Self-similar voiding solutions of a single layered model of folding rocks

In this paper we derive an obstacle problem with a free boundary to describe the formation of voids at areas of intense geological folding. An elastic layer is forced by overburden pressure against a V-shaped rigid obstacle. Energy minimization leads to representation as a nonlinear fourth-order ordinary differential equation, for which we prove their exists a unique solution. Drawing parallels with the Kuhn-Tucker theory, virtual work, and ideas of duality, we highlight the physical significance of this differential equation. Finally we show this equation scales to a single parametric group, revealing a scaling law connecting the size of the void with the pressure/stiffness ratio. This paper is seen as the first step towards a full multilayered model with the possibility of voiding

Determination of Drag From Three-Dimensional Viscous and Inviscid Flowfield Computations

A momentum balance approach is used to extract the drag from flowfield computations for wings and wing/bodies in subsonic/transonic flight. The drag is decomposed into vorticity, entropy, and enthalpy components which can be related to the established engineering concepts of induced drag, wave and profile drag, and engine power and efficiency. This decomposition of the drag is useful in formulating techniques for accurately evaluating drag using computational fluid dynamics calculations or experimental data. A formulation for reducing the size of the region of the crossflow plane required for calculating the drag is developed using cut-off parameters for viscosity and entropy. This improves the accuracy of the calculations and decreases the computation time required to obtain the drag results. The improved method is applied to a variety of wings, including the M6, W4, and Ml65 wings, Lockheed Wing A, a NACA 0016 wing, and an Elliptic wing. The accuracy of the resulting drag calculations is related to various computational aspects, including grid type (structured or unstructured), grid density, flow regime (subsonic or transonic), boundary conditions, and the level of the governing equations (Euler or Navier-Stokes). The results show that drag prediction to within engineering accuracy is possible using computational fluid dynamics, and that numerical drag optimization of complex aircraft configurations is possibl

Bending strength of delaminated aerospace composites

Buckling-driven delamination is considered among the most critical failure modes in composite laminates. This paper examines the propagation of delaminations in a beam under pure bending. A pre-developed analytical model to predict the critical buckling moment of a thin sub-laminate is extended to account for propagation prediction, using mixed-mode fracture analysis. Fractography analysis is performed to distinguish between mode I and mode II contributions to the final failure of specimens. Comparison between experimental results and analysis shows agreement to within 5 per cent in static propagation moment for two different materials. It is concluded that static fracture is almost entirely driven by mode II effects. This result was unexpected because it arises from a buckling mode that opens the delamination. For this reason, and because of the excellent repeatability of the experiments, the method of testing may be a promising means of establishing the critical value of mode II fracture toughness, G IIC , of the material. Fatigue testing on similar samples showed that buckled delamination resulted in a fatigue threshold that was over 80 per cent lower than the static propagation moment. Such an outcome highlights the significance of predicting snap-buckling moment and subsequent propagation for design purposes. </jats:p

Comparisons of depression, anxiety, well-being, and perceptions of the built environment amongst adults seeking social, intermediate and market-rent accommodation in the former London Olympic Athletes' Village.

The Examining Neighbourhood Activities in Built Living Environments in London (ENABLE London) study provides a unique opportunity to examine differences in mental health and well-being amongst adults seeking social, intermediate (affordable rent), and market-rent housing in a purpose built neighbourhood (East Village, the former London 2012 Olympic Athletes' Village), specifically designed to encourage positive health behaviours. Multi-level logistic regression models examined baseline differences in levels of depression, anxiety and well-being across the housing groups. Compared with the intermediate group, those seeking social housing were more likely to be depressed, anxious and had poorer well-being after adjustment for demographic and health status variables. Further adjustments for neighbourhood perceptions suggest that compared with the intermediate group, perceived neighbourhood characteristics may be an important determinant of depression amongst those seeking social housing, and lower levels of happiness the previous day amongst those seeking market-rent housing. These findings add to the extensive literature on inequalities in health, and provide a strong basis for future longitudinal work that will examine change in depression, anxiety and well-being after moving into East Village, where those seeking social housing potentially have the most to gain