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In-situ quantification of manufacturing-induced strains in fiber metal laminates with strain gages

Wiedemann, Johannes and Prussak, Robert and Kappel, Erik and Hühne, Christian (2022) In-situ quantification of manufacturing-induced strains in fiber metal laminates with strain gages. Composite Structures, pp. 1-14. Elsevier. doi: 10.1016/j.compstruct.2022.115967. ISSN 0263-8223. (Submitted)

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The predominant use of FBG sensors to characterize the residual stress state in composite materials to date does not permit absolute strain measurements. The reason for this is the loss of the connection between the sensor and laminate during phase transitions of the resin. Thus, points of significant changes in the measurement signal (e.g. bonding temperature) need to be used for the residual stress evaluation. For fiber metal laminates (FML) however, strain gages applied to the metal layer allow absolute strain measurements since the metal behaves purely elastic over the entire manufacturing process. Hence, residual stresses in the metal layer of an FML are quantified directly. Despite the sensors being applied to the metal layer, it is shown that the cure state of the resin can still be analyzed by changes in the coefficient of thermal expansion. Thus, the effects of different modifications to the cure cycle are assessed in terms of residual stress reduction. It is shown that assuming the bonding temperature to be equal to the stress-free temperature results in a conservative estimation of the residual stress state. The strain gage signal is shown to be in good agreement with FBG sensor data during a combined experiment.

Item URL in elib:https://elib.dlr.de/185944/
Document Type:Article
Title:In-situ quantification of manufacturing-induced strains in fiber metal laminates with strain gages
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Wiedemann, JohannesUNSPECIFIEDhttps://orcid.org/0000-0003-2040-0143UNSPECIFIED
Prussak, RobertUNSPECIFIEDhttps://orcid.org/0000-0002-9777-0495UNSPECIFIED
Kappel, ErikUNSPECIFIEDhttps://orcid.org/0000-0002-8760-8451UNSPECIFIED
Hühne, ChristianUNSPECIFIEDhttps://orcid.org/0000-0002-2218-1223UNSPECIFIED
Journal or Publication Title:Composite Structures
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 1-14
Keywords:Fiber metal laminate (FML) hybrid laminate residual stress curing strain strain gage fiber Bragg grating (FBG) process monitoring smart cure cycle
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Components and Systems
DLR - Research area:Aeronautics
DLR - Program:L CS - Components and Systems
DLR - Research theme (Project):L - Structural Materials and Design, L - Advanced Materials and New Manufacturing Technologies
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Functional Lightweight Structures
Deposited By: Kappel, Dr.-Ing. Erik
Deposited On:11 Apr 2022 06:47
Last Modified:30 Jun 2023 10:48

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