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采用喷丸成形工艺对国产7B50铝合金进行成形工艺研究,通过对平板件和单筋试验件进行不同参数的喷丸成形基础测试,获得曲率半径与喷丸成形工艺参数的对应关系,并在三筋试验件上验证,获得三筋试验件展向最小曲率半径及其对应的弦向曲率半径。结果表明,随着平板厚度和移动速度的增加,平板试验件弦向曲率半径递增;随着气压增大,平板试验件弦向曲率半径递减。不论是自由状态还是预应力状态,随着移动速度增加,单筋试验件展向曲率半径递增。采用预应力方式获得展向最大曲率变化的马鞍形型面,三筋试验件展向最小曲率半径达到37 692 mm,相应的弦向曲率半径为5 385 mm。 相似文献
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铝合金弹性预应力超声喷丸成形试验 总被引:2,自引:0,他引:2
超声喷丸作为一种新型的板料成形技术,具有易操作,能耗少及优良成形性能等优点,广泛应用于板料成形中。但自由状态下,超声喷丸成形也易发生球面变形,因而提出了弹性预应力超声喷丸成形方法,以2024-T351铝合金壁板为研究对象,分析预弯力矩大小、成形轨迹和壁板厚度对成形曲率半径及成形性能的影响。试验中通过控制壁板展向的弯曲曲率来实现弹性预弯。结果表明:预应力超声喷丸能够大幅度减小壁板展向的成形曲率半径,同时增大弦向成形曲率半径,且随着预弯曲率半径的减小,这种减小和增大的效应随之逐渐增大。此外,与自由状态相比,预应力超声喷丸能够产生幅度和深度更大的残余压应力场,且表面粗糙度并未随着预弯曲率的增大而增加。分析认为,弹性预应力超声波喷丸能够进一步提高受喷材料的成形曲率并在一定程度上减小球面变形趋势,对大变形大厚度的单曲率零件成形具有重要的意义。 相似文献
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《中国有色金属学会会刊》2019,(2)
采用弹性预应力超声喷丸成形技术解决自由超声喷丸成形中板材弯曲变形不充分及出现大球面变形的问题。通过对弹性预应力超声喷丸成形过程进行理论分析,研究弹性预弯力矩对弯曲变形的影响。为了定量描述喷丸过程中球面变形程度,定义球面变形系数。开展自由喷丸和弹性预应力喷丸实验,分析两种喷丸方式的区别,并研究喷丸成形参数对板材成形曲率及球面变形系数的影响。结果表明,弦向喷丸轨迹有利于提高板材展向弯曲变形、同时减小球面变形系数。大预弯曲率能增大展向弯曲变形,同时减小弦向变形,从而显著减小球面变形系数。大撞针速度、小板厚及小偏置距离均有利于提高展向弯曲变形;在预应力喷丸成形过程中,大撞针速度有利于减小球面变形,而板厚及偏置距离的变化对球面变形系数影响很小。综上,在预应力喷丸成形过程中,预弯曲率及喷丸轨迹是最重要的两个影响参数。本研究可为大厚度翼板类零件的预应力超声喷丸成形过程参数优化提供指导。 相似文献
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大型机翼整体壁板喷丸延展量数值模拟 总被引:1,自引:0,他引:1
分析了大型机翼整体壁板在喷丸成形及强化过程中产生延展变形的机理,并介绍了几种喷丸成形数值模拟的方法;对于弹丸不重叠排布的情况,采用长方形和三角形两种喷丸覆盖率计算模型,对于弹丸随机排布发生重叠的情况下,采用Avrami覆盖率计算模型,通过多弹丸撞击长方体胞元的有限元模拟方法,得到弹丸撞击后靶材的表层诱导应力场的分布规律;进而采用直接应力法建立了预测喷丸成形及强化延展变形的有限元模拟方法,通过试板喷丸成形参数和试板弯曲及延展的变形规律的试验,验证了其有效性,进而将其应用于C919机翼下前整体壁板板坯延展量的模拟,取得了与试验吻合较好的结果。 相似文献
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预应力对喷丸成形的影响 总被引:1,自引:0,他引:1
对预应力喷丸成形进行了试验研究,指出预应力可以改变其对应的预变形与预应力喷丸变形之间的大小关系,在以改善喷丸型面纵向直线度为主要目的的预应力喷丸成形中,预应变取值051000~11000较为适宜。 相似文献
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针对2024-T351铝合金试验件,利用直径Φ3. 18 mm大尺寸弹丸,选取喷丸气压、进给速度及弹丸流量3个重要喷丸工艺参数,通过设计均匀试验并运用MATLAB软件对喷丸试验结果进行逐步回归分析,建立弹坑直径、弹丸速度和覆盖率3项喷丸指标与喷丸工艺参数间的二阶响应面模型。利用该模型并结合多弹丸撞击有限元模型获得相应喷丸工艺参数下的平均诱导应力场,从而实现喷丸成形应力场法数值模拟。模拟变形结果与试验变形结果对比表明模拟值均小于相应试验值,最大误差14. 8%,平均误差9%,二者符合较好,表明基于喷丸指标响应面模型的应力场法数值模拟方法完全可以应用于喷丸成形数值模拟分析。 相似文献
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《锻压技术》2021,46(7):60-65
以运载火箭贮箱用2219陶铝材料数铣短壳壁板为研究对象,通过分析产品结构特点,利用四轴滚弯方式分区成形凸台区及网格区,合理控制上、下轴夹持间距及下压量,探究航向上、下端辅助筋条厚度设计对成形工艺参数及型面精度影响的机制,以实现2219陶铝材料的工程化应用。结果表明:同等模块曲率半径下,辅助筋条厚度影响材料的塑性流动及相对弯曲半径,受到弯曲三向应力,制约成形工艺参数及产品精度。辅助筋条厚度为6 mm时比厚度为5 mm时产生更大比例的塑性变形,更容易达到成形曲率要求,影响显著,但对弧度成形精度影响较小。当数铣短壳壁板航向上、下端设有3条辅助筋条时,控制辅助筋条厚度为5 mm,可控制弧度间隙在2 mm以内、焊接区直线度在1.5 mm以内、网格区直线度在2.5 mm以内。 相似文献
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板加筋壁板零件的喷丸成形数值模拟与工艺优化 总被引:2,自引:0,他引:2
