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 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.

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.

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 New Joining Technology for Optimized Metal/Composite Assemblies

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Holger Seidlitz ◽  
Lars Ulke-Winter ◽  
Lothar Kroll
Keyword(s):  
Process Management ◽  
High Strength ◽  
Galvanized Steel ◽  
Thermoplastic Composites ◽  
Metal Composite ◽  
The Novel ◽  
Reinforced Plastics ◽  
Joining Technology ◽  
Hybrid Joints ◽  
Fiber Reinforced Plastics

The development of a new joining technology, which is used to manufacture high strength hybrid constructions with thermoplastic composites (FRP) and metals, is introduced. Similar to natural regulation effects at trees, fibers around the FRP joint become aligned along the lines of force and will not be destroyed by the joining process. This is achieved by the local utilization of the specific plastic flow properties of the FRT and metal component. Compared with usual joining methods—such as flow drill screws, blind and self-piercing rivets—noticeably higher tensile properties can be realized through the novel process management. The load-bearing capability increasing effect could be proved on hybrid joints with hot-dip galvanized steel HX420LAD and orthotropic glass—as well as carbon—fiber reinforced plastics. The results, which were determined in tensile-shear and cross-shear tests according to DIN EN ISO 14273 and DIN EN ISO 14272, are compared with holding loads of established joining techniques with similar joining point diameter and material combinations.

scholarly journals RICE STRAW/THERMOPLASTIC COMPOSITE: EFFECT OF FILLER LOADING, POLYMER TYPE AND MOISTURE ABSORPTION ON THE PERFORMANCE

CERNE ◽  
2016 ◽  
Vol 22 (4) ◽  
pp. 449-456 ◽  
Author(s):  
Hossein Mohammadi ◽  
Seyedmohammad Mirmehdi ◽  
Lisiane Nunes Hugen
Keyword(s):  
Tensile Strength ◽  
Rice Straw ◽  
Moisture Absorption ◽  
Water Immersion ◽  
Filler Loading ◽  
Thermoplastic Composite ◽  
Modulus Of Rupture ◽  
Thermoplastic Composites ◽  
Composite Effect ◽  
Wet Condition

ABSTRAT Thermoplastic composites made with 45, 60 and 75% of rice straw as filler and two types of thermoplastics, virgin polyethylene (PE) and polypropylene (PP) were evaluated. The final boards were made with and without maleic anhydride modified polypropylene (MAPP) at 2% of the total weight of each specimen. The flexural and tensile strengths were measured for dry composites and also measured after 24 h of water immersion of the composites (wet condition). By increasing the filler content, the flexural and tensile strengths and also the density of the specimens decreased. The type of matrix (PE or PP) did not affect significantly the flexural strength, but PP led to higher values of tensile strength for low fiber loadings (45% and 60%). Coupling agents increased the flexural and tensile strength. After water immersion, modulus of elasticity and modulus of rupture were decreased, while tensile strength was less influenced.

scholarly journals Mechanical Properties of Compression Moulded Aggregate-Reinforced Thermoplastic Composite Scrap

2021 ◽  
Vol 5 (11) ◽  
pp. 299
Author(s):  
Julien Moothoo ◽  
Mahadev Bar ◽  
Pierre Ouagne
Keyword(s):  
Mechanical Properties ◽  
Tensile Properties ◽  
Test Method ◽  
Thermoplastic Composite ◽  
Recycled Aggregate ◽  
Thermoplastic Composites ◽  
Mechanical Recycling ◽  
Compression Moulding ◽  
Grain Sizes ◽  
Recycled Composites

Recycling of thermoplastic composites has drawn a considerable attention in the recent years. However, the main issue with recycled composites is their inferior mechanical properties compared to the virgin ones. In this present study, an alternative route to the traditional mechanical recycling technique of thermoplastic composites has been investigated with the view to increase mechanical properties of the recycled parts. In this regard, the glass/polypropylene laminate offcuts are cut in different grain sizes and processed in bulk form, using compression moulding. Further, the effect of different grain sizes (i.e., different lengths, widths and thicknesses) and other process-related parameters (such as mould coverage) on the tensile properties of recycled aggregate-reinforced composites have been investigated. The tensile properties of all composite samples are tested according to ISO 527-4 test method and the significance of test results is evaluated according to Student’s t-test and Fisher’s F-test respectively. It is observed that the tensile moduli of the recycled panels are close to the equivalent quasi-isotropic continuous fibre-reinforced reference laminate while there is a noteworthy difference in the strengths of the recycled composites. At this stage, the manufactured recycled composites show potential for stiffness-driven application.

Enhanced Infrared Heating of Thermoplastic Composite Sheets for Thermoforming Processes

2021 ◽  
Vol 36 (1) ◽  
pp. 35-43
Author(s):  
M. Längauer ◽  
G. Zitzenbacher ◽  
C. Burgstaller ◽  
C. Hochenauer
Keyword(s):  
Steady State ◽  
Composite Materials ◽  
Mechanical Performance ◽  
Heating Time ◽  
Thermoplastic Composite ◽  
Infrared Heating ◽  
Thermoplastic Composites ◽  
Steady State Condition ◽  
Reflector System ◽  
Heating Station

Abstract Thermoforming of thermoplastic composites attracts increasing attention in the community due to the mechanical performance of these materials and their recyclability. Yet there are still difficulties concerning the uniformity of the heating and overheating of parts prior to forming. The need for higher energy efficiencies opens new opportunities for research in this field. This is why this study presents a novel experimental method to classify the efficiency of infrared heaters in combination with different thermoplastic composite materials. In order to evaluate this, different organic sheets are heated in a laboratory scale heating station until a steady state condition is reached. This station mimics the heating stage of an industrial composite thermoforming device and allows sheets to slide on top of the pre-heated radiator at a known distance. By applying thermodynamic balances, the efficiency of chosen parameters and setups is tested. The tests show that long heating times are required and the efficiency of the heating is low. Furthermore, the efficiency is strongly dependent on the distance of the heater to the sheet, the heater temperature and also the number of heating elements. Yet, using a full reflector system proves to have a huge effect and the heating time can be decreased by almost 50%.

