scholarly journals Fused Filament Fabrication Printer Modified to Dispense Cement Paste for Concrete Additive Manufacturing Studies

2020 ◽  
Vol 125 ◽  
Author(s):  
Scott Z. Jones
Keyword(s):  
Additive Manufacturing ◽  
Cement Paste ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Flow Properties ◽  
Fused Filament Fabrication ◽  
Concrete Construction ◽  
Precise Control ◽  
Pumping System ◽  
Subsequent Layer

Additive manufacturing (AM) with cement-based materials is an emerging technology that has the potential to revolutionize concrete construction. The placement process is quite complex, requiring sufficient flow properties as the material leaves the nozzle, and sufficient stiffening properties before the subsequent layer is placed. Precise control of material proportions and in-line monitoring of the time-dependent rheology are required to ensure the successful adoption of AM in the concrete construction community. To facilitate the study of the rheological properties of cementitious materials, as they pertain to AM, a commercial bench-top fused filament fabrication three-dimensional (3-D) printer was modified to dispense cement paste mixtures. Modifications included the design and assembly of a pumping system and software modifications to the 3-D printer's firmware that were necessary to accommodate the new hardware. After assembly, a series of tests were conducted to verify machine movements and to calibrate the number of step pulses required per unit volume of extruded paste. The resulting software modifications and configuration files are publicly available.

Design of Three-Dimensional, Triply Periodic Unit Cell Scaffold Structures for Additive Manufacturing

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Mazher Iqbal Mohammed ◽  
Ian Gibson
Keyword(s):  
Additive Manufacturing ◽  
Periodic Structures ◽  
Three Dimensional ◽  
Unit Cell ◽  
Final Size ◽  
Fused Filament Fabrication ◽  
Cell Structures ◽  
Triply Periodic ◽  
Unit Cells ◽  
Scaffold Structure

Highly organized, porous architectures leverage the true potential of additive manufacturing (AM) as they can simply not be manufactured by any other means. However, their mainstream usage is being hindered by the traditional methodologies of design which are heavily mathematically orientated and do not allow ease of controlling geometrical attributes. In this study, we aim to address these limitations through a more design-driven approach and demonstrate how complex mathematical surfaces, such as triply periodic structures, can be used to generate unit cells and be applied to design scaffold structures in both regular and irregular volumes in addition to hybrid formats. We examine the conversion of several triply periodic mathematical surfaces into unit cell structures and use these to design scaffolds, which are subsequently manufactured using fused filament fabrication (FFF) additive manufacturing. We present techniques to convert these functions from a two-dimensional surface to three-dimensional (3D) unit cell, fine tune the porosity and surface area, and examine the nuances behind conversion into a scaffold structure suitable for 3D printing. It was found that there are constraints in the final size of unit cell that can be suitably translated through a wider structure while still allowing for repeatable printing, which ultimately restricts the attainable porosities and smallest printed feature size. We found this limit to be approximately three times the stated precision of the 3D printer used this study. Ultimately, this work provides guidance to designers/engineers creating porous structures, and findings could be useful in applications such as tissue engineering and product light-weighting.

scholarly journals Ultra-High Early Strength Cementitious Grout Suitable for Additive Manufacturing Applications Fabricated by Using Graphene Oxide and Viscosity Modifying Agents

Polymers ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 2900
Author(s):  
Alyaa Mohammed ◽  
Nihad Tareq Khshain Al-Saadi
Keyword(s):  
Graphene Oxide ◽  
Additive Manufacturing ◽  
3D Printing ◽  
Design Method ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Fresh Properties ◽  
Manufacturing Applications ◽  
Mechanical Strengths ◽  
The Impact

