Investigation of ultrasonically welded thermoplastic composite joints using netlike energy directors

2021 ◽  
pp. 1-23
Author(s):  
Kaifeng Wang ◽  
Xue Wang ◽  
Miran Yi ◽  
Yang Li ◽  
Jingjing Li
Keyword(s):  
Welding Process ◽  
Cyclic Strain ◽  
Fracture Morphology ◽  
Ultrasonic Welding ◽  
Thermoplastic Composite ◽  
Shear Load ◽  
Cross Sectional ◽  
Pull Out ◽  
Joint Fracture ◽  
Joint Quality

Abstract This paper proposes a netlike energy director (ED) made of carbon fiber-reinforced thermoplastic (CFRP) composites to improve the ultrasonic welding energy efficiency. To explore the benefits of using netlike EDs, the joint qualities with flat EDs and without EDs are included for references. Also, the influence of the netlike ED geometry (i.e., hexagonal nets with different side lengths and thicknesses) on weld attributes and joint quality are investigated in terms of joint cross-sectional microstructure, fracture morphology, and maximum shear load. It is found that for both the netlike and flat EDs, the welding process can be accelerated compared to the one without EDs, which is caused by the concentration of welding energy into the expected welding region and the avoidance of welding edges introduced by surface curvature. Meanwhile, compared with flat EDs, the maximum shear loads of the joints with netlike EDs are improved, introduced by the decrease of the contact area and consequent higher cyclic strain, resulting in more melted materials during the ultrasonic welding process. However, with the increasing of the netlike ED thickness, more porosities are generated in the welding layer leading to reduced bonded region and decrease of the maximum shear load. From the joint fracture morphology analysis, it is found that the netlike EDs introduces carbon fibers in the welding layer, and the fracture modes include fiber-matrix debonding and fiber pull-out in addition to polymer fracture, confirming the feasibility of improving joint quality by introducing CFRP netlike EDs.

The Effects of Energy Director Shape on Temperature Field during Ultrasonic Welding of Thermoplastic Composites

2007 ◽  
Vol 353-358 ◽  
pp. 2007-2010 ◽  
Author(s):  
Jiu Chun Yan ◽  
Xiao Lin Wang ◽  
Rui Qi Li ◽  
Hui Bin Xu ◽  
Shi Qin Yang
Keyword(s):  
Welding Process ◽  
Element Model ◽  
Ultrasonic Welding ◽  
The Body ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Glass Transformation ◽  
Different Shapes ◽  
Energy Director ◽  
Different Order

The ultrasonic welding process of thermoplastic composite with different shapes of energy director (ED) was simulated using finite element model. The results show that the highest temperature zone locates at the tip for the semicircular and triangular ones, and locates at the middle height for the trapezoid one. But it does not locate at the body of ED for the rectangular one. Energy director with different shapes lead to the temperature rising rate at different order of amplitude. The welding amplitude has same influence on the four shapes of ED. The temperature distributing profiles of semicircular, triangular and trapezoid ED keep constant from the initial welding time to that when the highest temperature on joints arrives the temperature of glass transformation (Tg), but the profile for rectangular ED changes greatly.

Comparison of Properties on Withdrawing and Refill Friction Stir Spot Welding Joints

2014 ◽  
Vol 633-634 ◽  
pp. 601-606
Author(s):  
Xi Jing Wang ◽  
Xiao Long Wang ◽  
Zhong Ke Zhang ◽  
Wen Xia Jing
Keyword(s):  
Spot Welding ◽  
Fracture Morphology ◽  
Friction Stir Spot Welding ◽  
Shear Load ◽  
Tensile Shear ◽  
Optimal Process ◽  
Cross Sectional ◽  
Friction Stir ◽  
Welding Joints ◽  
The Cross

