共查询到19条相似文献,搜索用时 93 毫秒
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提出并研究了利用两个纵向振动系统对塑料进行超声焊接的方法。 这种系统的焊接范围可以比单振动系统的普通超声焊接方法增大一倍。每个振动系统所需的焊接振动速度大约为原来的一半,因此所需功率就约为原来的四分之一。焊接对样品的损伤也比较小。 在对厚的和大的样品进行传输焊接的情况下,上下振动系统的频率相同时,焊样上的振动分布可以通过调整上下焊头之间的振动相位差加以改变。改变振动相位差,就可以使焊接的位置处于振动应力最大的地方。这种使用两个振动系统的焊接方法具有多种有用的特点,对塑料焊接最为有效。 相似文献
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(上接《塑料包装》2014年第6期)4.各种塑料的超声波焊接性塑料的性能影响超声波的成功焊接。塑料的超声波焊接性取决于塑料对超声振动的衰减能力和熔化温度的高低以及物理性能如弹性模量、抗冲击性、摩擦系数及导热系数等等。实验证明,塑料的焊接性G正比于弹性模量E、导热系数λ、摩擦系数μ,反比于塑料的密度ρ、比热C、熔点t,如 相似文献
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针对声学黑洞(Acoustic Black Hole,ABH)在圆柱壳结构上的应用问题,首先采用有限元法分析嵌入ABH的圆柱壳结构的振动特性并讨论不同结构尺寸对其振动特性的影响。随后对结构开展进一步研究,在嵌入ABH的圆柱壳结构外布置局域振子,分析其振动特性,并讨论不同材料振子及振子不同的质量分布对结构振动特性的影响。结果表明:相比原结构,嵌入ABH的圆柱壳结构的振动传递损失增加;当结构内径增大时,振动峰值向高频移动,振动衰减增大;在嵌入ABH的结构外侧附加振子使其发生局域共振可增加振动衰减,改善结构的振动特性;若采用不同材料振子,其质量增大时,振动衰减会向低频移动;随着振子外侧质量向中心集中,结构固有频率随之降低,振动衰减前移,可知振子质量及刚度参数对结构的振动特性有较大影响。 相似文献
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将表层、增强材料与芯材分开,应用有限元分析软件ANSYS,采用8节点SOLID45实体单元,对增强型夹层圆柱壳建立物理模型,进行自由振动及瞬态动力学过程分析。考虑树脂材性、尺寸以及分布等参数的变化,分析了点阵增强和齿槽增强对夹层圆柱壳动力学性能的影响,将两种增强方式进行了对比。结果显示,树脂柱及树脂齿槽均可改变圆柱壳的振动特性,对降低瞬态荷载下的动力响应有积极作用。其中树脂材性的影响较小,而点阵和齿槽的尺寸与分布对圆柱壳动力学性能的影响较为明显,分析显示,点阵增强对于提高结构固有频率比齿槽增强更好一些,而齿槽增强对于降低端部受冲击荷载时的动力位移比点阵增强更好一些。 相似文献
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本文研究由一部分变截面杆和一部分定截面杆构成的大尺寸矩形横截面复合变幅杆。文章中引进了变幅杆各轴向的等效弹性常数,并推出了具体表达式,利用表观弹性法探讨了大尺寸矩形变幅杆的耦合振动,得出了变幅杆的共振条件,即频率方程。实验表明,与一维理论的计算结果相比,利用耦合振动理论得出的变幅杆的共振频率更加接近于实测值。 相似文献
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研究焊接残余应力对薄圆板结构振动特性的影响,解决薄圆板结构振动中存在非均匀分布预应力问题。根据含预应力结构的应变-应力方程,建立含预应力薄圆板结构的运动控制方程。基于Rayleigh-Ritz法构造Lagrange能量泛函方程。将预应力和位移试函数展开成三角级数形式,对含预应力薄圆板结构的自由振动问题进行求解。以周边简支边界薄圆板结构为例,对比焊接残余应力的不同分布形式对薄圆板结构固有频率及振型的影响。数值计算结果验证了所提方法的有效性,可应用于解决任意分布预应力问题。 相似文献
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采用新型超声振动强化搅拌摩擦焊接工艺实现了6061-T6铝合金以及QP980高强钢的搭接焊, 对比分析了有无超声作用下, 接头的宏观形貌、微观组织和拉伸剪切性能, 同时研究了超声振动对焊接载荷的影响。结果表明: 焊接前对母材施加超声振动, 可以起到软化母材的作用, 促进了材料的塑性流动, 扩大了铝/钢界面区和焊核区, 使更多的钢颗粒随搅拌针旋转进入铝合金侧, 在界面区边缘形成钩状结构, 进而提高了接头的失效载荷; 超声改变了FSW接头断裂位置和断口形貌, 提高了接头力学性能, 在本实验工艺参数范围内, 接头最大的平均失效载荷为4.99 kN; 当焊接速度为90 mm/min, 下压量为0.1 mm时, 施加超声振动使接头的平均失效载荷提高了0.98 kN, 拉剪性能提升28.24%;施加超声振动后轴向力Fz、搅拌头扭矩Mt和主轴输出功率分别下降2.46%, 6.44%和4.59%。 相似文献
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Ultrasonic welding technology is a new and emerging concept, which can be applied to many industrial applications. The vital part of this technology is the horn, which acts as a tool, upon which the pressure and high-frequency vibration is applied to create a solid-state weld. In this study, a special type of horn is designed and its length is determined analytically. Dimensions obtained by finite-element method (FEM) are employed for the horn used in the present experiments to weld brass with aluminum sheet of thickness 0.1 mm. The dynamic analysis is also performed to find out the stress and amplitude distribution in the horn under loading conditions. Welding has been carried out using various parameter combinations in order to improvise the weld strength. Maximum weld strength of 4.05 MPa is obtained under the optimum welding conditions of 0.21 s weld time, 0.26 MPa weld pressure, and 60 µm vibration amplitude. The microhardness test also has been done on the optimized results to show the plastic flow at the weld zone. It confirms that the hardness of both materials up to 20 µm distance around the weld zone is increased with respect to the parent materials. 相似文献
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目的探究超声振动对铝合金搅拌摩擦焊的作用效果。方法分别采用普通搅拌摩擦焊和超声辅助搅拌摩擦焊方法,对7075铝合金进行焊接试验,并对焊接接头的微观组织、力学性能、断口形貌进行分析。结果普通搅拌摩擦焊焊缝中生成了隧道型缺陷,施加超声振动后,缺陷消失,形成了无缺陷的良好接头,且与普通搅拌摩擦焊相比,超声辅助搅拌摩擦焊焊缝热影响区晶粒长大程度较小,焊核晶粒细化。接头强度明显提高,达到铝合金母材强度的71.5%,接头断裂模式为韧窝和准解理的混合断裂形式。结论超声振动促进了塑性金属的流动,能有效抑制孔洞、隧道型缺陷等的形成,同时超声振动能在提升金属塑性的同时,降低焊缝的热输入。 相似文献
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Caroline Karina Chandra Niklas Sommer Ben Heider Marcel Hatzky Rüdiger Reitz Stefan Böhm Matthias Oechsner 《Advanced Engineering Materials》2023,25(15):2300130
