铜锣山隧道岩溶浅埋段地表注浆试验研究

针对目前隧道地表注浆工程中出现的一些问题,以铜锣山隧道岩溶浅埋段K33 940～K34 035地表注浆为例,利用正交试验方法对3种注浆材料及36种浆液配比进行室内浆液试验研究,找到了适合于铜锣山隧道岩溶浅埋段地表注浆的注浆材料和合理的浆液配比。通过该试验得出:铜锣山隧道岩溶地区及裂隙较发育的地段,地表注浆压力应控制在1.0～1.5 MPa,注浆扩散半径约为1.0～1.5 m。同时也提出了压水试验、声波测试及取芯试验等多种注浆质量检测手段,进一步完善了隧道地表注浆的技术方法。     

汽车后背门外板面品问题的解决方法

在汽车冲压件开发过程中,外板如翼子板、门外板、机盖外板及后背门外板等是出现面品问题最多的外板制件。由于面品问题造成的返工率最高,是当前冲压件生产的瓶颈,需要在车型量产前将冲压件外板面品问题尽量全部解决,保证后序不再进行返工处理。文章主要针对后背门外板冲压生产过程中,车标的左右两侧不平的面品问题进行分析,找出原因．制定相应措施,利用8D分析法解决问题。     

轿车用发动机异响声分析及测试识别方法

轿车异响越来越成为用户关注的重点,发动机是轿车噪声的主要激励源之一。文章介绍了发动机常见噪声,并通过CAE分析,确定了噪声源。结合生产中的问题,借助CAE分析手段,排除了设计影响因素。通过测量分析发动机噪声的声谱特点,快速识别了发动机异响声部位,并结合发动机凸轮轴表面加工工艺偏差,找到了引起发动机异响的根本原因,指出该方法可以在产品开发和批量生产中,对发动机机械噪声进行快速测试识别,并指导发动机凸轮轴加工。     

磨削淬火技术的温度场仿真研究

目前对磨削淬火的研究,多采用实验的方法,通过大量的实验来制定合适的工艺参数,但由于磨削加工的复杂性,常使得实验研究带有一定的偶然性和盲目性.文中对影响磨削淬火工艺的关键因素——温度场,利用有限元方法进行了仿真研究,得到了磨削温度场的等温线图和工件各处的温度变化历程,预测了工件表层是否发生马氏体相变及相变层厚度,并进行了实验验证.研究表明,磨削淬火技术可以替代常规表面淬火工艺,利用磨削温度场仿真技术可以减少实验量、节省实验费用.     

Lengthscales of motions that control air–water gas transfer in grid-stirred turbulence

The relationship between the gas transfer velocity and turbulent lengthscales is investigated experimentally in a grid-stirred turbulent flow. The horizontal velocity field at the water surface is measured using particle image velocimetry (PIV). The gas transfer velocity for oxygen is obtained through reaeration experiments. In addition, the gas transfer process by surface-renewal eddies is visualized using laser-induced fluorescence (LIF) technique, in which carbon dioxide is used as the tracer gas. The definition of the Taylor microscale holds that the root-mean-square (RMS) of the surface divergence is expressed by the square root of the turbulent kinetic energy divided by the Taylor microscale. Experimentally obtained data support this scaling. They show the gas transfer velocity to be proportional to the square root of the RMS of the surface divergence. These experimental results imply that the Taylor microscale is an important parameter for gas transfer velocity at the air–water interface. These relations indicate that a nondimensional gas transfer velocity is proportional to the − 1/4 power of a turbulent-macroscale Reynolds number, which is similar to a small-eddy model, assuming that turbulent eddies with the Kolmogorov scale control the gas transfer process. However, this Reynolds number dependence does not necessarily mean the superiority of turbulent eddies with the Kolmogorov scale in the gas transfer. The LIF visualizations in horizontal and vertical planes close to the air–water interface indicate that the horizontal CO₂-concentration field has a fine spatial pattern, which resembles that of the surface divergence field, and that surface-renewal motions observed in the vertical plane have a larger lengthscale than the Kolmogorov scale. We infer from both PIV and LIF results that the Taylor microscale is an important lengthscale for air–water gas transfer.     

重要零件表面品质检测手段的提升和应用

在以批量生产为特征的汽车零部件行业,凸轮轴、万向节、轴承、气门和活塞销等重要零件的表面品质是产品质量的一项重要指标,但传统的测试方法却难以满足准确和快速检测的要求。文章对零件的表面品质及其惯用检测手段进行了描述,着重推出了一种新颖和高效的磨削烧伤检测方法——磁弹法。文章介绍了这种方法的工作原理,以及在这基础上研制的专用仪器的基本结构和组成,叙述了应用磁弹法时的评定特征值mp和仪器的定标,并通过所举实例予以说明。     

客车彩条喷涂的探讨

针对客车装饰彩条的图案纷繁复杂且颜色我样，面漆光泽度、硬度等漆面性能指标要求越来越高的情况，具体从涂装材料，工艺流程两方面对涂质量加以改进，提高了装饰彩条的喷涂设备。     

智能轮胎传感器技术研究现状

综述了国外智能轮胎传感器技术的研究现状,并指出了当前研究中应着重解决的问题和今后的发展趋势。     

Spectral signature of wave breaking in surface wave components of intermediate-length scale

This paper investigates the length scale of ocean surface breaking waves in the spectral range of intermediate wavelength components a few centimeters to a few meters long. The spectral properties of wave breaking are examined first with the dissipation function of the wave action density conservation equation. The analysis reveals a strong breaking signature in wave components between 0.15 and 1.5 m long in the form of a quasi-singular behavior of the dissipation function using the present formulation of the wind-generation and breaking dissipation functions. Independent studies of more-direct breaking observations of radar tracking of sea spikes in the past have shown close correlation between sea spikes and scatterers traveling at the speed of surface waves a few meters long and much shorter than the dominant wavelength. This feature of sea-spike properties is consistent with the breaking signature of the dissipation function in similar wavelengths. The intermediate-scale waves are the primary contributor of the ocean surface mean-square slope. The close correlation between the gas transfer rate and the mean-square slope has been demonstrated repeatedly. A better understanding of the wave dynamics of intermediate-scale waves is important for clarification of various gas transfer mechanisms.     

基于逆向工程的汽车覆盖件多点成型研究

以某轿车发动机罩为例,运用逆向工程技术快速重构了轿车发动机罩的三维曲面模型,在此基础上采用多点成型工艺进行了缩小模型的成型工艺试验.试验结果表明,采用该方法压制成型后的轿车发动机罩最大增厚与最大减薄均分布在边缘处,对零件的成型质量无影响;板料目标成型区域具有较好的表面质量,表面无明显压痕和起皱等不良现象.