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).

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?.

Finite Element Method Applied to Fuse Protection Design

In a poloidal field （PF） converter module, fuse protection is of great importance to ensure the safety of the thyristors. The fuse is pre-selected in a traditional way and then verified by finite element analysis. A 3D physical model is built by ANSYS software to solve the thermal- electric coupled problem of transient process in case of external fault. The result shows that this method is feasible.

DETERMINATION OF STABILITY CONSTANTS OF THE COORDINATION COMPOUNDS OF Au(Ⅲ)-2-MERCAPTOPYRIDINE-1-OXIDE AND METHYL DERIVATIVES——METHOD OF DUAL-WAVELENGTH CORRESPONDING SOLUTIONS

In this paper,we report the deductive formula used for the method of dual-wavelength corresponding solutions under condition of having ligand interference and the stability constants of three new coordination compounds [AuL_2]^+determined with this method.The stability of the three compounds,the necessity of controlling pH in experimental systems and the advantage of this method are discussed in detail.

基于定位校正指数的嘧啶类含能材料爆轰性能

为研究嘧啶类含能化合物的爆轰性能与其分子结构的构效关系,根据嘧啶类含能化合物分子中原子相互连接的空间特性,提出了一种新的分子结构指数——定位校正指数B;此外还计算了19个含能化合物分子的电拓扑态指数,并优化筛选出其中的E 13作为分子结构描述符,将E 13与定位校正指数B结合,与嘧啶类含能化合物的爆轰性能进行回归分析;将B和E 13这两种结构指数作为BP神经网络的输入变量,神经网络结构采用2-3-1的结构方式,构建了预测嘧啶类含能化合物爆轰性能好的神经网络法模型。结果表明,每个模型的总相关系数均超过0.99,达优级相关,计算得到的氧平衡、爆热、爆速和爆压的预测值与文献值的平均相对误差分别为1.59%、1.05%、0.37%和1.28%;如将指数扩展到与噁三唑稠环类含能材料分子、含氟唑类含能化合物分子的爆轰性能等进行分析预测,同样能得到令人满意的结果。说明嘧啶类含能材料分子的爆轰性能与定位校正指数、电拓扑态指数有良好的非线性关系。

基于随机游走麻雀搜索算法的多特征结构尺寸熔融沉积成型工艺参数优化

在熔融沉积成型过程中,打印参数对成型样件精度有着重要影响.为了提高整体尺寸精度,采用随机游走的麻雀算法获得最优实验方案.首先,以熔融沉积成型的分层厚度、喷头温度、打印速度和填充率为实验变量设计4因素4水平的正交试验;然后,以样件不同特征结构尺寸的相对误差为优化对象,使用田口-灰色关联法对实验数据进行处理;最后,通过随机游走的麻雀算法计算最优参数方案.结果表明,相比常用的田口-灰色关联法,采用优化后工艺参数成型样件的综合尺寸精度提高了20%,灰色关联度提高了27%.

固废资源合成堇青石工艺及其性能研究

为了合理利用固废资源、缓解资源紧张,根据堇青石的化学组成,以质量分数分别为12%的电熔镁砂收尘粉、40%的电熔刚玉收尘粉、48%的石英尾砂为原料,分别在1320、1350、1380、1390、1400、1410℃保温3 h煅烧,制备堇青石质耐火原料,研究了煅烧温度对堇青石试样相组成、显微结构、物理性能等的影响。结果表明:在1390℃之前,镁铝尖晶石和方石英逐渐反应生成堇青石直至方石英相完全消除,当煅烧温度达到1390℃时,试样中的堇青石相含量达94%(w),次晶相为镁铝尖晶石,此时试样的热膨胀系数最低,为3.2×10^(-6)℃^(-1),体积密度较低,为1.85 g·cm^(-3),热导率较低,为1.279 W·(m·K)^(-1),显微结构较致密,综合性能最优。

基于多源信息融合的引信可靠性评估方法研究

针对高价值弹药引信利用全弹飞行试验验证其可靠性弹药价格昂贵,全弹的靶试试验量很小,且引信的可靠性指标高于全弹的可靠性指标的问题,充分地利用模拟试验数据对小子样进行重要数据补充;采用继承因子、环境因子折算数据,将不同类型的数据折合为成败型试验数据,再用CMSR方法根据系统串并联关系将多源数据融合,并将所得的数据与靶试数据结合,减少靶试试验样本量;以混合Beta分布为先验分布,得到了评估引信可靠性的Bayes方法,该法解决了模拟试验数据与靶试数据融合的问题;以某引信为应用背景进行了可靠性评估,证明该方法比经典方法减少了一定的靶场试验量。

