Experimental Analysis of Debonding of Skin/Stringer Interfaces under Cyclic Loading and Ageing

An experimental investigation aiming to characterize the fatigue failure mechanisms and effect of ageing of skin/stringer interfaces is presented. A simplified specimen known as a “stringer foot specimen” is used. The effects of local design, of the angle of plies located at the interface and of moisture ageing are studied. Among other results, it is shown that a quasiinfinite fatigue life can be obtained under 33% of the static damage initiation load for all designs. In the framework of multilevel analysis, this study is a preliminary investigation to study cyclic buckling of composite stiffened structures

Experimental analysis of impact and post-impact behaviour of inserts in Carbon sandwich structures

In aeronautics, honeycomb sandwich structures are widely used for secondary structures such as landing gear doors, flaps or floors, and for primary structures in helicopters or business jets. These structures are generally joined by using local reinforcements of the insert type. In the present study, 50 J low velocity impact tests were performed on inserts using a drop-weight device and the impact response and failure patterns were analysed. Impacted specimens were then pull-through tested to failure. Some of the tests were stopped before final failure in order to obtain precise details on the failure scenario. It was shown that, in the cases studied, the residual strength after impact was very high (about 90%) in comparison to the large reductions habitually observed in compression after impact tests

Distributed Shared Memory for Roaming Large Volumes

We present a cluster-based volume rendering system for roaming very large volumes. This system allows to move a gigabyte-sized probe inside a total volume of several tens or hundreds of gigabytes in real-time. While the size of the probe is limited by the total amount of texture memory on the cluster, the size of the total data set has no theoretical limit. The cluster is used as a distributed graphics processing unit that both aggregates graphics power and graphics memory. A hardware-accelerated volume renderer runs in parallel on the cluster nodes and the final image compositing is implemented using a pipelined sort-last rendering algorithm. Meanwhile, volume bricking and volume paging allow efficient data caching. On each rendering node, a distributed hierarchical cache system implements a global software-based distributed shared memory on the cluster. In case of a cache miss, this system first checks page residency on the other cluster nodes instead of directly accessing local disks. Using two Gigabit Ethernet network interfaces per node, we accelerate data fetching by a factor of 4 compared to directly accessing local disks. The system also implements asynchronous disk access and texture loading, which makes it possible to overlap data loading, volume slicing and rendering for optimal volume roaming

On the role of kinking in the bearing failure of composite laminates

Fibre kinking is one of the main failure modes of composite laminates under compression loading. In this paper, the role of kinking in the failure of quasi-isotropic composites subjected to a bearing load is investigated. High-resolution CT scans show that kinking is largely involved in the events leading to laminate collapse, notably by triggering other damage modes such as delamination. Kink bands develop extremely progressively, leading to the formation of a wide localization zone (or FPZ, failure process zone). Such behaviour calls for a non-local modelling approach. Local damage models would lead to overly conservative sizing. A simple model, based on Hashin failure criteria and non-local effective stresses is confronted to experiments, and its limits are highlighted. It will be shown that proper modelling of the bearing failure requires the characteristic behaviour of kink bands to be taken into account

