Table 9.
Research frontiers of 3DP with the burst strengths, brief introduction, and recent trends.
| Rank | Keywords | Strength | Begin | End | Brief introduction & recent trends |
| 1 | Fused filament fabrication | 3.6239 | 2019 | 2020 | Also known as fused deposition modelling (FDM). A continuous filament of a thermoplastic polymer is converted into a semi-liquid state by a heated nozzle and extruded on the top of the previously deposited layers to make objects [54]. |
| 2 | Polymer composite | 3.4766 | 2019 | 2020 | Two types of composites can be studied (i) polymer with polymer composites & (ii) polymer with metal or carbon fiber composites. E.g., composite of carbon fiber in polylactic acid [136], composite of dopamine with carbon nanotubes [139] via 3DP. |
| 3 | Rheology | 3.2018 | 2019 | 2020 | Study of the flow of matter, primarily in gas, liquid states or plastic flow of soft solids, under the action of external forces [140]. In 3DP, it is essential to study the rheology of heated materials in a paste form. E.g., the effects of vibrations on the rheology of concrete during 3DP [141], the study of rheology & printability of clay for 3D printed decorative architectural applications [142]. |
| 4 | Carbon nanotube | 2.9154 | 2019 | 2020 | Widely used in combinations with polymers, metals, and ceramics to form reinforced composite matrices superior in mechanical strength, wear, and erosion. Some examples are polyurethane and carbon nanotube composites based soft pneumatic actuators [143], embedment of carbon nanotubes within Ti-6Al-4 V alloy [85] for aerospace applications. |
| 5 | Direct ink writing | 2.7378 | 2019 | 2020 | Used to create materials with controlled architecture and composition, a computer-controlled translation stage causes a pattern-generating device or ink-deposition nozzle to move [144]. Currently, being used to make scaffolds (biomedical engineering) [145], supercapacitor electrodes [146], micro and nanostructures. |
| 6 | 3DP device | 2.6986 | 2018 | 2020 | Includes all types of 3D printing devices and their feasible products. Some examples are energy storage devices [147], devices for drug delivery [148], prosthetic implants (including hands, arms, legs, organs) [149], microactuators (for soft robotics) [150] and others. |
| 7 | Tensile properties | 2.4983 | 2019 | 2020 | Involves the study of mechanical properties, material behaviour of 3D printed objects under fatigue, tensile or compressive loadings. Some common properties are surface roughness [151], stiffness [131], yield stress [132], micro-hardness [134] and fracture toughness [133]. |
| 8 | Stability | 2.4983 | 2019 | 2020 | Study of stability of the 3D printed parts under thermal, mechanical loading. Recent trends are the enhancement of hydrogel stability with nano clay incorporation [152], investigating melt-pool stability on density & magnetic properties of 3D printed magnets [153]. |
| 9 | Strength | 2.3754 | 2019 | 2020 | Study of mechanical strength, residual stresses of the 3D printed specimens under various loadings for a wide range of applications. For example, the strength of 3D printed PLA parts [154]. |
| 10 | Sustainability | 2.3648 | 2019 | 2020 | The priority of the manufacturers and engineers for manufacturing and development of novel technology and customization of the products. For instance, Energy harvesting mechanisms and socially sustainable supply chain innovation through 3D printing. |
| 11 | Energy | 2.3608 | 2019 | 2020 | Related to energy harvesting from human-induced or ambient vibrations & energy efficiency of the 3D printed devices. E.g., 3D printed stretchable triboelectric nanogenerator fibers, MEMS vibrational-electromagnetic energy harvester made by inkjet 3D printing. |