基于fused惩罚的稀疏主成分分析

本文旨在研究基于fused惩罚的稀疏主成分分析方法,以适用于相邻变量之间高度相关甚至完全相等的数据情形。首先,从回归分析角度出发,提出一种求解稀疏主成分的简便思路,给出一种广义的稀疏主成分模型——GSPCA模型及其求解算法,并证明在惩罚函数取1-范数时,该模型与现有的稀疏主成分模型——SPC模型的求解结果一致。其次,提出将fused惩罚与主成分分析相结合,得到一种fused稀疏主成分分析方法,并从惩罚性矩阵分解和回归分析两个角度,给出两种模型形式。在理论上证明了两种模型的求解结果是一致的,故将其统称为FSPCA模型。模拟实验显示,FSPCA模型在处理相邻变量之间高度相关甚至完全相等的数据集上表现良好。最后,将FSPCA模型应用于手写数字识别,发现与SPC模型相比,FSPCA模型所提取的主成分具备更好的解释性。

面向作战决策智能体的融合赋权评估方法

在兵棋等对抗性作战实验环境下,通过使用基于强化学习方法训练的智能体进行仿真推演,能够检验作战决策效果,达到辅助决策的目的。针对当前作战决策智能体评估往往采用胜率这一单一数据指标的局限,提出了一种基于融合赋权的综合评估方法。通过构建涵盖作战决策有效性、作战意图实现性、作战环境适应性、智能体训练效率、智能体训练体系和智能体训练方法等技战术效果指标的评估体系,然后使用主客观方法对不同类型指标进行赋权,再根据指标性质将权值融合进入评估体系,实现基于融合权重的智能体决策效果评估。构建了陆上合成分队进攻作战场景,利用该方法对6个智能体进行评估验证,能够获得智能体的综合排名,有效避免了单一指标的评估局限。该方法对作战决策智能体评估提供了新的思路,符合作战环境需要,具有一定的应用价值。

基于ACO-BP算法的熔融沉积成型翘曲变形量的预测方法

针对熔融沉积成型翘曲变形量预测问题,提出了一种基于蚁群算法(ACO)-误差反向传播(BP)神经网络算法的预测方法。采用ACO算法优化BP神经网络的初始权值、阈值,防止其训练时收敛于局部极小。基于正交试验分别设计4因素4水平的训练样本集和4因素3水平的验证样本集。训练样本集用于预测模型的学习,验证样本集用于验证预测方法的精度。基于极差法分析了各工艺参数对翘曲变形量的影响程度。结果表明,工艺参数对翘曲变形量的影响程度从大到小分别为层高、填充率、喷头挤出温度和打印速度。采用训练样本集充分训练预测模型后,验证基于ACO-BP算法的翘曲变形量预测方法的效果。基于均方根误差(RMSE)、均方误差(MSE)、平均绝对误差(MAE)和平均绝对百分比误差(MAPE)评价模型预测精度。对于RMSE,BP算法的预测精度约为ACO-BP算法的1.7倍;对于MSE,BP算法的预测精度约为ACO-BP算法的2.9倍;对于MAE,BP算法的预测精度约为ACO-BP算法的1.6倍;对于MAPE,BP算法的预测精度约为ACO-BP算法的2.2倍。基于ACO算法优化的BP神经网络预测精度更高。

FDM多工艺参数对PLA制件尺寸误差的影响

为探索熔融沉积快速成型技术(FDM)的工艺参数对聚乳酸(PLA)制件成型尺寸误差的影响规律,通过逆向数据采集方法对制件的长度误差、宽度误差、厚度误差进行测量对比,在4个单一工艺参数(外墙打印速度、外墙线宽、打印温度、打印层高)变化对尺寸误差影响分析的基础上,采用响应面法对筛选出的3个主要因素进行交互实验与分析。结果表明,长度误差受工艺参数的影响最大,其次是厚度误差,工艺参数对长度误差、宽度误差以及厚度误差的影响程度的排序均为:打印层高>打印温度>外墙线宽。

