Influence of the internal yarn nesting (shifting) on the local structural response of a satin weave composite: an experimental and numerical overview

The current paper emphasizes on the effect of internal yarn nesting (shifting) on the local structural response, such as, local stress - strain and the local damage of a satin weave composite. Detailed study of the variation of the local stress – strain behavior in the plies of a satin weave composite leads to the following conclusions: 1) local longitudinal strain in the plies of a satin weave composite is not influenced by the internal yarn nesting of the adjacent plies (position of the ply in the laminate); 2) local transverse stress as well as the weft yarn transverse damage is sensitive to the position of the ply in the laminate

Local strain variation in the plies of a satin weave composite: experimental vs. numerical

Along with the advantages of multi directional load carrying capabilities, the complicated interlacing pattern of the yarns in a textile composite produce large stress – strain gradients. The stress-strain behavior in a textile composite is influenced by: a) stacking sequence; b) number of plies in the laminate; c) distance of the ply to the surface [1]. From the numerical perspective, the investigation of the free edge and free surface effects in a textile composite unit cell [2] reveals that the local stress behavior changes considerably depending upon the finite/ infinite conditions used for the unit cell FE analysis. In the above context, to capture the variation in local parameters such as strain and damage profiles at different locations (inside/surface) of the satin weave composite under the tensile load, experimental techniques such as strain mapping, Fibre Brag Grating sensors (FBG’s) and the microscopic analysis is used. For the numerical validation, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Comparison of the numerical and experimental results (Table 1) provides valuable information regarding the local strain variation (from edge to the centre) in a satin weave composite (Figure 1). In the similar guide lines, local damage variation is also studied using different unit cell stacks

Micro-CT-scanning as a valuable source of data for musculoskeletal studies in biology

Over time, so-called classic biological studies (such as anatomical studies) have evolved into modern, highly integrated strategies tackling important questions in evolutionary biology. Where early morphologists limited themselves to descriptions based on dissections, non-invasive imaging techniques nowadays allow to uncover details of anatomy in a way that morphologists can go far beyond basic and descriptive anatomy, e.g. through modelling. In this presentation, an overview is presented on some on-going research projects that rely on X-ray tomography data, which focus on the adaptive evolution of musculoskeletal systems in different vertebrate lineages. Cases discussed are (1) a study on the cranial anatomical diversity and functional implications in the feeding apparatus in seahorses, (2) as well as multi-body modelling of the tail system in these fishes; and (3) structural diversity in Darwin’s finches in relation to high performance seed cracking. These cases clearly show the (still not fully explored) potential for testing specific hypotheses with respect to adaptive evolution, where X-ray tomography provides the tools to model experimental conditions that are impossible to achieve with live specimens (e.g. perfect control of specific parameters)