熔融沉积3D打印材料粘接强度及模量预测研究

主要介绍了一种用于预测熔融沉积模型(FDM)层间粘接强度的扩散修复模型。根据流变数据确定温度相关扩散模型,基于一维瞬态热分析预测FDM部件层间的扩散。将温度历史上的扩散系数对时间积分得到界面分子总扩散,进而得到层间粘接强度预测模型。结果表明:不同打印条件下预测结果与测得的粘合强度结果的吻合度较好,且该模型经修正后也适用于FDM部件弹性模量的预测。通过三点弯曲实验与数值模拟的结果对比,验证了粘接强度及模量预测模型的可用性。因此,可以作为FDM打印件承载性能预测的有效模型。     

熔融沉积3D打印设备研究进展

阐述了3D打印技术的种类,介绍了熔融沉积成型(FDM)技术的原理、特点及其目前存在的问题;从控制方法(温度控制、运动控制、路径控制)和运动机构(送料机构、喷嘴、运动机构)两个方面系统综述了国内外FDM 3D打印设备的最新研究进展;最后,指出了目前FDM 3D打印设备所面临的挑战及需要解决的问题,展望了FDM 3D打印设...     

层间预熔温度对熔融沉积成型打印件力学性能的影响

以聚乳酸(PLA)为原料,通过对喷头装置进行改装,探究打印过程中,打印层预熔温度对垂直打印件层间结合强度及力学性能的影响。结果表明:随着预熔温度的升高,垂直打印件的最大拉伸强度呈先提高后降低的趋势,预熔温度为80℃时拉伸强度达到最大值,其平均强度可达到水平打印件的89.1%;而在无预热条件下,垂直打印件的力学性能只有水平打印件的66.9%。此外,通过对比实验发现,该层间预熔方式在提升打印件的层间结合强度方面优于传统的热处理方式。     

人工神经元网络模型预测3D打印部件力学性能的研究

熔融沉积成型(FDM)是一种高效的增材制造技术。将响应面模型与人工神经元网络(ANN)模型相结合,研究了FDM工艺的喷嘴温度、层高和层积角度对尼龙12(PA12)丝材制造部件力学性能的影响。当喷嘴温度、层高和层积角度分别在220～260℃、0.2～0.4 mm、0°～90°之间变化时,部件拉伸强度和缺口冲击强度分别在35.69～60.89 MPa和5.48～19.83 kJ/m²之间。喷嘴温度、层高、层积角度以及层积角度的二阶效应是影响部件拉伸强度的显著因素;喷嘴温度、层积角度以及层积角度的二阶效应是影响缺口冲击强度的显著因素。ANN模型预测拉伸强度和缺口冲击强度的最优结构分别是3-10-5-1和3-25-24-1,预测的拉伸强度和缺口冲击强度均方误差函数(MSE)最低分别为2.54×10^-4和2.07×10^-4,回归系数均在0.97以上。与响应面的二次回归模型相比,ANN模型预测的拉伸强度和缺口冲击强度与实验值的标准偏差分别为0.46和0.32,远低于二次回归模型的2.43和1.58,更适合于优化非线性的FDM工艺。     

熔融沉积成型3D打印技术应用进展及展望

介绍熔融沉积制造(FDM)3D打印技术的产生和特点。着重介绍了FDM 3D打印技术在汽车工业、航空航天、医疗卫生、教育教学、食品加工等领域的实际应用情况。并对FDM 3D打印技术的应用前景进行展望。     

