Ultrasonic Assisted Thermal Direct Joining of Thermoplastic Composites and Aluminum for Multi Material Design

2019 ◽  
Vol 809 ◽  
pp. 329-334
Author(s):  
Michael Roderus ◽  
Dominic Woitun ◽  
Elmar Kroner
Keyword(s):  
Material Design ◽  
Surface Topology ◽  
Thermoplastic Composites ◽  
Process Window ◽  
Maximum Heat ◽  
Cycle Times ◽  
Lap Shear ◽  
Optimum Energy ◽  
Ultrasonic Assisted ◽  
Joining Process

The trend towards multi material design is strongly driven by improved functionality and decreased total weight of hybrid parts. Conventional joining techniques for metals and polymers usually require a complex process and are thus time consuming and expensive. A novel technique addressing these shortcomings is ultrasonic assisted thermal direct joining of metals and thermoplastic polymers. The metallic joining partner is laser pre-treated to generate a specific surface topology. The subsequent joining process is a combination of thermal direct joining and ultrasonic joining. This hybrid joining process results in short cycle times, and the maximum heat input is localized to the joining area. The joint performance was measured by lap shear tests, resulting in strength values exceeding 18 MPa, while the duration of the joining process was about 1.5 seconds. The relevant joining parameters were identified and a process window was obtained. The results indicate that there may be an optimum energy range for successful joining. An appropriate energy map may allow a deeper understanding of the process and enables prediction of process windows for various material combinations.

Thermoactivated Pinning - A Novel Joining Technique for Thermoplastic Composites

2012 ◽  
Vol 188 ◽  
pp. 176-181 ◽  
Author(s):  
Werner Hufenbach ◽  
Robert Kupfer ◽  
Andreas Hornig
Keyword(s):  
Mechanical Properties ◽  
High Volume ◽  
Tensile Tests ◽  
Thermoplastic Composites ◽  
Structural Effects ◽  
Short Cycle ◽  
Cycle Times ◽  
Lap Shear ◽  
Thermoplastic Matrix ◽  
Manufacturing Techniques

Due to their good mechanical properties and short cycle times during processing, textile-reinforced thermoplastic composites gain increasing relevance for high-volume lightweight applications. Beyond that, by exploiting its specific processing capabilities, this composite material enables a variety of novel manufacturing techniques, e.g. for assembling. In this paper a joining technique is presented, which utilises the meltability of the thermoplastic matrix to establish a material-adapted joining method by introducing slender metallic pins into the composite structure. The processing principle is described and structural effects in the joining zone are analysed by means of microscopy. The load bearing behaviour is characterised by tensile tests on double-lap-shear specimen.

scholarly journals Computed tomography investigation of the material structure in clinch joints in aluminium fibre-reinforced thermoplastic sheets

2021 ◽  
Author(s):  
Benjamin Gröger ◽  
Daniel Köhler ◽  
Julian Vorderbrüggen ◽  
Juliane Troschitz ◽  
Robert Kupfer ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
Material Design ◽  
Material Behavior ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Material Structure ◽  
Research Activities ◽  
Reinforced Thermoplastics ◽  
Joining Process

AbstractRecent developments in automotive and aircraft industry towards a multi-material design pose challenges for modern joining technologies due to different mechanical properties and material compositions of various materials such as composites and metals. Therefore, mechanical joining technologies like clinching are in the focus of current research activities. For multi-material joints of metals and thermoplastic composites thermally assisted clinching processes with advanced tool concepts are well developed. The material-specific properties of fibre-reinforced thermoplastics have a significant influence on the joining process and the resulting material structure in the joining zone. For this reason, it is important to investigate these influences in detail and to understand the phenomena occurring during the joining process. Additionally, this provides the basis for a validation of a numerical simulation of such joining processes. In this paper, the material structure in a joint resulting from a thermally assisted clinching process is investigated. The joining partners are an aluminium sheet and a thermoplastic composite (organo sheet). Using computed tomography enables a three-dimensional investigation that allows a detailed analysis of the phenomena in different joining stages and in the material structure of the finished joint. Consequently, this study provides a more detailed understanding of the material behavior of thermoplastic composites during thermally assisted clinching.