One of the considerable challenges in the design of cementitious mixtures for additive manufacturing/three-dimensional (3D) printing applications is achieving both suitable fresh properties and significant mechanical strengths. This paper presents the use of graphene oxide (GO) as a promising nano reinforcement material with the potential to improve the printing feasibility and quality of a 3D printed cementitious matrix. Additionally, in this study, a viscosity modifying agent (VMA) was employed as a chemical additive to attain the required consistency and flow. The printed mixture was fabricated using various cementitious materials and waste materials. This study investigated the impact of GO and VMA on the enhancement of the 3D printing of cementitious composites through several tests. A flow test was conducted using the flow table test. The results showed a high fluidity and practical consistency, which are essential for nozzle pumping and accurateness in printed shapes. Furthermore, the bleeding test showed minimal bleeding up to hardening, and a considerable self-cleaning ability was noted during handling when conducting examinations of fresh properties. For hardened properties, the mechanical strengths were exceptionally high, especially at early ages, which is crucial for the stability of sequence layers of printed composites. The tensile strengths were 3.77, 10.5, 13.35, and 18.83 MPa at 1, 3, 7, and 28 days, respectively, and the compressive strengths were 25.1, 68.4, 85.6, and 125.4 MPa at 1, 3, 7, and 28 days, respectively. The test results showed the effectiveness of the fabricated cementitious mixture design method for meeting the requirements for 3D concrete printing applications.

scholarly journals A 3D weaving infill pattern for fused filament fabrication

2021 ◽  
Author(s):  
Yuan Yao ◽  
Cheng Ding ◽  
Mohamed Aburaia ◽  
Maximilian Lackner ◽  
Lanlan He
Keyword(s):  
Additive Manufacturing ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Fused Filament Fabrication ◽  
Repetitive Structure ◽  
Mechanical Linkage ◽  
Manufacturing Technologies ◽  
Dimensional Object ◽  
Anisotropy Of Mechanical Properties ◽  
3D Weaving

Abstract The Fused Filament Fabrication process is the most used additive manufacturing process due to its simplicity and low operating costs. In this process, a thermoplastic filament is led through an extruder, melted, and applied to a building platform by the axial movements of an automated Cartesian system in such a way that a three-dimensional object is created layer by layer. Compared to other additive manufacturing technologies, the components produced have mechanical limitations and are often not suitable for functional applications. To reduce the anisotropy of mechanical strength in fused filament fabrication (FFF), this paper proposes a 3D weaving deposit path planning method that utilizes a 5-layer repetitive structure to achieve interlocking and embedding between neighbor slicing planes to improve the mechanical linkage within the layers. The developed algorithm extends the weaving path as an infill pattern to fill different structures and makes this process feasible on a standard three-axis 3D printer. Compared with 3D weaving printed parts by layer-to-layer deposit, the anisotropy of mechanical properties inside layers is significantly reduced to 10.21% and 0.98%.

A Conceptual Design and Modeling Framework for Integrated Additive Manufacturing

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Hossein Mokhtarian ◽  
Eric Coatanéa ◽  
Henri Paris ◽  
Mouhamadou Mansour Mbow ◽  
Franck Pourroy ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Process Model ◽  
Conceptual Modeling ◽  
Three Dimensional ◽  
Integrated Model ◽  
Performance Model ◽  
Process Equipment ◽  
3D Printer ◽  
Fused Filament Fabrication ◽  
Modeling Framework

Modeling and simulation for additive manufacturing (AM) is commonly used in industry. Nevertheless, a central issue remaining is the integration of different models focusing on different objectives and targeting different levels of details. The objective of this work is to increase the prediction capability of characteristics and performances of additively manufactured parts and to co-design parts and processes. The paper contributes to this field of research by integrating part's performance model and additive technology process model into a single early integrated model. The paper uses the dimensional analysis conceptual modeling (DACM) framework in an AM perspective to generate causal graphs integrating the AM equipment and the part to be printed. DACM offers the possibility of integrating existing knowledge in the model. The framework supported by a computer tool produces a set of governing equations representing the relationships among the influencing variables of the integrated model. The systematic identification of the weaknesses and contradictions in the system and qualitative simulation of the system are some of the potential uses of the model. Ultimately, it is a way to create better designs of machines and parts, to control and qualify the manufacturing process, and to control three-dimensional (3D) printing processes. The DACM framework is tested on two cases of a 3D printer using the fused filament fabrication (FFF) powder bed fusion. The analysis, applied to the global system formed of the 3D printer and the part, illustrates the existence of contradictions. The analysis supports the early redesign of both parts and AM process (equipment) and later optimization of the control parameters.

