TY - JOUR A1 - Motra, Hem Bahadur A1 - Hildebrand, Jörg A1 - Dimmig-Osburg, Andrea T1 - Assessment of strain measurement techniques to characterise mechanical properties of structural steel JF - Engineering Science and Technology, an International Journal N2 - Strain measurement is important in mechanical testing. A wide variety of techniques exists for measuring strain in the tensile test; namely the strain gauge, extensometer, stress and strain determined by machine crosshead motion, Geometric Moire technique, optical strain measurement techniques and others. Each technique has its own advantages and disadvantages. The purpose of this study is to quantitatively compare the strain measurement techniques. To carry out the tensile test experiments for S 235, sixty samples were cut from the web of the I-profile in longitudinal and transverse directions in four different dimensions. The geometry of samples are analysed by 3D scanner and vernier caliper. In addition, the strain values were determined by using strain gauge, extensometer and machine crosshead motion. Three techniques of strain measurement are compared in quantitative manner based on the calculation of mechanical properties (modulus of elasticity, yield strength, tensile strength, percentage elongation at maximum force) of structural steel. A statistical information was used for evaluating the results. It is seen that the extensometer and strain gauge provided reliable data, however the extensometer offers several advantages over the strain gauge and crosshead motion for testing structural steel in tension. Furthermore, estimation of measurement uncertainty is presented for the basic material parameters extracted through strain measurement. KW - Baustahl KW - Werkstoffprüfung KW - Zugversuch KW - Affecting factors; Measurement uncertainty; Materials testing; Quantitative comparison; Strain comparison; Tensile test Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20170425-31540 SP - 260 EP - 269 ER - TY - THES A1 - Göbel, Luise T1 - Experimental and semi-analytical multiscale approaches for the characterization of the elastic and viscoelastic behavior of polymer-modified cement-based materials T1 - Experimentelle und semi-analytische Multiskalenmethoden für die Charakterisierung des elastischen und viskoelastischen Verhaltens polymermodifizierter zementgebundener Materialien N2 - Polymer-modified cement concrete (PCC) is a heterogeneous building material with a hierarchically organized microstructure. Therefore, continuum micromechanics-based multiscale models represent a promising method to estimate the mechanical properties. By means of a bottom-up approach, homogenized properties at the macroscopic scale are derived considering microstructural characteristics. The extension of existing multiscale models for the application to PCC is the main objective of this work. For that, cross-scale experimental studies are required. Both macroscopic and microscopic mechanical tests are performed to characterize the elastic and viscoelastic properties of different PCC. The comparison between experiment and model prediction illustrates the success of the modeling approach. N2 - Polymermodifizierter Beton (PCC) ist ein heterogener Baustoff mit einer hierarchisch organisierten Mikrostruktur. Deshalb sind Multiskalenmodelle, die auf Prinzipien der Kontinuumsmikromechanik beruhen, sehr gut für die Abschätzung mechanischer Eigenschaften geeignet. Mit Hilfe eines Bottom-Up-Ansatzes werden unter Berücksichtigung mikrostruktureller Charakteristika homogenisierte Eigenschaften auf der makroskopischen Materialebene erhalten. Die Erweiterung bestehender Multiskalenmodelle für die Anwendung auf PCC ist das Hauptziel dieser Arbeit. Dafür werden skalenübergreifende Experimente herangezogen. Sowohl makroskopische als auch mikroskopische mechanische Tests werden durchgeführt, um das elastische und viskoelastische Verhalten verschiedener PCC zu charakterisieren. Ein Vergleich zwischen experimentellen Ergebnissen und der entsprechenden Modellvorhersage verdeutlicht den Erfolg des Modellierungsansatzes. T3 - Schriftenreihe des DFG Graduiertenkollegs 1462 Modellqualitäten // Graduiertenkolleg Modellqualitäten - 19 KW - Elastizitätsmodul KW - Zementstein KW - Kunststoffadditiv KW - Modellierung KW - Mehrphasensystem KW - Multiskalenmodellierung KW - Multiscale modeling KW - Mikrostruktur KW - Polymermodifizierung KW - Kriechen KW - Elastizitätsmodul KW - Microstructure KW - Polymer modification KW - Creep KW - Young's modulus Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:gbv:wim2-20181211-38279 SN - 978-3-95773-269-9 PB - Bauhaus-Universitätsverlag CY - Weimar ER -