The 2 mm sheet of 6082 - T6 aluminum alloy was carried to develop refill friction stir welding and withdrawing friction stir spot welding,the forming of solder joints , the cross-sectional microstructure and fracture morphology of welding joints were observed and analyzed, the cross-sectional microhardness of welding joints were tested. Tensile shear load and fracture mode were contrasted simultaneously. The results showed that smooth surface and free of macroscopic defects of welding joints could be obtained in both welding type. Tensile shear load of WFSSW was up to 10.28kN under the optimal process parameters greater than RFSSW’s 8.62kN.

scholarly journals ROBOTIC SEQUENTIAL ULTRASONIC WELDING OF THERMOPLASTIC COMPOSITES: PROCESS DEVELOPMENT AND TESTING

2021 ◽  
Author(s):  
ABHAS CHOUDHARY, ◽  
IRENE FERNANDEZ
Keyword(s):  
Welded Joints ◽  
Industrial Robot ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Robot Arm ◽  
Spot Welds ◽  
Robotic Platform ◽  
Lap Shear

Multi-spot sequential ultrasonic welding is a promising joining technique for fibre-reinforced thermoplastic composites structures (TPC). In existing research on the multi-spot sequential ultrasonic welding process, welds are produced through the use of a static table-top welding machine, at a coupon level. However, in order to apply this joining technology to large structures, the welding process needs to be up-scaled through the use of a robotic platform. At the Smart Advanced Manufacturing (SAM|XL) automation field lab and TU Delft Aerospace Engineering, a robotic sequential ultrasonic welding system has been developed. The system consists of a welding end-effector (EEF) equipped with various sensors that enable online process monitoring and control, which can be mounted on an industrial robot arm to perform sequential multi-spot welds. The goal of this study was to assess the welding performance of the ultrasonic welding EEF, which was mounted on an industrial KUKA KR210 R2700 Extra 10-axis robot arm, by comparing it to the performance of welds produced through the static table-top machine. In this study, single and multi-spot welds were produced on thermoplastic composite coupons, based on welding conditions which were defined in a preliminary study. The robot and EEF deflections observed during the welding process were analysed to assess the deviation of the robotic process from the static one. The feedback obtained from the welding equipment in terms of consumed power and tool displacement in both processes was also compared. The weld quality was assessed though single lap shear testing of the welded joints as well as fractography of the failure surface. The results of this study indicate that the developed robotic welding process is quite robust and is capable of producing high-quality sequential welded joints despite significant system deflections observed during the welding process. Slightly lower welded area and weld strength was obtained which can be attributed to the system deflections. Finally, the results indicate that the use of a stiffer robotic platform as well as a stiffer EEF construction will result in better system rigidity and weld spot positioning accuracy, and through this the welding process shows promise for large-scale industrial applications.

Research on Resistance Spot Welding Process of Hot-Stamped Steel BTR165

2014 ◽  
Vol 1063 ◽  
pp. 112-119
Author(s):  
You Zhen Fang
Keyword(s):  
Resistance Spot Welding ◽  
Spot Welding ◽  
Welding Process ◽  
Fracture Morphology ◽  
Tensile Failure ◽  
Tensile Fracture ◽  
Resistance Spot ◽  
Pull Out ◽  
Fracture Appearance ◽  
Hot Stamped Steel

Resistance spot welding of BTR165 was applied to study property of its joint by using power-frequency alternating current welding equipments. The tension strength, hardness distribution, microstructure and tensile fracture appearance were analyzed. The test results show that the hot-stamped steel has good weldability and could obtain better performance by optimizing technology. The microstructure of spot welded metal is martensite (M), tensile failure mode is button pull-out fracture, The fracture morphology has plastic dimple characteristic.

scholarly journals Static ultrasonic welding of carbon fibre unidirectional thermoplastic materials and the influence of heat generation and heat transfer

2021 ◽  
pp. 002199832097681
Author(s):  
F Köhler ◽  
IF Villegas ◽  
C Dransfeld ◽  
A Herrmann
Keyword(s):  
Cross Sections ◽  
Weld Line ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Thermoplastic Composites ◽  
Squeeze Flow ◽  
Anisotropic Flow ◽  
Lap Shear ◽  
Anisotropic Thermal Conductivity ◽  
Edge Defects