Visualization of massive data volumes : applications to seismic data

Les données de sismique réflexion sont une source d'information essentielle pour la modélisation tridimensionnelle des structures du sous-sol dans l'exploration-production des hydrocarbures. Ce travail vise à fournir des outils de visualisation pour leur interprétation. Les défis à relever sont à la fois d'ordre qualitatif et quantitatif. Il s'agit en effet de considérer (1) la nature particulière des données et la démarche d'interprétation (2) la taille des données. Notre travail s'est donc axé sur ces deux aspects : 1) Du point de vue qualitatif, nous mettons tout d'abord en évidence les principales caractéristiques des données sismiques, ce qui nous permet d'implanter une technique de visualisation volumique adaptée. Nous abordons ensuite l'aspect multimodal de l'interprétation qui consiste à combiner plusieurs sources d'information (sismique et structurale). Selon la nature de ces sources (strictement volumique ou volumique et surfacique), nous proposons deux systèmes de visualisation différents. 2) Du point de vue quantitatif, nous définissons tout d'abord les principales contraintes matérielles intervenant dans l'interprétation, ce qui nous permet d'implanter un système générique de gestion de la mémoire. Initialement destiné au couplage de la visualisation et des calculs sur des données volumiques massives, il est ensuite amélioré et spécialisé pour aboutir à un système dynamique de gestion distribuée de la mémoire sur cluster de PCs. Cette dernière version, dédiée à la visualisation, permet de manipuler des données sismiques à échelle régionale (100-200 Go) en temps réel. Les problématiques sont abordées à la fois dans le contexte scientifique de la visualisation et dans le contexte d'application des géosciences et de l'interprétation sismiqueSeismic reflection data are a valuable source of information for the three-dimensional modeling of subsurface structures in the exploration-production of hydrocarbons. This work focuses on the implementation of visualization techniques for their interpretation. We face both qualitative and quantitative challenges. It is indeed necessary to consider (1) the particular nature of seismic data and the interpretation process (2) the size of data. Our work focuses on these two distinct aspects : 1) From the qualitative point of view, we first highlight the main characteristics of seismic data. Based on this analysis, we implement a volume visualization technique adapted to the specificity of the data. We then focus on the multimodal aspect of interpretation which consists in combining several sources of information (seismic and structural). Depending on the nature of these sources (strictly volumes or both volumes and surfaces), we propose two different visualization systems. 2) From the quantitative point of view, we first define the main hardware constraints involved in seismic interpretation. Focused on these constraints, we implement a generic memory management system. Initially able to couple visualization and data processing on massive data volumes, it is then improved and specialised to build a dynamic system for distributed memory management on PC clusters. This later version, dedicated to visualization, allows to manipulate regional scale seismic data (100-200 GB) in real-time. The main aspects of this work are both studied in the scientific context of visualization and in the application context of geosciences and seismic interpretatio

VolumeExplorer: Roaming Large Volumes to Couple Visualization and Data Processing for Oil and Gas Exploration

Abstract In this paper, we present a volume roaming system dedicated to oil and gas exploration. Our system combines probebased volume rendering with data processing and computing. The daily oil production and the estimation of the world proven-reserves directly affect the barrel price and have a strong impact on the economy. Among others, production and correct estimation are linked to the accuracy of the subsurface model used for predicting oil reservoirs shape and size. Geoscientists build this model from the interpretation of seismic data, i.e. 3D images of the subsurface obtained from geophysical surveys. Our system couples visualization and data processing for the interpretation of seismic data. It is based on volume roaming along with efficient volume paging to manipulate the multi-gigabyte data sets commonly acquired during seismic surveys. Our volume rendering lenses implement high quality pre-integrated volume rendering with accurate lighting. They use a generic multimodal volume rendering system that blends several volumes in the spirit of the "stencil" paradigm used in 2D painting programs. In addition, our system can interactively display non-polygonal isosurfaces painted with an attribute. Beside the visualization algorithms, automatic extraction of local features of the subsurface model also take full advantage of the volume paging.

Experimental Analysis of Composite Structures Debonding under Cyclic Loading

International audienceno abstrac

Mining 3D-Structures: Subparts Extraction and Transfer Learning

International audienc

Advanced volume visualization techniques for seismic interpretation

International audienceIn the past ten years, volume rendering tools have been progressively adopted by the geophysical community. The emergence of high‐end graphics workstations with 3D texture capabilities made real‐time volume rendering possible. Many interactive volume rendering packages are now available for seismic interpretation. However, interpretation is still mostly done in 2D. This is mainly due to the high spatial frequencies of seismic data that make it very difficult to produce meaningful volume images. Classical volume rendering often results in cluttered useless images. We adapt high quality volume rendering algorithms from the computer graphics community. These algorithms are more suitable for seismic data analysis than the classical ones. They use the capabilities of the recent programmable graphics hardware. Moreover, we present a versatile multimodal volume rendering system that enables the efficient co‐visualization of several volumes

Advanced Volume Visualization Techniques for Seismic Interpretation

In the past ten years, volume rendering tools have been progressively adopted by the geophysical community. The emergence of high-end graphics workstations with 3D texture capabilities made real-time volume rendering possible. Many interactive volume rendering packages are now available for seismic interpretation. However, interpretation is still mostly done in 2D. This is mainly due to the high spatial frequencies of seismic data that make it very difficult to produce meaningful volume images. Classical volume rendering often results in cluttered useless images. We adapt high quality volume rendering algorithms from the computer graphics community. These algorithms are more suitable for seismic data analysis than the classical ones. They use the capabilities of the recent programmable graphics hardware. Moreover, we present a versatile multimodal volume rendering system that enables the efficient co-visualization of several volumes