Freeform Fabrication of Thermoplastic Composites
1
Flexible Digital Manufacturing for Freeform Fabrication of Thermoplastic Composites *Pablo Jaramillo, Patrick JP Fairclough Department of Mechanical Engineering, University of Sheffield *Corresponding author E-mail address: [email protected] Introduction Fibre Reinforced Composites (FRCs) are considered as the materials of the future mainly because of the possibility to produce stronger and lighter structures. However, there is little in terms of traceability and limited feedback to improve manufacture which limits composite’s spread. In addition, even though several techniques might be suitable for small batches, individual customization is penalized due to the production of new and sometimes expensive moulds. Incremental Sheet Forming Recently, Incremental Sheet Forming (ISF), a new sheet metal manufacturing technique has evolved to overcome the need of expensive and complex moulds due to an incremental or step-by-step deformation to achieve a specific geometry as illustrated in Figure 1. Furthermore, to our knowledge, this technique has not been implemented in FRCs. Figure 1. Incremental Forming Process Objectives This research is conducted thanks to the Faculty of Engineering Doctoral Academy Scholarship Program of the University of Sheffield Acknowledgements References V. Franzen, L. Kwiatkowski, P. A. F. Martins, and A. E. Tekkaya, "Single point incremental forming of PVC," Journal of materials processing technology., vol. 209, no. 1, pp. 462-469, 2009. A. Fiorentino, C. Giardini, E. Ceretti, “Application of artificial cognitive system to incremental sheet forming machine tools for part precision improvement, Precision Engineering, Vol 39, pp. 167-172, 2015 Alcock, B. PhD Thesis, Queen Mary University of London, Chapter 2, pp. 26, 2004 Future Work Figure 5. Robotic single (left) and double point (right) incremental forming Robotic Prototype The robotic set up is in the design stage to perform single and/or double point forming operations covering the following aspects: • Kinematics • Dynamics • Heating • Mechanism • Actuation • Control • Sensing • Learning Preliminary Experiments In order to test the applicability of Incremental Sheet Forming to FRCs, a simplification of incremental forming machine was developed to perform single and multiple indentation forming operations as shown in Figure 2. The first used and external oven, while the second implemented a temperature controlled chamber. Single Indentation Forming Multiple Indentation Forming Figure 2. Singe and Multiple Indentation Forming Preliminary Experiments The material used was a Self-reinforced thermoplastic composite laminate made a co- extruded all-polypropylene tape-Armodon™ (Figure 3). Figure 3. Self-reinforced composite fabrication Indentation Forming Self-Reinforced Composites Results 0 5 10 15 20 -500 0 500 1000 1500 2000 Force (N) Displacement (mm) 1 2 3 4 Figure 3. Mould free resultant geometries for single (left) and multiple (right) indentation forming. Geometry is dependent of boundary conditions and indentation pattern. Conclusions • Mould Free cone-like composites were created via single and multiple indentation forming operations • The final geometry achievable is dependent in the boundary conditions such as: - Clamping Condition influence the wrinkles - Support geometry influence the overall shape of the final geometry - Indentation patter influence geometric details. • The forming forces measured during the test revealed a change in the flexibility to deformation of the material for each indentation. This means that the location of the point of contact and the state of material around at each indentation are relevant factors in the mechanism of the forming process . Figure 4. Forming Forces: 4 (Top) and 13 (Bottom) indentations in a 15-layer laminate. The flexibility of deformation increases for subsequent indentations. Based on the success of Indentation forming, the aim of this study is to implement machine learning algorithms for flexible digital manufacturing via Incremental Forming to create mould free composites for low cost, high-quality, and individual customization. The following objectives are proposed: 1. To build and adapt a prototype machine to produce mould free and data rich fabrication of composites. 2. To construct a design of experiments based on machine and material parameters suitable to obtain enough data. 3. To apply learning strategies to discover an approximate function that construct the input-output behavior observed in the data. Machine Learning An agent is learning if it improves its performance on future tasks based on previous observations. 5 layers 10 layers 15 layers Training Data Learning Algorithms Inputs & Outputs Clean, Prepare, and Manipulate Data Supervised, Unsupervised, or Reinforcement Learning Test & Improve Figure 5. Typical Machine Learning Flow
Transcript of Freeform Fabrication of Thermoplastic Composites
Flexible Digital Manufacturing for
Freeform Fabrication of Thermoplastic Composites
*Pablo Jaramillo, Patrick JP Fairclough
Department of Mechanical Engineering, University of Sheffield*Corresponding author
E-mail address: [email protected]
Introduction
Fibre Reinforced Composites (FRCs) areconsidered as the materials of the future mainlybecause of the possibility to produce stronger andlighter structures. However, there is little in terms oftraceability and limited feedback to improvemanufacture which limits composite’s spread. Inaddition, even though several techniques might besuitable for small batches, individual customizationis penalized due to the production of new andsometimes expensive moulds.
