: 395-39