Status on root cause investigation on airbag inflator failure mode

Fraunhofer ICT was approached by TAKATA Corporation to assist in investigations on unintended energetic disassembly of airbag inflators. Fundamental investigations on the AN based pyrotechnic main propellant revealed no problem with typical failure modes of pyrotechnic propellant e.g. phase stabilization of AN or chemical stability. Morphological changes and generation of pores in the core of the propellant grain were identified leading to an increased burn rate by so called porous burning mechanism. Additional investigations focused on characterization of moisture intrusion into the inflator and replication of moisture intrusion by environmental simulation programs used for product validation

Reconnaissances et diagnostics des interfaces dans les digues en remblai

International audienceThis paper presents an ongoing research about interfaces with earthen levees from a flood defence system. Interfaces or transitions zones can be found where there is a change in flood defence structure (e.g. earthen embankment to concrete flood wall), revetment protection (e.g. grass to riprap), cross section and in the construction or foundation materials. The investigation, supported by the Environment Agency in England, aims to consider the presence of transitions during flood defence condition assessment, quantify the effects of transitions on flood defence performance and manage the risk of transitions with improved design and retrofit solutions. The paper sets up an interface or transitions typology and discusses the main failure mechanisms at transitions. A framework to evaluate the performance of transitions in flood defence systems is also presented.Cet article présente une recherche en cours sur les interfaces dans les digues (ou levées) de terre d'un système de protection contre les inondations. Des interfaces ou des transitions peuvent être trouvées en cas de changement de la structure de la digue ou du type de revêtement de protection, de section transversale ou des matériaux de construction ou de fondation. Les travaux, financés par l'Environment Agency anglaise, vise à prendre en compte les transitions lors des diagnostics des ouvrages de protection contre les inondations, à quantifier les effets de ces transitions sur les performances de ces ouvrages et à gérer le risque posé par les transitions grâce à des solutions améliorées de conception et de confortement. La communication présente une typologie des interfaces ou des transitions et décrit les principaux mécanismes de défaillance liés aux transitions. Un cadre de méthodologie d'évaluation de la performance des transitions dans les systèmes de protection contre les inondations est également présenté

Reconnaissances et diagnostics des interfaces dans les digues en remblai

International audienceThis paper presents an ongoing research about interfaces with earthen levees from a flood defence system. Interfaces or transitions zones can be found where there is a change in flood defence structure (e.g. earthen embankment to concrete flood wall), revetment protection (e.g. grass to riprap), cross section and in the construction or foundation materials. The investigation, supported by the Environment Agency in England, aims to consider the presence of transitions during flood defence condition assessment, quantify the effects of transitions on flood defence performance and manage the risk of transitions with improved design and retrofit solutions. The paper sets up an interface or transitions typology and discusses the main failure mechanisms at transitions. A framework to evaluate the performance of transitions in flood defence systems is also presented.Cet article présente une recherche en cours sur les interfaces dans les digues (ou levées) de terre d'un système de protection contre les inondations. Des interfaces ou des transitions peuvent être trouvées en cas de changement de la structure de la digue ou du type de revêtement de protection, de section transversale ou des matériaux de construction ou de fondation. Les travaux, financés par l'Environment Agency anglaise, vise à prendre en compte les transitions lors des diagnostics des ouvrages de protection contre les inondations, à quantifier les effets de ces transitions sur les performances de ces ouvrages et à gérer le risque posé par les transitions grâce à des solutions améliorées de conception et de confortement. La communication présente une typologie des interfaces ou des transitions et décrit les principaux mécanismes de défaillance liés aux transitions. Un cadre de méthodologie d'évaluation de la performance des transitions dans les systèmes de protection contre les inondations est également présenté

Application of pyrotechnic gas generators in sheet metal forming technologies

High speed forming is a traditional and long known process for the forming, joining and plating of blanks. The advantages are in general the high forming velocity and the possibility to handle materials, which could not be treated by conventional processes The economic criteria for this technique are single piece or small lot production, pieces too large for available presses and the avoidance of a thermal treatment. An additional advantage of the process is the strain hardening of the work piece during the process. Scope of this work was the application of pyrotechnic gas generators in a hydro forming kind of process and to extend the technology for cutting processes. Experiments are described, which use gas generator materials as a driving force in a deep drawing and a cutting process. During the work a new gas generator formulation was developed, which showed a minimal slag formation and moderate combustion temperature. Interior ballistic behaviour and combustion temperature were characterized. Materials tested were steel, stainless steel and aluminium with different thicknesses. The results show, that gas generators are a suitable mean for deep drawing applications. The performance of the gas generator process is directly comparable to the hydro forming process, but the time for the drawing cycle is much faster with the new method. The application in cutting processes showed the ability to punch more than one hole of the same geometry simultaneously with flash free cutting edge

Umformen durch Einsatz von Gasgeneratoren

In dem durchgeführten Projekt wurde erstmals die Nutzung und Eignung von Gasgeneratoren für umformtechnische Aufgaben untersucht und praktiziert. Nach umfangreichen Entwicklungs- und Anpassungsarbeiten sowie der Zulassung der Gasgeneratoren gelangen Aussagen über erreichbare Verfahrensparameter und Prozessfelder. Drücke, erreichbare Geometrien und Blechdickenverläufe ordnen dieses Verfahren eindeutig im Bereich des Hydroforming ein. Der wesentliche Vorteil besteht jedoch in den Prozesszeiten und im Falle des Schneidens in den erreichbaren Kantenqualitäten. Mit dem Gasgenerator-Umformen wurde ein umformtechnisches Gebiet erschlossen, welches durchaus in der Lage ist, den bisher ungenutzten Bereich zwischen dem konventionellen und dem Hochgeschwindigkeitsumformen abzudecken

Transition zones: how to improve our flood defences resilience

Transition zones in flood defence systems are areas of weakness that can ultimately lead to flood defence failure and breach causing severe impacts on communities, as illustrated by the findings from reviews of UK flood events since 2007. The fact that transitions often form weak points within a defence infrastructure is broadly recognised and international agencies and organisations have directed efforts to understand how transitions affect overall defence performance and how these impacts should be addressed to improve systems resilience. However, in the UK, current risk based approaches for assessing and managing flood risks impacts at different levels, local, regional and national, do not include risk contributions made by transitions. The Environment Agency has therefore, teamed up with a group of international experts to conduct research to assess the risks associated to transitions, to quantify those risks and to manage them with improved design and retrofitting solutions. This research initiative will make a significant advance towards improving our knowledge about the impacts of transitions in flood risk and will contribute to strengthen our systems resilience. The paper will describe the issues associated with transitions in flood defence infrastructure and present early conclusions from the research