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61.
Self-piercing riveting as an alternative joining method to spot-welding has attracted considerable interest from the automotive industry and has been widely used in aluminium intensive vehicles. Pressing and stamping are important processes in automotive production and result in additional straining on the vehicle body sheet material. It is therefore important to have knowledge of the effect of sheet pre-straining on the quality of the self-piercing riveted joints and on the mechanical behaviour of the riveted aluminium alloy sheets. This paper reports the influence of sheet pre-straining on the static and fatigue behaviour of self-piercing riveted aluminium alloy sheet. Wrought aluminium alloy sheet, NG5754 with a nominal thickness value of 2 mm was used to obtain pre-strained NG5754 sheets with pre-straining levels of 3%, 5% and 10%. Pairs of pre-strained NG5754 sheets were joined to create single-riveted lap joints which subsequently underwent lap-shear and fatigue testing. Microscopic inspection showed that the joint quality was satisfactory despite the increasing sheet straining levels. The results showed that by increasing the pre-straining level up to 10%, the shear and fatigue strength also increased. The rate of increase of the static and fatigue strength differed as the pre-straining levels varied. 相似文献
62.
Fretting is associated with small amplitude oscillatory movements between two surfaces in contact. One possible consequence of fretting is the formation and subsequent growth of cracks at the edges of the contact. This paper presents an experimental investigation of the cracking behaviour under fretting loading of two different aluminium alloys: 2024-T351 and 7075-T651. Systematic and controlled experiments with a cylinder-flat contact under partial slip fretting conditions were carried out. A model which combines both crack nucleation and propagation processes is used to predict the crack extension throughout the life of the component. The direction of crack propagation experimentally observed was taken into account by the model. Furthermore, an analytical prediction of crack nucleation based on the process volume approach is made. The predictions of both crack extension and nucleation are compared with the experimental results, and show good agreement. 相似文献
63.
One of the most important objectives in the surface engineering of light-weight alloys is to enhance their fatigue properties, allowing both increased performance and an extended service life. This can be achieved by forming a hard surface layer while incorporating a favourable stress state. Single surface treatments, for example, Plasma Electrolytic Oxidation (PEO), are not always capable of creating optimal combinations of these characteristics, whereas greater durability can be achieved by applying mechanical pre-treatments prior to the coating. In this work, a combination of shot-peening pre-treatment with plasma electrolytic oxidation coating is studied as a means to improve the fatigue performance of 2024 T351 Al alloy. The shot-peening was carried out in a compressed air configuration using S110 gauge shot at 200% coverage with an intensity of 20 AlmenC. PEO coatings of 30 μm thickness were produced using pulsed bipolar current technology. Fatigue properties were evaluated by a four-point bending technique at a stress ratio of 0.1. Hardness, residual stress and microstructure of the surface layers were studied by Knoop microhardness tests, fluorescence spectroscopy and SEM analyses, respectively. The effect of the combined shot-peening and PEO treatment is an increased fatigue limit and elevated microhardness when compared to aluminium treated only with PEO. 相似文献
64.
大型铝电解槽添加锂盐工业试验及应用 总被引:2,自引:1,他引:2
介绍大型预焙铝电解槽添加锂盐的试验过程,分析了应用效果。 相似文献
65.
C. el Dsoki V. Landersheim H. Kaufmann T. Bruder P. Krug T. Bohn C. Müller 《Materialwissenschaft und Werkstofftechnik》2006,37(12):1006-1017
The fatigue behaviour of spray compacted aluminium materials. Material properties for component design data: From specimen to component. Spray compacted, high performance aluminium alloys (DISPAL = DISpersion hardened Aluminium) are characterised by their high strength, high Young’s modulus, good wear resistance and low coefficient of thermal expansion. These properties vindicate both the application of these materials and the increasing interest of the automobile manufacturers. Within the framework of a bilateral project, tests were carried out by varying different parameters under both strain‐ and load‐controlled conditions in order to describe the fatigue behaviour of these materials. 相似文献
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68.
热压缩2091 Al-Li合金的流变应力行为 总被引:14,自引:0,他引:14
采用Gleble1500高温等温压缩试验研究了一种2091铝锂合金高温塑性变形时的流变应力行为。结果表明,应变速率和变形温度的变化影响合金稳态流变应力的大小,稳态流变应力与真应力大小无关。应变速率和流变应力之间满足双曲正弦关系,温度和流变应力之间满足Arhenius关系。可用包含Arhenius项的ZenerHollomon参数描述2091合金高温塑性变形时的流变应力行为。 相似文献
69.
总结了我厂160kA系列加长阳极、提升电流后,电流效率提高1 66个百分点以上,年增产铝5617t、年创经济效益3909万元。 相似文献
70.