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机翼前缘蒙皮拉形工艺参数优化与试验 总被引:3,自引:1,他引:2
飞机机翼前缘蒙皮,由于其形状和成形材料的特点使拉形结束卸载回弹后会产生较大的回弹量,对零件的成形质量影响较大。文章分析机翼前缘蒙皮零件的典型成形方案,确定主要加载轨迹参数,利用正交试验设计方法设计拉形工艺方案,通过有限元模拟和结果分析,获得了主要工艺参数对成形零件回弹量的影响规律。针对某前缘蒙皮零件,根据有限元分析结果,对工艺参数进行设计和优化,通过生产性试验,获得了成形质量较好的试验零件,并进行厚度、应变测量和对比分析,验证了有限元模拟的精度。 相似文献
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基于SPH结合FEM的喷丸残余应力数值模拟 总被引:1,自引:0,他引:1
针对以往有限元模型中弹丸数量较少且为规则阵列排布的缺陷,采用光滑粒子流体动力学法(Smoothed particle hydrodynamics,SPH)与有限元法(Finite element method,FEM)相结合的方法,对喷丸过程进行数值模拟;使用MATLAB对弹丸空间位置坐标进行随机化处理,形成了大量丸粒冲击工件表面的随机喷丸仿真模型。通过分析确定了喷丸饱和时间,研究了喷射角度、弹丸流量对残余应力场的影响。结果表明:在喷丸参数一定的条件下,存在相应的饱和喷丸时间;研究喷丸参数对残余应力的影响时,应在喷丸达到饱和时间之后提取残余应力值;喷射角度增大,残余压应力增大;开始时弹丸流量增大,残余压应力会有所增大,但当其达到饱和值后,残余压应力不再变化。 相似文献
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采用仪器化(数字化)冲击试验机,对防锈铝表面喷丸强化后进行冲击试验,试验结果表明:喷丸后的最大冲击力比母材提高35%,最大力前弹塑性变形功提高166%。 相似文献
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The shotpeening process that is used in industry has an ambiguous influence on the contact surface fatigue life of the casehardened steels: it improves this characteristic of the steels 12Kh2N4A and 12Kh2NVFA when using the rational hardening regime and reduces the contact surface fatigue life for any regimes of shotpeening of the temperature-resistant steel 16Kh3NVFMB-Sh. Low-temperature post-deformation annealing improves the contact surface fatigue life of both steels, but it limits their operating temperature. We can broaden the operating temperature range by the use of thermal shotblasting, which involves strain hardening of the casehardened surface that is heated to 250 °C. This is shown in the present work.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5, pp. 21–24, May, 1994. 相似文献
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以汽车覆盖件拉深工序为研究对象,利用有限元数值模拟方法,探讨了不同类型覆盖件拉深成形压料面的设计方法.结果表明:浅拉深覆盖件宜采用平压料面,能够降低拉深成形难度;深拉深覆盖件宜采用随形起伏压料面,可以保证各部分塑性变形均匀;质量要求不高的骨架类覆盖件,可将作为零件本身的翻边作为压料面的一部分. 相似文献
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Stress corrosion cracks may develop between fasteners in the aluminum inner wing spars of F/A-18 Hornet aircraft. These fasteners secure carbon-fibre/epoxy composite wing skin, of nominal 13 mm thickness, to the spar. Inspection of the spar through the wing skin is required in order to avoid wing disassembly. Pulsed eddy currents, generated by a probe design that utilizes the ferrous fastener as a flux conduit, are demonstrated as having the capability of detecting simulated cracks within the spar with the wing skin present. Differentially connected pickup coils are used to sense differences in response due to asymmetries in induced eddy current fields arising in the presence of cracks. To overcome variability in PEC signal response due to variability in magnetic coupling to the fastener, a large measurement set was analyzed using Modified Principal Component Analysis (PCA). The modified PCA minimizes residual sum of squares to extract eigenfunction scores, which are used to detect the presence of cracks ending on one side of the fastener hole. The ability of the method to sense simulated cracks independent of confounding measurement parameters was demonstrated. 相似文献
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拉伸成形结束后,由于残余应力的存在导致蒙皮零件产生较大的回弹,会严重影响蒙皮的使用质量。基于回弹产生的原因,从工件的应力-应变机制阐述了振动减小残余应力的机理,提出了一种振动辅助飞机蒙皮拉伸成形的新工艺方法,给出了该工艺的主要参数——频率、振幅在应用选择上的依据条件及实际运用中可选择的合理范围。以飞机前缘蒙皮拉伸成形为例,通过数值仿真模拟,分析了施加振动对成形蒙皮零件回弹的影响以及频率、振幅对改善回弹的影响,并通过实验加以验证。结果表明,在飞机蒙皮拉伸成形过程中,施加振动可以更加有效地减小零件的回弹,当选取的工艺参数频率为30 Hz左右、振幅在1.5 mm左右时回弹值最小,效果最佳。 相似文献
