Numerical simulation and printability analysis of fused deposition modeling with dual-temperature control

Ideal tissue engineering scaffolds need interconnected pores and high porosity to enable cell survival,migration,proliferation,and differentiation.However,obtaining a high-resolution structure is difficult with traditional one-temperature control fused deposition modeling(FDM).In this study,we propose a dual-temperature control method to improve printability.A numerical model is developed in which the viscosity is a function of temperature and shear rate to study the influence of two different temperature control modes.Quantitative tests are used to assess filament formation and shape fidelity,including one-dimensional filament printing,deposition at corners,fusion,and collapse.By using dual-temperature control,the width of the deposited poly(ε-caprolactone)filament is reduced to 50μm.The comparative results of both the experimental method and numerical simulation suggest that the dual-temperature control FDM can manufacture spatially arranged constructs and presents a promising application in tissue engineering。

Multi-Objective Optimization of Fused Deposition Modeling for Mechanical Properties of Biopolymer Parts Using the Grey-Taguchi Method

The urgent need to develop customized functional products only possible by 3D printing had realized when faced with the unavailability of medical devices like surgical instruments during the coronavirus-19 disease and the ondemand necessity to perform surgery during space missions.Biopolymers have recently been the most appropriate option for fabricating surgical instruments via 3D printing in terms of cheaper and faster processing.Among all 3D printing techniques,fused deposition modelling(FDM)is a low-cost and more rapid printing technique.This article proposes the fabrication of surgical instruments,namely,forceps and hemostat using the fused deposition modeling(FDM)process.Excellent mechanical properties are the only indicator to judge the quality of the functional parts.The mechanical properties of FDM-processed parts depend on various process parameters.These parameters are layer height,infill pattern,top/bottom pattern,number of top/bottom layers,infill density,flow,number of shells,printing temperature,build plate temperature,printing speed,and fan speed.Tensile strength and modulus of elasticity are chosen as evaluation indexes to ascertain the mechanical properties of polylactic acid(PLA)parts printed by FDM.The experiments have performed through Taguchi’s L27orthogonal array(OA).Variance analysis(ANOVA)ascertains the significance of the process parameters and their percent contributions to the evaluation indexes.Finally,as a multiobjective optimization technique,grey relational analysis(GRA)obtains an optimal set of FDM process parameters to fabricate the best parts with comprehensive mechanical properties.Scanning electron microscopy(SEM)examines the types of defects and strong bonding between rasters.The proposed research ensures the successful fabrication of functional surgical tools with substantial ultimate tensile strength(42.6 MPa)and modulus of elasticity(3274 MPa).

Effect of Fibre Size on Mechanical Properties and Surface Roughness of PLA Composites by Using Fused Deposition Modelling (FDM)

Naturalfibre as a reinforcing agent has been widely used in many industrial applications.Nevertheless,several factors need to be considered,such as the size and weight percentage of thefibre used in binding.Using fused deposition modelling(FDM),this factor was investigated by varying the size of naturalfibre as the responding variable with afixed weight percentage of kenaffibre.The process of modifying the naturalfibre in terms of size might increase the dispersion of kenaffibre in the polymer matrix and increase the adhesion bonding between thefibre and matrix of composites,subsequently improving the interfacial bonding between these two phases.In this paper,the effect offibre size was evaluated by performing the mechanical test,Scanning Electron Micrograph(SEM)to observe the morphology of the composites,and also by surface analysis.The surface roughness was visualised using a 3D profilometer and thefigure was illustrated as colour shading in the image.The composite withfibre size≤100μm displayed better tensile andflexural strength,compared to other sizes.In conclusion,by reducing the size of thefibre,the composites could develop high strength performance for industrial applications.

DECISION-MAKING OF SLICING SCHEME IN FUSED DEPOSITION MODELING PROCESS BASED ON ANALYTICAL HIERARCHICAL PROCESS

Based on analyzing the influences of a slicing scheme on stair-stepping effect, supporting structure, efficiency and deformation, etc. , analytical hierarchical process （AHP） combining with fuzzy synthetic evaluation is introduced to make decision in slicing schemes for a processing part. The application in determining the slicing scheme for a computer mouse during prototyping shows that the method increases the rationality during decision- making and improves quality and efficiency for the prototyping part.

