Since the mid-1960s when the forms of curved shell "nite elements were originated, including those pioneered by Professor Gallagher, the published literature on the subject has grown extensively. The "rst two present authors and Liaw presented a survey of such literature in 1990 in this journal. Professor Gallagher maintained an active interest in this subject during his entire academic career, publishing milestone research works and providing periodic reviews of the literature. In this paper, we endeavor to summarize the important literature on shell "nite elements over the past 15 years. It is hoped that this will be a be"tting tribute to the pioneering achievements and sustained legacy of our beloved Professor Gallagher in the area of shell "nite elements. This survey includes: the degenerated shell approach; stress-resultant-based formulations and Cosserat surface approach; reduced integration with stabilization; incompatible modes approach; enhanced strain formulations; 3-D elasticity elements; drilling d.o.f. elements; co-rotational approach; and higher-order theories for composites.

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A finite-element procedure has been developed for temperature and microstructural analyses of quenching problems involving nonisothermal phase transformations. The finite-element analysis incorporates temperature-dependent material properties, time-temperature-transformation (TTT) diagrams to describe the microstructural evolution in steels, and the latent heat released during a phase change. The procedure is applied to calculate temperature, microstructure, and hardness distributions in 1080 steel cylinders quenched in water and in two polymeric quenchants. The calculated values for the three quantities are found to be in good agreement with corresponding measurements made in quenched 1080 steel cylinders. The effect of latent heat released during a phase change on the temperature and microstructural evolution is studied computationally. It is found that, when the latent heat is not included in the calculations, the resulting volume fractions of pearlite and martensite present in the quenched steel are nearly one order of magnitude different from the corresponding values calculated by including the latent heat in the formulation. Finally, the quenching of a large-diameter 1080 steel cylinder in water is analyzed to show the nonlinear effect of cylinder diameter on the temperatures and microstructures.

White layers (WLs) produced in hard steels by machining have been characterized using nanoindentation, optical microscopy, transmission electron microscopy (TEM), and X-ray diffraction. The WL is found to have a hardness of 12.85 Ϯ 0.80 GPa, which is significantly greater than that of untempered martensite produced by various heat-treatment processes. The grain size in the WL is shown to be in the submicrometer range with values ranging, typically, between 30 and 500 nm. These two characteristics of the WL distinguish it from various structures formed in steels by heat treatment. The formation of WLs is promoted by conditions of moderate to high cutting speed in conjunction with tool flank wear. Based on a consideration of the strain, stress, and temperature states associated with the formation of WLs in machining, it is hypothesized that deformation of material to very large strains is the principal factor contributing to the formation of these layers with ultrafine grained or nanocrystalline structures. The large strain deformation and elevated temperatures prevailing in the machining zone could also trigger dynamic recrystallization or cause decomposition and partial dissolution of the cementite present in the steels.

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A novel, hand-held Reference Point Indentation (RPI) instrument, measures how well the bone of living patients and large animals resists indentation. The results presented here are reported in terms of Bone Material Strength, which is a normalized measure of how well the bone resists indentation, and is inversely related to the indentation distance into the bone. We present examples of the instrument's use in: (1) laboratory experiments on bone, including experiments through a layer of soft tissue, (2) three human clinical trials, two ongoing in Barcelona and at the Mayo Clinic, and one completed in Portland, OR, and (3) two ongoing horse clinical trials, one at Purdue University and another at Alamo Pintado Stables in California. The instrument is capable of measuring consistent values when testing through soft tissue such as skin and periosteum, and does so handheld, an improvement over previous Reference Point Indentation instruments. Measurements conducted on horses showed reproducible results when testing the horse through tissue or on bare bone. In the human clinical trials, reasonable and consistent values were obtained, suggesting the Osteoprobe V R is capable of measuring Bone Material Strength in vivo, but larger studies are needed to determine the efficacy of the instrument's use in medical diagnosis.

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