Thermoplastic Components Research Articles

Investigation the Amplitude Uniformity on the Surface of the Wide-Blade Ultrasonic Plastic Welding Horn

Ultrasonic welding has been applied for joining thermoplastic components due to their advantages such as clean, fast and reliable. The basic principle is to use the mechanical energy of ultrasonic frequency vibration to produce the molten pool at the interface of the joined components under high pressure to create solid-state welding joints. Depending on the specific application, the ultrasonic horn is designed to generate suitable amplitudes on the surface of the welding zone. Uniformity of the amplitudes can be a challenge as the welding area increases. Therefore, design a welding horn in order to obtain the uniform amplitudes at the large area is significant difficult. This work presents a method for obtaining the uniform amplitudes at the working surface of the stepped wide-blade horn. Finite element method is used to analyze the amplitude distribution at the horn surface of 250 × 34 mm2 with working frequency of 15 kHz and aluminum alloy 7075. The uniformity of amplitude is obtained by changing the shape of the horn.

Mechanical performance of CF/PEEK–PEI foam core sandwich structures

Previous work showed that thermoplastic composite sandwich structures offer great potential to meet the demands of lightweight structures for aviation applications. In this study, the influence of several processing parameters on the mechanical properties of thermoplastic sandwich components, consisting of carbon fibre reinforced polyetheretherketone skins and polyetherimide foam cores, is characterised. Sandwich specimens are manufactured with varying skin temperatures, core compaction distances and different polyetherimide concentrations at the skin–core interface. Following, sandwich samples are mechanically tested to characterise the bond strength, the core performance as well as the performance of the whole sandwich. The results show that in most cases the processing parameters significantly affect the cell structure of the sandwich core, provided that a proper fusion bond between skins and core exists. Thereby, the core performance seems to be weakened and failure predominantly occurs in the transition between affected and original cell structures.

Tailored Inserts Based on Continuous Fibre for Local Bearing Reinforcement of Short Fibre Thermoplastic Components

The injection molding process is an economical process for manufacturing of thermoplastic components. Complex geometries can be realized with high automation and short cycle times. However the mechanical properties of injection-molded parts are not suitable for mechanical demanding components even by adding short or long fibre. As bold connections are used frequently for load transfer, the load introduction area particularly is limited by low bearing strength. The present paper shows the influence of tailored inserts based on continuous fibre on the bolt-loaded hole of injected test specimen.

Improved Adhesion Strength of Metal Textile Composites by Surface Texturing Using TIG Arc or CW Laser Process

Within the framework of the bilateral CORNET projects MeTexCom and MeTexCom2, new approaches were developed and tested to improve the adhesion strength of metal textile composites, with a focus on the targeted roughening of aluminum surfaces and the development of new acoustically insulating nonwovens. The metal textile composites were produced by melting thermoplastic components of the textile composites without a separately applied adhesive.For improved adhesion strength between metal and textile, roughness was generated on the metal surface by means of a novel arc treatment by an anodic polarized TIG process or a cw (continuous wave) fiber laser process. On the one hand, the goal was to produce uniformly rough, untercut surface structures in micro-and nanodimension by means of a highly dynamic arcing process. On the other hand, a similar approach was pursued with the cw laser method by using a single-mode as well as a multi-mode laser.

Process analysis for structural optimisation of thermoplastic composite component using the building block approach

Abstract The paper aim is to establish and optimise the prediction model of a thermoplastic fibre reinforced component designed and manufactured through an integrated injection moulding process (Hybrid Moulding). This is done by the Finite Element Analysis (FEA) and then the process simulations, considering the composite material as an elastic anisotropic woven fabric to study the deformations undergone during the manufacturing process. The proposed methodology for creating the predictive model is fairly accurate, and it is a novel method which can be easily integrated and adapted into a components initial design phase. This optimisation technique can replace the expensive and traditional trial and error procedures during the design and prototyping phase, and it significantly decreases the time to build the final component. The final scope of the research is to simplify the product development phase of general lightweight automotive thermoplastic components by creating an innovative methodology for predictive modelling.

Welding of 3D-printed carbon nanotube-polymer composites by locally induced microwave heating.

Additive manufacturing through material extrusion, often termed three-dimensional (3D) printing, is a burgeoning method for manufacturing thermoplastic components. However, a key obstacle facing 3D-printed plastic parts in engineering applications is the weak weld between successive filament traces, which often leads to delamination and mechanical failure. This is the chief obstacle to the use of thermoplastic additive manufacturing. We report a novel concept for welding 3D-printed thermoplastic interfaces using intense localized heating of carbon nanotubes (CNTs) by microwave irradiation. The microwave heating of the CNT-polymer composites is a function of CNT percolation, as shown through in situ infrared imaging and simulation. We apply CNT-loaded coatings to a 3D printer filament; after printing, microwave irradiation is shown to improve the weld fracture strength by 275%. These remarkable results open up entirely new design spaces for additive manufacturing and also yield new insight into the coupling between dielectric properties and radio frequency field response for nanomaterial networks.

