田口方法下钢化玻璃的冲蚀性能及损伤形貌

根据内蒙古沙尘暴分布特点,采用田口正交方法,利用模拟风沙环境侵蚀实验系统,分析可控因素(冲蚀角度、冲蚀速度和沙流量)在冲蚀试验中的稳定性以及对钢化玻璃的冲蚀磨损性能的影响,并采用扫描电子显微镜(SEM)和激光共聚焦显微镜(LSCM)对冲蚀形貌进行分析。结果表明:冲蚀角度和冲蚀速度越大,信噪比越大,在冲蚀试验中数据越稳定,沙流量则相反;冲蚀角度对冲蚀率的贡献最大,其次是冲蚀速度,沙流量的贡献最小。低角度时,钢化玻璃的质量损失主要由切削作用引起,SEM图中可见明显的犁沟;而高角度时,钢化玻璃的质量损失则由裂纹叠加引起,SEM图中显示为脆性断裂凹坑。随着冲蚀角度的增大,钢化玻璃表面损伤区域的深度和宽度相应增加;损伤区域形状由长条形趋向于圆锥形。     

盐冻条件下水泥砂浆受风沙冲蚀磨损性能及损伤机制

通过气流挟沙喷射法对水泥砂浆进行了复合盐-冻融循环后气-固两相流冲蚀磨损试验研究。基于SEM、激光共聚焦显微镜（LSCM）和XRD,观测了水泥砂浆试件冲蚀磨损后表面微观形貌,分析了盐冻前后其表面化学成分,探究其冲蚀损伤机制。结果表明：相同冲蚀试验条件下,水泥砂浆试件冲蚀率随冲蚀角度的增加而增大,在高冲蚀角下的增长趋势较为缓慢;冲蚀率随复合盐-冻融循环次数的增加出现先减小后增大的趋势,在冻融10次时冲蚀率最小;同等条件下,8%浓度下的冲蚀率均大于10%浓度下的冲蚀率。冲蚀损伤过程中动能法向分量起决定性作用,明显特征表现为冲蚀坑和微破坏区的出现。复合盐-冻融循环对冲蚀磨损性能的影响主要体现在两个方面：物理方面,表现为降温过程中溶液过饱和晶体析出以及冰胀压和渗透压对内部孔隙的作用;化学方面,溶液中的阴离子与水泥砂浆发生化学反应,生成钙矾石和石膏晶体填充在水泥砂浆内部,提高了其致密性,但后期晶体压力的增大会促进裂缝的产生,对水泥砂浆抗冲蚀磨损能力产生不利影响。     

基于田口方法低温对乳化炸药性能的影响

针对炸药在低温条件下的稳定性不足,以乳化炸药为例,用低温爆速试验,采用田口方法来测试低温条件下乳化炸药的爆速,以寻找最优乳化剂的配比。为今后的乳化炸药的制备提供了理论基础。     

纤维增强橡胶砂浆抗冲击性能研究

使用PVA纤维来增强橡胶砂浆的抗冲击性能,通过落锤试验研究PVA纤维体积掺量、纤维长度对橡胶砂浆冲击性能的影响规律,并通过抗压、抗折试验探究PVA纤维掺入后对橡胶砂浆的力学强度影响。试验结果表明,纤维的掺入对试件抗冲击韧性性能改善效果显著。橡胶等体积替代10%细集料时,9 mm PVA纤掺量为0.10%增强效果最佳,抗压强度、抗折强度出现峰值,冲击韧性提升明显。     

基于田口方法的小批量生产过程控制

针对传统过程控制方法在小批量生产领域面临的样本量不足而导致的统计特性减弱的困境,运用田口式反馈控制技术对某军品关键件生产过程建立起质量损失函数,计算出了最优过程控制方案,并绘制田口式反馈控制图进行监控.计算结果表明,过程控制成本有显著降低,过程能力显著提高.     

基于田口分析的烟包偏好评价方法

目的通过包装设计实现科学禁烟控烟需要掌握香烟包装设计与吸烟者对香烟偏好程度之间的联系,提出一种基于田口分析的烟包评价方法。方法对烟包的关键要素进行分割,确定主要控制参数,对烟包主要控制参数进行实验评价,建立偏好程度与参数间的田口模型。结果针对市场上主流香烟包装的形态、色彩、图案进行综合分析,确定吸烟者偏好的包装方案。结论在烟包要素分割明确的前提下,田口方法能够有效地评价吸烟者对各类烟包的反应,相关研究可以为香烟销售调控、禁烟控烟执行提供有效的技术手段与分析方法。     

基于田口方法的多质量特性优化研究

基于田口方法提出了一种解决多质量特性参数设计的优化方案.首先以判断矩阵确定各单质量特性在综合质量特性中的权重,利用统计线性回归得到单个质量特性满意值及综合质量满意值与可控制因素的关系式.然后基于模糊理论,构造了模糊目标规划模型,并提出了解决该目标规划模型的有效方法,使得单个质量特性达到设定的最低要求的同时,实现多质量特性达到最优.实例分析结果表明.这种优化方法优于单质量特性的变化.     

