Feasibility Of 3D Printing Technology Research Articles

Preliminary Study on Size Effect of Fractured Rock Mass with Sand Powder 3D Printing

The size effect has a significant effect on the mechanical behavior of rock, thereby fundamentally influencing the stability of rock excavations. The main challenge associated with the experimental research on the size effect of fractured rock mass lies in the difficulty of specimen preparation to represent the influence of size and fracture on the mechanical behavior of the rock material. In order to preliminarily explore the feasibility of 3D printing technology in the field of rock mechanics, fractured rock specimens of different sizes and different fracture characteristics were produced using sand powder 3D printing technology. The uniaxial compression test was combined with the digital image correlation method (DIC) technology to study the influence of the size effect on the mechanical properties and deformation and failure of different fractured specimens. The research finds that: (1) The elastoplastic mechanical characteristics of the sand powder 3D printed specimens are similar to soft rock. Specimen size and fracture angle have significant effects on the mechanical properties of specimens. Under different fracture conditions, the uniaxial compressive strength (UCS) and Elasticity Modulus of sand powder 3D specimens should be decreased with the increase of the specimen size, and the size effect has different influences on the specimens with different fracture characteristics. (2) Under different fracture conditions, the crack initiation position and failure mode of specimens of various sizes are affected by the fracture inclination to varying degrees. (3) The size effect of fractured rock mass is closely related to the defect level inside the rock mass. The size effect originates from the heterogeneity inside the material. The research results verify the feasibility of applying sand powder 3D printing technology to study the size effect of fractured rock masses and provide an innovative test method for the size effect test study. Preliminary exploration of the size effect of fractured rock masses provides a powerful reference for related research in this field. The study proves the feasibility of applying sand powder 3D printing technology in similar rock mechanics tests and contributes to understanding the size effect of a fractured rock mass.

Multi-material printing of PVDF composites: A customized solution for maintenance of heritage structures

In the past three decades, 3D printing technologies have emerged as a convenient tool for the repair and maintenance of heritage structures. But hitherto little has been reported on multi-material 3D printed composites with 4D properties for the repair and maintenance of heritage structures. The present study reports the investigations on multi-material 3D printing of conducting and non-conducting polyvinylidene fluoride (PVDF) composite layers with self-actuating and self-healing properties to repair non-structural cracks in heritage buildings. The non-conducting (PVDF-CaCO3) and conducting (PVDF-graphene-Mn doped ZnO) composites were 3D printed and tested for electrostriction-based strain measurement for 4D analysis. The thermo-mechanical properties of the composite solution were obtained from dynamic mechanical analysis (DMA). The electrical, bonding, and morphological properties were investigated by current-voltage (I-V), x-ray diffraction (XRD), Fourier transformed infrared (FTIR), and scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS) analysis. Results of the self-elongation and contraction by electrostriction in PVDF composite demonstrate the feasibility of 3D printing technology as a novel tool to fabricate cost-effective smart solutions for the repair and maintenance of heritage structures.

Comparison of the feasibility of 3D printing technology in the treatment of pelvic fractures: a systematic review and meta-analysis of randomized controlled trialsand prospective comparative studies.

The objective of this meta-analysis was to assess the influence of 3D printing technology on the open reduction and internal fixation (ORIF) of pelvic fractures from current randomized controlled trials and prospective comparative studies. In this meta-analysis, we conducted electronic searches of Pubmed, Embase, Cochrane library, Web of Science and CNKI up to February 2020. We collected clinical controlled trials using 3D printing-assisted surgery and traditional techniques to assist in pelvic fractures, evaluating the quality of the included studies and extracting data. The data of operation time, blood loss, follow-up function (Majeed function score), quality of fracture reduction (Matta score) and complications (infection, screw loosening, pelvic instability, venous thromboembolism, sacral nerve injury) were extracted. Stata 12.0 software was used for our meta-analysis. Five RCTs and 2 prospective comparative studies met our inclusion criteria with 174 patients in the 3D printing group and 174 patients in the conventional group. There were significant differences in operation time [SMD = - 2.03], intraoperative blood loss [SMD = - 1.66] and postoperative complications [RR = 0.17] between the 3D group and conventional group. And the excellent and good rate of pelvic fracture reduction in the 3D group [RR = 1.32], the excellent and good rate of pelvic function [RR = 1.29] was superior to the conventional group. The 3D group showed shorter operation time, less intraoperative blood loss, less complications, better quality of fracture reduction and fast function recovery. Therefore, compared with conventional ORIF, ORIF assisted by 3D printing technology should be a more appropriate treatment of pelvic fractures.

Simulation Analysis of the Influence of Nozzle Structure Parameters on Material Controllability.

With the evolution of three-dimensional (3D) printing, many restrictive factors of 3D printing have been explored to upgrade the feasibility of 3D printing technology, such as nozzle structure, print resolution, cell viability, etc., which has attracted extensive attention due to its possibility of curing disease in tissue engineering and organ regeneration. In this paper, we have developed a novel nozzle for 3D printing, numerical simulation, and finite element analysis have been used to optimize the nozzle structure and further clarified the influence of nozzle structure parameters on material controllability. Using novel nozzle structure, we firstly adopt ANSYS-FLUENT to analyze material controllability under the different inner cavity diameter, outer cavity diameter and lead length. Secondly, the orthogonal experiments with the novel nozzle are carried out in order to verify the influence law of inner cavity diameter, outer cavity diameter, and lead length under all sorts of conditions. The experiment results show that the material P diameter can be controlled by changing the parameters. The influence degree of parameters on material P diameter is shown that lead length > inner cavity diameter > outer cavity diameter. Finally, the optimized parameters of nozzle structure have been adjusted to estimate the material P diameter in 3D printing.

