Microstructure,Thermal and Mechanical Behavior of 3D Printed Acrylonitrile Styrene Acrylate

Fused deposition modeling (FDM) is one of the most popular additive manufacturing techniques for polymers. Despite the numerous works on the printability of various types of polymers, there is a lack in understanding the role of the microstructure on the mechanical performance of printed parts. This work aims at addressing this particular point for the case of a polymer that did not receive much attention, namely acrylonitrile styrene acrylate or ASA. This study emphasizes on the effect of the printing temperature on thermal and mechanical performance of printed ASA using differential scanning calorimetry, infra‐red measurements, mechanical testing, X‐ray micro‐tomography, and finite element computation. The experimental results demonstrate a narrow window of printability of ASA based on the thermal response of this polymer during the laying down process. In addition, both experimental and numerical results show an evident loss in the performance that represents one third of the performance of the raw material. Despite this loss, the limited amount of generated porosity and the level of tensile strength of ASA make it a good choice as a feedstock material for FDM compared to other polymers such as acrylonitrile butadiene styrene.     

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。     

纳米二氧化硅对白水泥基3D打印材料结构变形、流变及力学性能的影响

与传统建筑材料相比,3 D打印建筑材料的结构建立对打印材料的流变性能具有更高的要求.通过引入纳米二氧化硅来调控白水泥基3D打印材料的流变性能,旨在稳定打印后的浆体结构和改善材料的力学性能.研究表明,纳米二氧化硅的掺入可以明显缩短浆体的凝结时间,改善其早期力学性能.同时,纳米二氧化硅的掺入能够提高浆体的屈服应力和弹性模量...     

纤维对3D打印混凝土打印性能与力学性能的影响

为了研究纤维掺入对3D打印混凝土(3DPC)性能的影响,通过掺入聚乙烯醇(PVA)、聚丙烯(PP)纤维以及剑麻纤维,探究了纤维对3DPC流变性能、打印性能、力学性能以及孔结构的影响规律。流变性能测试结果表明,3DPC的静态屈服应力与三种纤维的掺量均呈线性上升关系,但纤维对3DPC流变性能的影响程度有所差异。打印性能测试结果表明PVA纤维的掺入会降低3DPC的可挤出性,但能明显提高挤出后混凝土的尺寸均匀性。力学性能与孔结构的测试结果表明,PP纤维对3DPC抗压强度有明显的提升效果,剑麻纤维对3DPC抗折强度有最显著的增强效果,而纤维掺量提高会降低3DPC表观密度,使内部孔隙率增加,从而导致高掺量纤维的增强效果弱于低掺量纤维。     

二维与三维机织复合材料的力学性能实验研究

通过对超厚三维正交机织复合材料及二维机织层合板分别进行拉伸和压缩实验，研究比较两复合材料刚度和强度特性的差异；研究发现无论是三维机织材料的拉、压，还是二维层合板的拉、压的应力一应变曲线都可近似为直线关系，而且具有脆性破坏的特点；三维复合材料的拉、压强度要高于二维层合板，是由于不同的增强相结构及纤维含量造成；不同的破坏模式对材料强度影响很大。     

Influence of Filler Precoating and Printing Parameter on Mechanical Properties of 3D Printed Acrylonitrile Butadiene Styrene/Zinc Oxide Composite

Acrylonitrile butadiene styrene (ABS)/zinc oxide(ZnO) composites have been fabricated via fused deposition modelling technique. The effect of filler precoating and printing parameters on mechanical properties of the composites are investigated. The incorporation of precoated fillers and increase of infill density improve the tensile strength, Young’s modulus and hardness of the composites. Printing pattern determines mainly the tensile properties of the composites but has no significant effect on the hardness. Based on experimental results, it is suggested that line pattern printed with precoated fillers at medium dispenser speed and 100% infill density has resulted improved mechanical properties.     

Enhancement of Mechanical Properties of FDM‐PLA Parts via Thermal Annealing

The objective of this study is to investigate the possibility of enhancing mechanical properties of poly(lactic acid) (PLA) samples processed by a rapid manufacturing (RM) technique by increasing PLA crystallinity degree via thermal annealing. The samples are manufactured by fused deposition modeling (FDM) at different temperatures and subsequently evaluated by three‐point bending flexural and tensile tests. The polymer processed at 215 °C is thermally annealed over its glass transition temperature in order to increase the degree of crystallinity to the maximum attainable level as measured by the differential scanning calorimetry and confirmed by X‐ray diffraction. The increase in the degree of crystallinity of FDM‐PLA enhances flexural stress of the samples by 11–17%. The study also demonstrates applicability of radiation sterilization for FDM‐PLA parts. Therefore, thermal annealing might be introduced into a standard RM technology of PLA, particularly for sterilizable customized implants, to efficiently improve their mechanical properties.     