基于田口方法的柔性铰链柔度稳健优化设计

柔顺机构柔度稳健性是柔性机构在微机电系统与精密工程等领域广泛应用的前提和基础,但在实际工程中传统设计方法未充分考虑其稳健性.引入田口稳健优化设计方法,选取柔性铰链各结构参数为可控因素,工作载荷为噪声因子,通过正交试验数据分析得出各个可控因素的信噪比和贡献率,进而选出最佳的参数水平组合,并对柔度综合稳健性能的最优方案进行了验证.算例表明,采用田口稳健优化设计的柔性铰链柔度稳健性比传统方法信噪比水平提高了4.68dB,降低了其质量损失,实现了柔性铰链柔度稳定性优化.田口稳健优化设计方法具有普适性,在实际工程应用中具有较高参考价值.     

基于田口方法的智能电能表选择性波峰焊参数优化

<正>为了降低插件印制板经过选择性波峰焊时产生锡渣锡珠的不良率,减少不良品的产生,提高公司效益,需要优化智能电能表选择性波峰焊工艺参数组合。故笔者在本文设计中尝试将田口方法与选择性波峰焊参数优化相结合,以期快速、高效实现工序能力、经济效益的提升。     

基于田口方法推导仪器的测量不确定度

目前,无论是国家或行业发布的校准规范,还是仪器生产商提供的校准方法,对于仪器众多的校准项目,只能要求对其典型点进行多次测量,求出算术平均值和实验标准偏差,从而求出测量不确定度.但很难给出测量范围内任一点的测量不确定度,而在仪器的实际使用过程中,往往需要知道非典型点的不确定度,如果能从这些典型点的数据推断出全量程任一点的测量数据,即求解出校准公式,就不仅能满足各类用户的需要,还能大大节省仪器校准成本,田口方法就很好地解决了仪器校准过程中的这一难题.     

基于田口方法齿圈压板精冲模具参数优化

在精密冲裁过程中,精冲模具结构参数和板料的摩擦系数显著影响精冲剪切面质量.采用有限元模拟和田口方法,对齿圈压板精冲模具精冲H62黄铜板料过程中凹模圆角半径、V形齿齿高、V形齿齿边距和板料摩擦系数对剪切面撕裂比的影响进行了研究.结果表明:参数按照减小撕裂比能力由大到小排序依次是凹模圆角半径,V形齿齿高,板料-模具摩擦系数和V形齿齿边距.研究发现:采用优化参数可显著减小剪切面上撕裂比,撕裂比最大减小24.8%,并可抑制凹模刃口附近微裂纹萌生,使剪切带内裂纹由凸模单向扩展至凹模刃口,避免裂纹的双向扩展-贯通导致较大撕裂比剪切面的出现.     

Application of Taguchi method on optimization of testing parameters for erosion of glass fiber reinforced epoxy composite materials

The target of this experimental study is to investigate solid particle erosion behavior of a new composite material formed by adding boric acid particles to glass fibers and epoxy resin at an amount of 15% and 30%. The tests which involved angular aluminum particles with two different sizes were conducted at different conditions of impact velocities, fiber directions and impingement angles. The test specimens were characterized by techniques of X-ray diffraction (XRD) and scanning electron microscope (SEM). In addition, the design of the experiments which utilizes Taguchi’s orthogonal arrays approach was used and an optimal parameter combination determined which led to minimization of erosion rate of the composites.     

橡胶粉改性水泥沥青砂浆的研究

采用橡胶粉改性水泥沥青(CA)砂浆,并对其力学性能进行了重点测试。结果表明,随着橡胶粉替加入量的增加,CA砂浆早期强度呈减小趋势,但28天强度则相反;抗压强度均随温度的升高而减小,且随加载速率的增大而增大;橡胶粉越多,CA砂浆对温度的敏感性降低,且加载速率对其抗压强度的影响减小。     

Study on well hard shut-in experiment based on similarity principle and erosion of ram rubber

