响应面法模拟轴肩和搅拌针形状对铝合金搅拌摩擦的影响(英文)

The present paper discusses the modeling of tool geometry effects on the friction stir aluminum welds using response surface methodology. The friction stir welding tools were designed with different shoulder and tool probe geometries based on a design matrix. The matrix for the tool designing was made for three types of tools, based on three types of probes, with three levels each for defining the shoulder surface type and probe profile geometries. Then, the effects of tool shoulder and probe geometries on friction stirred aluminum welds were experimentally investigated with respect to weld strength, weld cross section area, grain size of weld and grain size of thermo-mechanically affected zone. These effects were modeled using multiple and response surface regression analysis. The response surface regression modeling were found to be appropriate for defining the friction stir weldment characteristics.     

有限水深中垂直下潜弹性薄板的水波散射(英文)

The problem of water wave scattering by a thin vertical elastic plate submerged in uniform finite depth water is investigated here.The boundary condition on the elastic plate is derived from the Bernoulli-Euler equation of motion satisfied by the plate.Using the Green’s function technique,from this boundary condition,the normal velocity of the plate is expressed in terms of the difference between the velocity potentials(unknown)across the plate.The two ends of the plate are either clamped or free.The reflection and transmission coefficients are obtained in terms of the integrals’involving combinations of the unknown velocity potential on the two sides of the plate,which satisfy three simultaneous integral equations and are solved numerically.These coefficients are computed numerically for various values of different parameters and depicted graphically against the wave number in a number of figures.     

BMW公司新型4缸2.0 L增压直接喷射汽油机

BMW公司开发了一种新型2.0L 4缸涡轮增压直接喷射汽油机,旨在明显降低燃油耗的同时,进一步提高行驶动力性能和驾驶乐趣,使其成为高效动力学经营战略的另一个重要组成部分。将来,该机型计划被配装在BMW公司几乎所有车型上。     

马自达公司的新型Skyactiv-G汽油机

马自达汽车公司为新一代汽车开发了命名为"Skyactiv"的新技术,该技术将汽车的驾驶乐趣与环保性和可靠性相结合,对马自达汽车公司长期的技术开发规划作出了贡献。介绍一种压缩比高达14.0的新型高效缸内直接喷射汽油机的开发。     

瑞士联邦铁路Am 843型内燃机车

瑞士联邦铁路的干线铁路网几乎完全实现了电气化,所以内燃机车主要用于专用线牵引和调车作业。文中介绍该铁路新订购的Am 843型内燃机车的设计、结构特点,性能和主要技术参数。     

流体动力的研究改进

加拿大萨斯喀彻温大学的工程师们研制出一种旋转式电液流量控制阀。萨斯喀彻温大学的二位工程师研制出一种造价便宜的旋转式电液流量控制阀(图1和图     

新型货车的五个要素

正 新型货车需要有五个要素:易装、易卸、安全、容积大、可靠。 1963年新設备的另一个特点是采用单向一次作业专一用途的車辆(一个方向运货,另一个方向回空),铁路傳統习慣所采用的双向二次作业通用車辆的概念,随着运量的急剧上升在60年代初期,已消