振动时效机理研究及其工艺参数选择

从宏观和微观两个角度分析振动过程中残余应力的变化,阐述了振动消除残余应力的机理。从宏观上讲,当残余应力与外加动应力叠加大于材料屈服极限时发生塑性变形,残余应力会得到释放;从微观上讲,在外力作用下位错塞积开通的运动可以降低、均化残余应力峰值。同时,提出了检测残余应力和振动参数选择的方法。     

振动时效不可盲目采用全自动时效方式

振动时效工艺已广泛应用于焊接件、铸件、锻件、机加工件的去应力工序。但目前国内很多工艺人员不考虑工件的时效要求、需时效的部位和时效动应力的大小等具体特点,滥用全自动工艺。这是一种极端盲目、极端错误的做法,它将为工件的后     

基于有限元法的重大焊接结构振动时效工艺参数研究

依据行业标准,采用有限元方法对水轮机座环进行了动力学分析.给出了座环前4阶固有频率、振型和振幅频率曲线,并得到了振动时效减小座环上对接焊缝残余应力的重要工艺参数.该研究方法和结论为大型座环及其它重大焊接构件振动时效工艺参数确定提供了有价值的参考意见和理论依据.     

振动时效工艺应用探讨

残余应力是影响机床尺寸精度稳定性的关键因素之一，经10年的试验应用表明，振动时效是消除、均化残余应力的有效方法，该方法简单，不受工件形状、重量限制，无环境污染，生产效果明显。     

振动时效动应力参数选取的探讨

这里根据非对称循环载荷下的古得曼(Goodman)应力范围图,分析了在不同初始残余应力(平均应力)前提下,构件振动时效时动应力的选取应满足的条件。使当前普遍被认可的动应力参数选取原则(σ动 σ残Eσs;σ动Fσ-1)更加具体可操作化,并对其进行了修正。     

焊接件振动时效工艺

本语言采用振动时效工艺，对焊接件进行了工艺性试验，并详细叙述了７１５５／Ａ支架振动时效处理的工艺过程。     

振动时效技术在大型结构件上的应用

以振动时效技术在大型结构构件上的应用为例,从振动时效的机理、应用方法、检测结果等方面,介绍了振动时效技术代替热时效技术的优势与潜力。     

振动时效技术在大型结构件上的应用

以振动时效技术在大型结构件上的应用为例,从振动时效的机理、应用方法、检测结果等方面,介绍了振动时效技术代替热时效技术的优势与潜力。     

振动时效的机理工艺与设备

介绍振动时效技术的特点和机理 ,分析在振动时效工艺方案确定和参数选择等方面的有关问题。介绍国内外振动时效设备的基本情况     

Numerical study on determining design parameters of wheeled armored vehicles

The survivability of the crew is the most important factor to be considered when designing the body of a military combat vehicle, and the design must protect against armor-piercing projectiles and mine blasts, in order to enhance survivability. In this paper, we propose a numerical approach that can be used in the initial design stage when designing military combat vehicles that provide adequate protection against ballistics and mines. First, the basic shape of the vehicle is defined based on an analysis of the dimensions of a similar vehicle, and the thicknesses of the front and side plates are determined by performing a ballistic impact simulation. For the bottom plate design, the primary design parameters and their values, such as the stand-off, bottom angle, bottom thickness, and bottom-side thickness, are defined. Next, the results of a main effect analysis and an analysis of variance for each design parameter are compared to the response indices representing the performance of the vehicle as determined based on the results of the blast impact simulation and then main effect parameters for each response index are confirmed. In addition, the suitable shapes and dimensions of the vehicle that can meet the armor-piercing projectiles and mine blast threat conditions and design constraints are determined from the blast impact simulation results of the design models determined by the design of experiments method.