Modelling resistance welding of thermoplastic composites with a nanocomposite heating element

2020 ◽  
pp. 002199832095705
Author(s):  
David Brassard ◽  
Martine Dubé ◽  
Jason R Tavares
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Welding Process ◽  
Element Model ◽  
Resistance Welding ◽  
Thermoplastic Composites ◽  
Process Window ◽  
Cohesive Failure ◽  
Electrically Conductive ◽  
Lap Shear

Electrically conductive nanocomposite heating elements are being developed as a complement to traditional carbon fibre or stainless steel heating elements in resistance welding of thermoplastic composites. Here we present the development of a finite element model of the resistance welding process with these new heating elements, from which we establish a process window for high quality welded joints. The finite element model results were validated experimentally and a lap shear strength improvement of 28% is reported relative to previously published results. Fractography analysis of the broken joints revealed a thin-layer cohesive failure mode due to the brittleness of the nanocomposite heating elements.

scholarly journals Multi-Objective Optimization of Resistance Welding Process of GF/PP Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2560
Author(s):  
Guowei Zhang ◽  
Ting Lin ◽  
Ling Luo ◽  
Boming Zhang ◽  
Yuao Qu ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Welding Process ◽  
Welding Current ◽  
Resistance Welding ◽  
Thermoplastic Composites ◽  
Current Time ◽  
Process Factor ◽  
Welding Equipment ◽  
Lap Shear ◽  
Adhesive Connections

Thermoplastic composites (TPCs) are promising materials for aerospace, transportation, shipbuilding, and civil use owing to their lightweight, rapid prototyping, reprocessing, and environmental recycling advantages. The connection assemblies of TPCs components are crucial to their application; compared with traditional mechanical joints and adhesive connections, fusion connections are more promising, particularly resistance welding. This study aims to investigate the effects of process control parameters, including welding current, time, and pressure, for optimization of resistance welding based on glass fiber-reinforced polypropylene (GF/PP) TPCs and a stainless-steel mesh heating element. A self-designed resistance-welding equipment suitable for the resistance welding process of GF/PP TPCs was manufactured. GF/PP laminates are fabricated using a hot press, and their mechanical properties were evaluated. The resistance distribution of the heating elements was assessed to conform with a normal distribution. Tensile shear experiments were designed and conducted using the Taguchi method to evaluate and predict process factor effects on the lap shear strength (LSS) of GF/PP based on signal-to-noise ratio (S/N) and analysis of variance. The results show that current is the main factor affecting resistance welding quality. The optimal process parameters are a current of 12.5 A, pressure of 2.5 MPa, and time of 540 s. The experimental LSS under the optimized parameters is 12.186 MPa, which has a 6.76% error compared with the result predicted based on the S/N.

scholarly journals Clinching of Thermoplastic Composites and Metals—A Comparison of Three Novel Joining Technologies

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2286
Author(s):  
Benjamin Gröger ◽  
Juliane Troschitz ◽  
Julian Vorderbrüggen ◽  
Christian Vogel ◽  
Robert Kupfer ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Composite Material ◽  
Process Design ◽  
Failure Mechanisms ◽  
Thermoplastic Composites ◽  
Material Structure ◽  
Shear Tests ◽  
Load Bearing ◽  
Lap Shear ◽  
Resultant Material

Clinching continuous fibre reinforced thermoplastic composites and metals is challenging due to the low ductility of the composite material. Therefore, a number of novel clinching technologies has been developed specifically for these material combinations. A systematic overview of these advanced clinching methods is given in the present paper. With a focus on process design, three selected clinching methods suitable for different joining tasks are described in detail. The clinching processes including equipment and tools, observed process phenomena and the resultant material structure are compared. Process phenomena during joining are explained in general and compared using computed tomography and micrograph images for each process. In addition the load bearing behaviour and the corresponding failure mechanisms are investigated by means of single-lap shear tests. Finally, the new joining technologies are discussed regarding application relevant criteria.

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.

Joining sheets made from dissimilar materials by hole hemming

2022 ◽  
pp. 146442072110726
Author(s):  
Mohammad Mehdi Kasaei ◽  
Lucas FM da Silva
Keyword(s):  
Mechanical Properties ◽  
Research Work ◽  
Dissimilar Materials ◽  
Element Analysis ◽  
Lightweight Structures ◽  
Lap Shear ◽  
Gradual Failure ◽  
Peel Tests ◽  
Dp780 Steel ◽  
Joining Process

This research work presents a new joining process based on the hemming process for attaching sheets made from dissimilar materials with very different mechanical properties. The process is termed ‘hole hemming’ and consists in producing a mechanical interlock between pre-drilled holes which can be made anywhere on the sheets. The process is carried out in a two-stage operation including flanging the hole of an outer sheet and bending the flange over the hole of an inner sheet. First, the joining stages and the required tools are designed. Then, the joining of DP780 steel and AA6061-T6 aluminium alloy sheets, which are applied to manufacture lightweight structures in the automotive industries, is investigated using finite element analysis. Results show that the hole hemming process is able to successfully join these materials without fracture. The hole-hemmed joint withstood the maximum forces of 2.5 and 0.5 kN in single-lap shear and peel tests, respectively, and failed with hole bearing mode which is known as a gradual failure mode. The results demonstrate the applicability of the hole hemming process for joining dissimilar materials.