Ultrasonic welding is a promising technology to join fibre-reinforced thermoplastic composites. While current studies are mostly limited to fabric materials the applicability to unidirectional materials, as found in aerospace structures, would offer opportunities for joining primary aircraft structures. However, due to the highly anisotropic flow of a molten unidirectional ply undesired squeeze flow phenomena can occur at the edges of the weld overlap. This paper investigates how the fibre orientation in the plies adjacent to the weld line influences the welding process and the appearance of edge defects. Ultrasonic welding experiments with different layups and energy director configurations were carried out while monitoring temperatures at different locations inside and outside the weld overlap. The joints were characterized by single lap shear tests, analysis of corresponding fracture surfaces and microscopic cross-sections. Results showed that the anisotropic flow and the anisotropic thermal conductivity of the plies adjacent to the weld line have a distinct effect on the appearance and location of edge defects. By using energy directors that cover only part of the weld overlap area a new approach was developed to mitigate edge defects caused by the highly directional properties of the unidirectional plies.

Cold Metal Transfer Spot Joining of AA6061-T6 to Galvanized DP590 Under Different Modes

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
HaiYang Lei ◽  
YongBing Li ◽  
Blair E. Carlson ◽  
ZhongQin Lin
Keyword(s):  
Heat Input ◽  
Mechanical Performance ◽  
Welding Process ◽  
High Strength ◽  
Metal Transfer ◽  
Cold Metal Transfer ◽  
Spot Joining ◽  
Predrilled Hole ◽  
Joint Quality ◽  
Cold Metal

In order to meet the upcoming regulations on greenhouse gas emissions, aluminum use in the automotive industry is increasing. However, this increase is now seen as part of a multimaterial strategy. Consequently, dissimilar material joints are a reality, which poses significant challenges to conventional fusion joining processes. To address this issue, cold metal transfer (CMT) spot welding process was developed in the current study to join aluminum alloy AA6061-T6 as the top sheet to hot dip galvanized (HDG) advanced high strength steel (AHSS) DP590 as the bottom sheet. Three different welding modes, i.e., direct welding (DW) mode, plug welding (PW) mode, and edge plug welding (EPW) mode were proposed and investigated. The DW mode, having no predrilled hole in the aluminum top sheet, required concentrated heat input to melt through the Al top sheet and resulted in a severe tearing fracture, shrinkage voids, and uneven intermetallic compounds (IMC) layer along the faying surface, leading to poor joint properties. Welding with the predrilled hole, PW mode, required significantly less heat input and led to greatly reduced, albeit uneven, IMC layer thickness. However, it was found that the EPW mode could homogenize the welding heat input into the hole and thus produce the most stable welding process and best joint quality. This led to joints having an excellent joint morphology characterized by the thinnest IMC layer and consequently, best mechanical performance among the three modes.

Experimental Investigations on Aluminium Ultrasonic Welding Parameters

2014 ◽  
Vol 657 ◽  
pp. 306-310
Author(s):  
Lăcrămioara Apetrei ◽  
Vasile Rață ◽  
Ruxandra Rață ◽  
Elena Raluca Bulai
Keyword(s):  
Microstructural Analysis ◽  
Base Material ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Experimental Investigations ◽  
Welding Parameters ◽  
Material Structure ◽  
Welding Temperature ◽  
Wide Range ◽  
Made In

Research evolution timely tendencies, in the nonconventional technologies field, are: manufacture conditions optimization and complex equipments design. The increasing of ultrasonic machining use, in various technologies is due to the expanding need of a wide range materials and high quality manufacture standards in many activity fields. This paper present a experimental study made in order to analyze the welded zone material structure and welding quality. The effects of aluminium ultrasonic welding parameters such as relative energy, machining time, amplitude and working force were compared through traction tests values and microstructural analysis. Microhardness tests were, also, made in five different points, two in the base material and three in the welded zone, on each welded aluminium sample. The aluminum welding experiments were made at the National Research and Development Institute for Welding and Material Testing (ISIM) Timişoara. The ultrasonic welding temperature is lower than the aluminium melting temperature, that's so our experiments reveal that the aluminium ultrasonic welding process doesn't determine the appearance of moulding structure. In the joint we have only crystalline grains deformation, phase transformation and aluminium diffusion.

