High resolution adaptive framework for fast transient fluid-structure interaction with interfaces and structural failure Application to failing tanks under impact

International audienceFast transient phenomena involving multi-component flows with fluid-structure interaction have to be considered for liquid-filled structures subjected to failure under impact, because of the opening gaps through which the internal fluid flows. Numerical simulation with a generic adaptive computational framework based on combined indicators for fluid and structure improves the resolution in the representation of localized phenomena such as the cracks initiation and propagation in the structure, thus allowing for accurate prediction of fluid leakage through small gaps. The capabilities of the proposed methodology and the relative influence of its inner parameters are first analyzed with a parametric study on a simple yet representative test case, followed by a large scale comparison between simulations and complex experiments

Task-dependent structural modifications on reconfigurable general serial manipulators

The monolithic design of serial robot arms has become widely accepted in industrial applications. One might note that these manipulators are designed in such a way that they can implement as many applications as possible at the same time and therefore do usually not have an application-specific structure. In this article we describe the construction and modeling of a kinematic chain in which a mechanical modification is possible. As a result, the structure of a serial robot can be adapted in a wide range. For this purpose, the links of the kinematic chain are modified in such a way that the robot structure matches the desired Denavit-Hartenberg parameter set. This means also that optimizations with different kinematic goals can be realized in order to flexibly adapt the robot system to a current task

Resistance of structures to explosion effects: Review report of testing methods: ERNCIP thematic area Resistance of structures to explosion effects Deliverable D1

It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations against being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take into account these threats. The introduction of regulations or guidelines should support the resilience of the buildings and infrastructure against explosive incidents. In order to protect the infrastructure, methods are required to quantify the resistance of structural elements against explosive loading and to assess the hazards resulting from failure of an element. The applicable state-of-the-art techniques may be either experimental or numerical methods, or a combination of both. Therefore, the thematic group (TG) on the resistance of structures to explosion effects was formed in order to bring the required expertise together, make it commonly available and to find and define harmonised methods and solutions which can be provided to the decision-makers responsible for critical infrastructure protection. This first report of the TG gives a comprehensive summary of the existing methods which can be used to analyse and test the resistance of glazing and windows under blast-loading conditions. Within this context, the experimental methods of testing using high explosives and testing using blast simulators called shock tubes is presented and explained. In addition, the potential of numerical simulations is highlighted in terms of their applicability to the different glass materials. A short, comprehensive theoretical background is given for each method. Based on this, each method is described with its requirements, realisation and the related measurement techniques. Furthermore, an interpretation of the measurements is highlighted. For the numerical simulations, the basic discretisation and calculations schemes are presented in combination with the available constitutive material descriptions for the different significant materials. Finally the chances for verification and validation of the numerical results are presented. Hence the report builds the basis for an actual evaluation of the different test methods and their applicability to certain problems, and provides helpful information for critical infrastructure stakeholders, owners and operators considering the structural resistance of the infrastructure to the effects of explosion in a comprehensive document

Design of blast-loaded glazing windows and facades: A review of essential requirements towards standardization

The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This paper attempts to give a first idea of a possible standardization concerning such numerical simulations. Attention is drawn to the representation of the blast loading and to the proper description of the behaviour of the material of the mentioned products, to the geometrical meshing, and to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined

Investigation of strain-rate effects in Al foams and Ni/Al hybrid foams on different scales

Open-cell metal foams are a new class of cellular materials with structural features resembling those of lightweight loadbearing materials such as cancellous bones and wood. Their high stiffness-to-weight ratio coupled with their typical long, flat stress-strain response make them ideal candidates as cost-effective shock energy absorbers in crashworthiness, impact loading and blast mitigation strategies. The macroscopic mechanical properties of foams are strongly influenced by both the mechanical behaviour of single pores at the mesoscopic level and the struts and their structure at the microscopic length-scale, based on a strong structure-property relationship. This is shown in the present contribution where an experimental-numerical investigation has been conducted demonstrating the existence of strain-rate effects at different hierarchical scales. Micro inertia effects arising due to the pore geometry as well as further strain-rate effects stemming from the rate-sensitivity of the Ni coating in Ni/Al hybrid foams are also outlined.JRC.E.4-Safety and Security of Building

