提高水力机械抗磨蚀性能的喷丸工艺数值分析

针对流体机械磨蚀特点,对喷丸工艺引起的残余应力场进行数值模拟。运用有限单元法对弹丸撞击后钢板材料表面应力分布进行了数值计算。讨论了弹丸直径、喷射速度与残余应力的关系,选择几组典型参数比较,分析不同情况下喷丸对局部变形的影响,进而探讨了水力机械防磨蚀的喷丸强化工艺参数的选择。     

曲轴疲劳机理分析与圆角喷丸工艺技术研究

曲轴过渡圆角为应力集中处,在制造工艺过程中其表面会产生残余拉应力,对疲劳强度极为不利。根据材料裂纹的微观机理,对曲轴过渡圆角表面裂纹原因进行分析,在此基础上采用喷丸工艺对圆角进行强化。试验验证表明:喷丸强化能够使圆角表面形成残余压应力,提高曲轴的疲劳强度。并指出:目前喷丸工艺参数通过经验得到,须进一步研究更适合的喷丸强度,以及喷丸所形成的表面残余压应力和深度对曲轴疲劳强度的影响。     

连杆内孔喷丸工艺技术

为提高柴油机连杆的疲劳强度,采用喷丸强化工艺对其内孔进行处理。在保证喷丸强度、覆盖率、粗糙度等要求的前提下,制定合理的工艺参数,对经喷丸强化工艺处理的区域进行参与应力测试,测试结果表明：连杆大小端内孔表面为残余压应力,且残余压应力层较深,可为后续进行实机验证提供数据支撑。     

奥氏体不锈钢管内壁喷丸强化制造技术简述

本文主要阐述了奥氏体不锈钢管内壁喷丸强化的制造技术,喷丸强化是材料表面强化的重要方法之一,可以显著提高材料表面力学性能。通过研究空气压力,弹丸流量,喷丸速度对喷丸质量的影响,找出满足技术要求的喷丸强化工艺。通过优化喷嘴结构、合理选用弹丸尺寸,进一步提升产品质量和生产效率。本文通过对内壁喷丸强化机理和制造难点进行阐述及分析,梳理该奥氏体不锈钢管内壁喷丸强化制造工艺特点,并给出具体制造工艺措施。     

喷咀结构在喷丸参数中的作用探讨

本文介绍在喷丸工艺中弹丸材料和尺寸，空气压力，喷咀结构等参数选择对喷丸强度的影响。着重论述了喷丸参数选择的局限性，探讨了喷咀结构在喷丸参数选择中的重要作用。     

喷丸强化在汽轮机叶片上的应用

一、概述喷丸强化是借助金属弹丸或玻璃弹丸以很高速度撞击金属表面,使金属零件表面产生残余压缩应力和形成细化亚晶粒的冷作硬化层,从而提高零件疲劳强度或抗应力腐蚀能力的一种冷加工方法。该工艺在本世纪二十年代就开始采用了,三十年代首先在美国弹簧工业生产上使用,第二次世界大战期间,喷丸强化工艺引入航空工业。从四十年代起,随着各种“喷丸规范”“喷丸手册”等相继问世,它已成为机械加工中不可缺少的工艺之一。五十年代末,美国发展了新型的玻璃丸介质,使其在     

某型柴油机连杆工艺改进研究

针对某型柴油机连杆断裂故障,对连杆小端油孔抗疲劳加工和表面喷丸强化残余应力控制技术进行了研究,并根据研究结果对传统加工工艺进行了改进。工艺改进后的现场试验和小批量试制验证表明:采用新工艺加工的连杆其残余应力控制在合理范围。     

零件表面喷丸强化工艺应用研究

介绍了利用喷丸技术来提高喷油泵关键零件表面强化效果的试验案例,通过对喷丸强化设备、喷丸材料、喷丸工艺参数的优化选用,加之喷丸后的光饰处理,使得零件的表面压应力和压应力层深度得到有效提高,零件的疲劳强度和可靠性也得到提高.     

喷丸强化处理对核电汽轮机低压叶片表面残余应力的影响

文章采用喷丸强化处理的方法对核电汽轮机低压叶片进行了表面处理,研究了喷丸强化处理对叶片表面残余应力的影响。实验结果表明：喷丸强化处理能够显著提高叶片表面的残余压应力并使残余压应力分布较均匀且不会在叶片表面形成微裂纹等有害缺陷。     

基于BP神经网络的曲轴最佳滚压参数的研究

基于最佳残余应力理论,利用ANSYS有限元软件对480Q曲轴具体工况进行有限元模拟,得到对应的最佳残余应力。利用DEFORM有限元软件针对此曲轴进行了滚压试验,得到数组不同滚压参数对应的残余应力。利用神经网络进行训练得到滚压参数与残余应力的对应关系。最后,利用此网络找到与最佳残余应力对应的最佳滚压参数,为实际生产提供可靠的参考。     

改善零件疲劳寿命的激光冲击强化技术

喷丸强化在工业界已得到广泛的应用,而激光冲击强化处理是最近几年来出现的表面改性新工艺。它利用激光冲击波技术使零件表层材料的亚结构得到改善和产生有益残余压应力,因此降低了生成疲劳裂纹源的比例和增加抗应力腐蚀的能力,从而延长零件的疲劳使用寿命。同传统的机械喷丸强化相比,激光冲击强化具有更大的优势。     