Fabrication of nanocellulose/PEGDA hydrogel by 3D printing

2018 ◽  
Vol 24 (8) ◽  
pp. 1265-1271 ◽  
Author(s):  
Aimin Tang ◽  
Qinwen Wang ◽  
Shan Zhao ◽  
Wangyu Liu
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
3D Structure ◽  
Three Dimensional ◽  
Aqueous Dispersion ◽  
Compression Modulus ◽  
Content Type ◽  
Precise Control ◽  
Light Curing ◽  
Equilibrium Swelling Ratio

Purpose Nanocellulose is characterised by favourable biocompatibility, degradability, nanostructure effect, high modulus and high tensile strength and has been widely applied in various fields. The current research in the field of new nanocellulose materials mainly focuses on the hydrogel, aerogel and the tissue engineering scaffold. All of these are three-dimensional (3D) porous materials, but conventional manufacturing technology fails to realise precise control. Therefore, the method of preparing structural materials using 3D printing and adopting the nanocellulose as the 3D printing material has been proposed. Then, how to realise 3D printing of nanocellulose is the problem that should be solved. Design/methodology/approach By adding the photosensitive component polyethyleneglycol diacrylate (PEGDA) in the aqueous dispersion system of nanocellulose, the nanocellulose was endowed with photosensitivity. Then, nanocellulose/PEGDA hydrogels were prepared by the additive manufacturing of nanocellulose through light curing. Findings The results showed that the nanocellulose/PEGDA hydrogels had a uniform shape and a controllable structure. The nanocellulose supported the scaffold structure in the hydrogels. Prepared with 1.8 per cent nanocellulose through 40 s of light curing, the nanocellulose/PEGDA hydrogels had a maximum compression modulus of 0.91 MPa. The equilibrium swelling ratio of the nanocellulose/PEGDA hydrogel prepared with 1.8 per cent nanocellulose was 13.56, which increased by 44 per cent compared with that of the PEGDA hydrogel without nanocellulose. Originality/value The paper proposed a method for rapidly prototyping the nanocellulose with expected properties, which provided a theoretical basis and technological reference for the 3D additive manufacturing of nanocellulose 3D structure materials with a controlled accurate architecture.

Dry Effect of Cementitious Materials on Testing Results of X-Ray CT

2012 ◽  
Vol 450-451 ◽  
pp. 187-192 ◽  
Author(s):  
Jian De Han ◽  
Wei Sun ◽  
Gang Hua Pan
Keyword(s):  
Cement Paste ◽  
Three Dimensional ◽  
Cementitious Materials ◽  
Drying Process ◽  
X Ray ◽  
Before And After ◽  
X Ray Computed ◽  
The Mean ◽  
The Impact ◽  
Gray Values

In this study three-dimensional X-ray computed tomography (X-ray CT) is used to investigate the testing results differences of cement paste and mortar before and after drying. It can be found that the mean gray values of paste and mortar before drying are bigger than after drying, and the impact of drying on cement paste is more serious than mortar. In addition, the porosity of non-drying cement paste and mortar is 1.10% and 0.43%, while that of drying cement paste and mortar is 1.55% and 0.70%, respectively. So, the porosity of paste and mortar markedly increases after drying process. The numbers of pores of paste and mortar sharply increase after drying process in particular between 0.01mm3 and 0.1mm3. The impact of drying on smaller pores is more serious than bigger pores.

scholarly journals Sustainable Additive Manufacturing: Mechanical Response of Polyethylene Terephthalate Glycol over Multiple Recycling Processes

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1162
Author(s):  
Nectarios Vidakis ◽  
Markos Petousis ◽  
Lazaros Tzounis ◽  
Sotirios A. Grammatikos ◽  
Emmanouil Porfyrakis ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
3D Printing ◽  
Polyethylene Terephthalate ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Thermal Response ◽  
Fused Filament Fabrication ◽  
Hardness Tests ◽  
Multiple Recycling ◽  
A Minor

The continuous demand for thermoplastic polymers in a great variety of applications, combined with an urgent need to minimize the quantity of waste for a balanced energy-from-waste strategy, has led to increasing scientific interest in developing new recycling processes for plastic products. Glycol-modified polyethylene terephthalate (PETG) is known to have some enhanced properties as compared to polyethylene terephthalate (PET) homopolymer; this has recently attracted the interest from the fused filament fabrication (FFF) three-dimensional (3D) printing community. PET has shown a reduced ability for repeated recycling through traditional processes. Herein, we demonstrate the potential for using recycled PETG in consecutive 3D printing manufacturing processes. Distributed recycling additive manufacturing (DRAM)-oriented equipment was chosen in order to test the mechanical and thermal response of PETG material in continuous recycling processes. Tensile, flexure, impact strength, and Vickers micro-hardness tests were carried out for six (6) cycles of recycling. Finally, Raman spectroscopy as well as thermal and morphological analyses via scanning electron microscopy (SEM) fractography were carried out. In general, the results revealed a minor knockdown effect on the mechanical properties as well as the thermal properties of PETG following the process proposed herein, even after six rounds of recycling.