Fabrication and Characterization of Poly Lactic Acid Scaffolds by Fused Deposition Modeling for Bone Tissue Engineering

Three-dimensional porous poly-lactic acid(PLA) scaffold was fabricated using fused deposition modeling(FDM) method including 30%, 50% and 70% nominal porosity. Study of phases in initial polymeric material and printed scaffolds was done by X-ray diffraction(XRD), and no significant phase difference was observed due to the manufacturing process, and the poly-lactic acid retains its crystalline properties. The results of the mechanical properties evaluation by the compression test show that the mechanical properties of the scaffold have decreased significantly with increasing the porosity of scaffold. The microstructure of scaffolds were studied by scanning electron microscope(SEM), showing that the pores had a regular arrangement and their morphology changed with porosity change. The mechanical properties of the poly-lactic acid scaffolds printed using fused deposition modeling, can be adapted to the surrounding tissue, by porosity change.

Optimization of Fused Deposition Modelling (FDM) Process Parameters Using Bacterial Foraging Technique

Fused deposition modelling (FDM) is a fast growing rapid prototyping (RP) technology due to its ability to build functional parts having complex geometrical shapes in reasonable build time. The dimensional accuracy, surface roughness, mechanical strength and above all functionality of built parts are dependent on many process variables and their settings. In this study, five important process parameters such as layer thickness, orientation, raster angle, raster width and air gap have been considered to study their effects on three responses viz., tensile, flexural and impact strength of test specimen. Experiments have been conducted using central composite design (CCD) and empirical models relating each response and process parameters have been developed. The models are validated using analysis of variance (ANOVA). Finally, bacterial foraging technique is used to suggest theoretical combination of parameter settings to achieve good strength simultaneously for all responses.

A fiber Bragg grating based earth and water pressures transducer with three-dimensional fused deposition modeling for soil mass

A novel fiber Bragg grating(FBG)sensor with three-dimensional(3D)fused deposition modeling(FDM)approach is proposed for effective stress measurement in soil mass.The three-diaphragm structure design is developed to measure earth and water pressures simultaneously.The proposed transducer has advantages of small size,high sensitivity,low cost,immunity to electromagnetic interference and rapid prototyping.The working principle,design parameters,and manufacturing details are discussed.The proposed transducer was calibrated for earth and water pressures measurement by using weights and a specially designed pressure chamber,respectively.The calibration results showed that the wavelength of the transducer was proportional to the applied pressure.The sensitivity coefficients of the earth and water pressures were 12.633 nm/MPa and 6.282 nm/MPa,respectively.Repeated tests and error analysis demonstrated the excellent stability and accuracy of the earth and water pressure measurements.The performance of the proposed transducer was further verified by a model experimental test and numerical analysis,which indicated that the proposed transducer has great potential for practical applications.

Tensile Properties of Mechanically-Defibrated Cellulose Nanofiber-Reinforced Polylactic Acid Matrix Composites Fabricated by Fused Deposition Modeling

Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.

PROTOTYPE SURFACE MICRO- PRECISION IN FUSED DEPOSITION MODELING PROCESS

To aim at prototype parts fabricated with fused deposition modeling （FDM） process, the problems how to improve and enhance their surface micro-precision are studied. The producing mechanism of surface roughness is explained with three aspects concretely including the principle error of rapid prototyping （RP） process, the inherent characteristics of FDM process, and some mi- cro-scratches on the surface of the extruded fiber. Based on the micro-characters of section shape of the FDM prototype, a physical model reflecting the outer shape characters is abstracted. With the physical simplified and deduced, the evaluating equations of surface roughness are acquired. According to the FDM sample parts with special design for experimental measurement, the real surface roughness values of different inclined planes are obtained. And the measuring values of surface roughness are compared with the calculation values. Furthermore, the causes of surface roughness deviation between measuring values and calculation values are respectively analyzed and studied. With the references of analytic conclusions, the measuring values of the experimental part surface are revised, and the revised values nearly accord with the calculation values. Based on the influencing principles of FDM process parameters and special post processing of FDM prototype parts, some concrete measures are proposed to reduce the surface roughness of FDM parts, and the applying effects are better.