喷丸对汽轮机叶片残余内应力影响的研究

汽轮机末级叶片经局部高频淬火后其防水蚀抗力得到提高,然而由于过渡区的存在,导致叶片整体性能恶化。喷丸工艺可以改善过渡区的残余应力分布和提高汽轮机叶片的疲劳性能。研究了喷丸前后汽轮机末级叶片（909mm叶片和40in叶片）的残余内应力分布特点。研究表明,喷丸能优化汽轮机叶片表面的残余应力状态,引入有益的残余压应力,为提高其疲劳性能提供保障。     

Numerical simulation to study the effect of repair width on residual stresses of a stainless steel clad plate

Clad plates are widely used in the construction of corrosion resistant equipment. During the repair of clad plates, residual stresses are generated and influence the structure integrity. This paper uses the finite element method (FEM) to predict the residual stresses in a repair weld of a stainless steel clad plate. The effect of repair width on residual stresses has also been investigated by numerical simulation. Due to the material mismatching between clad metal and base metal, a discontinuous stress distribution has been generated across the interface between clad and base metals. The peak residual stress occurs in the heat affected zone (HAZ) of the base metal, because the yield strength of the base metal is larger than that of the clad metal. With an increase in repair width, the residual stresses are decreased. When the repair width is increased to 24 mm, the residual stresses in the weld have been decreased greatly and the peak residual stresses have been reduced to less than the yield strength. Therefore, the recommended repair width should not be less than 24 mm, which provides a reference for optimizing repair welding technology for this stainless steel clad pate.     

Technique for partially strengthening electrical steel sheet of IPM motor using cavitation peening

Abstract

Cavitation peening (CP), which utilises the impact caused by cavitation bubbles collapsing, can improve the fatigue strength of metallic materials as well as the yield stress and tensile strength. The rotor cores in interior permanent magnet motors use electrical steel sheet. In order to increase the permissible rotating speed of the motor and achieve high efficiency, the mechanical strength of the stress concentration area in the steel sheet where the magnet is pressed needs to be enhanced. In the present paper, to improve the yield stress and tensile strength, the steel sheet was peened by CP. The peening effect on these mechanical properties was evaluated by tensile and indentation tests. The experimental results from the tensile tests revealed that CP can increase the yield stress by 22% compared to that before CP. In addition, the yield stress and tensile strength increased along with the CP processing time.     

Residual stress and plastic strain analysis in the brazed joint of bonded compliant seal design in planar solid oxide fuel cell

This paper uses finite element method (FEM) to predict the residual stress and plastic strain in the brazed joint of sealing foil-to-window frame in bonded compliant seal (BCS) design in a planar solid oxide fuel cell (PSOFC). The effects of window frame material type, sealing foil thickness, filler metal thickness and window frame thickness on residual stress and plastic strain are discussed. Large residual stress is generated in the joint, and the stress and strain are concentrated around the fillet. It is proved that the BCS design can mitigate and trap some residual stress by plastic deformation within the sealing foil. The residual stress and the ability of trapping stress of sealing foil are affected by window frame material and structure thickness. Based on the comprehensive considerations of the impact of residual stress and plastic strain, Alloy 625 as a window frame material is found to be better than Haynes 214, Hastelloy X and SUS 316L. The optimum thickness of sealing foil and filler metal BNi2 are found to be 150 μm and 75 μm, respectively. The residual stress and plastic strain are increased with the increase of window frame thickness.     

THERMOELASTO-PLASTIC STRESSES AND THERMAL DISTORTIONS IN A BRAKE DRUM

Most analyses of thermal stresses generated in a brake drum are studies within either an elastic or a plastic region with constant yield strength. As a matter of fact, however, a severe brake application will create a thermal environment on the friction surface with an excessively high surface temperature. At a high temperature, the degradation of yield strength of a drum material may become significant and an important factor to be taken into account in the analysis. This article deals with the thermoelasto-plastic stresses and the thermal distortions produced in a brake drum during a severe braking condition, taking account of the temperature dependence of the yield strength of a drum material. It is found that high compressive thermoelastoplastic stresses are created during a brake application but eventually residual tensile stresses are developed in the vicinity of the rubbing surface in the course of cooling. These residual tensile stresses are strongly presumed to be one of the significant factors causing the heat crack in a brake drum. In addition, the thermal distortions of the drum suggest a loss of the contact area between the drum fictional surface and the brake shoe linings during braking.     

单层整锻式超高压容器液压试验压力的分析

根据我国单层整段式超高压容器的设计和材料的实际情况，从超高压容器的安全性能出发，分析了超高压容器液压试验压力值的确定。本文认为超高压液压强度试验压力的确定应遵循以下原则：1）液压试验时应保证容器内壁不屈服，确保不出现过大的残余变形量；2）液压试验时压力容器的平均一次周向应力计算值不得超过所用材料在试验温度下90％的屈服强度；5）液压试验时超高压容器的平均一次周向应力计算值不超过同类材料制作的薄壁容器的最大周向应力。