填充结构对熔融沉积3D打印制件拉伸性能的影响

为提高熔融沉积3D打印制件的拉伸性能,通过熔融沉积3D打印工艺制作哑铃型试样,探究填充结构对3D打印制件拉伸性能的影响。结果表明,根据平面线型及空间特征,熔融沉积3D打印制件的填充结构分为三类：平行线型填充、立体单元型填充和网格线型填充;其中,平行线型填充结构中与拉伸方向一致的填充线条(丝材本体)数量影响了3D打印制件的拉伸性能,填充线条数量越多,制件的强度和刚度越大;立体单元型填充结构中的立体单元数量影响了3D打印制件的拉伸性能,立体单元的数量越多,制件的强度和刚度越大;网格线型填充结构中的网格密度影响了3D打印制件的拉伸性能,网格密度越大,制件的强度和刚度越大;相同工艺参数条件下,平行线型填充结构的比强度和比刚度最大,拉伸性能最强,立体单元型填充结构的拉伸性能次之,网格线型填充结构的拉伸性能最弱。     

基于锥形螺杆挤出单元的熔融沉积成型3D打印机及实验研究

研制了一种基于锥形螺杆挤出单元的桌面式熔融沉积成型（FDM）3D打印机,采用锥形螺杆塑化聚合物并挤出丝条,配合沉积平台的运动打印制品。使用聚乳酸（PLA）、 高密度聚乙烯（PE-HD）材料对设备挤丝性能进行了研究,并研究了打印参数包括电机脉冲频率、走丝间距、层厚等对 PLA 拉伸样条性能的影响。结果表明,自制锥形螺杆挤出式 FDM 打印机具有较好的打印效果,合适的电机脉冲频率、走丝间距、层厚等工艺参数可以使打印制件获得较好的表观质量和强度,而较大的走丝间距使制件的拉伸强度下降了约20 %。     

熔融沉积成型材料的研究与应用进展

对熔融沉积（FDM）成型材料、支撑材料的性能要求进行了分析;综述了近年来熔融沉积成型材料的国内外研究现状;归纳了其应用情况,展望了其发展前景.     

熔融沉积成型用高分子材料的研究进展

介绍了熔融沉积成型(FDM)原理及所需材料要求,详细阐述了国内外FDM用丙烯腈–丁二烯–苯乙烯塑料(ABS)、聚乳酸(PLA)、聚碳酸酯(PC)的研究进展,展望了其发展前景。     

Mechanical properties of 3D parts fabricated by fused deposition modeling: Effect of various fillers in polylactide

Weak mechanical strength and serious mechanical anisotropy are two key limiting factors for three-dimensional (3D) parts prepared by fused deposition modeling (FDM) in industrial applications. In this work, we investigated the relationships between mechanical properties and surface quality of FDM parts with the properties of materials used. Three kinds of polylactide (PLA) filaments, composed of the same PLA matrix but different fillers (carbon fibers and talc), were used to prepare FDM specimens. Due to the nature of FDM process, FDM parts exhibited tensile properties weaker and more anisotropic than their injection-molding counterparts. The presence of fillers affected the tensile properties of FDM parts, especially the degree of mechanical anisotropy. It is found that the interlayer bond governing the mechanical performance of FDM parts was improved since the fillers added in the polymer materials facilitates the molecular diffusion across the bond interface. Also, the surface quality of FDM parts varied with fillers. Neat PLA parts exhibited surface quality superior to the 3D parts printed with composites filaments. This work is believed to provide highlights on the development of polymer composites filament and improvement of mechanical properties of FDM parts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47824.     

Effect of processing parameters on flexural properties of 3D-printed polyetherketoneketone using fused deposition modeling

Polyetherketoneketone (PEKK) is an engineering plastic with ultrahigh mechanical performance and has attracted considerable attention in the medical and technical fields. Printing parameters during fused deposition modeling (FDM) for PEKK have a significant impact on final part quality. In this study, a relationship between the process parameters and flexural properties of PEKK was investigated by conducting three-point bending tests, and scanning electron microscopy was employed to analyze the microstructure of fracture surfaces. Nozzle temperature, layer thickness, and infill density affected flexural properties by changing the porosity and interlayer bonding strength. Interlayer separation is the main failure mode of the upright orientation samples, while intralayer failure is likely to occur in the on-edge orientation samples. The flexural properties of FDM-printed PEKK under optimum parameters are comparable to those of mandibular bones, indicating that PEKK is a potential candidate for repairing mandibular defects. The results highlighted in this study are fundamental to the optimal design of complex ultralight, highly efficient structures.     

