Infill Design Reinforcement of 3D Printed Parts Using Refinement Technique Adapted to Continuous Extrusion

In this paper, we introduce an advanced numerical tool aimed to optimise the infill design of 3D printed parts by reducing printing time. In 3D printing, the term infill refers to the internal structure of a part. To create the infill design, slicing software is used, which generally creates the infill uniformly throughout the part. When such a part is subjected to external loading, all the infill regions will not experience the same amount of stress. Therefore, using uniform infill throughout the part is not the most optimised solution in terms of material usage. We do propose to evolve the infill design with respect to the mechanical stresses generated by the external loads. To achieve this, an advanced numerical tool has been developed, based on refinement techniques, to control the infill design. This tool is coupled with Finite Element Simulation (FE Simulation) software, which helps to identify the zones where the material is required as an infill to reinforce a part, whereas the refinement technique makes it possible to place the material as an infill in such a way that the airtime during the printing of the part is zero. Zero airtime printing is defined as the ability to deposit each layer of a part, without stopping the material extrusion during the displacement of the nozzle. Therefore, the proposed numerical tool guides us to generate the infill design of a part, in such a way that it will consume zero airtime while manufacturing. Simultaneously, it will increase the stiffness of the part. The proposed approach is here applied to a rectangular structure subjected to four-point bending, made up of PLA material (Poly-Lactic Acid).

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Pressure Orientation-Dependent Recovery of 3D-Printed PLA Objects with Varying Infill Degree

Polymers ◽

10.3390/polym13081275 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1275 ◽

Cited By ~ 1

Author(s):

Guido Ehrmann ◽

Andrea Ehrmann

Keyword(s):

Shape Memory ◽

Fused Deposition Modeling ◽

Static Load ◽

Shape Memory Polymer ◽

Applied Pressure ◽

Poly Lactic Acid ◽

Fused Deposition ◽

Deposition Modeling ◽

Load Tests ◽

3D Printed

Poly(lactic acid) is not only one of the most often used materials for 3D printing via fused deposition modeling (FDM), but also a shape-memory polymer. This means that objects printed from PLA can, to a certain extent, be deformed and regenerate their original shape automatically when they are heated to a moderate temperature of about 60–100 °C. It is important to note that pure PLA cannot restore broken bonds, so that it is necessary to find structures which can take up large forces by deformation without full breaks. Here we report on the continuation of previous tests on 3D-printed cubes with different infill patterns and degrees, now investigating the influence of the orientation of the applied pressure on the recovery properties. We find that for the applied gyroid pattern, indentation on the front parallel to the layers gives the worst recovery due to nearly full layer separation, while indentation on the front perpendicular to the layers or diagonal gives significantly better results. Pressing from the top, either diagonal or parallel to an edge, interestingly leads to a different residual strain than pressing from front, with indentation on top always firstly leading to an expansion towards the indenter after the first few quasi-static load tests. To quantitatively evaluate these results, new measures are suggested which could be adopted by other groups working on shape-memory polymers.

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Bending Response of 3D-Printed Titanium Alloy Sandwich Panels with Corrugated Channel Cores

Materials ◽

10.3390/ma14030556 ◽

2021 ◽

Vol 14 (3) ◽

pp. 556

Author(s):

Zhenyu Zhao ◽

Jianwei Ren ◽

Shaofeng Du ◽

Xin Wang ◽

Zihan Wei ◽

...

Keyword(s):

Titanium Alloy ◽

Heat Dissipation ◽

Sandwich Panels ◽

Face Sheet ◽

Collapse Mechanism ◽

Corrugated Channel ◽

Four Point Bending ◽

Numerical Predictions ◽

Load Carrying ◽

3D Printed

Ultralight sandwich constructions with corrugated channel cores (i.e., periodic fluid-through wavy passages) are envisioned to possess multifunctional attributes: simultaneous load-carrying and heat dissipation via active cooling. Titanium alloy (Ti-6Al-4V) corrugated-channel-cored sandwich panels (3CSPs) with thin face sheets and core webs were fabricated via the technique of selective laser melting (SLM) for enhanced shear resistance relative to other fabrication processes such as vacuum brazing. Four-point bending responses of as-fabricated 3CSP specimens, including bending resistance and initial collapse modes, were experimentally measured. The bending characteristics of the 3CSP structure were further explored using a combined approach of analytical modeling and numerical simulation based on the method of finite elements (FE). Both the analytical and numerical predictions were validated against experimental measurements. Collapse mechanism maps of the 3CSP structure were subsequently constructed using the analytical model, with four collapse modes considered (face-sheet yielding, face-sheet buckling, core yielding, and core buckling), which were used to evaluate how its structural geometry affects its collapse initiation mode.