ADDITIVE MANUFACTURING AND VULCANIZATION OF CARBON BLACK–FILLED NATURAL RUBBER–BASED COMPONENTS

2021 ◽  
Author(s):  
Sebastian Leineweber ◽  
Lion Sundermann ◽  
Lars Bindszus ◽  
Ludger Overmeyer ◽  
Benjamin Klie ◽  
...  
Keyword(s):  
High Pressure ◽  
Additive Manufacturing ◽  
Flow Behavior ◽  
Three Dimensional ◽  
High Viscosity ◽  
Thermoplastic Elastomers ◽  
Second Step ◽  
Fused Filament Fabrication ◽  
Hot Air ◽  
Twin Screw

ABSTRACT Additive manufacturing of thermoplastics or metals is a well-approved sustainable process for obtaining rapidly precise and individual technical components. Except for crosslinked silicone rubber or thermoplastic elastomers, there is no method of additive manufacturing of elastomers. Based on the development of the additive manufacturing of elastomers (AME) process, the material group of rubber-based cured elastomers may gain first access to the process field of three-dimensional (3D) printing. Printing and crosslinking of rubber is separated into two steps. In the first step, printing is realized by extrusion of the rubber by using a twin-screw extruder, which works according to the derived fused-filament-fabrication principle. In the second step, the component is vulcanized in a high-pressure hot-air autoclave. Because of the plastic flow behavior of non–crosslinked rubber materials, a thermoplastic shell is probably needed to maintain the geometry and position of the additively manufactured rubber. In this way, one layer of thermoplastic and one layer of rubber are printed alternatingly until the component is finished. Afterward, the manufactured binary component is placed in an autoclave to obtain the elastomer after vulcanization under a hot-air and high-pressure atmosphere. Then, the thermoplastic shell is removed from the elastomer and can subsequently be recycled. As compared with conventional thermoplastics, the high viscosity of rubber during processing and its instable shape after extrusion are challenging factors in the development of the AME. This contribution will show a modified 3D printer; explain the printing process from the designed component, via shell generation, to the vulcanized component; and show first printed components.

Additive manufacturing of mechanochromic polycaprolactone on entry-level systems

2015 ◽  
Vol 21 (5) ◽  
pp. 520-527 ◽  
Author(s):  
Gregory I. Peterson ◽  
Mete Yurtoglu ◽  
Michael B Larsen ◽  
Stephen L. Craig ◽  
Mark A. Ganter ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Smart Materials ◽  
Color Change ◽  
Three Dimensional ◽  
Analytical Techniques ◽  
Force Sensor ◽  
Fused Filament Fabrication ◽  
Content Type ◽  
Entry Level ◽  
Chemical Response

Purpose – This paper aims to explore and demonstrate the ability to integrate entry-level additive manufacturing (AM) techniques with responsive polymers capable of mechanical to chemical energy transduction. This integration signifies the merger of AM and smart materials. Design/methodology/approach – Custom filaments were synthesized comprising covalently incorporated spiropyran moieties. The mechanical activation and chemical response of the spiropyran-containing filaments were demonstrated in materials that were produced via fused filament fabrication techniques. Findings – Custom filaments were successfully produced and printed with complete preservation of the mechanochemical reactivity of the spiropyran units. These smart materials were demonstrated in two key constructs: a center-cracked test specimen and a mechanochromic force sensor. The mechanochromic nature of the filament enables (semi)quantitative assessment of peak loads based on color change, without requiring any external analytical techniques. Originality/value – This paper describes the first examples of three-dimensional-printed mechanophores, which may be of significant interest to the AM community. The ability to control the chemical response to external mechanical forces, in combination with AM to process the bulk materials, potentiates customizability at the molecular and macroscopic length scales.

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