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.

scholarly journals Development of a new joining technology for hybrid joints of sheet metal and continuous fiber-reinforced thermoplastics

2021 ◽  
Author(s):  
Dimitri Krassmann ◽  
Elmar Moritzer
Keyword(s):  
Sheet Metal ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Stress Concentrations ◽  
Joining Technology ◽  
Hybrid Joints ◽  
Process Reliability ◽  
Fiber Breaks ◽  
Reinforced Thermoplastics ◽  
Joining Process

AbstractPunctiform mechanical joining technologies, such as riveting, clinching, or screwing, which are widely used in sheet metal processing, are frequently applied because they have been established for many years. Depending on the process, they offer a variety of advantages such as one-sided accessibility, re-detachability, and no need for pre-punching operations or auxiliary joining elements. In addition, the processes often guarantee a high process reliability and extensive process monitoring. However, with thermoplastic composites, they lead to considerable stress concentrations at the joint due to the fibers. Undesirable fiber and inter-fiber breaks then result. With the development of the novel joining technology of joint stamp riveting, an improvement is achieved in this situation that has been described for hybrid joints on components made of thermoplastic composites and metal sheets. The joining principle is based on the formation of a form lock between the joining partners. The thermoplastic composite is thermomechanically formed by means of a joint stamp without using an auxiliary joining element. Within the scope of a research project, the joining process was characterized with regard to the structure of the joining spot, the geometry of the forming tools, and also the mechanical properties for purposes of analyzing and designing the joining process.

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.

Quality Controlled UD Tape Production for the Individualised Production of Load Optimised Thermoplastic Composite Parts

2017 ◽  
Vol 742 ◽  
pp. 90-95
Author(s):  
Christian Hopmann ◽  
Christian Beste ◽  
Markus Hildebrandt ◽  
Arne Boettcher ◽  
Kai Fischer
Keyword(s):  
Manufacturing Process ◽  
Individual Component ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Quality Data ◽  
Fibre Distribution ◽  
Weight Content ◽  
Plastics Processing ◽  
Component Manufacturing ◽  
Joining Process

A flexible and individual component manufacturing process for thermoplastic composites (TPC) has been developed at the Institut fuer Kunststoffverarbeitung in Industrie und Handwerk an der RWTH Aachen (Institute of Plastics Processing (IKV) at RWTH Aachen University). The process consists of a quality controlled tape production and a combined forming and joining process with additive manufactured functional structures. This paper describes the requirements for the unidirectional (UD) tape properties and the quality controlled tape production line in order to allow for a flexible and individual component manufacturing of load optimised thermoplastic composite parts. Besides the UD tape geometry and fibre impregnation quality an even fibre distribution over the width of the UD tape is an important characteristic. Results of investigations regarding the online measured quality data (fibre distribution) and offline measured UD tape properties (local fibre weight content) are presented and discussed.

Advances in In Situ SiC Growth Analysis Using Cone Beam Computed Tomography

2019 ◽  
Vol 963 ◽  
pp. 5-9 ◽  
Author(s):  
Michael Salamon ◽  
Matthias Arzig ◽  
Norman Uhlmann ◽  
Peter J. Wellmann
Keyword(s):  
Computed Tomography ◽  
Three Dimensional ◽  
In Situ Monitoring ◽  
Material Structure ◽  
Two Dimensional ◽  
Accurate Analysis ◽  
X Ray ◽  
Characteristic Features ◽  
Third Dimension

Computed Tomography is becoming a valuable method for the in-situ monitoring of vapor grown silicon carbide single crystals [1]. Already the two-dimensional X-ray radiography has shown the potential of surveilling the growth process [2] and its characteristic features like the evolution of the facet, the crystal volume or the source material structure from one imaging plane. Even though the demands on imaging capability of the applied X-ray components used for a tomographic analysis are higher than for two-dimensional imaging, the extension of this method to the third dimension is highly beneficial. It allows investigating the full geometry and three-dimensional location of the features and by this provides a more accurate analysis. In this contribution we present the physical characteristics and the latest advances of our technique for the visualization of facets.

3D Predictive Model for Controlled Resistance Welding of Composites for Manufacturing Applications

2009 ◽  
Author(s):  
Imad Zammar ◽  
Iraj Mantegh ◽  
Mojtaba Ahmadi
Keyword(s):  
Weld Seam ◽  
Three Dimensional ◽  
Infrared Camera ◽  
Temporal Variations ◽  
Resistance Welding ◽  
Thermoplastic Composites ◽  
Voltage Source ◽  
Transfer Model ◽  
Manufacturing Applications ◽  
Joining Process

A three-dimensional transient heat transfer model is developed for a sequential joining process (resistance welding) applied on thermoplastic composites. This process involves with moving a voltage source along a heating element that conducts the power throughout a resistive mesh, generating heat and melts and bounds two composite surfaces. The model developed here is used to predict the spatial and temporal variations in the current and temperature over the weld seam for different set of input variables. The model integrates both the resistive and thermal behaviours of components involved. The significance of this modeling approach is that it captures the movement of the electrical connection, simulating a sequential joining process along a continuous weld seam. The modeling results are compared with experimental data obtained by thermocouples and infrared camera, and accurately predict the trend of variations in weld temperature.