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Numerical modeling of a wing skin peen forming process 总被引:3,自引:0,他引:3
For many years shot peering has been used to provide fatigue resistance and form to airplane wing skins at the Boeing Commercial
Airplane Company. In this process, the peening intensities used to form a new wing skin have been obtained through the use
of approximate geometric relationships, along with a considerable amount of trial and error testing. This paper describes
a numerical model that has been applied to replicate the shot peening process used at Boeing. The model is used to predict
peening intensities and the initial size of the skin (flat pattern) given an arbitrary aerodynamic contour requirement. Discussion
focuses on the finite element method and special optimization techniques used in the approach. 相似文献
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A. Gariépy S. Larose C. Perron P. Bocher M. Lévesque 《Journal of Materials Processing Technology》2013,213(6):926-938
Peen forming is commonly used in the aerospace industry to shape large and thin panels, such as wing skins. This manufacturing process uses shot peening to introduce unbalanced compressive stresses near the surface of the component. These stresses tend to bend the panel and, when optimized, lead to the desired contour. Sheet materials often exhibit both elastic and plastic anisotropy, which can alter the development of curvatures. Since peen forming relies on compressive stresses to upset equilibrium, resulting curvatures may also be affected by initial stresses in the part. In this work, the influence of the rolling direction orientation with respect to the sample was investigated experimentally and numerically for the first time for aluminium alloy 2024-T3 specimens. Although maximum deflections were only slightly dependent on the rolling direction orientation, it was found that radii of curvature varied by as much as 10% with respect to this parameter. Finite element simulations allowed quantification of the individual effects of non-equibiaxial initial stresses and elastic orthotropy. It was found that these factors can significantly influence curvature development. Comparison of experimental and numerical results suggested that plastic anisotropy should also be taken into account in future studies. The tools developed in this study show promises for the accurate prediction of peen forming process for large scale components. 相似文献
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拉伸成形工艺是飞机蒙皮零件的基本成形方法。针对某大厚度双曲度铝合金飞机蒙皮进行了拉伸成形工艺研究和优化。为了保证数值模拟的准确性和可靠性,进行了材料性能测试试验,获取了该蒙皮多道次加工时每一道次、不同热处理状态下的材料性能。通过数值模拟,研究了拉伸成形工艺参数包括各道次拉伸量、上模压力、合模间距对贴模和回弹的影响规律。结果表明:合模间距为7 mm时,成形后零件的厚度在大部分区域基本均匀;上模压力在200~1000 kN之间时,增加压力能有效地改善贴模度。据此,提出了优化拉伸成形工艺。针对该蒙皮零件厚度大而导致的回弹大、仅靠工艺优化不能完全满足贴模度要求的问题,进行了模具型面补偿研究。结果表明,该工艺可用于生产满足质量要求的蒙皮零件,并能减少成形道次、降低加工成本、提高生产效率。 相似文献
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喷丸残余应力对裂纹闭合效应影响的数值仿真 总被引:3,自引:2,他引:1
基于裂纹闭合效应,利用ABAQUS软件建立用于预测残余应力场中疲劳裂纹扩展特性的弹塑性有限元模型。考虑塑性和残余应力场对裂纹闭合的作用,分析残余应力、应力比和裂尖单元尺寸对裂纹闭合效应的影响。研究结果表明:未喷丸试样的裂纹闭合类型为塑性诱导裂纹闭合,喷丸残余应力场中的裂纹闭合为塑性和残余压应力共同作用,且裂纹张开力的大小与残余应力的分布相对应;正应力比越大,裂纹闭合效应越不明显,疲劳裂纹扩展速率越快;裂尖单元尺寸小于塑性区范围时可以真实反映裂尖的闭合状态;喷丸残余压应力通过提高裂纹闭合力,增强裂纹闭合效应,抑制疲劳裂纹扩展。 相似文献
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整体壁板增量压弯过程应力应变模拟 总被引:7,自引:1,他引:7
整体壁板结构特点为蒙皮和纵横交错的加强筋为一整体,将机械加工后的平面外形的壁板毛坯成形为具有复杂曲面外形的壁板零件具有很大的难度。本文采用MARC有限元软件分析了整体壁板成形过程中应力应变变化情况。研究表明:整体壁板成形过程中,筋条处的应力状态最为恶劣,筋条与蒙皮过渡区处于三向拉应力状态,同时有剪切塑性应变发生,容易导致该处开裂,对于高筋条来说,还容易导致失稳现象发生;筋条的塑性变形既有凸模下压导致的塑性变形,又有蒙皮回弹导致的塑性变形;塑性变形区主要集中于筋部,蒙皮几乎不发生塑性变形;成形后的壁板将保留较大的残余应力,该应力主要是由蒙皮弹性回复所引起。 相似文献