共查询到19条相似文献,搜索用时 73 毫秒
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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。 相似文献
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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。 相似文献
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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. 相似文献
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基于田口方法的多质量特性优化研究 总被引:2,自引:0,他引:2
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. 相似文献
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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. 相似文献
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<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。 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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. 相似文献
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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)。 相似文献
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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. 相似文献
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Ahmet Murat Pinar Onuralp Uluer Volkan Krmaci 《International Journal of Refrigeration》2009,32(6):1487-1494
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. 相似文献
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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. 相似文献
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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. 相似文献