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Hang Li ◽  
Hongseok Choi ◽  
Chao Ma ◽  
Jingzhou Zhao ◽  
Hongrui Jiang ◽  
...  
Keyword(s):  
Thin Film ◽  
Heat Flux ◽  
Heat Generation ◽  
Welding Process ◽  
Ultrasonic Welding ◽  
Transient Temperature ◽  
Monitoring And Control ◽  
Change Rate ◽  
Flux Change ◽  
And Control

Process physics understanding, real time monitoring, and control of various manufacturing processes, such as battery manufacturing, are crucial for product quality assurance. While ultrasonic welding has been used for joining batteries in electric vehicles (EVs), the welding physics, and process attributes, such as the heat generation and heat flow during the joining process, is still not well understood leading to time-consuming trial-and-error based process optimization. This study is to investigate thermal phenomena (i.e., transient temperature and heat flux) by using micro thin-film thermocouples (TFTC) and thin-film thermopile (TFTP) arrays (referred to as microsensors in this paper) at the very vicinity of the ultrasonic welding spot during joining of three-layered battery tabs and Cu buss bars (i.e., battery interconnect) as in General Motors's (GM) Chevy Volt. Microsensors were first fabricated on the buss bars. A series of experiments were then conducted to investigate the dynamic heat generation during the welding process. Experimental results showed that TFTCs enabled the sensing of transient temperatures with much higher spatial and temporal resolutions than conventional thermocouples. It was further found that the TFTPs were more sensitive to the transient heat generation process during welding than TFTCs. More significantly, the heat flux change rate was found to be able to provide better insight for the process. It provided evidence indicating that the ultrasonic welding process involves three distinct stages, i.e., friction heating, plastic work, and diffusion bonding stages. The heat flux change rate thus has significant potential to identify the in-situ welding quality, in the context of welding process monitoring, and control of ultrasonic welding process. The weld samples were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to study the material interactions at the bonding interface as a function of weld time and have successfully validated the proposed three-stage welding theory.

scholarly journals Monitoring of the ultrasonic welding process

2020 ◽  
Author(s):  
M. Kornely ◽  
J. Rittmann ◽  
M. Kreutzbruck
Keyword(s):  
Welding Process ◽  
Ultrasonic Welding

Investigation of the Cleaning and Welding Steps From the Friction Element Welding Process

2017 ◽  
Author(s):  
Jamie D. Skovron ◽  
Brandt J. Ruszkiewicz ◽  
Laine Mears ◽  
Tim Abke ◽  
Ankit Varma ◽  
...  
Keyword(s):  
Weld Zone ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Process Time ◽  
Friction Element ◽  
Joint Quality ◽  
Head Height ◽  
Friction Element Welding ◽  
Step Parameters

The requirement of increased fuel economy standards has forced automakers to incorporate multi-materials into their current steel dominant vehicles in order to lightweight their fleets. Technologies such as Self Piercing Rivets and Flow Drill Screws are currently implemented for joining aluminum to high-strength steels but only one-technology is viable for joining aluminum to ultra-high-strength steels without pre-holes, namely Friction Element Welding. This study is aimed at investigating how variations in the cleaning and welding steps of the Friction Element Welding process influence joint quality. A design of experiment was conducted to understand the influence of key process parameters (endload, spindle RPM, and relative distance) during these steps on the pre-defined joint quality metrics of head height, weld zone diameter, under-head fill area, temperature, and microhardness. It is found that cleaning step parameters have the greatest influence on process time and energy consumption, while welding step parameters greatly influence maximum torque on the element, head height, and underhead fill, with both cleaning force and weld force influencing weld diameter, all parameters influence temperature.

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