Minimizing Warpage for Macro-Size Fused Deposition Modeling Parts

In this study,we investigated warpage and corner lifting minimization for three-dimensional printed parts generated by macro-size fused deposition modeling(FDM).First,the reasons for warpage were theoretically elucidated.This approach revealed that the thermal deformation and differential volumetric shrinkage of the extruded molten plastic resulted in warpage of FDM parts.In addition,low adhesion between the deposited model and the heated or non-heated printing bed may intensify warpage further.As a next step,initial small-size and medium-size models were used to identify parameters to manage and minimize warpage in a way that would reduce material consumption and running time.Finally,a macro-size model was built to experimentally investigate and verify the technical solutions to minimize the warpage of FDM parts.In conclusion,an improved part with reduced warpage was efficiently produced after detailed consideration of thermal effects and adhesion force.Potential exists to widen the application scope of FDM technology in manufacturing for processes like thermoforming that involve mold core fabrication with heating.This technology,which has applications not only in mechanical engineering but also in related engineering fields,is convenient and could readily be applied to practical manufacturing industries.

Comparison of wear behavior of ABS and Nylon6-Fe powder composite parts prepared with fused deposition modelling

Fused deposition modeling(FDM) is one of the latest rapid prototyping techniques in which parts can be manufactured at a fast pace and are manufactured with a high accuracy. This research work is carried out to study the friction and wear behavior of parts made of newly developed Nylon6-Fe composite material by FDM. This work also involves the comparison of the friction and wear characteristics of the Nylon6-Fe composite with the existing acrylonitrile butadiene styrene(ABS) filament of the FDM machine. This Is carried out on the pin on disk setup by varying the load(5, 10, 15 and 20 N) and speed(200 and 300 r/min). It is concluded that the newly developed composite is highly wear resistant and can be used in industrial applications where wear resistance is of paramount importance. Morphology of the surface in contact with the Nylon6-Fe composite and ABS is also carried out.

Properties of ABS/Organic-Attapulgite Nanocomposites Parts Fabricated by Fused Deposition Modeling

The paper discusses the mechanical and thermal performance manifested in natural nanorods attapulgite(ATP)reinforced Acrylonitrile butadiene styrene(ABS)nanocomposites in the process of fused deposition modeling(FDM).Molten extrusion technique was taken to manufacture the filaments of ABS/organic-attapulgite(OAT)nanocomposites with different mass fraction and the printing operation was made by one commercial FDM three-dimensional(3D)printer.Results indicate that the mechanical performance of these FDM 3D printed specimens are improved obviously via the introduction of OAT,and tensile strength of the ABS/OAT nanocomposites parts with only 2 wt%OAT addition is enhanced by 48.1%.At the same time,the addition OAT can reduce the linear expansion coefficient and creep flexibility,and improve the thermal stability and dimensional accuracy of these FDM 3D printed parts.

Cleated Print Surface for Fused Deposition Modeling

FDM （fused deposition modeling） has become popular among Additive Manufacturing technologies due to its speed, geometric scalability, and low cost; however, the primitive nature of the FDM build surface fundamentally limits the utility of FDM in terms of reliability, autonomy, and material selection. Currently, FDM relies on adhesive forces between the first layer of a print and the build surface; depending on the materials involved, this adhesive bond may or may not be reliable. Thermal contraction between the build plate and build materials can break that bond, which causes warpage and delamination of the part from the build surface and subsequent failure of the part. Furthermore, with each print, the user must use tools or manual maneuvering to separate the printed part from the build surface as well as retexture or replace the used build surface. In this paper, we present a novel build platform that allows for a mechanical bond between the print and build surface by using dovetail-shaped features. The first layer of the print flows into the features and becomes mechanically captivated by the build platform. Once the print is completed, the platform is rolled or flexed open to release the part from the mechanical bond. This design not only lowers the risk of delamination during printing but also eliminates the need for a user to reset or replace the build surface between print jobs. The effectiveness of each geometry was determined by measuring the distance at the pinch point compared to the distance that the extrusion filled below the pinch point. The captivation ratio was measured to compare the different geometries tested and determine which direction of extrusion creates a better ratio.

