Low-velocity impact damage can drastically reduce the residual strength of a composite structure even when the damage is barely visible. The ability to computationally predict the extent of damage and Compression-After-Impact (CAI) strength of a composite structure can potentially lead to the exploration of a larger design space without incurring significant time and cost penalties. A high-fidelity three-dimensional composite damage model, to predict both low-velocity impact damage and CAI strength of composite laminates, has been developed and implemented as a user material subroutine in the commercial finite element package, ABAQUS/Explicit. The intralaminar damage model component accounts for physicallybased tensile and compressive failure mechanisms, of the fibres and matrix, when subjected to a threedimensional stress state. Cohesive behaviour was employed to model the interlaminar failure between plies with a bi-linear traction-separation law for capturing damage onset and subsequent damage evolution. The virtual tests set up in ABAQUS/Explicit were executed in three steps, one to capture the impact damage, the second to stabilize the specimen by imposing new boundary conditions required for compression testing and the third to predict the CAI strength. The observed intralaminar damage features, delamination damage area as well as residual strength are discussed. It is shown that the predicted results for impact damage and CAI strength correlated well with experimental testing without the need of model calibration which is often required with other damage models.

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In this study, 39 sets of hard turning (HT) experimental trials were performed on a Mori-Seiki SL-25Y (4-axis) computer numerical controlled (CNC) lathe to study the effect of cutting parameters in influencing the machined surface roughness. In all the trials, AISI 4340 steel workpiece (hardened up to 69 HRC) was machined with a commercially available CBN insert (Warren Tooling Limited, UK) under dry conditions. The surface topography of the machined samples was examined by using a white light interferometer and a reconfirmation of measurement was done using a Form Talysurf. The machining outcome was used as an input to develop various regression models to predict the average machined surface roughness on this material. Three regression models-Multiple regression, Random Forest, and Quantile regression were applied to the experimental outcomes. To the best of the authors' knowledge, this paper is the first to apply Random Forest or Quantile regression techniques to the machining domain. The performance of these models was compared to each other to ascertain how feed, depth of cut, and spindle speed affect surface roughness and finally to obtain a mathematical equation correlating these variables.

Fuselage panels are commonly fabricated as skin-stringer constructions, which are permitted to locally buckle under normal flight loads. The current analysis methodologies used to determine the post buckling response behaviour of stiffened panels relies on applying simplifying assumptions with semi-empirical / empirical data. Using the Finite Element method and employing non-linear material and geometric analysis procedures it is possible to model the post buckling behaviour of stiffened panels without having to place the same emphases on simplifying assumptions or empirical data. Investigation of element, mesh, idealisation, imperfection and solution procedure selection is been undertaken, with results validated against mechanical tests. The research undertaken has demonstrated that using a commercial implicit code, the Finite Element method can be used successfully to model the post buckling behaviour of flat riveted panels. The work has generated a series of guidelines for the non-linear computational analysis of flat riveted panels subjected to uniform axial compression.

SUMMARYA method is presented for subdividing a large class of solid objects into topologically simple subregions suitable for automatic finite element meshing with hexahedral elements. The technique uses a geometric property of a solid, its medial surface, to define the necessary subregions. The subregions are defined explicitly to be one of only 13 possible types. The subdividing cuts are between parts of the object in geometric proximity and produce good quality meshes of hexahedral elements. The method as introduced here is applicable to solids with convex edges and vertices, but the extension to complete generality is feasible.

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A short, efficient, and highly stereoselective synthesis of a series of (3R,6R,7R)-2,5-diketopiperazine oxytocin antagonists and their pharmacokinetics in rat and dog is described. Prediction of the estimated human oral absorption (EHOA) using measured lipophilicity (CHI log D) and calculated size (cMR) has allowed us to rank various 2,5-diketopiperazine templates and enabled us to focus effort on those templates with the greatest chance of high bioavailability in humans. This rapidly led to the 2',4'-difluorophenyl-dimethylamide 25 and the benzofuran 4 with high levels of potency (pK(i)) and good bioavailability in the rat and dog. Dimethylamide 25 is more potent (>20-fold) than 4 in vivo and has a high degree of selectivity toward the vasopressin receptors, >10,000 for hV1a/hV1b and approximately 500 for hV2. It has a good Cyp450 profile with no time dependent inhibition and was negative in the genotoxicity screens with a satisfactory oral safety profile in rats.

SUMMARYA method is presented for the subdivision of a large class of solids into simple subregions suitable for automatic finite element meshing with hexahedral elements. The medial surface subdivision technique described previously in the literature is used as the basis for this work and is extended here to cover solids which have flat and concave edges. Problems where the medial surface is degenerated are also addressed.