喷丸成形是在喷丸工艺基础上发展起来的特种成形方法,是飞机整体壁板成形的首选工艺。本文针对板加筋结构壁板零件,应用等效静态载荷温度场来模拟变形过程,将一个复杂的动态冲撞过程近似的转化为一个静态加载过程,并通过优化程序找到满足特定要求的喷丸工艺方案。从而可以快速估量喷丸工艺参数以及喷丸成形整体效果,制定喷丸工艺优化方案,避免实际生产中常用的试错方法。 相似文献
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In order to control welding stress and distortion, a new welding with trailing peening method based on the electromagnetic hammer was developed. This method uses the idea of constant frequency pulse width modulation for designing the control circuit of peening force and peening frequency. The peening force can be adjusted between 0 and 1 000 N and the peening frequency ranges from 0 to 25 Hz. Peening force is applied to the weld metal and the weld toe during the welding by peening head. The experiments show that the method is portable and flexible, and it can adjust the distribution state of welding residual stress, making grain refinement. When the peening force is changed to 700 N and the peening frequency to 3 Hz, both the transverse and longitudinal residual stresses will drop obviously. 相似文献
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高玉魁 《稀有金属材料与工程》2016,45(5):1230-1234
对FGH97粉末高温合金进行激光冲击强化和喷丸强化,利用X射线应力分析仪测定强化层的残余应力,测定650℃下旋转弯曲疲劳性能,利用SEM观察分析疲劳断口特征。 结果表明,2种表面强化方法都可以提高FGH97粉末高温合金的疲劳性能,但激光冲击强化试样比喷丸强化试样具有更深的残余压应力层和较好的表面粗糙度,且残余应力在高温疲劳载荷下的松弛较小,因此具有更好的强化效果;与未表面强化的试样相比,喷丸强化试样和激光冲击强化试样的疲劳裂纹源都出现在亚表面,而未强化试样的疲劳裂纹源则出现在表面。 相似文献
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目的通过改变喷丸的压力或时间,在钛合金表面制备出剧烈塑性变形(SPD)层较厚、硬度较高的梯度纳米晶结构。方法改变喷丸压力(0.3~0.6 MPa)或喷丸时间(15~60 min),调控TC4钛合金表面梯度纳米晶结构的变形层厚度和纳米晶晶粒尺寸。利用金相显微镜观察塑性变形层截面的组织形貌,通过X射线衍射仪(XRD)和透射电子显微镜(TEM)确定喷丸表面纳米晶的晶粒尺寸,通过显微硬度计对塑性变形层的截面硬度进行研究。结果一定喷丸压力(0.6MPa)下,SPD层和总变形层厚度分别在喷丸25、30 min时达到饱和值78μm和143μm。一定喷丸时间(25 min)下,SPD层和总变形层的厚度随喷丸压力的增加而增厚,在0.4 MPa时达到饱和,分别为78μm和120μm。当SPD层厚度进入饱和阶段后,表层晶粒大小和硬度强化程度都趋于稳定;在0.6 MPa下,当表面α相细化至稳定阶段时,晶粒尺寸为30~90 nm,表面硬度提高约30%。结论喷丸SPD层及总变形层的厚度随喷丸时间的延长或喷丸压力的增大而增厚,当SPD层厚度趋于饱和后,表面晶粒尺寸和硬度强化程度都已饱和。 相似文献
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E. Maawad H.-G. Brokmeier L. WagnerY. Sano Ch. Genzel 《Surface & coatings technology》2011,205(12):3644-3650
As a result of the variety of mechanical surface treatments, studies of surface and near-surface characteristics are becoming increasingly important in a variety of industrial fields. This is to achieve more gains by balancing between optimum conditions and costs. In the present study, shot peening (SP), ball-burnishing (BB), laser shock peening (LSP) and ultrasonic shot peening (USP) processes were performed on the α-titanium alloy Ti-2.5Cu after two different heat treatments. The influence of such surface treatments on the surface and near-surface characteristics, such as residual stress, work hardening or dislocation density and surface roughness, was studied. The depth profiles of residual stress and full width at half maximum (FWHM) were obtained by using energy-dispersive X-ray diffraction. Results show that the BB process produced the highest and deepest maximum residual stress and LSP produced the lowest work hardening close to the surface. 相似文献