Incremental Sheet FormingRecently, Incremental Sheet Forming (ISF), a newsheet metal manufacturing technique has evolvedto overcome the need of expensive and complexmoulds due to an incremental or step-by-stepdeformation to achieve a specific geometry asillustrated in Figure 1. Furthermore, to ourknowledge, this technique has not beenimplemented in FRCs.
Figure 1. Incremental Forming Process
Objectives
This research is conducted thanks to the Facultyof Engineering Doctoral Academy ScholarshipProgram of the University of Sheffield
Acknowledgements
References
V. Franzen, L. Kwiatkowski, P. A. F. Martins, and A. E.
Tekkaya, "Single point incremental forming of PVC,"
Journal of materials processing technology., vol. 209,
no. 1, pp. 462-469, 2009.
A. Fiorentino, C. Giardini, E. Ceretti, “Application of
artificial cognitive system to incremental sheet forming
machine tools for part precision improvement,
Precision Engineering, Vol 39, pp. 167-172, 2015
Alcock, B. PhD Thesis, Queen Mary University of
London, Chapter 2, pp. 26, 2004
Future Work
Figure 5. Robotic single (left) and double point (right) incremental forming
Robotic PrototypeThe robotic set up is in the design stage toperform single and/or double point formingoperations covering the following aspects:
• Kinematics• Dynamics• Heating• Mechanism
• Actuation• Control• Sensing• Learning
Preliminary Experiments
In order to test the applicability of IncrementalSheet Forming to FRCs, a simplification ofincremental forming machine was developed toperform single and multiple indentation formingoperations as shown in Figure 2. The first usedand external oven, while the second implementeda temperature controlled chamber.
Single Indentation Forming
Multiple Indentation Forming
Figure 2. Singe and Multiple Indentation Forming
Preliminary Experiments
The material used was a Self-reinforcedthermoplastic composite laminate made a co-extruded all-polypropylene tape-Armodon™(Figure 3).
Figure 3. Self-reinforced composite fabrication
Indentation Forming
Self-Reinforced Composites
Results
0 5 10 15 20
-500
0
500
1000
1500
2000
Forc
e (
N)
Displacement (mm)
1
2
3
4
Figure 3. Mould free resultant geometries for single (left)and multiple (right) indentation forming. Geometry isdependent of boundary conditions and indentation pattern.
Conclusions• Mould Free cone-like composites were created
via single and multiple indentation formingoperations
• The final geometry achievable is dependent inthe boundary conditions such as:
- Clamping Condition influence the wrinkles- Support geometry influence the overallshape of the final geometry
- Indentation patter influence geometricdetails.
• The forming forces measured during the testrevealed a change in the flexibility todeformation of the material for eachindentation. This means that the location of thepoint of contact and the state of materialaround at each indentation are relevant factorsin the mechanism of the forming process .
Figure 4. Forming Forces: 4 (Top) and 13 (Bottom)indentations in a 15-layer laminate. The flexibility of
deformation increases for subsequent indentations.
Based on the success of Indentation forming, theaim of this study is to implement machinelearning algorithms for flexible digitalmanufacturing via Incremental Forming to createmould free composites for low cost, high-quality,and individual customization.
The following objectives are proposed:1. To build and adapt a prototype machine to
produce mould free and data rich fabricationof composites.
2. To construct a design of experiments basedon machine and material parameterssuitable to obtain enough data.
3. To apply learning strategies to discover anapproximate function that construct theinput-output behavior observed in the data.
Machine LearningAn agent is learning if it improves itsperformance on future tasks based on previousobservations.
5 layers
10 layers
15 layers
Training
Data
Learning
Algorithms
Inputs & Outputs
Clean, Prepare,
and Manipulate
Data
Supervised,
Unsupervised, or
Reinforcement
Learning
Test &
Improve
Figure 5. Typical Machine Learning Flow
