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Procedure for the transferability of application-specific boundary conditions for the testing of components and products
... Die Lasteinleitungselemente werden zusätzlich in entsprechenden Komponenten-Tests getestet, wobei keine Standard-Tests existieren und gemäß den Empfehlungen aus dem Insert Design Handbook [4] getestet wird. Insbesondere der Schub-und Pull-Out Test sind hierbei die auslegungsrelevanten Tests, wobei die Randbedingungen in diesen Tests stark idealisiert werden und nicht den Randbedingungen aus der realen Anwendung entsprechen [11,12]. Erste Ansätze für Testaufbauten mit realitätsnahen Randbedingungen existieren, welche als Grundlage dienen können, um entsprechende Optimierungen durchzuführen, in denen das globale Strukturverhalten und damit die Weiterleitung der Lasten mitberücksichtigt werden kann [13,14]. ...
... Hierbei erfolgt eine numerische Nachbildung der physischen Versuche, womit Entwicklungszeiten und -kosten eingespart werden können [6]. Der Aufbau der virtuellen Modelle erfolgt dabei hierarchisch aufbauend von den Konstituenten bis zur Zielstruktur [6,11,12]. Entsprechende virtuelle Modelle, mit Hilfe derer es möglich ist, das progressive Schädigungsverhalten der Sandwichstrukturen bis zum Komponenten-Level darzustellen, sind in der Literatur beschrieben [14][15][16][17]. Eine Erweiterung der detaillierten Modelle auf höhere strukturelle Komplexitätsebenen unter Berücksichtigung des globalen Strukturverhaltens ist in der Literatur nicht beschrieben, jedoch zeigen Hanna et al. [18] einen ersten Ansatz, um die detaillierten Modelle sowie Tests mit realitätsnahen Randbedingungen in die Sandwichoptimierung miteinzubeziehen. ...
... Dabei können bestehende Standardtests, wie der Pull-Out Test [4], verwendet werden. Meist werden die Randbedingungen in diesen Tests zwar zu stark abstrahiert, um Gestaltungsoptimierung sinnvoll durchzuführen [9], die Ergebnisse können aber als Datengrundlage dienen, um ein virtuelles Testmodell stufenweise nach der Produkt-Komponenten-Testpyramide (PKT-Pyramide) [11,12] aufzubauen, das Potential von Gestaltungsänderungen aufzuzeigen und eine Basis für den finalen physischen Testaufbau zu bilden. Hartwich et al. [13] zeigen, wie aus der realen Anwendung ein geeigneter Testaufbau für Sandwichstrukturen abgeleitet werden kann. ...
... However, these are approximate and conservative equations [4,5] that do not fully exploit the lightweight design potential and lead to over-dimensioning. Detailed numerical meso-models based on the finite element method (FEM), which are hierarchically structured, have been established in research as an alternative to the analytical equations [6][7][8]. With such FEMmodels, for example, it is possible to predict the structural behavior of Nomex honeycomb sandwich structures in the pull-out test [4,9,10]. ...
In Nomex honeycomb sandwich structures, inserts are often used for local load introduction. In the surroundings of the inserts, complicated stress conditions occur, which can often lead to local failure of the structure. Due to design measures, several inserts often have to be positioned next to each other, which can lead to interferences of the stress fields, reducing the load-bearing capacity of the individual inserts. For such cases, only rough reduction factors are specified in the ESA insert design handbook, which can lead to large safety factors. To predict the influence of the positioning of two inserts and to minimize oversizing, pull-out tests as well insert proximity tests are carried out. Respective virtual models are build-up for further numerical investigations.
... In recent years this variety of different test setups on component level has made the comparability of published results more difficult. As shown in [6,7] the consideration of the existing boundary conditions of the application has fundamental relevance for the quality of a design. This is usually not the case for the abstracted tests. ...
