通过单搭接剪切试验的热塑性复合材料优惠券焊接接头的力学特性的超声波焊接
Summary
A straightforward procedure for ultrasonic welding of thermoplastic composite coupons for basic mechanical testing is described. Key characteristics of this ultrasonic welding process are the use of flat energy directors for simplified process preparation and the use of process data for the fast definition of optimum processing conditions.
Abstract
This paper presents a novel straightforward method for ultrasonic welding of thermoplastic-composite coupons in optimum processing conditions. The ultrasonic welding process described in this paper is based on three main pillars. Firstly, flat energy directors are used for preferential heat generation at the joining interface during the welding process. A flat energy director is a neat thermoplastic resin film that is placed between the parts to be joined prior to the welding process and heats up preferentially owing to its lower compressive stiffness relative to the composite substrates. Consequently, flat energy directors provide a simple solution that does not require molding of resin protrusions on the surfaces of the composite substrates, as opposed to ultrasonic welding of unreinforced plastics. Secondly, the process data provided by the ultrasonic welder is used to rapidly define the optimum welding parameters for any thermoplastic composite material combination. Thirdly, displacement control is used in the welding process to ensure consistent quality of the welded joints. According to this method, thermoplastic-composite flat coupons are individually welded in a single lap configuration. Mechanical testing of the welded coupons allows determining the apparent lap shear strength of the joints, which is one of the properties most commonly used to quantify the strength of thermoplastic composite welded joints.
Introduction
热塑性复合材料（TPC）具有待焊接的能力，这有助于其成本效益的生产。焊接需要的压力，以软化或熔化的接合表面的热塑性树脂并允许紧密接触并穿过焊接界面的热塑性聚合物链的后续相互扩散下局部加热。一旦分子相互扩散实现时，在压力下冷却巩固了焊接接头。几个焊接技术适用于其中的主要区别在于热1，但是，主要的“粘着”的机制， 即，分子的缠结源热塑性复合材料，保持不变。超声波焊接提供了非常短的焊接时间（在几秒钟的数量级），易于自动化并且这几乎是独立加固在热塑性复合衬底的类型。此外，它提供了用于原位监控2,3的可能性</sup>，它可用于在线路的质量保证或用于处理窗口4快速定义。热塑性复合材料的超声波焊接是大多点焊过程中，通过连续的超声波焊接更长接缝然而成功焊接已经报道在文献5。相对于电阻或感应焊接，超声波焊接尚未在工业上应用用于热塑性复合材料部件之间的结构接头为止。然而，显著的努力，目前正在致力于进一步为飞机应用热塑性复合材料结构超声波焊接的发展。
在超声波焊接，要接合的部分进行的静力和高频低幅的机械振动的组合横向于焊接界面，它通过表面和粘弹加热导致热量的产生。在焊接界面优先加热促进通过在表面上利用树脂突起待焊接其经受更高环状应变，并且因此更高的粘弹性加热，比基片6。力和振动施加在部分通过连接到一个媒体以及包括压电转换器和助力器的超声波列车超声焊极进行焊接。取决于其中超声焊极接触部分被接合点和焊接界面之间的距离，可以区别近场和远场超声波焊接之间进行。近场焊接（超声波发生器和焊接界面之间小于6毫米）是适用于更广范围的，而远场焊接的适用性到特定的热塑性材料的材料是高度依赖于材料的，进行声波6的能力。
超声波焊接过程可以分成三个主要阶段。首先，一个力建阶段，在此期间，sonotro德逐渐增加要被焊接的零件上的力，直到达到一定的触发力。在此阶段没有施加振动。其次，振动相位，一旦达到触发力，开始。在这个阶段，超声焊极振动在用于产生所需的焊接过程中的热量一定量的时间在规定的幅度。微处理器控制的超声波焊接机提供了多种选择，以控制振动阶段的持续时间，其中的时间（ 即直接控制），位移或能量（间接控制）。在这个阶段施加的力即焊接力，可以保持恒定并等于触发力或可振动的应用过程中逐渐改变。第三，凝固阶段，在此期间的焊接部分被允许冷却下一定的凝固力为一定的时间。在这个最后阶段无振动被应用。
焊接FORCE，振动幅度，振动频率和振动相位的持续时间（无论是直接或间接通过能量或位移控制）是控制热生成焊接参数。力，幅度和持续时间是用户定义的参数，而频率被固定为每个超声波焊接。凝固力和凝固时间，也焊接参数，不要在加热过程中与参数的休息，焊接接头的最终质量干预反而影响了巩固和一起。
本文提出了个人TPC券的近场超声波焊接在单圈配置随后的机械，单搭接剪切（LSS），测试按ASTM（美国测试和材料）D 1002标准的一种新型直接的方法。焊接试样的机械测试允许确定关节的表观搭接剪切强度，这是性能最COMM之一仅用于量化的热塑性复合材料的焊接接头7的强度。在本文中所述的焊接方法是基于三个主要支柱。首先，松平能量导向器以在焊接过程中的接合界面8,9用于优先发热。其次，通过超声波焊机提供的方法的数据被用于快速确定振动相位的最佳持续时间为特定的力/幅度组合2,4。第三，振动阶段的持续时间是间接通过超声焊极的位移，以确保焊接接头4的稳定的质量控制。这种焊接方法提供与问候国家的最先进的焊接工艺热塑性复合材料主要有以下新奇和优势：（1）通过使用松平能量导向，而不是传统的成型能源董事3的启用简化的样品制备，和（二）快速和c的基础上在原位过程监控，而不是普通的试验和错误的方法处理参数OST效率定义。虽然在本文中描述的方法，向得到一个非常具体和简单的焊接几何面向它可以作为一个基础，以定义实际部件的焊接过程。在这种情况下，一个主要的区别来自能源主任约束流结果在单圈券重叠的四个边缘反对自由流动。
Protocol
Representative Results
Discussion
在上一节中提供的结果表明，在本文中用于热塑性复合单搭接券用于机械测试的目的的超声波焊接所提出的简单的方法的适当性。以下段落讨论的结果如何验证了该方法的三大支柱， 即采用平松能源董事，使用过程中的反馈来定义振动和使用位移控制的最佳时间，还有的适用性和局限性的技术。
至于第一支柱，扁平能量导向器被示为允许在TPC券的成功焊接。在的?…
Divulgazioni
The authors have nothing to disclose.