Concurrent Material Selection of Natural Fibre Filament for Fused Deposition Modeling Using Integration of Analytic Hierarchy Process/Analytic Network Process

The employment of natural fibres in fused deposition modeling has raised much attention from researchers in finding a suitable formulation for the natural fibre composite filaments.Moreover,selection of suitable natural fibres for fused deposition modeling should be performed before the development of the composites.It could not be performed without identifying selection criteria that comprehend both materials and fused deposition modeling process requirements.Therefore,in this study,integration of the Analytic Hierarchy Process(AHP)/Analytic Network Process(ANP)has been introduced in selecting the natural fibres based in different clusters of selection concurrently.The selection process has been performed based on the interdependency among the selection criteria.Pairwise comparison matrices are constructed based on AHP’s hierarchical model and super matrices are constructed based on the ANP’s network model.As a result,flax fibre has ranked at the top of the selection by scored 19.5%from the overall evaluation.Flax fibre has excellent material properties and been found in various natural fibre composite applications.Further investigation is needed to study the compatibility of this fibre to be reinforced with a thermoplastic polymer matrix to develop a resultant natural fibre composite filament for fused deposition modeling.

The Effect of Cell Size and Surface Roughness on the Compressive Properties of ABS Lattice Structures Fabricated by Fused Deposition Modeling

Researchers looking to improve the surface roughness of acrylonitrile butadiene styrene(ABS)parts fabricated by fused deposition modeling(FDM)have determined that acetone smoothing not only achieves improved surface roughness but increases compressive strength as well.However,the sensitivity of ABS parts to acetone smoothing has not been explored.In this study we investigated FDM-fabricated ABS lattice structures of various cell sizes subjected to cold acetone vapor smoothing to determine the combined effect of cell size and acetone smoothing on the compressive properties of the lattice structures.The acetone-smoothed specimens performed better than the as-built specimens in both compression modulus and maximum load,and there was a decrease in those compressive properties with decreasing cell size.The difference between as-built and acetone-smoothed specimens was found to increase with decreasing cell size for the maximum load.

Characterization for elastic constants of fused deposition modelling-fabricated materials based on the virtual fields method and digital image correlation

Fused deposition modelling(FDM), a widely used rapid prototyping process, is a promising technique in manufacturing engineering. In this work, a method for characterizing elastic constants of FDM-fabricated materials is proposed. First of all, according to the manufacturing process of FDM, orthotropic constitutive model is used to describe the mechanical behavior. Then the virtual fields method(VFM) is applied to characterize all the mechanical parameters(Q, Q, Q, Q) using the full-field strain,which is measured by digital image correlation(DIC). Since the principal axis of the FDM-fabricated structure is sometimes unknown due to the complexity of the manufacturing process, a disk in diametrical compression is used as the load configuration so that the loading angle can be changed conveniently. To verify the feasibility of the proposed method, finite element method(FEM) simulation is conducted to obtain the strain field of the disk. The simulation results show that higher accuracy can be achieved when the loading angle is close to 30?. Finally, a disk fabricated by FDM was used for the experiment. By rotating the disk, several tests with different loading angles were conducted. To determine the position of the principal axis in each test, two groups of parameters(Q, Q, Q, Q) are calculated by two different groups of virtual fields. Then the corresponding loading angle can be determined by minimizing the deviation between two groups of the parameters. After that, the four constants(Q, Q, Q, Q) were determined from the test with an angle of 27?.