三维机织复合材料力学性能分析与研究

通过对三维机织复合材料几何细观结构的研究,分析了三维机织复合材料的力学性能,采用椭圆形纤维束截面假设并结合实际的纱线形态建立了一种新的三维机织复合材料力学模型,对三维机织复合材料的拉伸、压缩和层间剪切强度进行了理论分析,并与实验结果进行了对比,验证了力学模型的正确性。     

聚乳酸/木粉3D打印复合材料的制备与性能研究

以杨木木粉和聚乳酸(PLA)为原料、甘油为增塑剂,采用熔融挤出和3D打印的方法制备了PLA/木粉3D打印复合材料,并研究了增塑剂用量对复合材料性能的影响。结果表明:增塑剂甘油的加入破坏了PLA的结晶结构,并在一定程度上提高了PLA/木粉复合材料两相间的界面相容性。复合材料的各项性能随甘油用量增加呈规律性变化,其中,复合材料的拉伸强度逐渐减小,断裂伸长率先增大后减小,热稳定性小幅降低,而吸水率则逐渐增大。     

热活化和机械活化对拜耳法赤泥性能影响

为提高赤泥基碱激发胶凝材料的力学性能,分别通过焙烧和机械研磨对赤泥基复合粉体进行活化处理.结果表明,600℃煅烧180 min制备的胶砂试件28 d抗压强度最大,为27.0 MPa,对比未煅烧处理的赤泥粉体混合物,抗压强度提高了15.3％.机械研磨300 s制备的胶砂试件28 d抗压强度最小,为20.2 MPa,比研磨60 s制备的试件抗压强度降低了16.8％.热活化可以提高碱激发材料的强度但需要控制煅烧温度,赤泥本身较细不需要研磨活化处理.     

Effect of Nano-CaCO3 on Mechanical and Thermal Properties of Polyamide Nanocomposites

Polyamide-CaCO₃ nanocomposites were prepared by melt intercalation on twin-screw extruder. Various particle sizes (23, 17 and 11 nm) of CaCO₃ were synthesized by in-situ deposition technique. The shape and sizes of nano-CaCO₃ particles were confirmed by transmission electron microscopy (TEM). Nano-CaCO₃ was added from 1 to 4 wt% in the polyamide. Properties such as Tensile strength, Elongation at break, Hardness, and Flame retardency were studied. These results were compared with commercial CaCO₃ filled composites. Nano-CaCO₃ filled in polyamide shows, 3 fold improvement in Young's modulus in comparison to commercial CaCO₃ and 4–7 folds to virgin polyamide. Besides that, a polyamide nanocomposite shows 2 times improvements in flame retarding and vicat softening properties compared to commercial CaCO₃. Moreover, thermal degradation was studied on TGA and found to be improved compared to commercial CaCO₃. This was due to uniform dispersion of nano-CaCO₃ with greater surface area in comparison to commercial CaCO₃ in the polyamide matrix. Extent of dispersion of nano-CaCO₃ was studied along with microcracks generated during tensile testing using scanning electron microscope (SEM).     

HDPE/CaCO3复合材料的力学和热性能

应用Instron材料试验机和Ceast冲击试验机于室温下测量碳酸钙填充高密度聚乙烯(HDPE)复合材料.随着填料质量分数(Φ)的增加,试样的拉伸模量和拉伸断裂能呈非线性增大;而拉伸屈服应力、拉伸强度和冲击断裂能则仅在Φ＝10%时稍大于未填充的HDPE.热重分析实验结果表明,试样的热分解温度随着Φ的增加而呈非线性函数形式增大.     

Effects of Thermal Aging on the Mechanical Properties of a Porous-Matrix Ceramic Composite

The present article focuses on changes in the mechanical properties of an all-oxide fiber-reinforced composite following long-term exposure (1000 h) at temperatures of 1000–1200°C in air. The composite of interest derives its damage tolerance from a highly porous matrix, precluding the need for an interphase at the fiber–matrix boundary. The key issue involves the stability of the porosity against densification and the associated implications for long-term durability of the composite at elevated temperatures. For this purpose, comparisons are made in the tensile properties and fracture characteristics of a 2D woven fiber composite both along the fiber direction and at 45° to the fiber axes before and after the aging treatments. Additionally, changes in the state of the matrix are probed through measurements of matrix hardness by Vickers indentation and through the determination of the matrix Young's modulus, using the measured composite moduli coupled with classical laminate theory. The study reveals that, despite evidence of some strengthening of the matrix and the fiber–matrix interfaces during aging, the key tensile properties in the 0°/90° orientation, including strength and failure strain, are unchanged. This strengthening is manifested to a more significant extent in the composite properties in the ±45° orientation, wherein the modulus and the tensile strength each exhibit a twofold increase after the 1200°C aging treatment. It also results in a change in the failure mechanism, from one involving predominantly matrix damage and interply delamination to one which is dominated by fiber fracture. Additionally, salient changes in the mechanical response beyond the maximum load suggest the existence of an optimum matrix strength at which the fracture energy in the ±45° orientation attains a maximum. The implications for long-term durability of this class of composite are discussed.     