The Effect of Infill Patterns and Annealing on Mechanical Properties of Additively Manufactured Thermoplastic Composites

2017 ◽  
Author(s):  
Sridher Rangisetty ◽  
Larry D. Peel
Keyword(s):  
Best Practices ◽  
Composite Structures ◽  
Fused Deposition Modeling ◽  
Mechanical Performance ◽  
Short Fiber ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Limited Information ◽  
Fused Deposition ◽  
Reinforced Thermoplastics

Recently, carbon fiber-reinforced thermoplastics (CFRTPs) have become popular choices in desktop-based additive manufacturing, but there is limited information on their effective usage. In Fused Deposition Modeling (FDM), a structure is created by layers of extruded beads. The degree of bonding between beads, bead orientation, degree of interlayer bonding, type of infill and the type of material, determines overall mechanical performance. The presence of chopped fibers in thermoplastics increases melt viscosity, changes coefficients of thermal expansion, may have layer adhesion issues, and causes increased wear on nozzles, which makes FDM fabrication of thermoplastic composites somewhat different from neat thermoplastics. In the current work, best practices and the effect of annealing and infill patterns on the mechanical performance of FDM-fabricated composite parts were investigated. Materials included commercially available PLA, CF-PLA, ABS, CF-ABS, PETG, and CF-PETG. Two sets of ASTM D638 tensile and ASTM D790 flexural test specimens with 3 different infill patterns and each material were fabricated, one set annealed, and all tested. Anisotropic behavior was observed as a function of infill pattern. As expected, strength and stiffness were higher when the beads were oriented in the direction of the load, even for neat resins. All fiber-filled tensile results showed an increase in stiffness, but surprisingly, not in strength (likely due to very short fiber lengths). Tests of annealed specimens resulted in clear improvements in tensile strength, tensile stiffness and flexural strength for PLA, CF-PLA, and PETG, CF-PETG but a reduction in flexural stiffness. Also, annealing resulted in mixed improvements for ABS and CF-ABS and is only useful in certain infill patterns. This work also establishes ‘Best Practices’ of FDM-type fabrication of thermoplastic composite structures and documents the minimum critical fiber lengths and fiber fractions of several CF-filled FDM filaments.

scholarly journals Insight into 3D micro-CT data: exploring segmentation algorithms through performance metrics

2017 ◽  
Vol 24 (5) ◽  
pp. 1065-1077 ◽  
Author(s):  
Talita Perciano ◽  
Daniela Ushizima ◽  
Harinarayan Krishnan ◽  
Dilworth Parkinson ◽  
Natalie Larson ◽  
...  
Keyword(s):  
Image Segmentation ◽  
Performance Metrics ◽  
Imaging Modality ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Ground Truth ◽  
Material Design ◽  
Material Structure ◽  
Segmentation Algorithms ◽  
Micro Tomography

Three-dimensional (3D) micro-tomography (µ-CT) has proven to be an important imaging modality in industry and scientific domains. Understanding the properties of material structure and behavior has produced many scientific advances. An important component of the 3D µ-CT pipeline is image partitioning (or image segmentation), a step that is used to separate various phases or components in an image. Image partitioning schemes require specific rules for different scientific fields, but a common strategy consists of devising metrics to quantify performance and accuracy. The present article proposes a set of protocols to systematically analyze and compare the results of unsupervised classification methods used for segmentation of synchrotron-based data. The proposed dataflow for Materials Segmentation and Metrics (MSM) provides 3D micro-tomography image segmentation algorithms, such as statistical region merging (SRM),k-means algorithm and parallel Markov random field (PMRF), while offering different metrics to evaluate segmentation quality, confidence and conformity with standards. Both experimental and synthetic data are assessed, illustrating quantitative results through the MSM dashboard, which can return sample information such as media porosity and permeability. The main contributions of this work are: (i) to deliver tools to improve material design and quality control; (ii) to provide datasets for benchmarking and reproducibility; (iii) to yield good practices in the absence of standards or ground-truth for ceramic composite analysis.

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.