A set of essential requirements towards standardising the numerical simulation of blast-loaded windows and facades

The determination of the blast protection level of laminated glass windows and facades is of crucial importance, and it is normally done by using experimental investigations. In recent years numerical methods have become much more powerful also with respect to this kind of application. This report attempts to give a first idea of a possible standardisation concerning such numerical simulations. Attention is drawn to the representation of the blast loading and of the behaviour of the material of the mentioned products, to the geometrical meshing, as well as to the modelling of the connections of the glass components to the main structure. The need to validate the numerical models against reliable experimental data, some of which are indicated, is underlined

Suggestions for adaptations of existing European norms for testing the resistance of windows and glazed fa\ue7ades to explosive effects

It is important to protect critical infrastructure buildings, such as shopping centres, government buildings and embassies as well as structures of traffic infrastructure (networks and utilities) from being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take into account these unexpected threats. The introduction of appropriate regulations or guidelines, where deemed necessary, should enhance the resilience of buildings and infrastructures against explosion incidents. In order to protect the built infrastructure, testing methods are required which can answer the question as to whether specific building elements can withstand extraordinary high loading conditions created by an explosive event. The applicable state-of-the-art techniques may include either experimental or numerical methods, or a combination of both. Therefore, the thematic group (TG) on the resistance of structures to explosion effects was formed in order to bring the required expertise, to make it accessible and to find and define harmonised methods and solutions which can be provided to the decision-makers responsible for critical infrastructure protection. The TG described in a first report [JRC87202] the physical phenomena which have to be understood in order to ensure proper testing of the building elements and correct interpretation of the results. In a second step, the differences between the existing standards for testing blast-resistant glazing and windows have been derived, and a basis for fundamental recommendations for the future development of the suite of European Standards has been addressed [JRC94930]. It describes recommendations for improvements of the current test standards. The report at hand takes the findings of the report [JRC94930] into account. It formulates suggestions for the implementation of improvements of existing testing standards for the evaluation of explosive resistance of security glazing products. New and adapted text passages are provided as suggestions for improvements. Thereby the structure and the format of the existing testing standards EN13123-1 and EN13124-1 were taken as the basis. Thus, the original formulations and the suggestions for adaptations are provided in one document. This document presents only the suggestions for the modifications of the shock tube testing procedure. The recommended modifications to the existing standards EN13123-2 and EN13124-2 for arena testing based on the findings of [JRC94930] will be presented in another document

Recommendations for the improvement of existing European norms for testing the resistance of windows and glazed fa\ue7ades to explosive effects

It is important to protect critical buildings (shopping centres, government buildings and embassies), infrastructure and utilities, train and underground stations from being damaged, destroyed or disrupted by deliberate acts of terrorism, criminal activity and malicious behaviour. Normal regulations and building guidelines do not generally take into account these threats. The introduction of appropriate regulations or guidelines, where deemed necessary, should enhance the resilience of buildings and infrastructures against explosion incidents. In order to protect the built infrastructure, testing methods are required which can answer the question whether certain building elements can withstand certain loading conditions created by an explosive event. The applicable state-of-the-art techniques may include either experimental or numerical methods, or a combination of both. Therefore, the thematic group (TG) on the resistance of structures to explosion effects was formed in order to bring the required expertise together, to make it commonly available and to find and define harmonised methods and solutions which can be provided to the decision-makers responsible for critical infrastructure protection. The TG described in a fist report [JPC87202] the physical phenomena which have to be understood in order to ensure a proper testing of the elements and a correct interpretation of the results. In a second step, the differences between the existing standards for testing blast-resistant glazing and windows have been derived, and a basis for fundamental recommendations for the future development of the suite of European standards has been addressed [JRC94930]. Based on the prior findings, this report now formulates the proper enhancements of the existing standards in terms of actual recommendations for the improvement of the test standards