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Development of three-dimensional printing filaments based on poly(lactic acid)/hydroxyapatite composites with potential for tissue engineering

Journal of Composite Materials ◽

10.1177/0021998320988568 ◽

2021 ◽

pp. 002199832098856

Author(s):

Marcela Piassi Bernardo ◽

Bruna Cristina Rodrigues da Silva ◽

Luiz Henrique Capparelli Mattoso

Keyword(s):

Tissue Engineering ◽

Lactic Acid ◽

Fused Deposition Modeling ◽

Three Dimensional ◽

Poly Lactic Acid ◽

Scanning Calorimetry ◽

Three Dimensional Printing ◽

Fused Deposition ◽

Deposition Modeling ◽

3D Printed

Injured bone tissues can be healed with scaffolds, which could be manufactured using the fused deposition modeling (FDM) strategy. Poly(lactic acid) (PLA) is one of the most biocompatible polymers suitable for FDM, while hydroxyapatite (HA) could improve the bioactivity of scaffold due to its chemical composition. Therefore, the combination of PLA/HA can create composite filaments adequate for FDM and with high osteoconductive and osteointegration potentials. In this work, we proposed a different approache to improve the potential bioactivity of 3D printed scaffolds for bone tissue engineering by increasing the HA loading (20-30%) in the PLA composite filaments. Two routes were investigated regarding the use of solvents in the filament production. To assess the suitability of the FDM-3D printing process, and the influence of the HA content on the polymer matrix, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were performed. The HA phase content of the composite filaments agreed with the initial composite proportions. The wettability of the 3D printed scaffolds was also increased. It was shown a greener route for obtaining composite filaments that generate scaffolds with properties similar to those obtained by the solvent casting, with high HA content and great potential to be used as a bone graft.

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Effects of Rice Straw Powder (RSP) Size and Pretreatment on Properties of FDM 3D-Printed RSP/Poly(Lactic Acid) Biocomposites

Molecules ◽

10.3390/molecules26113234 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3234

Author(s):

Wangwang Yu ◽

Lili Dong ◽

Wen Lei ◽

Yuhan Zhou ◽

Yongzhe Pu ◽

...

Keyword(s):

Lactic Acid ◽

Rice Straw ◽

Fused Deposition Modeling ◽

Flexural Modulus ◽

Tensile Modulus ◽

Cost Effective ◽

Poly Lactic Acid ◽

Fused Deposition ◽

Interfacial Compatibility ◽

3D Printed

To develop a new kind of environment-friendly composite filament for fused deposition modeling (FDM) 3D printing, rice straw powder (RSP)/poly(lactic acid) (PLA) biocomposites were FDM-3D-printed, and the effects of the particle size and pretreatment of RSP on the properties of RSP/PLA biocomposites were investigated. The results indicated that the 120-mesh RSP/PLA biocomposites (named 120#RSP/PLA) showed better performance than RSP/PLA biocomposites prepared with other RSP sizes. Infrared results showed that pretreatment of RSP by different methods was successful, and scanning electron microscopy indicated that composites prepared after pretreatment exhibited good interfacial compatibility due to a preferable binding force between fiber and matrix. When RSP was synergistically pretreated by alkaline and ultrasound, the composite exhibited a high tensile strength, tensile modulus, flexural strength, and flexural modulus of 58.59, 568.68, 90.32, and 3218.12 MPa, respectively, reflecting an increase of 31.19%, 16.48%, 18.75%, and 25.27%, respectively, compared with unmodified 120#RSP/PLA. Pretreatment of RSP also improved the thermal stability and hydrophobic properties, while reducing the water absorption of 120#RSP/PLA. This work is believed to provide highlights of the development of cost-effective biocomposite filaments and improvement of the properties of FDM parts.

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Hybrid Spine Simulator Prototype for X-ray Free Pedicle Screws Fixation Training

Applied Sciences ◽

10.3390/app11031038 ◽

2021 ◽

Vol 11 (3) ◽

pp. 1038

Author(s):

Sara Condino ◽

Giuseppe Turini ◽

Virginia Mamone ◽

Paolo Domenico Parchi ◽

Vincenzo Ferrari

Keyword(s):

Augmented Reality ◽

Low Cost ◽

Lumbar Vertebrae ◽

Pedicle Screws ◽

Simulation Software ◽

Patient Specific ◽

Innovative Strategy ◽

X Ray ◽

3D Printed ◽

Harmful Radiation

Simulation for surgical training is increasingly being considered a valuable addition to traditional teaching methods. 3D-printed physical simulators can be used for preoperative planning and rehearsal in spine surgery to improve surgical workflows and postoperative patient outcomes. This paper proposes an innovative strategy to build a hybrid simulation platform for training of pedicle screws fixation: the proposed method combines 3D-printed patient-specific spine models with augmented reality functionalities and virtual X-ray visualization, thus avoiding any exposure to harmful radiation during the simulation. Software functionalities are implemented by using a low-cost tracking strategy based on fiducial marker detection. Quantitative tests demonstrate the accuracy of the method to track the vertebral model and surgical tools, and to coherently visualize them in either the augmented reality or virtual fluoroscopic modalities. The obtained results encourage further research and clinical validation towards the use of the simulator as an effective tool for training in pedicle screws insertion in lumbar vertebrae.