田口方法在熔融沉积成形中的应用与展望

熔融沉积成形(FDM)是增材制造(AM)领域中应用最为广泛的技术之一,通常用于制造具有复杂几何形状的零件,在航空航天、汽车、船舶及生物医疗等领域得到广泛使用。然而,由于力学性能不足及成形质量低等问题,通过FDM技术打印的零件在应用过程中受到了一定的限制。优化工艺参数能够明显降低零件在打印过程中出现的缺陷,田口方法(Taguchi Method)则非常适合FDM打印过程中工艺参数的优化,从表面质量、力学性能及材料消耗3方面综述田口方法优化工艺参数,并展望未来潜在的应用前景,为进一步的研究提供了方向。

Damage characteristics of laser plasma shock wave on rear surface of fused silica glass

The damage to the rear surface of fused silica under the action of high power laser is more severe than that incurred by the front surface,which hinders the improvement in the energy of the high power laser device.For optical components,the ionization breakdown by laser is a main factor causing damage,particularly with laser plasma shock waves,which can cause large-scale fracture damage in fused silica.In this study,the damage morphology is experimentally investigated,and the characteristics of the damage point are obtained.In the theoretical study,the coupling and transmission of the shock wave in glass are investigated based on the finite element method.Thus,both the magnitude and the orientation of stress are obtained.The damage mechanism of the glass can be explained based on the fracture characteristics of glass under different stresses and also on the variation of the damage zone’s Raman spectrum.In addition,the influence of the glass thickness on the damage morphology is investigated.The results obtained in this study can be used as a reference in understanding the characteristics and mechanism of damage characteristics induced by laser plasma shock waves.

Optical modulation of repaired damage site on fused silica produced by CO2 laser rapid ablation mitigation

CO2 laser rapid ablation mitigation(RAM)of fused silica has been used in high-power laser systems owing to its advantages of high efficiency,and ease of implementing batch and automated repairing.In order to study the effect of repaired morphology of RAM on laser modulation and to improve laser damage threshold of optics,an finite element method(FEM)mathematical model of 351 nm laser irradiating fused silica optics is developed based on Maxwell electromagnetic field equations,to explore the 3D near-field light intensity distribution inside optics with repaired site on its surface.The influences of the cone angle and the size of the repaired site on incident laser modulation are studied as well.The results have shown that for the repaired site with a cone angle of 73.3°,the light intensity distribution has obvious three-dimensional characteristics.The relative light intensity on z-section has a circularly distribution,and the radius of the annular intensification zone increases with the decrease of z.While the distribution of maximum relative light intensity on y-section is parabolical with the increase of y.As the cone angle of the repaired site decreases,the effect of the repaired surface on light modulation becomes stronger,leading to a weak resistance to laser damage.Moreover,the large size repaired site would also reduce the laser damage threshold.Therefore,a repaired site with a larger cone angle and smaller size is preferred in practical CO2 laser repairing of surface damage.This work will provide theoretical guidance for the design of repaired surface topography,as well as the improvement of RAM process.

A Convenient Method for the Synthesis of 1,3,2-Oxazaphospholidin-[3,2-a]-8-oxo-10-thio(or seleno)-[1,3,2]-benzodiazaphosphorines

A Convenient method for the synthesis of fused phosphorusheterocycle 1,3,2-oxazaphosphorin-[3.2-a]-8-oxo-10-thio(or seleno)-[1,3,2]-benzodiazaphosphorines was carried out in one pot by the reaction of Tris(diethylamino)phosphine with multifunctional compounds 2-(N-(beta or gamma-hydroxyl) alkylene) amino-benzamides 1. When PCL3 was used, only chlorinated product was obtained.

