Optimization of mechanical properties of recycled plastic products via optimal processing parameters using the Taguchi method

The large amount of plastic products presently produced necessitates recycling and reuse of these non-biodegradable materials. However, the degradation in the mechanical properties of products made from recycled plastic is a major drawback that limits their use. This study aims to improve the mechanical properties of products made from recycled plastic by utilizing the Taguchi optimization method, instead of coupling the products with additives. By adopting L₉ Taguchi OA, products made from various compositions of virgin and recycled plastic are produced by injection moulding. Four controllable factors (i.e., melt temperature, packing pressure, injection time, and packing time), each at three levels, are tested to determine the optimal combination of factors and levels in the manufacturing process. By determining the optimal combination of factors and levels, the appropriate blending ratio of virgin and recycled plastic can be evaluated from the mechanical performance exhibited by the compound. The effects of the optimal processing parameters and the addition of recycled plastic in various compositions on the mechanical properties and melt flow index of the produced parts are also investigated. The results reveal that the product made of 25% recycled polypropylene (PP) and 75% virgin PP exhibits a better flexural modulus compared to the virgin form. The same product exhibits a 3.4% decrease in flexural strength. The degradation in mechanical properties of products produced from recycled plastic can be improved by optimizing the influence processing parameters during the manufacturing process.     

Process parameters optimization for friction stir welding of RDE-40 aluminium alloy using Taguchi technique

Taguchi approach was applied to determine the most influential control factors which will yield better tensile strength of the joints of friction stir welded RDE-40 aluminium alloy. In order to evaluate the effect of process parameters such as tool rotational speed, traverse speed and axial force on tensile strength of friction stir welded RDE-40 aluminium alloy, Taguchi parametric design and optimization approach was used. Through the Taguchi parametric design approach, the optimum levels of process parameters were determined. The results indicate that the rotational speed, welding speed and axial force are the significant parameters in deciding the tensile strength of the joint. The predicted optimal value of tensile strength of friction stir welded RDE-40 aluminium alloy is 303 MPa. The results were confirmed by further experiments.     

Taguchi统计学分析方法优化Al 7068-TiC纳米复合材料的凝固行为

采用机械合金化和热压工艺制备高强Al 7068?5%TiC(质量分数)纳米复合材料。基于致密化的重要性和晶粒生长的影响,以获得较高抗压强度为目标,采用Taguchi统计法对制备Al 7068?5%TiC块体纳米复合材料的热压条件进行优化。结果表明：在500 MPa和385°C下热压30 min能获得抗压强度为938 MPa、硬度为HV 265的Al 7068?TiC纳米复合材料。此外,方差分析结果表明,外加压力是影响纳米复合材料热压过程最关键的因素。各因素对纳米复合材料热压过程影响贡献率为外加压力(61.3%)、热压温度(29.53%)和热压时间(4.49%)。     

基于Taguchi的水壶塑件注射工艺参数优化

以水壶塑件为研究对象,应用Moldflow有限元分析软件,针对塑件质量缺陷或问题产生的原因,合理设计了模具浇注系统和温度调节系统。以翘曲变形量作为质量指标,采用多因素Taguchi法,获得了塑料在熔料温度、模具温度、保压压力、保压时间、冷却时间五因素四水平下成型塑件的翘曲变形量。采用方差分析法比较了不同工艺参数对翘曲变形量的影响程度,得到了优化的工艺参数组合。     

Waveform based clustering and classification of AE transients in composite laminates using principal component analysis

Acoustic emission (AE) transients in composite laminate tensile test specimens are analyzed by principal component analysis (PCA). Signals resulting from matrix cracking and local delaminations were acquired by broadband transducers. The aim was to study the clustering and classification ability of PCA based on the time history of the recorded AE events. An unsupervised clustering analysis showed that AE signatures from matrix cracking and local delaminations were separated in different clusters. Some differentiations within these two types of signals were also observed. From the classification based on a training set, a majority of the signals in the test set were given the correct class membership. The applied pattern recognition method is an objective method using the complete information in the AE transients and the investigation shows that it may be a useful complement in the field of non-destructive evaluation.     

《搅拌摩擦加工制备GNPs/Al复合材料的微观结构与力学性能》

本文以纯铝为基体,利用搅拌摩擦加工(FSP)制备GNPs/Al复合材料,研究了复合材料基体组织、增强相与界面等微观结构与力学性能,探讨了其增强机理。结果表明,添加GNPs并经FSP后复合材料基体晶粒得到明显细化且晶界由小角度为主转变为大角度为主;FSP制备过程致使GNPs片层一定程度剥离的同时,较大片径的GNPs被破碎而形成众多边缘缺陷,使其易发生Al-C原子扩散,结果在GNPs边缘与基体形成界面过渡;GNPs加入量约1.8vol%时,复合材料的屈服强度和抗拉强度达到72MPa和147MPa,较同等条件FSP的基体分别提高了89.5%和79.3%,理论计算界面载荷传递、Orowan和细晶强化依次是复合材料的主要增强机制;随着GNPs加入量的增加,复合材料屈服强度实验值与理论值的增长趋势一致,且偏差也略有提高,但可能因GNPs在复合材料中的杂乱排布,界面载荷传递强化不能充分发挥,实际的复合材料屈服强度与理论值尚有差距。     