三维编织复合材料的细观结构与力学性能

归纳、梳理了三维编织复合材料细观结构表征方面较有代表性的单胞模型,分析、比较各结构模型的优缺点,从理论分析与试验测试两方面总结三维编织复合材料刚度和强度性能的研究成果与进展,探讨了细观结构表征与力学性能预报中存在的主要问题,并展望今后的研究重点与发展方向。     

热空气老化对丁基橡胶交联密度和力学性能的影响

采用热空气老化试验机研究了丁基橡胶（IIR）的老化行为,获得了不同老化温度和老化时间对IIR交联密度和力学性能的影响规律。结果表明,随着老化时间的延长,IIR硫化胶的交联密度先增大后减小,并随老化温度的升高变化幅度较为明显。拉伸强度、定伸应力和硬度均出现类似变化规律,而拉断伸长率先迅速下降后逐渐趋于平缓。     

3D打印光敏树脂表面楔形冠状织构的摩擦学性能

为了研究光敏树脂表面楔形冠状织构的摩擦学性能,以C-UV9400A光敏树脂为材料,利用3D打印立体光固化成型技术制备表面光滑和具有不同织构面积占有率的楔形冠状织构试样。在MRTR多功能摩擦磨损试验机上检测表面织构化的光敏树脂的摩擦学性能,利用体式显微镜观察织构宏观形貌。探究不同载荷(5,20 N)、不同转速(100,200,300 r/min)对不同织构面积占有率(10%,15%,20%,25%,30%,35%,40%,45%,50%)试样的摩擦学性能影响。有限元分析软件Fluent分析表明,织构的存在使得油液内部产生空化现象,抑制了负压的形成;油膜正压力升高,有效提高了油膜承载能力;织构内部存在涡流现象,对于吸附磨屑起到积极作用;转速的升高导致油膜承载能力进一步增强。与光滑表面试样相比,具有织构的试样具有更低的摩擦系数,织构面积占有率为35%时在大部分工况下具有最佳的减摩抗磨效果。     

环氧树脂/POSS杂化材料力学性能和耐热性研究

以自行合成的环氧基倍半硅氧烷（POSS）为改性剂,分别对环氧树脂139S/六氢苯酐和环氧树脂BE 188EL/六氢苯酐进行改性,制备环氧树脂/POSS杂化材料。力学性能分析结果表明,两种杂化材料的冲击强度和弯曲强度都有明显的提高,冲击强度分别提高了57.45 %和32.26 %,弯曲强度分别提高了9.23 %和5.07 %。热性能分析结果表明,两种杂化材料在高温时的热残留量都有所提高,分别提高了50.19 %和20.16 %。两种杂化材料的热膨胀系数也得到了降低,即热稳定性得到了提高。     

3D打印条件对可降解聚乳酸力学性能的影响

采用3D打印方式制备降解左旋聚乳酸（PLLA）样品,通过冲击及拉伸试验研究不同打印条件对样品冲击强度、拉伸强度、拉伸模量及断裂伸长率的影响。结果表明,随着打印填充密度的增加,样品的冲击强度、拉伸强度及拉伸模量增大,断裂伸长率先增后减;随着打印速度的增加,样品的拉伸强度和拉伸模量增大,冲击强度及断裂伸长率减小;随着打印温度的增加,样品的冲击强度、拉伸强度和拉伸模量增大,断裂伸长率减小;打印填充密度、打印速度、打印温度分别为70 %、100 mm/s、210 ℃时,样品的综合性能最佳。     

不同填充率下FDM 3D打印预制件建模及力学性能分析

以拉伸、压缩、弯曲、扭转4种受载情况下的熔融沉积型三维（FDM 3D）打印预制件为研究对象,以填充率、填充单元结构类型为分析参数,通过确定3D打印预制件填充率的影响因素,建立了填充率与格子形填充单元几何参数的通用解析式,据此构建不同填充率下3D打印预制件的三维几何模型;然后对不同受载类型3D打印预制件进行有限元仿真分析,明确填充率对不同载荷工况下3D打印预制件力学特性的影响规律。仿真和实验结果表明,填充率对3D打印预制件所受拉伸应力、压缩应力、弯曲应力均有较大影响,而扭转情况下影响较小,据此进一步确定了一定受载情况下3D打印预制件的较优填充率;基于本文提出的不同填充率下预制件三维模型建立方法,可有效实现对预制件的力学性能仿真分析,对减少产品试验验证次数、降低研发成本具有积极作用。