Effect of Main Material Ratio on Properties of SiC-Al_2O_3 Porous Ceramics via Polymeric Replication Method

In order to fabricate porous ceramics with good properties and proper production cost,SiC-Al2 O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundum via a polymeric replication method. Effects of the mass ratio of SiC powder to white fused corundum powder（ 1 ∶ 3,1 ∶ 1 and 3 ∶ 1） on the appearance,phase composition,sintering properties and thermal shock resistance were investigated. The research results indicate that the as-prepared Si C-Al2 O3 porous ceramics have uniform pores,and their linear shrinkage ratio,apparent porosity and bulk density reach 4. 70%,67. 17%and 0. 83 g·cm-3,respectively. The thermal shock cycles from 1 400 ℃ to room temperature reach 23 including 15 cycles in air cooling condition and then 8 cycles in water cooling condition. Their main phases areα-Al2 O3 and Al6 Si2 O13 as well as a small amount of SiC and free SiO2. The as-prepared porous ceramic with the ratio of m（ SiC） ∶ m（ Al2 O3） = 1∶ 1 possesses prior comprehensive properties.

Corrosion Resistance of Fused Cr_2O_3-Al_2O_3 Grains with Different Compositions

Six kinds of Cr2O3 - Al2 O3 fused grains （the mass percent of Cr203 was 15%, 40%, 50%, 60%, 85% and 99%, respectively ） were prepared using chrome green and Al203 powder as starting materials by electro-fnsion, named as CR15, CR40, CR50, CR60, CR85, and CR99, respectively. The corrosion resistance of the six kinds of Cr2O3- Al2O3.fused grains （4-1 ram） was studied using rotary slag corrosion method. The results show that： （ 1 ） the corrosion resistance of the fused grains increases with the Cr203 content and the grain size increasing; （2）the grains of CR99 and CR85 with higher Cr2O3 content are corroded at the slag surJace layer, because FeO and Al2O3. in the slag corrode the grains ; FeO reacts with Cr2O3 in the aggregates.forming （Fe, Cr ）3O4 ,spinel firstly, and the spinel reacts with other phases forming composite spinel; when FeO is fidly consumed, Al2 O3 penetrated into the grains reacts with Cr2O3 Jorming Al2O3 - Cr2O3 solid solution on the grains surface; （3） for CR60, the corrosion exists both in the slag surface layer and in the penetration layer; in the penetration layer, CaO and SiO2 react with Al2O3 in Al2O3 - Cr2O3 solid solution forming anorthite , gehlenite ,and glass phase; the grains of CR50, CR40 and CRI5 have the same corrosion mechanism with CR60 in the penetration layer.

A critical quality parameter in quantitative fused-core chromatography: The injection volume

As part of the method development, the injection volume as a critical quality attribute in fast fused-core chromatography was evaluated. Spilanthol, a pharmaceutically interesting N- alkylamide currently under investigation in our laboratory, was chosen as the model compound. Spilanthol was dissolved in both PBS and MeOH/H20 （70/30, v/v） and subsequently analyzed using a fused-core system hereby selecting five chromatographic characteristics （retention time, area, height, theoretical plates and symmetry factor） as responses. We demonstrated that the injection volume significantly influenced both the qualitative and quantitative performance of fused-core chromatography, a phenomenon which is confounded with the nature of the used sample solvent. From 2 ~tL up to 100 laL injection volume with PBS as solvent, the symmetry factor decreased favorably by 20%. Moreover, the theoretical plates and the quantitative parameters （area and height） increased up to 30%. On the contrary, in this injection volume range, the theoretical plates for the methanol-based samples decreased by more than 60%, while the symmetry factor increased and the height decreased, both by 30%. The injection volume is thus a critical and often overlooked parameter in fused-core method description and validation.

引信MEMS安解装置二维过载加载方法及仿真分析

针对引信安全与解除隔离装置后坐过载和离心过载的加载难题,介绍了一种引信二维过载加载模拟方法。综合运用离心机旋转储能、撞击加速模拟法以及等效离心旋转模拟法,通过离心机带动冲击锤高速撞击装有引信安解装置试件的滑车并使其瞬间加速,模拟后坐过载加载;通过电磁制动器控制冲击锤瞬间收回,使滑车绕轨离心旋转,模拟离心过载加载。建立了模拟试验系统的动力学方程和冲击锤的运动方程,计算并选定了离心机的转速和电磁制动器的制动力。利用ANSYS/LS-DYNA软件建立冲击锤撞击滑车的动力学模型进行仿真分析,得到了不同离心机转速、缓冲垫材质以及缓冲垫厚度条件下的后坐过载和离心过载加速度曲线,仿真结果表明:该方法能够实现超10000g后坐过载和超1000g离心过载的二维过载加载模拟。