【作者】 艾菊兰；

【导师】 邓建新；

【作者基本信息】 山东大学 ， 机械设计及理论， 2007， 硕士

【摘要】 本课题从车体钢结构亟需提高其使用寿命的实际需求出发,运用计算机仿真技术对车体钢结构进行喷丸强化过程的运动仿真,通过喷丸工艺引起的应力、应变场进行数值模拟,运用有限单元法对弹丸撞击后钢板材料表面应力、应变的分布进行了数值计算和统计分析。研究了喷射速度、喷射角度和弹丸直径与残余应力、应变的关系,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,进而对车体钢结构喷丸强化工艺参数进行了优化选择。对得到的优化参数进行试验研究,主要研究喷射速度和角度对钢结构表面强化效果的影响规律。首先建立了有限元模型,设定喷射速度分别为40m/s、60m/s、80m/s、100m/s,喷射角度分别为45°、60°、75°、90°,弹丸直径分别为φ0.8mm、φ1.0mm、φ1.2mm、φ1.6mm、φ2.0mm的情况下,进行单粒弹丸冲击同一目标钢板的喷丸强化过程仿真分析。分析结果表明目标钢板受到弹丸反复冲击时应力和应变的变化规律是:喷射速度和弹丸直径对应力、应变影响很大,而喷射角度主要影响应变。通过对弹丸直径、喷射速度、喷射角度工艺参数优化,得出:对于弹丸直径为φ1.0mm,喷射角度为90°,选60～80m/s的速度可以获得较好的综合效果;对于喷射速度为80m/s,弹丸直径为1.0mm,喷射角度为60°较合适;喷射速度为80m/s,喷射角度为90°,弹丸直径应取φ1.0～φ1.2mm。对所确定的优化工艺参数进行了试验研究,主要分析了强化钢板表面宏观粗糙度和硬度的变化规律,从中得出:在其它工艺参数相同时,弹丸速度越大,表面粗糙度Ra升高越大;喷射角度越大,表面粗糙度越大。速度为60m/s时表面硬度提高24.1%;速度为80m/s时,表面硬度提高38.6%;而在其它工艺参数相同时,喷射角度对硬度的影响基本一致,角度为60°时表面硬度提高24.1%;角度为90°时表面硬度提高27.6%。速度一定时,喷射角度为60°比90°。能更好地改善钢板表面质量。角度一定时,仅仅考虑速度对钢板表面粗糙度的影响,60m/s的速度更合适。这一结论与模拟计算得出的优化参数是一致的。本课题的结果和研究方法应用于铁道车辆的生产与制造,将有助于材料表面处理时选择恰当的工艺参数,对提高车体钢结构表面质量,延长车辆使用寿命有重要的现实意义。更多还原

【Abstract】 This topic researched on how to enhance its service life of the chassis steel structure urgently according to our actual demand. It carries on using the computer simulation technology to the chassis steel structure shot peening strengthening process the movement simulation, through shot peening the stress, the strain field which the pill craft caused carries on the value simulation, the utilization limited unit law to the projectile hit rear spring material surface stress, the strain distribution has carried on the value computation and the statistical analysis. I have discussed the relations between the jet speed, spray angle, the projectile diameter, the residual stress and the strain. I choose several groups of typical parameters to compare, in the analysis different situationshot peening to the local distortion influence, then shot peening strengthening craft parameter to the chassis steel structure to carry on the optimized choice. To the optimized parameter which obtains has conducted the experimental study, mainly discussed the jet velocity and the angle to the steel structure surface strengthening effect influence rule.Firstly I have establishedshot peening strengthening finite element model at the jet velocity as 40m/s, 60m/s, 80m/s, 100m/s, the spray angle for 45°, 60°, 75°, 90°, the projectile diameter ;0.8mm, 1.0mm,1.2mm,1.6mm,2.0mm, the impact identical goal steel plate single grain of the pill. I have carried on the movement simulation using the finite element software to the establishment each kind of finite element model, had discovered the goal steel plate receives the projectile attacks repeatedly when the stress and the strain change rule: The jet velocity and the projectile diameter counter stress, the strain influence are very big, but spray angle major effect strain.Through to the projectile diameter, the jet velocity, the spray angle craft parameter optimizes, obtains: Regarding the 1mm diameter projectile, the spray angle for 90°, chooses 60～80m/s the speed to be possible to obtain the good comprehensive effect; Regarding the jet velocity is 80m/s, the projectile diameter for 1.0mm, spray angle for 60°appropriate; The jet velocity is 80m/s, the spray angle for 90°, the projectile diameter should take 1.0～1.2mm. To the optimized craft parameter which determined has conducted the experimental study, mainly has analyzed the strengthened steel plate surface macroscopic roughness and hardness changed rule, I found: When other craft parameter same, the projectile speed is bigger, the surface roughness Ra ascension is bigger; The spray angle is bigger, the surface roughness is bigger. The speed is when 60m/s the surface hardness enhances 24.1%. The speed is when 80m/s the surface hardness enhances 38.6%.But when other craft parameter same, spray angle to degree of hardness influence basic consistent, angle for 60°when the surface hardness enhances 24.1%; Angle for 90°when the surface hardness enhances 27.6%. When speed certain, the angle for 60°compared to 90°can improve the steel plate surface quality well. When angle fixed, considered merely the speed to the steel plate surface roughness influence, the 60m/s speed is more appropriate. This conclusion is consistent with the optimized parameter which obtains with the analog computation.On the one hand the experiment explained this topic will use the research technique feasibility, more importantly the result and the method apply in the railroad vehicles manufacturing industry, will be helpful to when will carry on the surface treatment chooses the appropriate craft parameter, thus will improve the chassis steel structure surface quality, will lengthen the vehicles service life.更多还原