Modelling adhesive bonding

Modelling adhesive bonding

1. VCCT

   • HyperX
     • Callum can support
       • Meeting with him after playing with HyperX

2. CZM

   • Abaqus
     • Jesper
     • Pablo's team already modelled skin with stiffner
   • SIMCENTER
     • New software, more time required
     • Alexandru may support

3. Novel outcomes expected from university

   • New testing configuration
     • Predicting the performance on bonds better by updating models
       • Adhesive cell modelling
     • Mixed loads
     • Related to Pablo's work

4. How close does the modelling get to bonded joints in reality

5. Topics to dive into

   • Fracture mechanics
   • Adhesive materials
   • Surface treatments
     • Sandblasting
     • Anodising
     • Peel ply
     • Plasma treatment
     • UV irradiation
     • Abrade
   • Defect detection
   • Strength enhancement
   • Fatigue characteristics
   • Adhesion theory
     • Mechanical interlocking theory 1925
     • Physical absportion theory Schonhorn and Sharpe
     • Electronics/electrostatic theory
     • Diffusion theory
   • Analytical method
     • Goland and Reissner - beam-adhesive model

6. Pablo Bonded Covers study

   • Sudden collapse is predicted at 6.64mm displacement, all stringers disbond completely
     • Contrary to test observations
     • Skin-stringer contact has not been considered
       • Contributing to excessive disbond prediction
         • Therefore CZM should be used to assess the growth of disbond, and consider interface bond

7. TESTS to complete

   • Analytical
     • CZM
     • VCCT
   • Physical
     • Single Lap Shear
       • Film/Paste adhesive
       • repeated x3
       • Composite
       • Surface Prepped
     • Floating roller peel
     • Static and quasistatic tests no longer meet requirements of in-depth studies on failure modes of ADJ
       • Complex dynamic tests
     • Simple stress state cannot be replicated in real service conditions.
       • Complex stress state of ABJ's in cyclic loading.
     • Single test environments are not representative.
       • Different temperatures and humidity.

8. Secondary effects in ABJ's

   • https://www.sciencedirect.com/science/article/pii/S026382232400117X
   • Investigation into load eccentricity
     • How do I quantify the load eccentricity level in SLJ's tests. From CHATGPT
       • Distance between the centerline of applied loads and the N.A of the adhesive joint.
         • eccentricity distance
         • Bending moment induced due to eccentricity
           • Applied force X eccentricity distance
       • Using analytical or FE methods to calculate bending stresses
         • (M x y) / I
           • y = distance from N.A to point where stress is evaluated.
           • I = second moment area of adherent cross section
       • Use strain gauges or DIC to measure secondary bending
         • Strain gauges on the top and bottom surface of adherent can measure bending strain.
           • This is a direct result of eccentric loading.
           • If there is no bending the strain gauges will be the same on both surfaces. (pure shear)
           • Eccentricity will induce different strains, causing a bending effect. With this difference you can infer the bending moment/eccentricity.
       • Define the eccentricity ratio
         • e/t
         • Higher ratio means more secondary bending effect
         • e = eccentricity distance
         • t = thickness of adherent
   • Use of ductile/brittle adhesives