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Research on Surface Roughness of Supersonic Vibration Auxiliary Side Milling for Titanium Alloy

10.21203/rs.3.rs-704632/v1 ◽

2021 ◽

Author(s):

XueTao Wei ◽

caixue yue ◽

DeSheng Hu ◽

XianLi Liu ◽

YunPeng Ding ◽

...

Keyword(s):

Surface Roughness ◽

Finite Element ◽

Prediction Model ◽

Simulation Model ◽

Finite Element Simulation ◽

Simulation Software ◽

Surface Roughness Prediction ◽

Contour Shape ◽

Element Simulation ◽

Roughness Prediction

Abstract The processed surface contour shape is extracted with the finite element simulation software, and the difference value of contour shape change is used as the parameters of balancing surface roughness to construct the infinitesimal element cutting finite element model of supersonic vibration milling in cutting stability domain. The surface roughness trial scheme is designed in the central composite test design method to analyze the surface roughness test result in the response surface methodology. The surface roughness prediction model is established and optimized. Finally, the finite element simulation model and surface roughness prediction model are verified and analyzed through experiment. The research results show that, compared with the experiment results, the maximum error of finite element simulation model and surface roughness prediction model is 30.9% and12.3%, respectively. So, the model in this paper is accurate and will provide the theoretical basis for optimization study of auxiliary milling process of supersonic vibration.

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Wear of Coated Cutting Tool Based on AdvantEdge

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.551.221 ◽

2014 ◽

Vol 551 ◽

pp. 221-227

Author(s):

Zhi Qiang Zhang ◽

Tie Qiang Gang ◽

Yi Kai Yi

Keyword(s):

Wear Rate ◽

Coating Thickness ◽

Cutting Tool ◽

Cutting Tools ◽

Simulation Software ◽

Machining Process ◽

Sliding Velocity ◽

Coating Materials ◽

Element Simulation ◽

Coated Tool

In this paper, based on finite element simulation software AdvantEdge, the effects of different coating materials and thickness on the wear of cutting tools during the machining process have been studied. For the tools with coating materials of TiAlN, Al2O3, TiN, TiC, we can calculate the wear rate according to the Usui mathematical model of tool wear, and then consider thickness factor of TiC coating. Because of the lowest thermal conductivity, the workpiece cut by TiC coated tool will soften first and more over cutting time, it result in the lowest wear rate. And with the increase of coating thickness, the effect of "thermal barrier" is more obvious for the relatively thicker coating tool, but the relative sliding velocity between the chip and tool is increasing meanwhile, so a suitable coating thickness is necessary.

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Evaluation of a poly(lactic-acid) scaffold filled with poly(lactide-co-glycolide)/hydroxyapatite nanofibres for reconstruction of a segmental bone defect in a canine model

Veterinární Medicína ◽

10.17221/80/2019-vetmed ◽

2019 ◽

Vol 64 (No. 12) ◽

pp. 531-538

Author(s):

JW Yun ◽

SY Heo ◽

MH Lee ◽

HB Lee

Keyword(s):

Lactic Acid ◽

Bone Defect ◽

Bone Defects ◽

Bone Morphogenetic Protein 2 ◽

Poly Lactic Acid ◽

Micro Computed Tomography ◽

Bone Parameters ◽

3D Printed ◽

Group 3 ◽

Group 2

Critical-sized bone defects are a difficult problem in both human and veterinary medicine. To address this issue, synthetic graft materials have been garnering attention. Abundant in vitro studies have proven the possibilities of poly(lactic-acid) (PLA) scaffolds and poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HAp) nanofibres for treating bone defects. The present study aimed at conducting an in vivo assessment of the biological performance of a three dimensional (3D)-printed PLA scaffold filled with a PLGA/HAp nanofibrous scaffold to estimate its potential applications in bone defect reconstruction surgery. Defects were created in a 20 mm-long region of the radius bone. The defects created on the right side in six Beagle dogs (n = 6) were left untreated (Group 1). The defects on the left side (n = 6) were filled with 3D-printed PLA scaffolds incorporated with PLGA/Hap nanofibres with gelatine (Group 2). The other six Beagle dog defects were made bilaterally (n = 12) and filled with the same material as that used in Group 2 along with recombinant bone morphogenetic protein 2 (rhBMP-2) (Group 3). Both the radiological and histological examinations were performed for observing the reaction of the scaffold and the bone. Micro-computed tomography (CT) was utilised for the evaluation of the bone parameters 20 weeks after the experiment. The radiological and histological results revealed that the scaffold was biodegradable and was replaced by new bone tissue. The micro-CT revealed that the bone parameters were significantly (P < 0.05) increased in Group 3. Based on these results, our study serves as a foundation for future studies on bone defect treatment using synthetic polymeric scaffolds.

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