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Material Characterization and Modeling for the Simulation of Adhesive Joints with Polyurethane Adhesives

Sikora, Sebastian P. and Meschut, Gerson and Kolling, Stefan (2015) Material Characterization and Modeling for the Simulation of Adhesive Joints with Polyurethane Adhesives. In: Proceedings of NAFEMS World Congress 2015. NAFEMS World Congress 2015, 21.-24. Juni 2015, San Diego, USA. ISBN ISBN-13: 978-1-910643-24-2

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High-strength, toughness-modified epoxy adhesives (EP) combined with spot-welding is state of the art for the assembly of the metallic body-in-white (BiW) in automotive industry. To open up further potentials in lightweight engineering, multi-material design now is in the focus of the BiW development. Such structural parts motivate the development of innovative joining techniques, especially advanced adhesive joining. Through challenges in the production process and during vehicle operation, a trend towards more flexible adhesives can be observed in recent applications. Joining dissimilar materials, e.g. steel and carbon fiber-reinforced plastics, polyurethane adhesives (PU) offer many advantages over EPs. These include an increased flexibility when joining materials with different coefficients of thermal expansion, potentially higher energy absorption and the compensation of tolerances required in the assembly. However, no methods are established so far to simulate the local mechanical behavior of this softer type of adhesive, which exhibits a highly non-linear elastic behavior. As experiments indicate that PUs show characteristic features of rubber-like materials, they can be approached by hyperelastic material models for quasi-static loading, i.e. rate effects are neglected. Experiments describing the behavior of the adhesive bulk form the basis of the hyperelastic material characterization. For the typical joint load cases of shear and normal loading, it becomes evident that – beyond the established characterization tests (uniaxial tension and hydrostatic compression) for rubber materials – it is crucial to take hydrostatic tension into account. Exposed to equitriaxial loads, the change in volume of the material shows an asymmetric behavior in tension and compression that needs to be described in the material model. Validations for uniaxial compressive loading, so-called pure as well as simple shear tensile tests are conducted. For the prediction of a local damage initiation, and thus structural strength, a failure criterion for the adhesive material is proposed based on hydrostatic strength. The developed approach is considered to be the basis for the simulation of the structural response of PU-joints in a reliable, conservative design concerning stiffness and strength.

Item URL in elib:https://elib.dlr.de/97484/
Document Type:Conference or Workshop Item (Speech)
Title:Material Characterization and Modeling for the Simulation of Adhesive Joints with Polyurethane Adhesives
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Sikora, Sebastian P.sebastian.sikora (at) dlr.deUNSPECIFIED
Meschut, GersonLWF, Universität PaderbornUNSPECIFIED
Kolling, StefanIMM, TH Mittelhessen GießenUNSPECIFIED
Date:June 2015
Journal or Publication Title:Proceedings of NAFEMS World Congress 2015
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
ISBN:ISBN-13: 978-1-910643-24-2
Keywords:Polyurethane, adhesive, hyperelasticity, triaxiality, hydrostatic strength, failure criterion
Event Title:NAFEMS World Congress 2015
Event Location:San Diego, USA
Event Type:international Conference
Event Dates:21.-24. Juni 2015
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Transport
HGF - Program Themes:Terrestrial Vehicles (old)
DLR - Research area:Transport
DLR - Program:V BF - Bodengebundene Fahrzeuge
DLR - Research theme (Project):V - NGC Fahrzeugstruktur (old)
Location: Stuttgart
Institutes and Institutions:Institute of Vehicle Concepts > Lightweight and Hybrid Design Methods
Deposited By: Sikora, Sebastian
Deposited On:04 Sep 2015 13:58
Last Modified:04 Sep 2015 13:58

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