liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
Quasi-static bearing failure of CFRP composite in biaxially loaded bolted joints
Linköping University, Department of Management and Engineering. Linköping University, Faculty of Science & Engineering. Saab AB, SE-58188 Linkoping, Sweden.
Saab AB, SE-58188 Linkoping, Sweden.
Swedish Def Research Agency, Sweden.
Linköping University, Department of Management and Engineering, Solid Mechanics. Linköping University, Faculty of Science & Engineering.
2015 (English)In: Composite structures, ISSN 0263-8223, Vol. 125, 60-71 p.Article in journal (Refereed) Published
Abstract [en]

Hybrid composite-aluminium bolted joints develop internal loads at elevated temperatures, due to the difference in thermal expansion properties of their constituent materials. In aircraft joints, the thermally induced bolt loads are commonly directed perpendicular to the mechanical loads, inducing a biaxial bearing load state. In this work, carbon-epoxy laminate specimens were tested in uniaxial and biaxial quasi-static bearing failure experiments in a specially designed test rig, at elevated temperature. A microscopy study of a failed specimen revealed that the failure process was mainly driven by fibre kinking, although extensive matrix cracking and delaminations were also found. The experiments were simulated by three-dimensional, explicit, finite element analyses, which included intralaminar damage and delamination. The experimental and simulated bearing failure loads differed by 1.7% in the uniaxial case and 2.1% in the biaxial case. It was suggested that the load-displacement response is influenced by the interaction of all damage mechanisms. Delamination modelling was, however, not essential for the prediction of the maximal bearing strength. The same effective bearing strengths were obtained for the biaxially loaded specimens as for the uniaxially loaded ones, but the damage accumulation process and the resulting damage distributions were different. (C) 2015 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
Elsevier , 2015. Vol. 125, 60-71 p.
Keyword [en]
Hybrid joint; Carbon-epoxy; Thermally induced load; Bearing failure; Finite element analysis
National Category
Mechanical Engineering
URN: urn:nbn:se:liu:diva-118234DOI: 10.1016/j.compstruct.2015.01.038ISI: 000353177600008OAI: diva2:813546

Funding Agencies|Swedish Armed Forces; Swedish Defence Materiel Administration; Swedish Governmental Agency

Available from: 2015-05-22 Created: 2015-05-22 Last updated: 2015-11-02
In thesis
1. Static and Fatigue Failure of Bolted Joints in Hybrid Composite-Aluminium Aircraft Structures
Open this publication in new window or tab >>Static and Fatigue Failure of Bolted Joints in Hybrid Composite-Aluminium Aircraft Structures
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of fibre composites in the design of load carrying aircraft structures has been increasing over the last few decades. At the same time, aluminium alloys are still present in many structural parts, which has led to an increase of the number of hybrid composite-aluminium structures. Often, these materials are joined at their interface by bolted connections. Due to their different response to thermal, mechanical and environmental impact, the composite and the aluminium alloy parts are subject to different design and certification practices and are therefore considered separately.The current methodologies used in the aircraft industry lack well-developed methods to account for the effects of the mismatch of material properties at the interface.One such effect is the thermally induced load which arises at elevated temperature due to the different thermal expansion properties of the constituent materials. With a growing number of hybrid structures, these matters need to be addressed. 

The rapid growth of computational power and development of simulation tools in recent years have made it possible to evaluate the material and structural response of hybrid structures without having to entirely rely on complex and expensive testing procedures.However, as the failure process of composite materials is not entirely understood, further research efforts are needed in order to develop reliable material models for the existing simulation tools.

The work presented in this dissertation involves modelling and testing of bolted joints in hybrid composite-aluminium structures.The main focus is directed towards understanding the failure behaviour of the composite material under static and fatigue loading, and how to include this behaviour in large scale models of a typical bolted airframe structure in an efficient way. In addition to that, the influence of thermally induced loads on the strength and fatigue life is evaluated in order to establish a design strategy that can be used in the industrial context.

The dissertation is divided into two parts. In the first one, the background and the theory are presented while the second one consists of five scientific papers.

Place, publisher, year, edition, pages
Linköping University Electronic Press, 2015. 53 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1706
Hybrid structures; Composites; Bearing failure; Bolted joints
National Category
Aerospace Engineering
urn:nbn:se:liu:diva-122349 (URN)10.3384/diss.diva-122349 (DOI)978-91-7685-942-1 (print) (ISBN)
Public defence
2015-12-03, C3, Hus C, Campus Valla, Linköping, 10:15 (English)
Available from: 2015-11-02 Created: 2015-10-29 Last updated: 2015-11-02Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Search in DiVA

By author/editor
Kapidzic, ZlatanSimonsson, Kjell
By organisation
Department of Management and EngineeringFaculty of Science & EngineeringSolid Mechanics
In the same journal
Composite structures
Mechanical Engineering

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 240 hits
ReferencesLink to record
Permanent link

Direct link