Improving the ductility of polylactic acid parts produced by fused deposition modeling through polyhydroxyalkanoate additions

Polylactic acid (PLA) is one of the most commonly used materials for fused deposition modeling (FDM) due to its low cost, biocompatibility, and desirable printing characteristics. However, its low ductility is a major disadvantage for engineering applications where high damage tolerance is needed. This study investigates the feasibility of polyhydroxyalkanoate (PHA) additions to PLA for improving the ductility of parts produced by FDM. Thermal and mechanical behavior of PLA/PHA specimens containing 12 wt % PHA is investigated for a range of printing nozzle temperatures. All PLA/PHA specimens exhibit amorphous PLA phase with semicrystalline PHA and possess outstanding ductility exceeding 160% for nozzle temperatures in the range of 200 °C–240 °C. Lower and higher nozzle temperatures result in low ductility, similar to that of pure PLA. Overall, PLA/PHA is a very promising polymer blend for FDM processes, providing a combination of sufficient strength with excellent damage tolerance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48154.     

Effects of laser polishing on surface quality and mechanical properties of PLA parts built by fused deposition modeling

Fused deposition modeling (FDM) produces parts through layer by layer on the top of each other, making it almost impossible to obtain smooth printed parts. Hence, there is a huge demand for the postprocessing of the FDM-printed parts. Laser polishing is a novel technique that can be used to polish products to obtain a smoother surface. The aim of this work was to explore the feasibility of surface-finishing FDM-printed polylactic acid (PLA) parts by laser polishing. The surface roughness, surface morphology, dynamic mechanical analysis (DMA), and tensile properties were investigated. The results indicated that the lower laser power and the bigger laser beam diameter within a certain range could facilitate the formation of smoother surface. With optimized parameters, the surface roughness was reduced by 90.4%. DMA showed that the storage modulus (E’) and glass transition temperature of PLA specimens were significantly improved due to the decrease of molecular mobility of denser structures. Moreover, the tensile strength and Young's modulus of the PLA specimen were also significantly increased after laser polishing. The fracture morphologies were observed, and the possible strengthening mechanism was also discussed. These results indicated that laser polishing could be an efficient method for surface polishing of FDM parts. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48288.     

Pore parameter selection for fused deposition modeling of gas diffusion layers in proton exchange membrane fuel cells

Because of the global energy crisis, many researchers have focused their efforts on fuel cells. The gas diffusion layer (GDL) is a fundamental component of proton exchange membrane (PEM) fuel cells. The manufacturing procedures for traditional carbon-based GDLs are sophisticated and energy-intensive, and have design flexibility constraints, making it difficult to build complicated forms and structures. Additive manufacturing is widely used in a variety of fields, with the fused deposition modeling (FDM) technique being the most popular method. Prior to conducting systematic research on the printed GDLs, it is necessary to investigate the pore parameters with the support of FDM technique. In this research, the initial step involves material selection, FDM printer selection, and modeling. Subsequently, printing analysis and sample characterization are conducted to select an acceptable pore shape. A water drainage test determines the appropriate pore size, followed by additional tests for acceptable porosity range. The square pore shape is determined to be more suitable. A pore side length of 1.0 mm is identified. Furthermore, a suitable pore range of 10.9%–30.3% is identified. Next step, the printed GDLs will undergo further testing to investigate their suitability to be used in PEM fuel cells.     

