Hybrid joints

1. WEBINAR “CHALLENGES AND SOLUTIONS FOR
IMPROVED DURABILITY OF MATERIALS”
ORGANISED BY SIRRIS, 22/10/2020
Prof. dr. ir. Wim De Waele, Ghent University

2. ENABLING QUALIFICATION OF HYBRID
STRUCTURES FOR LIGHTWEIGHT AND
SAFE MARITIME TRANSPORT
Prof. dr. ir. Wim De Waele, Ghent University

3. WHY USE ADHESIVELY BONDED BI-MATERIAL JOINTS?
 A composite ship superstructure leads to a
 Reduction of the top weight of naval ships (10%) and
1%-7% less fuel consumption (and harmful emissions)
 Increase in ship stability
 Less maintenance required
 Adhesively bonded joints vs bolted and welded joints
 Low-cost and fast manufacturing +
 lower tolerance requirements compared with bolting
 Increased building safety (no hot works), no induced welding deformations +
 can join dissimilar materials such as composite-steel, which is not possible by welding

4. WHY STILL A LIMITED USE IN MARINE APPLICATIONS?
 Lack of knowledge
 Harsh marine environment
 Interaction of damage mechanisms: fatigue and corrosion
 Multi-materials, multi-physics, multi-scale, interfaces
Will the joint last 25 years? Is it safe?
Can we predict failure? How will it fail?
 No certification guidelines
 Limits its application to secondary structures
Adhesive
FRP
Steel
Wood
Foam
water, ions

5. PROJECT DETAILS
 BUDGET 3.78 M€
 Funding Interreg2seas (60%)
 Start 14/8/17 - End 30/06/21
 11 partners: shipbuilders, class
societies, research centers and
technology providers
 20 observers
 4 countries: The Netherlands,
Belgium, United Kingdom, France

6. z
WP1 LONG TERM PERFORMANCE
 Test pyramid (reviewed by class)
SIMULATIONS
Develop (multi-physics)
numerical models
Value: predict complex joints,
less (expensive) experiments
EXPERIMENTS
Understand materials and
joints
Calibrate and validate
simulations

7. WP1 LONG TERM PERFORMANCE
 Material/coupon level: basic mechanical
properties of constituents
 Tensile testing
 Water uptake / diffusion coefficient
 Dynamic mechanical analysis
 Thick adherend shear stress

8. WP1 LONG TERM PERFORMANCE
 Structural detail/idealized joint: failure
characterization and toughness, accelerated
determination of fatigue properties
 Double cantilever beam
 End-notched-flexure
 Double strap joint

9. WP1 LONG TERM PERFORMANCE
 Component level (both thin and thick adhesive):
failure at real scale and representative loading
conditions
 Scoping tests to identify failure modes
 Quasi-static tensile and compression tests
 Bending tests
 Fatigue tests (tensile, bending)
 Arcan tests (mixed mode, quasi-static and fatigue)

10. WP1 LONG TERM PERFORMANCE
 Ageing of specimens
 Salt spray ageing
 Electrochemical corrosion
 Immersion in seawater

11. WP2 INSPECTION AND MONITORING
 A variety of techniques are used to enhance our knowledge about the mechanical
and damage behaviour of the joints
 Develop a structural health monitoring methodology for in-situ monitoring of
adhesively bonded joints
Sensors
Bonding joint

12. WP2 INSPECTION AND MONITORING
 Techniques used to support laboratory testing
 CT scanning
 Infrared Thermography
 Digital Image Correlation
 Ultrasound inspection
 Acoustic emission
A
B
C
D
shear
shear
shear
peel
peel
peel

13. WP2 INSPECTION AND MONITORING

14. WP2 INSPECTION AND MONITORING (+ WP1 LONG TERM PERFORMANCE)
 Acoustic emission
 Damage monitoring

15. WP2 INSPECTION AND MONITORING
 Strain measurements using optical fibre Bragg
sensors
 Surface mounted versus embedded
 Robustness against corrosion

16. WP3 GUIDELINES FOR THE QUALIFICATION OF THE ADHESIVE BONDS
 A consistent approach across and within classification
societies is needed
 Currently, structural adhesive joint design is approached on a case by
case
 Guidelines will help direct designers and manufacturers towards the
most straightforward approach for their application

17. WP3 GUIDELINES FOR THE QUALIFICATION OF THE ADHESIVE BONDS
 Assessment of current requirements for adhesively bonded joints in marine and
offshore applications, and in other industrial sectors
 Load analysis
 Multi-scale modelling approach
 Evaluation of design load cases and definition of
load histograms
 Drafting of guidelines
 Risk and goal based approach

18. z
TO CONCLUDE, THE “QUALIFY” AMBITIONS
 Enable the certification of hybrid joints for primary structures applications (2022)
 Evaluation of the long term structural performance
 Testing and simulations campaign
 Tailored testing equipment and accelerated testing
 Development of a reliable inspection and maintenance methodology
 Structural health and condition monitoring tests
 Development of a procedure (guidelines) for the qualification
 On the longer term
 Widespread use of adhesively bonded hybrid structures in shipbuilding (2022 - 2025)
 Gradual replacement of metallic parts with hybrid structures in other sectors, e.g. wind turbines (2022 -
2030)

19. This research was carried out within the project “QUALIFY – Enabling Qualification of Hybrid Joints for
Lightweight and Safe Maritime Transport”, co-funded by the INTERREG 2SeasMers Zeeën programme
http://www.interreg2seas.eu/qualify