禽蛋在输送支撑辊上倾角影响因素的理论分析与试验验证

为了阐明禽蛋在输送支撑辊上轴向运动的机理,运用力学原理和几何关系对禽蛋在水平面和两平行等径支撑辊子上平衡时长轴径倾角变化,以及不同辊子直径和辊间中心距对倾角的影响进行了理论分析,并进行了试验验证。揭示了均质蛋形体在平面、两平行等径支撑辊子上平衡时,存在一个"平衡接触圆"且是唯一的,而禽蛋是一个近似"平衡接触圆";建立了不同支撑条件下平衡时"平衡接触圆"倾角分析方法,以及支撑方式和支撑结构参数与倾角的关系;均质蛋形体和禽蛋在平面上平衡时的倾角小于在两平行等径支撑辊子上平衡时的倾角;均质蛋形体和禽蛋在两平行等径支撑辊子上平衡时,倾角与支撑辊子直径(25～50mm)呈线性负相关关系,与支撑辊子中心距(47～67mm)呈线性正相关关系;在相同支撑条件下,倾角取决于禽蛋品种及其长轴径、短轴径、质量和体积等基本特征参数。用"平衡接触圆"法分析不同支撑条件下倾角是准确的、可行的,为分析禽蛋在输送支撑辊上轴向运动提供参考。

偏心螺旋传动

提出一种新型的螺旋传动———偏心螺旋传动 ,该传动结构简单 ,成本低 ,传动效率较高 ,能够将快速旋转运动转换为慢速直线运动 ,实现大减速比传动 。

Loaded multi-tooth contact analysis and calculation for contact stress of face-gear drive with spur involute pinion

The analytical method based on "Hertz theory on normal contact of elastic solids" and the numerical method based on finite element method (FEM) calculating the contact stress of face-gear drive with spur involute pinion were introduced, and their relative errors are below 10%, except edge contact, which turns out that these two methods can compute contact stress of face-gear drive correctly and effectively. An agreement of the localized bearing contact stress is gotten for these two methods, making sure that the calculation results of FEM are reliable. The loaded meshing simulations of multi-tooth FEM model were developed, and the determination of the transmission error and the maximal load distribution factor of face-gear drive under torques were given. A formula for the maximal load distribution factor was proposed. By introducing the maximal load distribution factor in multi-tooth contact zone, a method for calculating the maximal contact stress in multi-tooth contact can be given. Compared to FEM, the results of these formulae are proved to be reliable, and the relative errors are below 10%.

Tooth surface geometry optimization of spiral bevel and hypoid gears generated by duplex helical method with circular profile blade

In order to effectively improve meshing performance of spiral bevel and hypoid gears generated by the duplex helical method, the effects of straight lined and circular cutting edges profile on meshing and contact of spiral bevel and hypoid gears were investigated analytically. Firstly, a mathematical model of spiral bevel and hypoid gears with circular blade profile was established according to the cutting characteristics of the duplex helical method. Based on a hypoid gear drive, the tooth bearings and the functions of transmission errors of four design cases were analyzed respectively by the use of the tooth contact analysis(TCA), and the contact stresses of the four design cases were analyzed and compared using simulation software. Finally, the curvature radius of the circular profile blade was optimized. The results show that the contact stresses are availably reduced, and the areas of edge contact and severe contact stresses can be avoided by selecting appropriate circular blade profile. In addition, the convex and concave sides are separately modified by the use of different curvature radii of inside and outside blades, which can increase the flexibility of the duplex helical method.

Numerical Analysis of the Interaction between Shallow （Square, Circular and Strip） Foundations and Subsoil

In this paper, the effects of the stiffness of circular, square and strip foundation structures and bonding effects were analyzed. Presented analysis was oriented on the influence of stiffness system ＂foundation--subsoil＂ and bonds （bi-directional bond and one-directional bond with and without friction）. The results of numerical calculations have proved that the relative stiffness of system ＂foundation--subsoil＂ affect considerably the value and the distribution of contact stresses （vertical normal and shear stresses） in the foundation gap and value of the displacements （settlement, deflection and relative deformations） of foundation. From the numerical point of view, this problem was solved by deformation variant of the FEM （finite element method）. The numerically obtained results were presented in the graphical and tabular forms. Obtained results were qualitative and quantitative compared with one another. From the calculation results it is obvious that relative stiffness of the system ＂foundation structure--subsoil＂ substantially affects distribution of contact stresses in the foundation subsoil and displacements （settlement, deflection and relative deformations, flexibility） of foundation. In the case of flexible foundations, the bond on the contact surfaces must be considered during the calculation. On the other hand, the effects of friction on the contact surface between the foundation and subsoil affect the distribution of contact stresses and deformations only to smaller extent.

The effect of surface anisotropy on contact angles and the characterization of elliptical cap droplets

In this paper, the variation of contact angles of a droplet on grooved surfaces was studied from microscale to macroscale experimentally and theoretically. The experimental results indicated that the contact angle changes nonlinearly with anisotropic factor. To get clear of the changing process of contact angle on grooved surfaces from microscale to macroscale, we carried out theoretical analysis with moment equilibrium method being adopted. In addition, the variation of contact angles in different directions was investigated and a mathematic model to calculate arbitrary contact angles around the elliptic contact line was suggested. For the convenience of potential applications, a symbolic contact angle was proposed to characterize the ellipsoidal cap droplet on grooved surfaces. Our results will offer help to the future design of patterned surfaces in practical applications,and deepen the understanding of wetting behavior on grooved surfaces.

Relationship between Quality and Attributes of Elliptical Spot Welds of High Strength Steel

More high strength steel （HSS） sheets are being applied in the automobile industry to improve safety and fuel efficiency. When HSS is spot welded, the strength of the welded-joint is usually determined by the attributes of the weld nugget. However, it is difficult to obtain the circular nugget and to establish the relationship between the weld attributes and welding quality because of a large number of variables and experimental uncertainty. In the paper, the numerical analysis model of tensile-shear strength test for HSS spot welds was established. And the critical ellipticity of the elliptical spot weld was determined through finite element analysis. Quantitative relationship between elliptical weld attributes and weld strength was investigated statistically using the Latin hypercube and regression analysis method. The sheet thickness, nugget eUipticity, hardness radio and yield strength have the most influential attributes in affecting welding quality. The research results can be used as a guideline for HSS resistance spot welding design.