     

LY12CZ铝合金激光搭焊工艺研究

通过对LY12CZ铝合金填充LY12和A1-Y焊粉激光搭接焊缝的金相组织分析、显微硬度测试,研究如何有效控制JHM-1GX-200B型YAG脉冲式激光器搭焊LY12CZ铝合金的有关工艺参数,从而使焊缝达到较好的性能。研究结果表明,填充LY12和A1-Y两种不同的粉末对LY12材料进行搭焊处理,粉末和基体均结合牢固,但LY12粉焊缝的硬度总体高于A1-Y粉焊缝的硬度。由于焊缝靠近基体位置有退火过程,强化相析出聚集长大,强化作用下降,其显微硬度分布规律由基体向焊缝中心过渡呈现下降的趋势。同时由于焊缝内部气孔、裂纹的缺陷较多,造成焊缝各点硬度分布不均匀,且相差较大。     

转移型等离子焊接枪电弧形态的数值模拟

采用FLUENT软件对等离子焊枪内部流场进行了数值模拟,从计算结果可以看出,等离子焊枪喷嘴通道长度在一定范围缩短,孔径越小,等离子弧的温度越高,为等离子焊枪韵设计提供了理论依据.     

基于PID-模糊控制梯子梁焊接电路的仿真

采用电阻焊批量生产梯子梁时,受外界干扰及负载电阻的变化,焊接电流幅值变化较大,常出现突变现象。PID控制对于这种非线性时变系统效果并不理想。针对以上现象提出了一种用利用PID控制器与模糊控制器联合分段控制焊接电流的方法。电流偏差值在规定范围内采用模糊控制,超出范围采用PID控制。并利用MATLAB中的Simulink模块对梯子梁焊接电路进行仿真。分析对比了传统PID控制与PID-模糊控制的控制效果。     

基于ANSYS APDL的堆焊热过程数值模拟

结合课题研究需要，本文建立了适当的有限元计算模型，利用ANSYS软件的APDL语言编写了程序，解决了呈高斯函数分布且移动的焊接热源的施加，实现了焊接温度场的三维动态模拟。     

三种内夹层双层舱壁结构的数值仿真

反舰导弹在侵彻进入舰艇装甲内部时, 爆炸产生冲击波和飞散破片对人员和舰艇内部设备具有严重毁坏性. 研究了三种不同内夹层结构形式的双层舱壁结构: X型与六边形组合夹层结构、 十字型蜂窝夹层结构以及细胞增长型蜂窝夹层结构. 采用ANSYSY/LS-DYAN模拟了自锻破片对三种不同舱壁结构的侵彻过程. 根据破片的速度衰减和靶板的能量变化可知, 十字型蜂窝夹层结构的双层舱壁结构最适合作为舱壁的中间结构, 并对其动态响应特性进行了分析.     

Numerical study of welding simulation and residual stress on butt welding of dissimilar thickness of austenitic stainless steel

It has been well documented in the literature the importance of strict surface integrity checks upon performance and quality of machined components, especially for the safety critical components (e.g., aerospace) that work at cyclic high mechanical loads and elevated temperatures. In this field, Waspaloy, within the commercially available nickel-based superalloys, is extensively applied in different industries such as aircraft, chemical plant equipment, and petrochemical equipment. The main objective of this paper is to implement a reliable FE model, for dry orthogonal machining of Waspaloy, capable to predict microstructural changes and dynamic recrystallization during the cutting process. A user subroutine was implemented in FE code to simulate the dynamic recrystallization and consequently grain refinement and hardness variation on the machined surface and below it. Zener–Hollomon (Z-H) and Hall–Petch (H-P) equations were employed to, respectively, predict grain size and microhardness. In addition, depth of the affected layer was controlled using the critical strain equation. FE numerical model was properly calibrated using an iterative procedure based on the comparison between simulated and experimental results. Finally, very good agreement was found between experimental and simulated results of grain size, microhardness, depth of the affected layer, and other fundamental variables such as cutting forces, temperature, and chip morphology.     

不同装夹方式下叶片焊接过程数值模拟

采用了有限元计算的方法,对汽轮机隔板叶片焊接的焊接过程进行模拟仿真,得出了不同装夹条件下结构上的残余应力分布情况,验证了生产中采用刚性固定防变形的方式会产生裂纹这一现象。分析结果表明,采用外环完全固定、内环半自由固定的装夹方式,可降低焊缝上的残余应力,避免焊缝开裂现象的发生。生产结果完全符合数值模拟的分析结果,这是焊接过程数值模拟在生产中成功应用的案例之一。     

焊接参数变化对点焊质量的影响

低碳钢点焊U-I图主要有三种类型:椭圆型、双头型、多头型.未发生飞溅时呈现椭圆状,在发生飞溅时呈现双头或多头状,此外基于点焊质量检测研究的点焊u-I图反映焊接过程动特征的特征信息,可为低碳钢焊接参数的优化提供依据.