Using shut-in procedures is one of the oil-well-control measures to curtail kicks and prevent a blowout from occurring. Shut-in procedures are the specific procedures for closing a well in the case of a kick. If the well is not shut-in immediately after a kick is observed then a blowout will very likely happen. There are generally two types of shut-in procedures, which are soft shut-in and hard shut-in. Of these two methods, the hard shut-in is the fastest method to shut in the well; therefore, it will minimize the volume of kick allowed into the wellbore. The drawback of the hard shut-in is that it may result in the water hammer pressure on the capping hookup to increase and therefore damage the BOP (blowout preventer). In this work two devices were designed, one is for testing the water hammer pressure, and the other is for assessing the damage to the BOP caused by the hard shut-in. The experiments show that a hard shut-in can shut the well in a very short time, but it can cause obvious water hammer damage. By simulating the gas drilling process, it can be seen that the hard shut-in also causes obvious damage to the ram rubber of the BOP, which will reduce the seal reliability and may cause potential accidents.     

橡胶对水泥基材料干燥收缩性能的影响

为了考察橡胶增加水泥基材料干燥收缩量的机制,以橡胶水泥砂浆作为研究对象,采用毛细管张力理论分析了造成水泥砂浆干燥收缩的因素。使用压汞试验研究橡胶/水泥砂浆的孔结构,并进行了弹性模量和干燥收缩试验。研究结果表明,橡胶掺入会降低水泥砂浆的弹性模量,增加其孔隙率和干燥收缩量,且相同掺量条件下,小粒径橡胶的作用效果更明显。基于试验数据,考虑橡胶掺入对砂浆弹性模量的折减系数KE和橡胶掺入对毛细孔(孔径50nm的孔隙)数量的增加系数K_h,拟合了橡胶对水泥砂浆干燥收缩的影响参数δ_(mr)。     

Effects of partial oxidation of crumb rubber on properties of rubberized mortar

It is a generally accepted result that the inclusion of rubber particles causes the concrete to degrade physical properties of the concrete. In this study the crumb rubber was partially oxidized and used as additives of mortars. Dramatically, the compressive strength of the rubberized mortars (with 6 wt.%) was greater than that of mortars without the crumb rubber. To understand these phenomena, Fourier Transform Infrared Spectroscopy (FTIR) was used to explore the functional groups on surfaces of the crumb rubber, and Scanning Electron Microscopy (SEM) was used to observe microstructures of mortars. With the partial oxidation treatment, rubber surfaces produced hydrophilic functional groups as indicated by IR spectra and the hydration of the cement near the crumb rubber was enhanced as shown by SEM, leading to stronger mortars.     

Optimization of counter flow Ranque–Hilsch vortex tube performance using Taguchi method

This study discusses the application of Taguchi method in assessing maximum temperature gradient for the Ranque–Hilsch counter flow vortex tube performance. The experiments were planned based on Taguchi's L27 orthogonal array with each trial performed under different conditions of inlet pressure, nozzle number and fluid type. Signal-to-noise ratio (S/N) analysis, analysis of variance (ANOVA) and regression analysis were carried out in order to determine the effects of process parameters and optimal factor settings. Finally, confirmation tests verified that Taguchi method achieved optimization of counter flow Ranque–Hilsch vortex tube performance with sufficient accuracy.     

The effect of impact velocity and target thickness on ballistic performance of layered plates using Taguchi method

This paper presents the effect of test parameters such as Impact velocity, configuration and target thickness on ballistic performance of weldox steel plates against 7.62 mm APM2 projectile using Taguchi method. Trials were planned using an L 18 orthogonal array with 18 combinations of test variables to assess the influence of various factors. Numerical simulations have been carried out using Ansys Autodyn code with the above three process variables. Failure mechanisms of target plates of various single and multi-layered configurations were also discussed. Most portion of the kinetic energy of the projectile was expended in plastic deformation of the target material before perforation due to better bending stiffness of the target plate. Results showed that target thickness and impact velocity were the significant variables on residual velocity. Layer configuration was found to be insignificant relating to ballistic performance. Significant interaction is observed between impact velocity and target thickness from interaction plots. Simulated and experimental results showed good agreement with each other.     

Frictionless 2D Contact formulations for finite deformations based on the mortar method

In this paper two different finite element formulations for frictionless large deformation contact problems with non-matching meshes are presented. Both are based on the mortar method. The first formulation introduces the contact constraints via Lagrange multipliers, the other employs the penalty method. Both formulations differ in size and the way of fulfilling the contact constraints, thus different strategies to determine the permanently changing contact area are required. Starting from the contact potential energy, the variational formulation, the linearization and finally the matrix formulation of both methods are derived. In combination with different contact detection methods the global solution algorithm is applied to different two-dimensional examples.