Acknowledgements
The authors would like to acknowledge the support of Ten Cate Advanced Materials in the form of free material supply to the work described in this paper.
Materials
| Material/Reagent | |||
| Cetex® carbon fiber / polyetherimide (CF/PEI) 5 harness satin prepreg | TenCate Advanced Composites (www.tencate.com) | Contact vendor | Material used in this study for the specimens. |
| PFQD solvent degreaser | PT Technologies Europe (now Socomore – www.socomore.com) | Contact vendor | Solvent degreaser for cleaning the specimens and energy directors. |
| Cotton cloths | – | – | For general cleaning purposes. No specific vendor was used. |
| 0.25 mm PEI film | TenCate Advanced Composites (www.tencate.com) | Contact vendor | Thin film used as energy director. |
| Adhesive tape | Airtech Advanced Materials Group (www.airtechintl.com) | 1" x 72 yds MFG # 327402 Contact vendor for catalog number | Used to attach energy director to bottom sample for ultrasonic welding. |
| Name | Company | Catalog Number | Comments |
| Equipment | |||
| Vötsch oven | Vötsch Industrietechnik (www.voetsch-ovens.com) | VTU 60/60 – Contact vendor for specific catalog number | Oven used to dry PEI film (energy directors) and PEI specimens before welding. |
| Rinco Dynamic 3000 ultrasonic welder | Aeson BV (www.aeson.nl/en/) | Contact vendor | 20 kHz ultrasonic welding machine used for the welding experiments. Several sonotrode sizes available. Contact vendor for details. ACUCapture software included. |
| Zwick/Roell universal testing machine | Zwick (www.zwick.com) | Z250 – Contact vendor for specific catalog number | Universal testing machine with maximum load of 250 kN used for single lap shear strength measurements. |
Riferimenti
- Yousefpour, A., Hojjati, M., Immarigeon, J. P. Fusion bonding/welding of thermoplastic composites. J Thermoplast Compos. 17, 303-341 (2004).
- Villegas, I. F. In situ monitoring of ultrasonic welding of thermoplastic composites through power and displacement data. J Thermoplast Compos. 28 (1), 66-85 (2015).
- Benatar, A., Gutowski, T. G. Ultrasonic welding of PEEK Graphite APC-2 composites. Polym Eng Sci. 29 (23), 1705-1721 (1989).
- Villegas, I. F. Strength development versus process data in ultrasonic welding of thermoplastic composites with flat energy directors and its application to the definition of optimum processing parameters. Compos Part A-Appl S. 65, 27-37 (2014).
- Lu, H. M., Benatar, A., He, F. G. Sequential ultrasonic welding of PEEK/graphite composite plates. Proceedings of the ANTEC’91 Conference. , 2523-2526 (1991).
- Potente, H. Ultrasonic welding – principles & theory. Mater Design. 5, 228-234 (1984).
- Stavrov, D., Bersee, H. E. N. Resistance welding of thermoplastic composites – an overview. Compos Part A-Appl S. 36, 39-54 (2005).
- Villegas, I. F., Valle-Grande, B., Bersee, H. E. N., Benedictus, R. A comparative evaluation between flat and traditional energy directors for ultrasonic welding of CF/PPS thermoplastic composites. Compos Interface. , (2015).
- Levy, A., Le Corre, S., Villegas, I. F. Modelling the heating phenomena in ultrasonic welding of thermoplastic composites with flat energy directors. J Mater Process Tech. , 1361-1371 (2014).
- Shi, H., Villegas, I. F., Bersee, H. E. N. Strength and failure modes in resistance welded thermoplastic composite joints: effect of fibre-matrix adhesion and fibre orientation. Compos Part A-Appl S. 55, 1-10 (2013).
- Villegas, I. F., Bersee, H. E. N. Ultrasonic welding of advanced thermoplastic composites. An investigation on energy-directing surfaces. Adv Polym Tech. 29 (2), 113-121 (2010).
- Harras, B. K., Cole, C., Vu-Khanh, T. Optimization of the ultrasonic welding of PEEK-carbon composites. J Reinf Plast Comp. 15 (2), 174-182 (1996).
