Entwicklung und Anwendung von mathematischen Optimierungsmethoden zur Ableitung von vereinfachten Prüfungen für Fahrwerksbauteile

Testing the fatigue life time of chassis components is necessary during the development process and for quality supervision during the period of series production. In many cases a simplified test is done to reduce the complexity of the test. The development engineer has to develop the specification of those simplified tests. According to the task different approaches are possible: Looking for an adaquate test load or for a simplified mounting ore both. This paper deals with several numerical methods for test specification development. Especially a numerical optimization routine is presented for detection of a signifcant load case. Also the iterative searching for a simplified mounting in combination with damage based selection of load channel is shown. Exemplary the application of the routines is demonstrated by Porsche PANAMERA wheel carrier and a suspension‐strut receiving. The actual stage of development of the numerical routines is presented. In addition intended upgrades of the software are shown.     

Wechsellast‐Prüfung von Hüftgelenk‐Pfannen mit keramischen Einsätzen

Fatigue Test of Hip‐Joint Cups with Ceramic Inserts A safe design of hip‐joint components for the long‐term use in humans requires an evaluation of the fatigue lifetime under the in‐vivo loading conditions. For compound cups with ceramic inserts no standardized or commonly agreed procedure exists up to now. Therefore, a test is presented here which is practised by the authors and which possibly could be the basis for a standard. Because of the expensive testing procedure and the large number of possible cup‐insert combinations a failure test with only few samples was chosen.     

Verfahren zur Bestimmung der Messunsicherheit bei der Härteprüfung. Excel Datei zur Durchführung

Methods for the Determination of Uncertainty for Hardness Testing. EXCEL file for the Determination The determination of uncertainty for hardness testing [1, 2, 3] on the basis of the CRM hardness reference blocks according to GUM [4] are described. The application of an EXCEL based file for this determination of the uncertainty as part of the periodic check is presented.     

Analyse von Spannungen und Verformungen im Brüstungsbereich von Wandmodellen aus Porenbeton und Kalksandstein

Stress‐strain analysis in the window zone area of full‐scale wall models made of AAC and calcium silicate units This article presents results of tests on full‐scale wall models with two window openings. Tested walls were made of autoclaved aerated concrete (AAC) units and calcium silicate (C‐S) units. They were erected on thin unfilled perpend joints. This article strictly corresponds to previous tests performed in the spandrel area. The aim of the research was to verify results obtained for smaller models. Stress‐strain analysis of the spandrel area in full‐scale models was performed and results were compared with results obtained for smaller models. According to the analysis of the stress‐strain graphs, it was found that the horizontal stress in the spandrel area was ca. 0.2 N/mm². The software based on the finite element method was used to perform calculations for tested walls. Results from laboratory tests and numerical simulations were analysed to determine the level of stress and strain in tested walls.     

The two‐shearfield test – A suitable method for the empirical shear capacity design of masonry / Der Zweifeld‐Schubversuch – Eine praxistaugliche Methode zur versuchsgestützten Bemessung der Schubtragfähigkeit von Bestandsmauerwerk

The investigations [1] demonstrate that the two‐shearfield test is a suitable method for the determination of the shear capacity of masonry. The testing equipment is mounted directly on the wall in order to retain realistic boundary conditions like stiffness, load and prior damage. The behaviour factor q and the capacity curves of certain masonry walls can be directly obtained from the experimental results and realistic material behaviour in earthquake design can be represented. In particular, existing masonry can be assessed realistically with methods like the response spectrum, the push‐over and the capacity spectrum by using the two‐shearfield test.     

Evaluation of the quality of historic brickwork / Die Ermittlung der Mauerwerksgüte von Bestandsmauerwerk aus kleinformatigen Ziegeln

The quality of historic brickwork is a significant matter for structural engineers for modernisation, also due to its concentration in public areas. One substantial issue for structural inspection is the characteristic masonry strength or allowable masonry stress, which are defined by the compressive strength. There are several ways of assessing the compressive strength of brickwork or its components, but most of these test methods are not described in engineering standards or are only based on standards for new buildings. This article provides information about the various testing methods and gives recommendations for the selection of applicable test procedures and the experimental scope.     

A students' challenge for the estimation of the maximum compressive load of masonry prisms / Studentenwettbewerb zur Ermittlung der maximalen Druckfestigkeit von Mauerwerksprismen

The paper presents the “IMC Students' Challenge” competition held in 2014, during the 9th International Masonry Conference, in Guimarães. The objective of the competition was to predict the maximum compressive load of two masonry prisms built of solid bricks, and of hollow blocks, with mortar joints. To increase the complexity of the problem, all prisms were tested under eccentric load. The students, who enthusiastically participated in the final laboratory tests, presented different approaches to estimate the maximum eccentric compressive force on masonry prisms. The challenge was a great experience, not only for students and conference participants, but also for sponsors and organizers.     