Honeycomb sandwich structures are widely used for cabin interior components in passenger aircrafts. The load introduction into the sandwich structure proves to be particularly critical. However, the verification takes place based on non‐standardized tests abstracted from the application so that influences caused by boundary conditions and multiple load introduction points cannot be investigated. Moreover, these tests also do not allow comparisons of different designs. The variety of different test setups on component level has made the comparability of published results more difficult. This paper summarizes the state of the art of existing component tests. Based on that and using the example of an aircraft cabin partition, the existing test set‐ ups are checked for their suitability to cover all given load cases. New test setups with extended boundary conditions and several load introduction points are developed. For one test setup, test results are shown and compared to a conventional component test.
... One example is structural analysis, in which calculations can be performed based on FEM (Werkle, 2021). In the field of aircraft cabins, virtual models are used for this purpose, which are hierarchically constructed across different structural complexity levels (Heyden et al., 2019;Schwan et al., 2021). Furthermore, optimization calculations in combination with FEM can be used to optimize a product or structure with respect to a specific target parameter (Werkle, 2021). ...
The modular lightweight design attempts to reconcile the partially conflicting goals between modularization and lightweight design in order to establish a harmonized modular hybrid design. This requires a close exchange of the resulting development data between the two areas. In this contribution a concept for an interface for the data exchange between system models and FEM models is presented and successfully implemented in the Cameo Systems Modeler and applied to examples from the aircraft cabin. With the interface the homogenization step of modular lightweight design can be performed.
... The design of such models is complex due to the large number of constituents with partially anisotropic material behavior and the large number of contacts to be modeled. Therefore, a hierarchical model design under constant comparison with physical test results is required (Heyden et al., 2019;Schwan et al., 2021). A first approach for creating virtual models for testing sandwich joints was created and successfully applied in previous work (Seemann and Krause, 2018). ...
Aircraft cabin monuments must be optimized in terms of lightweight design, cost structure and variance. Model-based approaches support the aircraft data and help to modify them consistently during further development. In this paper, a holistic methodological approach for product families of aircraft cabin development is shown, which integrates lightweight and cost-efficient aspects, in addition to the variance focus. For this purpose, the development of cost-efficient and ligthweight optimized cabin modules is supported in a model-based way.
Preclinical radiotherapy studies using small animals are an indispensable step in the pathway from in vitro experiments to clinical implementation. As radiotherapy techniques advance in the clinic, it is important that preclinical models evolve to keep in line with these developments. The use of orthotopic tumour sites, the development of tissue-equivalent mice phantoms and the recent introduction of image-guided small animal radiation research platforms has enabled similar precision treatments to be delivered in the laboratory.
These technological developments, however, are hindered by a lack of corresponding dosimetry standards and poor reporting of methodologies. Without robust and well documented preclinical radiotherapy quality assurance processes, it is not possible to ensure the accuracy and repeatability of dose measurements between laboratories. As a consequence current RT-based preclinical models are at risk of becoming irrelevant.
In this review we explore current standardization initiatives, focusing in particular on recent developments in small animal irradiation equipment, 3D printing technology to create customisable tissue-equivalent dosimetry phantoms and combining these phantoms with commonly used detectors.
Translational research aims to provide direct support for advancing novel treatment approaches in oncology towards improving patient outcomes. Preclinical studies have a central role in this process and the ability to accurately model biological and physical aspects of the clinical scenario in radiation oncology is critical to translational success. The use of small animal irradiators with disease relevant mouse models and advanced in vivo imaging approaches offers unique possibilities to interrogate the radiotherapy response of tumors and normal tissues with high potential to translate to improvements in clinical outcomes. The present review highlights the current technology and applications of small animal irradiators, and explores how these can be combined with molecular and functional imaging in advanced preclinical radiotherapy research.
In diesem Kapitel werden die innovativen und methodischen Ansätze in der Entwicklung von Leichtbaustrukturen am PKT vorgestellt. Es ist eng mit dem Anwendungsfeld Luftfahrt verbunden, das in
Kap. 9 Neue Trends in der Flugzeugkabinenentwicklung vorgestellt wird.