Structural performance of 3D-printed composites under various loads and environmental conditions

Sandwich-structured composites are in high demand in various industries, and additive manufacturing has proven its ability to meet this demand. As a result of the advances in three-dimensional (3D) printing techniques, 3D-printed polymers have received considerable attention in fabrication of sandwich structures with complex geometries. This paper is concerned with design, manufacturing, and analysis of the 3D-printed sandwich-structured components which experienced various loadings and environmental conditions. The core structure plays a major role in the in-plane behavior of lattice composites, therefore in this study, sandwich specimens with two types of core topologies made of two common and similar 3D printing filaments, acrylonitrile butadiene styrene (ABS) and acrylonitrile styrene acrylate (ASA), were manufactured. Based on the applications of sandwich-structured parts, they might experience different temperatures in their service life. In order to determine effects of thermal environment, we conducted accelerated thermal aging within temperatures of 22-60 °C, which is below glass temperature of the examined materials. Based on a series of three-point bending tests, the failure behavior of the original and aged components are determined, and the effects of temperature change on the bending behavior of 3D-printed sandwich parts are discussed. The experimental practice revealed that ASA with honeycomb core specimens indicated highest stability under bending load after thermal aging. The current study sheds lights on durability of 3D-printed sandwich structural elements, and the obtained results demonstrate feasibility of 3D printing technology in fabrication of thermal-stable sandwich structures.

3D printing fabrication of conductivity non-uniform insulator for surface flashover mitigation

Solid insulators applying functionally graded material (d-FGM) have spatially non-uniform dielectric properties. The d-FGM insulator is effective on insulation performance improvement without complicating the structure; however, the fabrication of such insulators remains a challenge. To investigate the feasibility of 3D printing technology on d-FGM, we designed and fabricated a conductivity non-uniform insulator and tested its surface flashover characteristics. First, a modified genetic algorithm is employed to design the conductivity distribution in the non-uniform insulator. The designed insulator is then fabricated using a 3D printing process named fused deposition modeling (FDM), in which we verified the applicability of 3D printing materials on electrical insulation. Finally, compared to the uniform insulator, the surface flashover voltages of non-uniform insulators were improved by 23% in SF6 and 20% in vacuum. From above, we envision potential application feasibility for 3D printing of d-FGM in practical insulation design.

The Feasibility of 3D Printing Technology on the Treatment of Pilon Fracture and Its Effect on Doctor-Patient Communication.

Purpose The aim of this study was to assess the feasibility and effectiveness of the three-dimensional (3D) printing technology in the treatment of Pilon fractures. Methods 100 patients with Pilon fractures from March 2013 to December 2016 were enrolled in our study. They were divided randomly into 3D printing group (n = 50) and conventional group (n = 50). The 3D models were used to simulate the surgery and carry out the surgery according to plan in 3D printing group. Operation time, blood loss, fluoroscopy times, fracture union time, and fracture reduction as well as functional outcomes including VAS and AOFAS score and complications were recorded. To examine the feasibility of this approach, we invited surgeons and patients to complete questionnaires. Results 3D printing group showed significantly shorter operation time, less blood loss volume and fluoroscopy times, higher rate of anatomic reduction and rate of excellent and good outcome than conventional group (P < 0.001, P < 0.001, P < 0.001, P = 0.040, and P = 0.029, resp.). However, no significant difference was observed in complications between the two groups (P = 0.510). Furthermore, the questionnaire suggested that both surgeons and patients got high scores of overall satisfaction with the use of 3D printing models. Conclusion Our study indicated that the use of 3D printing technology to treat Pilon fractures in clinical practice is feasible.

Comparison of the Conventional Surgery and the Surgery Assisted by 3d Printing Technology in the Treatment of Calcaneal Fractures

ABSTRACTPurpose: This study was aimed to compare conventional surgery and surgery assisted by 3D printing technology in the treatment of calcaneal fractures. In addition, we also investigated the effect of 3D printing technology on the communication between doctors and patients. Methods: we enrolled 75 patients with calcaneal fracture from April 2014 to August 2016. They were divided randomly into two groups: 35 cases of 3D printing group, 40 cases of conventional group. The individual models were used to simulate the surgical procedures and carry out the surgery according to plan in 3D printing group. Operation duration, blood loss volume during the surgery, number of intraoperative fluoroscopy and fracture union time were recorded. The radiographic outcomes Böhler angle, Gissane angle, calcaneal width and calcaneal height and final functional outcomes including VAS and AOFAS score as well as the complications were also evaluated. Besides, we made a simple questionnaire to verify the effectiveness of the 3D-printed model for both doctors and patients. Results: The operation duration, blood loss volume and number of intraoperative fluoroscopy for 3D printing group was 71.4 ± 6.8 minutes, 226.1 ± 22.6 ml and 5.6 ± 1.9 times, and for conventional group was 91.3 ± 11.2 minutes, 288.7 ± 34.8 ml and 8.6 ± 2.7 times respectively. There was statistically significant difference between the conventional group and 3D printing group (p < 0.05). Additionally, 3D printing group achieved significantly better radiographic results than conventional group both postoperatively and at the final follow-up (p < 0.05). However, No significant difference was noted in the final functional outcomes between the two groups. As for complications, there was no significant difference between the two groups. Furthermore, the questionnaire showed that both doctors and patients exhibited high scores of overall satisfaction with the use of a 3D printing model. Conclusion: This study suggested the clinical feasibility of 3D printing technology in treatment of calcaneal fractures.