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Understanding the lamination process
- 1. www.bris.ac.uk/composites Michael Elkington Supervisors: CWard, K Potter. University of Bristol michael.elkington@bristol.ac.uk Understanding the Lamination Process
- 2. 2/18 Understanding the laminationprocess Hand layup of prepreg • Complex parts • Short lead times • Low setup costs • High labour costs • Low production rates • Variability • Potential shortage of laminators The process has changed little in decades: Scope for optimisation.
- 3. 3/18 Understanding the laminationprocess • Flat sheet + Double Curved mould = In-plane shear deformation • VFP (Virtual fabric placement) provides deformation predictions The knowledge gap: “How is the deformation achieved…?”
- 4. 4/18 Understanding the laminationprocess Analysis Methodology 1. Record operators at work Areas 2. Watch the footage 3. Record the frequency and location of specific techniques 6 laminators 19 layup trials 3 Repeats each
- 5. 5/18 Understanding the laminationprocess 7 key Techniques Guiding with two hands (G2H) One handed Guiding (1HG) Manually Folding material (MF) Tension Secured shearing (TSS) Smoothing with tension (S&T) Tool interaction shear forming (TIS) Tension-Tension Shear forming (TTS).
- 6. 6/18 Understanding the laminationprocess Results: Common techniques Certain techniques saw use across all tasks. Example: One handed Guiding, (1HG): Used almost exclusively to align edge of plies.
- 7. 7/18 Understanding the laminationprocess Two sample results A - Starting at the front B - Starting at the back 20˚ shear
- 8. 8/18 Understanding the laminationprocess Common techniques in task A 1. Regular Prepreg 2. Technique applied 3. Prepreg shears “Tension secured shearing”: Used exclusively 4+ per ply. 4. Prepreg shape formed.
- 9. 9/18 Understanding the laminationprocess Common techniques in task B 1. Regular Prepreg 2. TIS being applied. 3. Prepreg shears 3. Prepreg shape formed. “Tool interaction shearing” : Used exclusively 12+ times per ply
- 10. 10/18 Understanding the laminationprocess Discovering techniques Apply tension directly to ply edge. e.g. Fibres pivot towards the free edge. 1 Layup models: Predict shear deformation. 3 Discover the technique: The techniques most commonly used to shear the material can be predicted 2 Feature analysis: • Shear deformation angle, • Direction, • Location and local topology, • Overall Drape direction. Starting point, Undeformed cloth, Sheared Cloth,
- 11. 11/18 Understanding the laminationprocess Conclusions 1. Identified 7 techniques for lamination 2. Links between areas and techniques 3. The shear angle is not the only variable to consider. Training Automation Evolution of the process What the techniques are and where to use them What techniques an automated solution might have to replicate Multiple options to evolve the process
- 12. 12/18 Understanding the laminationprocess Further work: Evolution of the process Current projects at Bristol: 1. Improved layup tools. 2. Providing detailed layup instructions 3. Utilising VFP to aid layup projection systems. 4. ‘Preshearing’ of the plies. Starting point Sheared areas Grasping sign Securing sign ?
- 13. 13/18 Understanding the laminationprocess Further work: Pre-shearing Starting with a kinematic model Apply shear prior to tool contact. Ply already fits into tool and deforms easily Reduced Layup time and effort Large number of applications = Complex and time consuming Solution: Shearing the plies prior to layup: ‘Preshearing’ Reduction in on tool and overall layup time Less defects Lamination became ‘easy’
- 14. 14/18 Understanding the laminationprocess Thank you for listening. Questions and ideas welcome: michael.elkington@bristol.ac.uk Doctoral Training Centre (DTC)