Design and Manufacturing Strategies for Fused Deposition Modelling in Additive Manufacturing:A Review

Although several research works in the literature have focused on studying the capabilities of additive manufacturing(AM) systems, few works have addressed the development of Design for Additive Manufacturing(DfAM) knowledge,tools, rules, and methodologies, which has limited the penetration and impact of AM in industry. In this paper a comprehensive review of design and manufacturing strategies for Fused Deposition Modelling(FDM) is presented.Consequently, several DfAM strategies are proposed and analysed based on existing research works and the operation principles, materials, capabilities and limitations of the FDM process. These strategies have been divided into four main groups: geometry, quality, materials and sustainability. The implementation and practicality of the proposed DfAM is illustrated by three case studies. The new proposed DfAM strategies are intended to assist designers and manufacturers when making decisions to satisfy functional needs, while ensuring manufacturability in FDM systems.Moreover, many of these strategies can be applied or extended to other AM processes besides FDM.

Design Consideration for Additive Manufacturing: Fused Deposition Modelling

Additive Manufacturing (AM) technologies have progressed in the past few years and many of them are now capable of producing functional parts instead of mere prototypes. AM provides a multitude of benefits, especially in design freedom. However, it still lacks industrial relevance because of the absence of comprehensive design rules for AM. Although AM is usually advertised as being the solution for all traditional manufacturing design limitations, the fact is that AM only replaces these limitations with a different set of restrictions. To fully exploit the advantages of AM, it is necessary to understand these limitations and consider them early during the design process. The establishment of design considerations in AM enables parts and process optimization. This paper discusses the design considerations that will lead to optimize part quality. Specifically, the work discusses the Fused Deposition Modeling (FDM) due to its common use and availability. These considerations are drawn from literature and from experiments done by the authors. The experiments done by the authors include an investigation for the influence of elevated service temperature on the performance of FDM PLA parts, benchmarking the capability of FDM to print overhangs and bridges without supports, studying the influence of processing parameters over dimensional accuracy, and the effect of processing parameters on the final FDM samples modulus of elasticity. The work presents a case study investigating the correct clearances for FDM parts and finally a redesign for AM case study of a support bracket originally manufactured using traditional manufacturing methods taking into consideration the design considerations discussed in this paper.

基于机器学习耦合模型预测FDM零件的表面粗糙度

熔融沉积工艺(FDM)制造的零件表面粗糙度高,不仅影响了零件外观,还降低了性能。采用响应面实验设计,研究了层高(A)、填充密度(B)、喷嘴温度(C)、床层温度(D)和打印速度(E)对聚乳酸(PLA)零件表面粗糙度的影响。同时,将遗传算法(GA)与决策树(DT)、人工神经元网络(ANN)两种机器学习模型相结合,预测了零件的表面粗糙度。结果表明,A、B、C和E是显著影响零件表面粗糙度的主效应,A×B、A×C、A×E、B×C、B×E、C×E是影响显著的交互效应。GA+DT耦合模型预测PLA零件表面粗糙度的准确性更高,预测值与实验值的相关系数(R2)、均方误差(MSE)和平均绝对误差(MAE)分别为0.952、0.132和0.234,优于GA+ANN的0.823、1.561和1.759。GA+DT模型的预测值与实验值的Pearson相关系数为0.984,而GA+ANN模型仅为0.903,这表明GA+DT模型在预测PLA零件表面粗糙度时准确度更高。

FDM技术打印参数对成型效率的影响研究

FDM技术可用于工业领域中大型零件模型的打印,提升成型效率成为重要的研究课题。本研究通过响应面分析方法,探究了FDM打印参数对聚乳酸圆柱件成型效率的影响规律,得到了最优打印参数,并经过实际打印验证。结果表明层厚增加,成型效率提高;打印速度增加,成型效率提高;填充率增加,成型效率降低;路径规划和壁厚对成型效率影响不大。影响成型效率的因素按照顺序排列是:层厚>打印速度>填充率,其中层厚和打印速度影响显著。最优打印参数为打印速度85mm·s^(-1)、层厚0.175mm、填充率55%,预测时间为58.8min,实际时间为59min,预测精度达99.7%,为提升成型效率提供了依据。