The Hybrid Compression Moulding of Structural Composite Materials for Automotive Applications

2020 ◽  
Vol 843 ◽  
pp. 3-8 ◽  
Author(s):  
Helena C. Simmonds ◽  
Neil C. Reynolds ◽  
Kenneth N. Kendall
Keyword(s):  
Composite Materials ◽  
Manufacturing Process ◽  
Fibre Composite ◽  
Material Design ◽  
High Volume ◽  
Ford Motor Company ◽  
Compression Moulding ◽  
Cycle Times ◽  
Class Project ◽  
Automotive Suspension

The Innovate-UK-funded Composite Lightweight Automotive Suspension System (CLASS) project, led by Ford Motor Company and partnered by Gestamp UK, GRM Consulting and WMG, investigated the use of carbon fibre reinforced composite materials to decrease the weight of a complex automotive rear suspension component in support of reduction in vehicle emissions. A multi-material design comprising discontinuous fibre composite (C-SMC), aligned fibre composite laminate (prepreg) and steel was developed. A high volume hybrid compression moulding manufacturing process was developed at WMG, achieving total press cycle times of around 5 minutes. Prototype parts were manufactured and evaluated using materials characterisation techniques to validate the manufacturing methods. The optimum C-SMC charge pattern was investigated to achieve complete fill with minimal pre-processing. Destructive and nondestructive analysis of the hybrid parts was performed to understand resultant hybrid material macrostructure. This innovative design and manufacturing process resulted in a component 35% lighter than the original multi-piece steel design.

Modelling and analysis of the thermal characteristic of thermoplastic composites from hybrid textiles during compression moulding

2019 ◽  
pp. 089270571987520
Author(s):  
Maximilian Koerdt ◽  
Michael Koerdt ◽  
Tobias Grobrüg ◽  
Marco Skowronek ◽  
Axel S Herrmann
Keyword(s):  
Optical Sensors ◽  
Thermal State ◽  
Process Analysis ◽  
Thermal Characteristic ◽  
Thermoplastic Composites ◽  
Compression Moulding ◽  
Cycle Times ◽  
Reinforced Plastics ◽  
Thermoset Resin ◽  
Thermoplastic Matrix

A promising strategy to decrease cycle times for manufacturing continuous-fibre–reinforced composites is processing of thermoplastic matrix systems due to their fast processability, since no cross-linking of molecular chains is required as for thermoset resin systems. Nevertheless, thermoplastic carbon fibre-reinforced plastics nowadays are predominantly manufactured with pre-impregnated sheet materials, which result in limited drapability and freedom of design. Hybrid textiles, consisting of thermoplastic and carbon fibres, can avoid these disadvantages. This class of reinforcements combines the drapability of dry textiles with thermoplastic matrices, which furthermore allow near net-shape processes. Relative shifting between the fibres and, consequently, draping is possible in a preforming step. The objective of this article is to expand our knowledge about hybrid textiles with regard to their thermal behaviour during compression moulding. Accordingly, the necessary parameters for modelling the thermal state of the dry textile and the impregnated laminate are investigated. Moreover, an in situ process analysis based on the reflection spectra of glass fibre-optical sensors, which are embedded inside the stacking, is investigated to provide information about the state of aggregation and to validate the thermal model.

Experimental Investigation of Chip Formation and Surface Topology in Ultrasonic-Assisted Milling of X20Cr13 Stainless Steel

2013 ◽  
Author(s):  
M. Mahdi Abootorabi Zarchi ◽  
M. R. Razfar ◽  
A. Abdullah
Keyword(s):  
Stainless Steel ◽  
Chip Formation ◽  
Milling Process ◽  
Surface Topology ◽  
Ultrasonic Vibrations ◽  
Machined Surface ◽  
Side Milling ◽  
One Dimensional ◽  
Digital Microscope ◽  
Ultrasonic Assisted

In the present paper, by using longitudinal one dimensional ultrasonic vibrations, characteristics of side milling of X20Cr13 martensitic stainless steel has been investigated. In order to experimentally investigate the chip formation and machined surface topology of workpiece, conventional milling (CM) and ultrasonic-assisted milling (UAM) processes have been applied and compared in certain cutting conditions. Imaging by digital microscope shows that applying ultrasonic vibrations on milling process leads to thinner and smaller formed chips and it also makes machined surface of workpece flatter. In both CM and UAM processes, as feed rate increases, chips become thicker and machine surface loses its flatness.

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