Dem Forschungsbereich Strukturanalyse und Versuchstechnik am PKT ist das Themengebiet Analyse von Leichtbaustrukturen angebunden. Weitere Testaktivitäten sind in Kap. 7 und Kap. 8 aufgeführt. Aus Sicht des Leichtbaus sind hier die statische und dynamische Analyse und Auslegung von
Sandwichstrukturen, Dämpfung von Leichtbaustrukturen durch Partikel- und Schnittstellendämpfung sowie das virtuelle Testen hervorzuheben.
Für die Produktentwicklung in der Luft- und Raumfahrt sind Leichtbauaspekte entscheidende Designkriterien. Leichtbaustrukturen sind meist auf wenige exakte Belastungszustände optimiert und
reagieren somit empfindlich auf nicht definierte Belastungszustände. Für Leichtbaustrukturen sind
die Randbedingungen möglichst genau zu modellieren, da diese den internen Belastungszustand
des Testobjektes beeinflussen.
Bei der Entwicklung von Leichtbauprodukten sind die Bestimmung und der Nachweis der mechanischen Produkteigenschaften in realen Tests einer der Hauptkostentreiber. Die Verwendung von
FEM-basierten virtuellen Testmodellen kann daher einen Beitrag zur Reduzierung der Entwicklungskosten leisten.
Ein weiterer Forschungsaspekt ist die Kombination von Leichtbau und Modularisierung, um einerseits die Masse zu reduzieren und gleichzeitig eine variantengerechte Produktgestaltung zu ermöglichen. Hierfür wird das methodische Vorgehen des Modularen Leichtbau hergeleitet und beschrieben.
Virtual test methods can contribute to reducing the great effort for physical tests in the development of lightweight products. The present work describes an approach for virtual testing of sandwich panel joints based on the Building Block Approach and the Finite Elements Method. Building on a multitude of physical tests on sandwich materials and joints, adequate sub-models are developed, validated and synthesized to top-level models. The developed approach is eventually applied for the development of a novel sandwich panel joint.
The Author
Ralf Seemann studied mechanical Engineering at TU Hamburg (TUHH) and at National University of Singapore. From 2011-2016 he worked as research engineer at the Institut of Product Development and Mechanical Engneering Design at TUHH. Since 2017 he works as stress & weight engineer at Diehl Aviation.
In the product development process testing and validation is necessary to certify the function of the product. but it is time and cost extensive. A high ratio between output and input effort has to be aimed. To reach this effect a hierarchy of test levels is sensible. This paper shows an approach to describe and map the transferability of boundary conditions between these scale levels and model layers. The chosen scale levels are material. structure and product level and the model layers are reality. physical and virtual models. The challenges of the transferability of boundary conditions will be shown for three research topics. static testing for cylinders. optimization of sandwich inserts and dynamic testing of cabin interior.
This paper will focus on the prediction of aircraft structural strength using virtual testing analysis methods. Virtual testing is a concept with several attributes and is to be understood as the simulation of aircraft
structure using advanced nonlinear finite element analysis. It will involve the combination of analysis software, methods,
people skills and experience to predict the actual aircraft structural strength with a high level of confidence. This is achieved
through the creation and execution of a detailed nonlinear finite element analysis model of an aircraft structure, which represents
as accurately as possible the actual physical behaviour when subjected to a wide range of loading scenarios. Creating a virtual
representation of an aircraft structure presents the analysts with several significant challenges, including the creation
of the complex finite element model that accurately represents the global aircraft structure, and then adding the significant
detail in terms of material and construction required to make accurate failure predictions with confidence. An overview will
be provided of the general principles used in the process of virtual testing of both metallic and composite aircraft structures.
The paper will focus on the key challenges and enablers for future successful virtual testing demonstrations in an industrial
context.
KeywordsVirtual testing–Aircraft structures–Non-linear analysis–Strength predictions–Industrial requirements–The wishbone analysis framework
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