Friction stir welding enables joining of high-strength, lightweight aluminum alloys, e.g., EN-AW-7075, below the melting point by induced plastic deformation. Therefore, heat transfer into the adjacent regions beneath the weld seam is significantly reduced as compared to fusion welding processes such as laser beam welding. However, specific zones along the weld seam area are susceptible to localized corrosion due to grain growth and the precipitation of intermetallic phases. Thus, several approaches toward lowering the corrosion susceptibility of the heat-affected zone are presented. Special interest is given to increasing the plastic deformation by the use of novel multipin welding tools that eventually facilitate reduced heat input during welding as a result of substantially lower tool revolutions. The corrosion behavior is tested by means of full material immersion tests and electrochemical measurements which provide insight into the corrosion kinetics. Using pre- and postmortem microstructural analysis, the mechanisms influencing the initiation of corrosion can be identified. Supported by in-operando temperature measurements, the varied welding parameters and their interrelationships to corrosion resistance can be derived. Furthermore, recommendations on optimal welding parameters to obtain enhanced corrosion resistance can be deduced. 相似文献
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刘光铮 《中国材料科技与设备》2011,(3):60-63
文中介绍了铝基复合材料搅拌摩擦焊搅拌头材料选择和结构设计方案。根据铝基复合材料复杂的微观和宏观结构,选定钢结硬质合金GT35制造搅拌头,并与选用工具钢制作的普通搅拌头进行对比。对比结果表明,普通搅拌头焊后磨损严重,焊缝质量较差。对搅拌头形状和尺寸进行了设计:最初的“一字凹凸槽”设计存在不同心德患,给加工制造造成困难;后改为分体式搅拌头,采用螺纹连接。采用这种搅拌头能得到表面光滑,宏观形貌良好的接头。 相似文献
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Friction stir welding (FSW) is a solid state welding process for joining aluminum alloys and has been employed in aerospace, rail, automotive and marine industries for joining aluminium, magnesium, zinc and copper alloys. In FSW, the base metal properties such as yield strength, ductility and hardness control the plastic flow of the material under the action of rotating non-consumable tool. The FSW process parameters such as tool rotational speed, welding speed, axial force, etc. play a major role in deciding the weld quality. In this investigation, an attempt has been made to establish relationship between the base material properties and FSW process parameters. FSW joints have been made using five different grades of aluminium alloys (AA1050, AA6061, AA2024, AA7039 and AA7075) using different combinations of process parameters. Macrostructural analysis has been done to check the weld quality (defective or defect free). Empirical relationships have been established between base metal properties and tool rotational speed and welding speed, respectively. The developed empirical relationships can be effectively used to predict the FSW process parameters to fabricate defect free welds. 相似文献
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The effects of different pin features and dimensions of scrolled shoulder bobbin friction stir welding were tested for welding marine grade aluminium, Al6082-T6. Welds were created in longitudinal and transverse plate extrusion directions in thin plate aluminium clamped and supported at one side. Measured outcomes included visual inspection, plate distortion, mechanical properties, metallurgical examination, and hardness test. This study shows that tool features cannot be directly transferable from conventional friction stir welding technology without comprising process variables and tool part functionality. Process setting such as clamps, support arrangements, shoulder gap and welding direction create compression, vibration and heat distribution hence influence the weld quality. The best joint was produced by four flats tool pin followed by threaded tool pin with three flats. These findings were used to develop a conceptual theory representing the underlying physics of the friction stir welding process. The effects of pin features, specifically threads and flats, are identified. This model is useful for direct linking welding factors towards the expected consequences. 相似文献