Einfluss von Temperatur und Vorverformung auf das plastische Werkstoffverhalten von modernen Karosseriestählen

Influence of temperature and prestraining on the plastic material behaviour of modern sheet steels for autobody applications Within the scope of a common research project of the automotive and steel industry, characteristic values describing the plastical behaviour of 20 sheet steels have been determined. In detail, quasistatic tensile tests at the testing temperatures ‐40 °C, 23 °C and 100 °C were carried out to obtain flow curves for the as delivered materials as well as for steels after a defined prestraining or heat treatment. Additionally, sheet metal testing led to forming limit diagrams and limiting drawing ratios including the working ranges for deep drawing. The results of the tensile tests showed significant differences between steel groups with regard to their strain hardening behaviour, which can be described by the ratio of yield and tensile strength R_p0,2/R_m or the Θ_IV‐value, and their temperature sensitivity. Within one steel group, consisting of steels with similar strain hardening behaviour, it might be possible to determine flow curves of one steel in a defined condition in order to calculate the flow curves of other steels with different strength. An advantage would be a lesser number of experimental tests which have to be performed in order to supply reliable input data for numerical material and component modelling.     

Ermittlung von Berechnungskennwerten an Karosseriewerkstoffen – Bericht über ein Gemeinschaftsprojekt der Stahl‐ und Automobilindustrie

Determination of input data for numerical design of sheet steels – Report on a common research project of the steel and automotive industry Within the scope of a common research project of the steel and automotive industry, 20 sheet steels have been investigated to obtain input data for FE‐analysis. In detail, elastic, plastic and fatique characteristical values were determined by several testing institutes for a period of 3 years. The investigated sheet steels differ with regard to the microstructure and the steel concept. Beside several ferritic steels, multiphase steels like dual phase‐, complex phase‐ and TRIP steels as well as 2 austenitic stainless steels were characterised. The starting materials and selected steels with a defined predeformation and heat treatment were investigated. Within this project, the partners developed a testing and documentation precept in which the ways and means were fixed to reach the defined steel condition and to enable a standardised testing and data output for the material database, realised by the automotive industry. Before the actual elastic, plastic and fatique testing, a reception test for all steels was carried out to characterise the materials with regard to the microstructure, surface condition, chemical composition and mechanical properties, obtained in the quasistatic tensile test. The results of the different testing institutes (elastic, plastic and fatique) will be presented in separate publications in detail. As a result of this project it became obvious that the investigated steels can be divided into steel groups which show a similar strain hardening behaviour. Thus, a prediction of mechanical values and flow curves for cognate steels within one steel group seems to be possible. This subject will be the focus of further investigations within the scope of a new project started on January 1^st, 2003.     

Experimental determination of the load‐bearing capacity of a reinforced perforated brick facade

For a new multi‐storey car park over the Central Bus Station (ZOB) in Kiel, a perforated clinker brick veneer facade not conforming to standards was planned. The design and technical characteristics of the facade have already been described in the article by Medzech and Schrade in this issue [1]. This article deals with the experimental investigations carried out to obtain a project‐related one‐off approval (ZiE). These experiments contain in particular large tests on storey‐height wall sections, which were subjected to eccentric compressive loading and partly to horizontal loads representing wind action. Supplementary small tests on unreinforced and reinforced masonry served to determine the bending capacity, the anchoring capacity of the reinforcement and the load‐bearing capacity of the wall anchors in the masonry. Due to the special facade construction with special bricks for the project, wall anchors, reinforcement bar couplers and unique test set‐ups had to be developed for the specific project.     

Versuche am Bau mit Injektionsankern im Mauerwerk nach Technischer Regel des DIBt

Tests on construction site for metal injection anchors for use in masonry according to the DIBt Technical Rule – Part 1: Overview On construction sites, one encounters a large number of bricks that differ in material (clay, autoclaved aerated concrete, calcium silicate, lightweight concrete or normal concrete), structure (solid bricks, perforated bricks with or without insulation filling), geometry, bulk density and compressive strength. In the context of approval procedures for plastic anchors and metal injection anchors, however, it will only ever be possible for anchor manufacturers to map part of this variety of masonry stones as a permissible base material. Tests on construction site allow the user, under certain conditions, to design and install in accordance with the approval if the base material actual available on construction site is not shown in the approval for the anchor system. This article is an excerpt from issue 4 of the series of publications of the ?Deutscher Ausschuss für Mauerwerk e.V. (DAfM)” (Dübel‐)Versuche am Bauwerk in Mauerwerk – Aktuelle Regelungen für Kunststoffdübel und Metall‐Injektionsanker zur Verankerung im Mauerwerk” and provides an overview to the existing set of rules to be observed – in particular to one of the two current Technical Rules of the Deutsches Institut für Bautechnik (DIBt) ?Durchführung und Auswertung von Versuchen am Bau für Injektionsankersysteme im Mauerwerk”.