Thermal and mechanical properties of polyamide 12/graphene nanoplatelets nanocomposites and parts fabricated by fused deposition modeling

The printable polyamide 12 (PA12) nanocomposite filaments with 6 wt % graphene nanoplatelets (GNPs) for fused deposition modeling (FDM) were prepared by melting compounding and smoothly printed via a commercial FDM three‐dimensional (3D) printer. The thermal conductivity (λ) and elastic modulus (E) of 3D printed PA12/GNPs parts along to the printing direction had an increase by 51.4% and 7% than that of compression molded parts, which is due to the GNPs preferentially aligning along to the printing direction. Along with these improved properties, ultimate tensile strength of 3D printed PA12/GNPs parts was well maintained. These results indicate that FDM is a new way to achieve PA12/GNPs parts with enhanced λ over compression moulding, which could contribute to realize efficient and flexible heat management for a wide range of applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45332.     

Effect of IR-laser treatment parameters on surface structure,roughness, wettability and bonding properties of fused deposition modeling-printed PEEK/CF

In this study, laser surface treatment was applied to alter the surface texturing and chemical compositions of fused deposition modeling (FDM)-printed PEEK/CF samples to improve the deficiency of inert surface of PEEK as adherend substrate. The influence of IR-laser parameters including treatment gaps, single pulse energy and pulse widths on surface properties and shear bond strength were discussed. The results indicated that surface roughness was enhanced with decreasing treatment gap or increasing pulse energy, which reached the highest value of Ra = 32.44 μm at 0.4*0.4 mm² treatment gap and 300 mJ single pulse energy. By adjusting laser pulse width, surface wettability changed from hydrophobicity to hydrophilicity. After micro-second laser ablation, the texturing structure was changed and acted as mechanical interlocking effect, and therefore make the shear bond strengths improve from 3.28 to 6.42 MPa compared with the untreated groups. On the other hand, functional groups on substrate surface were activated after nano-second laser ablation, which contributes to an enhancement of shear bond strength through chemical interaction between adhesives and substrates. Therefore, our work highlights an efficient method of laser surface treatment on the adhesion property of FDM-printed substrates.     

Re-entrant auxetic structures fabricated by fused deposition modeling: An experimental study of influence of process parameters under compressive loading

The present article is focused on investigating the influence of process parameters under compressive loading in case of reentrant auxetic structures fabricated by fused deposition modeling (FDM). Auxetic structures of acrylonitrile butadiene styrene (ABS) and poly-lactic acid (PLA) materials are fabricated. Three process parameters of FDM namely layer thickness, raster angle, and number of contours are considered to investigate their influence on compressive strength, stiffness, and specific energy absorption (SEA). Experiments are performed on the basis of central composite design and analysis is performed using ANOVA. It is found that compressive strength of auxetic structure improves with increase in layer thickness. But with increase in raster angle, it increases first and then decreases. Compressive stiffness of structures initially decreases and then increases with increase in raster angle, while it increases with increase in number of contours. SEA of structures increases with decrease in layer thickness. Based on the analysis of experimental results, regression models are developed to predict these responses. Also, multi-response optimization is performed to optimize strength, stiffness, and SEA. Auxetic structures failed under compressive loading are also examined using scanning electron microscope.     

熔融沉积工艺参数对热塑性聚氨酯弹性体静动态力学性能的影响

为揭示通过熔融沉积成型（FDM）工艺制备的热塑性聚氨酯弹性体（TPU）的静动态力学性能及工艺参数对其力学性能的影响,采用万能材料试验机和分离式霍普金森压杆（SHPB）实验装置对使用3种打印速率（10、40、70 mm/s）和3种喷头温度（200、220、240 ℃）制备的TPU开展准静态（0.01 s^-1）和动态（1 000 s^-1）加载下的力学性能试验,并进行工艺参数优选,同时进一步获取了材料在较宽应变率范围（0.001~2 500 s^-1）的应力?应变样本空间数据。结果表明,准静态和动态加载下,喷头温度220 ℃、打印速率40 mm/s为最优工艺参数;试样在准静态和动态下均具有应变率效应;准静态下试样超弹性特征显著,动态下结合朱?王?唐（ZWT）方程构建的材料黏弹性本构模型拟合曲线与实验曲线吻合较好;采用最优工艺参数制备的试样出现明显“微相分离”现象。