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GH742高温合金激光冲击强化和喷丸强化残余应力 总被引:1,自引:1,他引:0
高玉魁 《稀有金属材料与工程》2016,45(9):2347-2351
对GH742高温合金进行激光冲击强化和喷丸强化,利用X射线应力分析仪测定强化层的残余应力,对比分析2种残余应力的差异和特征,并采用不同的退火温度进行退火,研究表面残余应力在高温下的稳定性。结果表明,2种表面强化方法都可以在GH742高温合金表层引入残余压应力,但激光冲击强化试样比喷丸强化试样具有更深的残余压应力层和较好的稳定性,且残余压应力最大值在表面;与激光冲击强化的试样相比,喷丸强化试样的残余压应力较浅,而且随着喷丸强度的增加,最大残余压应力也由表面移向了次表面。 相似文献
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Omar Hatamleh 《Journal of Materials Engineering and Performance》2008,17(5):688-694
Peening techniques like laser peening and shot peening were used to modify the surface of friction stir welded 7075-T7351
Aluminum Alloy specimens. The tensile coupons were machined such as the loading was applied in a direction perpendicular to
the weld direction. The peening effects on the global and local mechanical properties through the different regions of the
weld were characterized and assessed. The surface hardness levels resulting from various peening techniques were also investigated
for both sides of the welds. Shot peening resulted in an increase to surface hardness levels, but no improvement was noticed
on the mechanical properties. In contrast, mechanical properties were improved by laser peening when compared to the unpeened
material. 相似文献
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Omar Hatamleh Iris V. Rivero Jed Lyons 《Journal of Materials Engineering and Performance》2007,16(5):549-553
The effects of laser, and shot peening on the residual stresses in friction stir welds (FSW) has been investigated. The surface
residual stresses were measured at five different locations across the weld in order to produce an adequate residual stress
profile. The residual stresses before and after sectioning the coupon from the welded plate were also measured, and the effect
of coupon size on the residual stress relaxation was determined and characterized. Measurements indicate that residual stresses
were not uniform along the welded plate, and large variation in stress magnitude could be exhibited at various locations along
the FSW plate. Sectioning resulted in significant residual stress relaxation in the longitudinal direction attributed to the
large change in dimensions in this direction. Overall, laser and shot peening resulted in a significant reduction in tensile
residual stresses at the surface of the specimens. 相似文献