On programming of polyvinylidene fluoride–limestone composite for four-dimensional printing applications in heritage structures

2021 ◽  
pp. 146442072110442
Author(s):  
Vinay Kumar ◽  
Rupinder Singh ◽  
Inderpreet Singh Ahuja
Keyword(s):  
Surface Properties ◽  
Polyvinylidene Fluoride ◽  
Chemical Weathering ◽  
Carbonic Acid ◽  
Three Dimensional ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Public Authorities ◽  
Maintenance And Repair ◽  
Dimensional Printing

Heritage structures are under the effect of chemical, physical and biological weathering, and out of these common effects, chemical weathering has a significant impact (as it results in nifty formation and causes fractures in heritage structures). Chemical weathering may include carbonation, oxidation, hydration, hydrolysis, and acidification. Most heritage structures are made up of limestone, which is more susceptible to carbonation. According to the reported literature, commercial practices for the maintenance and repair of these heritage structures use epoxy-based solutions, which may not be best suited as per the various regulations imposed by different government/public authorities. But so far little has been reported on the use of innovative, programmable thermoplastic composites for the maintenance and repair of such structures. This study highlights the effect of chemical treatment (as a stimulus) using a one-way programming of three-dimensional-printed thermoplastic composite-based (polyvinylidene fluoride–6% limestone) functional prototype as a solution for the maintenance and repair of heritage structures (grade III). For one-way programming, three-dimensional-printed substrate is exposed to dimethylformamide, and the changes in morphological and surface properties are noticed. After this, carbonation cycle (with carbonic acid) is performed and the changes in morphological and surface properties are compared to ascertain the stimulus effect for one-way programming (of polyvinylidene fluoride–6% limestone composite). The results of the study outline that the prepared composite may be programmed by controlling the exposure of dimethylformamide and carbonic acid (as a stimulus). Further best settings for preparing feedstock filament (for three-dimensional printing of functional prototypes in case of a selected heritage structure) are 200 °C screw temperature, 0.35 N m torque and an applied load of 8 kg in terms of better mechanical properties and shore D hardness.

Transverse Impact and Tensile Behavior of the Three-Dimensional Woven Fabric Reinforced Thermoplastic Composites

2010 ◽  
Vol 129-131 ◽  
pp. 1238-1243 ◽  
Author(s):  
Wei Gou Dong ◽  
Hai Ling Song
Keyword(s):  
Composite Materials ◽  
Damage Tolerance ◽  
Three Dimensional ◽  
Thermoplastic Composite ◽  
Woven Fabric ◽  
Thermoplastic Composites ◽  
Two Dimensional ◽  
Energy Impact ◽  
Commingled Yarns ◽  
The Impact

Two forms of perform were prepared by a Glass fiber/Polypropylene fiber commingled yarn. One was a three-dimensional woven fabric with an angle-interlock structure, and another was a two-dimensional plain woven fabric laminate. The three-dimensional woven fabric reinforced thermoplastic composites(3-DWRC) and two-dimensional woven fabric reinforced thermoplastic composites(2-DWRC) were fabricated by hot-press process. The Impact and tensile performances of both 3-DWRC and 2-DWRC were examined. Compared to the 2-DWRC, the 3-DWRC have better impact properties, the energy required to initiate cracks, the threshold force of the first oscillation and maximum load increased by 41.90%, 54.41%, 38.75% respectively under the low-energy impact conditions. The tensile tests shown that the 3-DWRC presented batter fracture toughness than the 2-DWRC. The use of thermoplastic composites is growing rapidly because of their excellent properties, a high toughness and damage tolerance, short processing cycles, and the ability to be reprocessed. But thermoplastic materials usually have a difficulty to impregnate between reinforcing fibers, due to high melt polymer viscosity. It is a technology innovation that the commingled yarns composed of reinforced fibers and thermoplastic fibers are used as prepreg for thermoplastic composite materials. Because thermoplastic fiber and reinforced fiber are closely combined, which reduces distances of resin’s infiltration, this can effectively overcome the difficulties of resin’s impregnation. The commingled yarns can be woven and knitted, and can facilitate the processing of complex structural composites. Three-dimensional fabrics reinforced composites are ideal materials with excellent integrity because it is linked with yarns between layers. Its shearing strength between layers, damage tolerance and reliability are better than the two-dimensional fabric laminated composites. At present, the researches of thermoplastic materials with two-dimensional fabric reinforced structure made from commingled yarns are much more, such as manufacturing technology, material properties ,effects of process conditions on properties, relationship between structures and properties, and so on [1-8]. However, only a few studies appear in literature on the structure-property relationships of three-dimensional fabric reinforced thermoplastic composite materials made of commingled yarns [9-10]. Byun, Hyung Joon et al. [9] undertook the impact test and the tensile test on 3-D woven thermoplastic composite materials and 2-D plain woven laminate which is made by CF/PEEK mixed yarn. Dong Weiguo and Huang Gu[10] studied the porosity, tensile and bending properties on 3-D woven thermoplastic composites which make from core-spun yarn containing glass fibers and polypropylene fibers. The aim of this study was to investigate the impact behavior of and tensile properties of 3-D woven fabric thermoplastic composites made by a GF/PP commingled yarns. Attempts was made to identify the damage mode of the 3-D woven fabric thermoplastic composites under the low energy impact and tensile conditions.

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