Academic literature on the topic 'Draping'

Surgical draping practices throughout the UK vary between hospitals. This national survey (funded through an NATN/3M Clinical Fellowship) sought to determine the extent of various draping practices and identify practitioners’ reasons for selecting specific draping products.

Abstract. When the interplanetary magnetic field (IMF) encounters the Earth's magnetosphere, it is compressed and distorted. This distortion is known as draping, and plays an important role in the interaction between the IMF and the geomagnetic field. This paper considers a particular aspect of draping, namely how the orientation of the IMF in a plane perpendicular to the Sun-Earth line (the clock angle) is altered by draping in the magnetosheath close to the dayside magnetopause. The clock angle of the magnetosheath field is commonly estimated from the interplanetary magnetic field (IMF) measured by upstream monitoring spacecraft either by assuming that the draping process does not significantly alter the clock angle ("perfect draping") or that the change in clock angle is reasonably approximated by a gas dynamic model. In this paper, the magnetosheath clock angles measured during 36 crossings of the magnetopause by the Geotail and Interball-Tail spacecraft are compared to the upstream IMF clock angles measured by the Wind spacecraft. Overall, about 30% of data points exhibit perfect draping within ±10°, and 70% are within 30°. The differences between the IMF and magnetosheath clock angles are not, in general, well-ordered in any systematic fashion which could be accounted for by hydrodynamic draping. The draping behaviour is asymmetric with respect to the y-component of the IMF, and the form of the draping distribution function is dependent on solar wind pressure. While the average clock angle observed in the magnetosheath does reflect the orientation of the IMF to within ~30° or less, the assumption that the magnetosheath field direction at any particular region of the magnetopause at any instant is approximately similar to the IMF direction is not justified. This study shows that reconnection models which assume laminar draping are unlikely to accurately reflect the distribution of reconnection sites across the dayside magnetopause.

Unidirectional non-crimp fabrics (UD-NCF) are often used to exploit the lightweight potential of continuous fiber reinforced plastics (CoFRP). During the draping process, the UD-NCF fabric can undergo large deformations that alter the local fiber orientation, the local fiber volume content (FVC) and create local fiber waviness. Especially the FVC is affected and has a large impact on the mechanical properties. This impact, resulting from different deformation modes during draping, is in general not considered in composite design processes. To analyze the impact of different draping effects on the mechanical properties and the failure behavior of UD-NCF composites, experimental results of reference laminates are compared to the results of laminates with specifically induced draping effects, such as non-constant FVC and fiber waviness. Furthermore, an analytical model to predict the failure strengths of UD laminates with in-plane waviness is introduced. The resulting stiffness and strength values for different FVC or amplitude to wavelength configurations are presented and discussed. In addition, failure envelopes based on the PUCK failure criterion for each draping effect are derived, which show a clear specific impact on the mechanical properties. The findings suggest that each draping effect leads to a “new fabric” type. Additionally, analytical models are introduced and the experimental results are compared to the predictions. Results indicate that the models provide reliable predictions for each draping effect. Recommendations regarding necessary tests to consider each draping effect are presented. As a further prospect the resulting stiffness and strength values for each draping effect can be used for a more accurate prediction of the structural performance of CoFRP parts.

With a view to minimizing production costs of carbon fiber-reinforced plastics (CFRP), a contoured, variable-axial reinforcing fabric, so-called “CoCo – contoured composites,” has been developed for complex, primary structural components,. Thereby, scrap in the production of lightweight high-performance components out of CFRP is reduced. Furthermore, components can be designed in an anisotropic way, thus lighter and adapted to the fiber properties. Moreover, production speed will be by far higher than that of conventional variable-axial textiles, like tailored fiber placement and fiber patch preforming. Furthermore, these textiles will show higher drapability than conventional production techniques, like tape-laying or standard textiles. The main focus of this paper is the investigation of draping mechanisms of variable-axial, tailored textiles and their feasibility. To reach high drapability of these semi-finished products, a new draping strategy has been developed. Reinforcing rovings are laid in meander way onto a carrier material holding excess material available for draping. For the textile “CoCo” new draping characteristics have been investigated, showing a kind of stretch forming of the carrier material and a straightening of the reinforcing fibers previously laid in meander. Due to this draping mechanism the material has the ability to form over very complex shapes without showing draping defects, like loops, gaps, or waviness. The calculation of the excess material and the draping mechanism are investigated on a complex form and proven by draping trials.