Deposition dynamics and analysis of polyurethane foam structure boundaries for aerial additive manufacturing

ABSTRACT

Additive manufacturing in construction typically consists of ground-based platforms. Introducing aerial capabilities offers scope to create or repair structures in dangerous or elevated locations. The Aerial Additive Manufacturing (AAM) project has developed a pioneering approach using Unmanned Aerial Vehicles (UAV, ‘drones’) to deposit material during self-powered, autonomous, untethered flight. This study investigates high and low-density foams autonomously deposited as structural and insulation materials. Drilling resistance, mechanical, thermal and microscopy tests investigate density variation, interfacial integrity and thermal stability. Autonomous deposition is demonstrated using a flying UAV and robotic arm. Results reveal dense material at interfaces and directionally dependent cell expansion during foaming. Cured interfacial regions are vulnerable to loading parallel to interfaces but resistant to perpendicular loading. Mitigation of trajectory printing errors caused by UAV flight disturbance is demonstrated by a stabilising end effector, with trajectory errors ≤10 mm. AAM provides a significant development towards on-site automation in construction.

Highlights

• Aerial Additive Manufacturing (AAM) releases additive manufacturing (AM) for construction applications from ground-based and tethered restraints.

• Multiple self-powered flying Unmanned Aerial Vehicles (UAV) can deposit layers of polyurethane foam in planned trajectories.

• High-density polyurethane foam and low-density foam can be suitable for structural and insulating layers, respectively.

• Laboratory tests, including drilling resistance, demonstrate the high-density of interfacial boundary regions in relation to material located away from a boundary.

• The challenges of reducing lateral deformation of extruded material are evaluated, and improved flight stabilisation provided by an end effector keeping trajectory errors within 10 mm is demonstrated.

KEYWORDS:

• Aerial additive manufacturing
• polyurethane foam
• density
• interface
• boundary
• printing stabilisation

ABBREVIATIONS:

• AAM: Aerial Additive Manufacturing
• AM: Additive Manufacturing
• DMA: Dynamic Mechanical Analysis
• DoF: Degrees of Freedom
• DSC: DifferentialScanning Calorimetry
• E': Elastic/storage modulus (DMA)
• E”: Viscous/loss modulus(DMA)
• FTIR: Fourier Transform Infrared Spectroscopy
• G': Elastic/storage modulus(Rheology)
• G”: Viscous modulus (Rheology) nm: Nanometres
• PSD: Position Sensitive Detector
• STA: Simultaneous ThermalAnalysis
• TGA: Thermal Gravimetric Analysis
• Tan δ: Damping factor (DMA)
• UAV:Unmanned Aerial Vehicle
• Vf: Volume fraction
• XRD: X-Ray Diffraction
• δ: PhaseAngle

Acknowledgments

The authors express thanks to the following: Dr Ketao Zhang (Automated deposition device development, Imperial College London, UK and Queen Mary University, London, UK). Dr Sina Sareh (Automated deposition device development, Imperial College London, UK and Royal College of Art, London, UK). Shamsiah Awang-Ngah and Sheldon Wang for adhesion and mechanical removal of samples support (University of Strathclyde and University of Bath, UK). Members of the Aerial Robotics Laboratory at Imperial College, London, UK and the Laboratory of Sustainability Robotics at Empa, Switzerland. The technical support of the Department of Architecture and Civil Engineering laboratories and the Microscopy analysis suite, MC${}^2$, University of Bath, UK.

Data availability statement

The data that support the findings of this study are openly available in the ‘University of Bath data archive’ at https://doi.org/10.15125/BATH-00385, reference number [00385].

Disclosure statement

The authors report there are no competing interests to declare.The authors declare that they have no financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors confirm approval of the finished manuscript and consent to co-authorship. All listed authors contributed to the final manuscript, which is wholly original and is not under consideration by an alternative publication.

Geo-location

The authors of this paper are based primarily in the United Kingdom, with affiliations in London, Bath and Bristol. Selected authors have an additional affiliation based in Dubendorf, near Zurich, Switzerland.

Author contribution

Barrie Dams: Writing − Original Draft, Writing -- Review & Editing, Conceptualisation, Methodology, Validation, Investigation, Formal Analysis, Visualisation. Lachlan Orr: Writing − Original Draft, Investigation, Formal Analysis, Visualisation. Yusuf Furkan Kaya: Writing − Original Draft, Investigation, Formal Analysis, Visualisation. Bahadir Basaran Kocer: Writing − Original Draft, Investigation, Formal Analysis, Visualisation. Paul Shepherd: Conceptualisation, Writing − Review & Editing, Supervision, Methodology. Mirko Kovac: Conceptualisation, Writing − Review & Editing, Supervision, Funding Acquisition, Project Administration, Methodology. Richard Ball: Conceptualisation, Writing − Review & Editing, Supervision, Funding Acquisition, Project Administration, Methodology.

Additional information

Funding

The Aerial Additive Manufacturing project is funded by the Engineering and Physical Sciences Research Council (EPSRC) [grant number EP/N018494 /1]. The project was supported by the Royal Woolfson Society [fellowship grant number RSWF/R1/18003]. Further support was provided by the EPSRC Centre for Decarbonisation of the Built Environment (dCarb) [grant number EP/L016869/1], a University of Bath Research Scholarship and an Imperial College fellowship.