Taguchi optimization in drilling of AISI 316L stainless steel to minimize burr size using multi-performance objective based on membership function

Burr in drilling plays an important role on product quality and hence it is essential to minimize the burr size at the production stage. This paper presents the application of Taguchi optimization method for simultaneous minimization of burr height and burr thickness influenced by cutting conditions and drill geometry. The approach of Taguchi design for drilling optimization problem is based on multi-performance objective, which employs the membership functions. In the present work, optimal values of cutting speed, feed, point angle and lip clearance angle are determined for selected drill diameter values to minimize burr height and burr thickness during drilling of AISI 316L stainless steel workpieces. The effectiveness of the proposed approach is demonstrated through simulation results and experimental verifications.     

U盘上盖的翘曲变形分析与工艺参数优化

以U盘上盖的注塑成型为实例,运用Taguchi试验设计法,结合信噪比(S/N)和变量分析方法(ANOVA),以减少塑件的翘曲量为目的,研究熔体温度、模具温度、保压压力和保压时间等工艺参数对塑件翘曲的影响,分析各工艺参数的影响程度,并优化成型工艺。结果表明:保压压力、熔体温度对塑件翘曲变形影响最大,优化后的塑件翘曲量降低了约16%。     

Research on edge identification of a defect using pulsed eddy current based on principal component analysis

It is difficult to identify the edge of a defect in nondestructive testing (NDT), which affects the result of a C-scan image acquired by arrays of pulsed eddy current sensors (APECS). To overcome the problem of low accuracy in identification of the edge of a defect using the conventional eddy current techniques, which only extract features in time domain, features from pulsed eddy current that has a broadband frequency are extracted both in time and frequency domains. A method based on principal component analysis (PCA) is proposed to enhance the accuracy in identification of the edge of a defect, the agreement between theory and experiment shows that the proposed method is applicable and preferable to APECS.     

主成分分析法在脉冲涡流缺陷识别中的应用

在钢结构脉冲涡流缺陷识别中,通常采用信号的峰值幅度、过零时间、主峰面积等特征参数对缺陷进行表征。但上述参数相互关联,存在一定的信息冗余,增加了数据分析量及信息筛选难度,进而影响了缺陷识别的效率。针对上述问题,采用主成分分析法对脉冲涡流信号的6个特征参数进行降维处理,构造了一个主成分特征,减少了信息冗余;将上述主成分特征输入Logistic分类器,实现了对钢结构减薄缺陷的准确识别。结果表明:主成分分析法可以在确保缺陷识别准确率的情况下,有效减少分类器处理的数据量,提高缺陷识别效率。     

Application of artificial neural network and Taguchi method to preform design in metal forming considering workability

This study describes a new method of perform design in muti-stage metal forming processes considering workability limited by ductile fracture. The finite element simulation combined with ductile fracture criterion has been performed in order to predict ductile fracture. The artificial neural network using the Taguchi method has been implemented for minimizing objective functions relevant to the forming process. The combinations of design parameters used in finite element simulation are selected by orthogonal array in statistical design of experiments. The orthogonal array and the result of simulation are used as train data for artificial neural networks. The cold heading process is taken as an example of designing preforms which do not form any fracture in the finished product. The results of analysis to validate the proposed design method are presented.     

Measurement of residual stresses in dissimilar friction stir-welded aluminium and copper plates using the contour method

The longitudinal residual stresses in the friction stir-welded plates of 5A06 aluminium and pure copper were determined using the contour method. The results revealed the presence of high tensile and compressive residual stresses on the aluminium and copper sides, respectively. The residual stresses were detected on the weld zone as well as the thermo-mechanically affected zone (TMAZ) of the aluminium plate. In contrast, the compressive residual stresses in the copper plate had a much narrower width along the weld line. Peak tensile stresses up to 240?MPa were found in the TMAZ of the aluminium plate.     

Optimization of a roller levelling process for Al7001T9 pipes with finite element analysis and Taguchi method

This paper is concerned with the optimization of process parameters for a roller leveller that is an indispensable piece of equipment to eliminate the undesirable curvature of a thin-walled aluminum pipe. Optimization of process parameters has been carried out for a multi-staggered-type 14-roller leveller. A finite element model of a multi-staggered 14-roller leveller was constructed for numerical analysis. The analysis is carried out with the fractional model and the Taguchi method for evaluation of the effect of process parameters such as the intermesh and the slanted angle of rollers. The response variable is set to the plastic strain along the pipe length. The optimum combination of process parameters is determined from the numerical result and confirmed by experiments. The comparison of the numerical result with the experimental one shows good coincidence for its validity and reliability.     

