Analysis of residual transverse stresses in a thick UD glass/polyester pultruded profile using hole drilling with strain gage and digital image correlation

Yuksel, Onur; Baran, Ismet; Ersoy, Nuri; Akkerman, Remko

Abstract

© 2018 Author(s). Process induced stresses inherently exist in fiber reinforced polymer composites particularly in thick parts due to the presence of non-uniform cure, shrinkage and thermal expansion/contraction during manufacturing. In order to increase the reliability and the performance of the composite materials, process models are developed to predict the residual stress formation. The accuracy of the process models is dependent on the geometrical (micro to macro), material and process parameters as well as the numerical implementation. Therefore, in order to have reliable process modelling framework, there is a need for validation and if necessary calibration of the developed models. This study focuses on measurement of the transverse residual stresses in a relatively thick pultruded profile (20×20 mm) made of glass/polyester. Process-induced residual stresses in the middle of the profile are examined with different techniques which have never been applied for transverse residual stresses in thick unidirectional composites. Hole drilling method with strain gage and digital image correlation are employed. Strain values measured from measurements are used in a finite element model (FEM) to simulate the hole drilling process and predict the residual stress level. The measured released strain is found to be approximately 180 μm/m from the strain gage. The tensile residual stress at the core of the profile is estimated approximately as 7-10 MPa. Proposed methods and measured values in this study will enable validation and calibration of the process models based on the residual stresses.

Citation

Yuksel, O., Baran, I., Ersoy, N., & Akkerman, R. (2018). Analysis of residual transverse stresses in a thick UD glass/polyester pultruded profile using hole drilling with strain gage and digital image correlation. AIP Conference Proceedings, 1960, 020040. https://doi.org/10.1063/1.5034841

• Journal Article Type: Conference Paper
• Conference Name: 21st International ESAFORM Conference on Material Forming
• Conference Location: Palermo, Italy
• Acceptance Date: Apr 23, 2018
• Online Publication Date: May 3, 2018
• Publication Date: May 2, 2018
• Deposit Date: Jan 24, 2019
• Journal: AIP Conference Proceedings
• Print ISSN: 0094-243X
• Electronic ISSN: 1551-7616
• Publisher: AIP Publishing
• Peer Reviewed: Not Peer Reviewed
• Volume: 1960
• Pages: 020040
• DOI: https://doi.org/10.1063/1.5034841
• Keywords: pultrusion, residual stresses, fibre reinforced cmposites
• Public URL: https://uwe-repository.worktribe.com/output/868386
• Publisher URL: http://doi.org/10.1063/1.5034841
• Additional Information: Title of Conference or Conference Proceedings : 21st International ESAFORM Conference on Material Forming