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Evaluation of residual stress development in FRP-metal hybrids using fiber Bragg grating sensors

Prussak, Robert and Stefaniak, Daniel and Hühne, Christian and Sinapius, Michael (2018) Evaluation of residual stress development in FRP-metal hybrids using fiber Bragg grating sensors. Production Engineering. Springer. DOI: 10.1007/s11740-018-0793-4 ISSN 0944-6524

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Abstract

This paper presents experimental measurement methods for the determination and evaluation of process related thermal residual stresses in fiber metal laminates. A cure monitoring system with fiber Bragg grating (FBG) sensors is used to measure the in-plane strains during processing of carbon fiber reinforced plastic (CFRP)-steel laminates. The simultaneous measurement captures the thermal expansion during the heating stages, the cure shrinkage, and the cooling thermal shrinkage. The results enable the characterization of the co-cure bonding process and the stress transfer between the metal and FRP-layers during the creation process. The residual strains, which are used for calculation of the residual stresses, are recorded at room temperature after manufacturing. In addition, an advanced method using FBG-sensors and the deflection of asymmetric hybrid specimens is developed to validate the gained residual stress data. Asymmetrical specimens are created by removing selected layers after cure. Quantitative evaluation is achieved by determination of their curvature and measuring the strain changes with the embedded FBG-sensors. For validation, the methods were successfully demonstrated on two different curing cycles with different resulting residual stress levels. The simultaneous strain measurement enables the investigation of stress development and delivers more in-depth process knowledge for further optimization of the manufacturing process.

Item URL in elib:https://elib.dlr.de/119298/
Document Type:Article
Title:Evaluation of residual stress development in FRP-metal hybrids using fiber Bragg grating sensors
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Prussak, Robertrobert.prussak (at) dlr.deUNSPECIFIED
Stefaniak, Danieldaniel.stefaniak (at) dlr.deUNSPECIFIED
Hühne, Christianchristian.huehne (at) dlr.deUNSPECIFIED
Sinapius, Michaelmichael.sinapius (at) dlr.deUNSPECIFIED
Date:January 2018
Journal or Publication Title:Production Engineering
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1007/s11740-018-0793-4
Publisher:Springer
Series Name:Production Process
ISSN:0944-6524
Status:Published
Keywords:Fiber metal laminate, Residual stress, Co-cure bonding, Process monitoring, FBG
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Structures and Materials
Location: Braunschweig
Institutes and Institutions:Institute of Composite Structures and Adaptive Systems > Functional Lightweight Structures
Deposited By: Prussak, Robert
Deposited On:19 Mar 2018 06:10
Last Modified:14 Dec 2019 04:20

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