Effect of Hot-Wet Storage Aging on Mechanical Response of a Woven Thermoplastic Composite

Aerospace ◽  
2020 ◽  
Vol 7 (2) ◽  
pp. 18
Author(s):  
Theofanis S. Plagianakos ◽  
Kirsa Muñoz ◽  
Diego Saenz-Castillo ◽  
Maria Mora Mendias ◽  
Miguel Jiménez ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Batch Mode ◽  
Static Tests ◽  
Test Execution ◽  
Aerospace Applications ◽  
Wet Storage ◽  
Wide Range ◽  
Fracture Tests

The effect of hot-wet storage aging on the mechanical response of a carbon fiber polyether ether ketone (PEEK)-matrix woven composite has been studied. A wide range of static loads and selected cyclic load tests on the interlaminar fatigue strength were performed. Static tests were conducted in batch mode, including on- and off-axis tension, compression, flexure, interlaminar shear strength (ILSS) and fracture tests in Modes I, II and I/II. Respective mechanical properties have been determined, indicating a degrading effect of aging on strength-related properties. The measured response in general, as well as the variance quantified by batch-mode test execution, indicated the appropriateness of the applied standards on the material under consideration, especially in the case of fracture tests. The material properties presented in the current work may provide a useful basis towards preliminary design with PEEK-based woven thermoplastic composites during service in aerospace applications.

scholarly journals Porosity Elimination in Modified Direct Laser Joining of Ti6Al4V and Thermoplastics Composites

2019 ◽  
Vol 9 (3) ◽  
pp. 411 ◽  
Author(s):  
Haipeng Wang ◽  
Yang Chen ◽  
Zaoyang Guo ◽  
Yingchun Guan
Keyword(s):  
Glass Fiber ◽  
Fracture Strength ◽  
Joint Strength ◽  
Surface Texturing ◽  
Practical Applications ◽  
Laser Joining ◽  
Glass Fiber Reinforced ◽  
Hybrid Joints ◽  
Direct Laser ◽  
Joining Process

Hybrid lightweight components with strong and reliable bonding qualities are necessary for practical applications including in the automotive and aerospace industries. The direct laser joining method has been used to produce hybrid joints of Ti6Al4V and glass fiber reinforced polyamide (PA66-GF30). Prior to the laser joining process, a surface texturing treatment is carried out on Ti6Al4V to improve joint strength through the formation of interlock structures between Ti6Al4V and PA66-GF30. In order to reduce the generated micro-pores in Ti6Al4V-PA66-GF30 joints, a modified laser joining method has been proposed. Results show that only very few small micro-pores are generated in the joints produced by the modified laser joining method, and the fracture strength of the joints is significantly increased from 13.8 MPa to 41.5 MPa due to the elimination of micro-pores in the joints.

Experimental investigation on a fully thermoplastic composite subjected to repeated impacts

2019 ◽  
Vol 233 (19-20) ◽  
pp. 6985-7002
Author(s):  
S Boria ◽  
A Scattina ◽  
G Belingardi
Keyword(s):  
Composite Laminates ◽  
Mechanical Performance ◽  
Impact Damage ◽  
Energy Levels ◽  
Thermoplastic Composite ◽  
Thermoplastic Composites ◽  
Low Velocity ◽  
Repeated Impacts ◽  
Structural Parts ◽  
The Impact

In the last years, the spread of composite laminates into the engineering sectors was observed; the main reason lies in higher values of strength/weight and stiffness/weight ratios with respect to conventional materials. Firstly, the attention was focused on fibres reinforced with thermosetting matrix. Then, the necessity to move towards low density and recyclable solutions has implied the development of composites made with thermoplastic matrix. Even if the first application of thermoplastic composites can be found into no structural parts, the replacement of metallic structural parts with such material in areas potentially subjected to impact has become worthy of investigation. Depending on the field of application and on the design geometry, in fact, some components can be subjected to repeated impacts at localized sites either during fabrication, activities of routine maintenance or during service conditions. When composite material was adopted, even though the impact damage associated to the single impact event can be slight, the accumulation of the damage over time may seriously weaken the mechanical performance of the structure. In this overview, the capability of energy absorption of a new composite completely made of thermoplastic material was investigated. This material was able to combine two conflicting requirements: the recyclability and the lightweight. In particular, repeated impacts at low velocity, on self-reinforced laminates made of polypropylene (PP), were conducted by experimental drop dart tests. Repeated impacts up to the perforation or up to 40 times were performed. In the analysis, three different energy levels and three different values of the laminate thicknesses were considered in order to analyse the damage behaviour under various experimental configurations. A visual observation of the impacted specimens was done, in order to evaluate the damage progression. Moreover, the trend of the peak force interchanged between specimen and dart and the evolution of both the absorbed energy and of the bending stiffness with the impacts number were studied. The results pointed out that the maximum load and the stiffness of the specimens tended to grow increasing the number of the repeated impacts. Such trend is opposite compared to the previous results obtained by other researchers using thermosetting composites.

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