Three-dimensional (3D) printing (also known as additive manufacturing) is an advanced manufacturing process that can produce complex shape geometries automatically from a 3D computer-aided design ...model without any tooling, dies and fixtures. This automated manufacturing process has been applied to many diverse fields of industries today due to significant advantages of creating functional prototypes in reasonable build time with less human intervention and minimum material wastage. However, a more recent application of this technology towards the built environment seems to improve our traditional building strategies while reducing the need for human resources, high capital investments and additional formworks. Research interest in employing 3D printing for building and construction has increased exponentially in the past few years. This paper reviews the latest research trends in the discipline by analysing publications from 1997 to 2016. Some recent developments for 3D concrete printing at the Singapore Centre for 3D Printing are also discussed here. Finally, this paper gives a brief description of future work that can be done to improve both the capability and printing quality of the current systems.
Full text
Available for:
BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
The advent of digital concrete fabrication calls for advancing our understanding of the interaction of 3D printing with material rheology and print parameters, in addition to developing new ...measurement and control techniques. Thixotropy is the main challenge associated with printable material, which offers high yield strength and low viscosity. The higher the thixotropy, the better the shape stability and the higher buildability. However, exceeding a minimum value of thixotropy can cause high extrusion pressure and poor interface bond strength if the printing parameters are not optimized to the part design. This paper aims to investigate the effects of both material and process parameters on the buildability and inter-layer adhesion properties of 3D printed cementitious materials, produced with different thixotropy and print head standoff distances. Nano particles are used to increase the thixotropy and, in this context, a lower standoff distance is found to be useful for improving the bond strength. The low viscosity "control" sample is unaffected by the variation in standoff distances, which is attributed to its flowability and low yield stress characteristics that lead to strong interfacial bonding. This is supported by our microscopic observations.
Full text
Available for:
IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
AbstractIn this paper, a novel method for printing path design in the three-dimensional (3D) concrete printing process (3DCP) has been developed and applied to a large-scale construction process. ...Despite the large number of research works in digital concrete printing over the last decade, few studies have explored the method of automatic printing path design, specifically designing the printing path by directly extracting building information modeling (BIM) information from the BIM platform in 3DCP. To obtain BIM information and automatically design the printing path, a script package was developed using a single scripting environment called Dynamo, a Revit plug-in. The proposed method was evaluated using the results of simulation and real-time printing. Compared with the conventional method, the simulation results show that the proposed approach can reduce data loss from a 3D BIM model to printing path generation. The real-time printing test implies that the proposed approach is perfectly suitable for integrating BIM with 3DCP.
Measurement of tensile bond strength of 3D printed geopolymer mortar Panda, Biranchi; Paul, Suvash Chandra; Mohamed, Nisar Ahamed Noor ...
Measurement : journal of the International Measurement Confederation,
January 2018, 2018-01-00, 20180101, Volume:
113
Journal Article
Peer reviewed
Open access
Display omitted
•The central concept of 3D concrete printing was described.•A novel fly ash based geopolymer mortar was formulated for large scale concrete printing application.•Fresh and hardened ...properties were characterized for printability of geopolymer mortar.•Tensile bond strength of the printed geopolymer was evaluated with respect to printing parameters.
The structural capacity of construction joints in concrete bridges, deck and pavements mainly depends on the bond strength between the old substrate and new overlaid concrete. Sometimes, a mismatch in the properties of old and new concrete may lead to early age failure and shortened service life. Since in 3D concrete printing (3DCP), the whole object is made by layer by layer, bond strength is considered as one of the key parameters to ensure stability in the structure. For understanding bond mechanism, it is essential to measure bond strength at the interface between new and old layer and investigate significant parameters affecting this property. In this direction, our current work targets to analyse tensile bond strength of 3D printed geopolymer mortar with respect to printing time gap between layers, nozzle speed and nozzle standoff distance. A novel formulation of fly ash based geopolymer was made and printed using four-axis automated gantry system. Experimental findings reveal that the bond strength is a function of state of interface material between two nearby layers which can be influenced by material strength development rate and 3D printing parameters.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Introduction
3D-printed temporal bone models enable the training and rehearsal of complex otological procedures. To date, there has been no consolidation of the literature regarding the developmental ...process of 3D-printed temporal bone models. A brief review of the current literature shows that many of the key surgical landmarks of the temporal bone are poorly represented in models. This study aims to propose a novel design and production workflow to produce high-fidelity 3D-printed temporal bone models for surgical simulation.
Methods
Developmental phases for data extraction, 3D segmentation and Computer Aided Design (CAD), and fabrication are outlined. The design and fabrication considerations for key anatomical regions, such as the mastoid air cells and course of the facial nerve, are expounded on with the associated strategy and design methods employed. To validate the model, radiological measurements were compared and a senior otolaryngologist performed various surgical procedures on the model.
Results
Measurements between the original scans and scans of the model demonstrate sub-millimetre accuracy of the model. Assessment by the senior otologist found that the model was satisfactory in simulating multiple surgical procedures.
Conclusion
This study offers a systematic method for creating accurate 3D-printed temporal bone models for surgical training. Results show high accuracy and effectiveness in simulating surgical procedures, promising improved training and patient outcomes.
In recent years, digital fabrication is termed as "third industrial revolution" and its interaction with extrusion based cementitious material has been well known as concrete printing. In concrete ...printing, a gantry/robotic system deposits concrete layer by layer following G-codes generated from slicing of the 3D component. However, the robotic system does not consider the material (concrete) properties and component geometry which sometimes cause failure in the printing process. Concrete properties are usually attributed with time and therefore the system parameters such as extruder velocity and layer height are necessarily to be controlled accordingly to obtain an uninterrupted smooth flow. In line with this, our current research aims to automate the printing process by collecting material's fresh properties through a feedforward control system. A six-axis industrial Denso robot was used for 3D printing of geopolymer concrete with the help of screw pump and ten-millimeter circular extruder. The obtained experimental results confirmed the validity and robustness of this automated set up.
PDF