Microstructure and properties in friction stir weld of 12Cr steel

Friction stir welding was employed for joining of 12Cr heat resistant ferritic steel. Microstructure and mechanical properties in the obtained welds were examined and their relationship was established. The stir zone microstructure was found to consist of quenched martensite with numerous fine dispersoids uniformly distributed in grain interiors. The formation of this microstructure remarkably strengthened the stir zone. Tempering for 3·6 ks at 923 K reduced the as welded hardness of friction stir weld to nearly base material level.     

Effect of reprocessing on shrinkage and mechanical properties of ABS and investigating the proper blend of virgin and recycled ABS in injection molding

In this research, the effect of reprocessing of acrylonitrile–butadiene–styrene (ABS) on the mechanical properties of the polymer was studied through a five-stage reprocessing. To this end, the injection mold of the standard samples was manufactured. Then, using an injection molding machine, all of the virgin material was processed. After sampling, the rest of the parts were ground and then reprocessed under the same conditions. In order to get a proper combinational ratio of virgin and recycled ABS with respect to shrinkage and mechanical properties, another experiment was designed. In order to do this, virgin material was blended with 20%, 35% and 50% of the recycled material. The blends were reprocessed and samples were obtained. Impact, tensile, flexural and shrinkage tests, selected from ASTM standard, were used to investigate the mechanical properties of the polymer as well as its shrinkage. Furthermore, viscosity test was used to investigate the changes in the structure of the polymer. As the reprocessing cycles increased, shrinkage decreased and tensile and flexural ultimate strengths increased, more in flexural strength than in tensile. While Young's modulus slightly increased, viscosity decreased and consequently molecular weight decreased too. The proper blend for the least shrinkage was 50% whereas the best mechanical properties were achievable by the 20% blend. The obtained results suggest that reprocessing causes polymer degradation which is a result of the break in the bonds of poly butadiene. Moreover, it can be concluded that reprocessing in ABS can lead to the loss of effectiveness of some additives.     

神经网络与正交试验法结合优化注射工艺参数

结合人工神经网络所表现出来的良好特性,利用正交试验获得的数据作为神经网络的训练样本,建立输入为工艺参数、输出为翘曲变形量的神经网络模型,并通过样本检验了ANN模型的准确性,从而缩短设定工艺参数的时间,在工艺参数取值范围内,采用ANN模型代替CAE软件模拟试验,结合正交试验法,对工艺参数进一步优化。结果表明:将神经网络与正交试验、数值模拟三者结合用于注射过程参数优化可以缩短优化工艺参数的时间,提高工艺设计效率,并能获得比单纯使用正交试验和数值模拟方法更为优化的结果。     

翻钢机对中体的受力分析及优化设计

某钢厂检查生产线上的翻钢机在翻转钢卷过程中,当钢卷宽度中心超过对中体中心时,钢卷发生明显偏转,容易出现钢卷翻落的危险。运用SolidWorks有限元法对极限工况下的对中体进行应力、变形分析,发现对中体刚性不足。本文提出了相应的优化设计方案,取得了良好的效果,保证了生产的正常进行。     

基于有限元法的六面顶压机顶锤应力分析及结构优化

六面顶压机硬质合金顶锤的应力分析和结构优化,是提高顶锤设计寿命的重要手段之一。首先,运用有限元(FEM)分析方法和弹性力学知识,结合ANSYS有限元分析软件,计算出硬质合金顶锤的最大应力及其位置;其次,初步分析了最大应力出现在正方形顶面与41.5°小锥面相交处的原因;然后,提出了双倒角顶锤设想,并进行了仿真计算,得出了双倒角顶锤比目前顶锤更优的结论;最后,通过模拟分析不同结构参数下的最大应力,提出了结构参数优化的思路。     

Residual stress analysis in thermally sprayed layer composites,using the hole milling and drilling method

Residual stresses are related to the thermophysical properties of substrate and coating materials and occur after the coated component has undergone thermal spraying and machining processes. All residual stresses in layer composites result from different individual stress mechanisms occurring during the manufacturing process, mainly based on heat and mass transfer during the coating deposition. Using the hole-milling-and-drilling method, residual stress fields can be measured in a quasi-nondestructive way over the drilling depth with appropriate resolution. In several drilling and milling operations, a cylindrically shaped hole is brought step by step into the component surface. The residual stresses are locally relieved due to material removal, deform the surface around the drilled microhole, and are measured by high-resolution measurement tools (e.g., strain gages (DMS)), for every drilling step in the form of relaxed surface strains. Using calibration curves and material data (E, μ), the measured surface strains are converted into nominal strains at the bottom of the drilled hole for every drilling step. Out of the differentiated strains, in-plane stress fields can be incrementally determined by Hooke’s law. This study describes residual stress measurement features, the finite-element method (FEM) calculation, and the idealization of calibration curves, as well as the results of exemplary stress measurements. The original version of this article was published as part of the ASM Proceedings, Thermal Spray 2003: Advancing the Science and Applying the Technology, International Thermal Spray Conference (Orlando, FL), May 5–8, 2003, Basil R. Marple and Christian Moreau, Ed., ASM International, 2003.