Thermal direct joining of metal to fiber reinforced thermoplastic components

In the field of lightweight construction, load-capable mixing compounds with the material specific advantages of metal and thermoplastics become increasingly significant. For this efficient process, chains including adapted pretreatment and joining processes in combination with process simulation tools are required. Post- or in-mold assembly processes, mechanical joining by screws or rivets, and adhesive bonding are state-of-the-art techniques for joining dissimilar materials such as metal and thermoplastics [R. Hoffschlag, Forschungsbedarf zum Fügen von Kunststoffen im Leichtbau und im Bereich erneuerbarer Energien (DVS-Berichte Band, Düsseldorf, 2012), p. 294; M. Gude, G. Meschut, M. Zäh, H. Lieberwirth, FOREL-Studie: Chancen und Herausforderungen im ressourceneffizienten Leichtbau für die Elektromobilität (2015)]. Specific restrictions can be found with the limited geometry flexibility, the use of an additional material and comparable long joining times. Hence, new joining solutions are needed. In this presentation, the use of thermal induced joining for metal and thermoplastic parts will be shown. These processes are characterized by short joining times and the substitution of glue, screws, or rivets. The key technology to enable high joint strengths is the material adapted surface modification. As a research result, the influence of physical and chemical pretreatment will be presented. It could be shown that metal ablation by high power lasers can efficiently generate a macroscopic surface structure, which enables mechanical fastening of the polymer at the metal surface. Depending on the materials to be joined, different kinds of heat inputs can be used. In this presentation, the joining by hotplates and by lasers will be introduced. It will be shown that an optimized surface pretreatment enables joints with a lap shear strength of 20 N/mm2 and more, depending on the material configuration.

Experimental investigation of effects of build parameters on flexural properties in fused deposition modelling parts

ABSTRACTAdditive manufacturing is a group of fabrication techniques that is used to build components by depositing material in a layer-by-layer manner. Fused deposition modelling (FDM) is one of the additive manufacturing techniques which is widely used for prototyping and production applications of thermoplastic components. In load-bearing applications, flexural and compression forces often coexist. In order to avoid failure under these loads, it is essential to study the mechanical properties of FDM components. The main focus of this research is to study the flexural properties of FDM components and to comprehend their dependence on various build parameters. It has been observed from a series of flexural tests that FDM parts have anisotropic properties and this anisotropy was not due to the material in use, but due to the fabrication process itself. In this study Ultem 9085 is used as the material to fabricate coupons with variations in build parameters including build direction, raster angle and negative air gap. A full-factorial experimental design was used to study the individual and combined effects of these build parameters on the flexural properties of the coupons. Solid and sparse-build styles were used in the coupon fabrication. Flexural properties investigated include flexural yield strength, flexural modulus, flexural strength/mass ratio and flexural modulus/mass ratio. Qualitative observation and reasoning is used to comprehend how the flexural properties are affected by the build parameters.

Automation Concepts for Manufacturing Fibre-reinforced Thermoplastic Components

Automation Concepts for Manufacturing Fibre-reinforced Thermoplastic Components

Estimation of Fibre Orientation in Injection Moulding Plastics Parts

Fibre orientation in short fibre reinforced thermoplastics depends on injection moulding parameters. There are a lot of different parameters that must be established and controlled to achieve proper injection moulding of a plastic part. These parameters fall within four major areas: pressure, temperature, time, and distance. The aim of this article is estimation of fibre orientation in injection moulding plastics parts and comparison of these results with numerical simulated ones. Stereological metallography was used for estimation of experimental orientation of fibres. The orientation of simple fibre may be defined by the two angles θ and Φ. In a Short Fibre Reinforced Thermoplastic (SFRT) component there are frequently millions of fibres, therefore each individual fibre orientation specifying is very impractical. The fibres orientation in space can be described by the probability distribution function (PDF), Ψ(θ, Φ). Numerical modelling of fibre orientation was realised using MOLDEX3D software. Moldex3D is the CAE product for the plastics injection moulding industry. This software allows to view results of fibre orientation as an orientation of the X direction, Y direction, Z direction, the total orientation and orientation at surface. These first three orientations are relevant for the establishment of second-order orientation tensor. They belong to tensor ́s values a11, a22 and a33. Utilization of stereological metallography for short fibre orientation in plastic matrix is very similar to its utilization for estimation of grain boundaries orientation in polycrystalline alloys cased by plastic deformation. In the case of short glass fibres reinforced thermoplastics it’s structure consist of thermoplastic matrix and reinforcing fibres, which has some preferred orientation in most of cases – the structure is anisotropy. The way of scalar measurement of structure anisotropy is determination of degree of orientation. The anisotropic microstructure is decomposed into isotropic, planar or linear oriented components using stereology methods.

Fast prediction of the fatigue behavior of short-fiber-reinforced thermoplastics based on heat build-up measurements: application to heterogeneous cases

Short-fiber-reinforced thermoplastics components for structural applications are usually very complex parts as stiffeners, ribs and thickness variations are used to compensate the quite low material intrinsic stiffness. These complex geometries induce complex local mechanical fields but also complex microstructures due to the injection process. Accounting for these two aspects is crucial for the design in regard to fatigue of these parts, especially for automotive industry. The aim of this paper is to challenge an energetic approach, defined to evaluate quickly the fatigue lifetime, on three different heterogeneous cases: a classic dog-bone sample with a skin-core microstructure and two structural samples representative of the thickness variations observed for industrial components. First, a method to evaluate dissipated energy fields from thermal measurements is described and is applied to the three samples in order to relate the cyclic loading amplitude to the fields of cyclic dissipated energy. Then, a local analysis is detailed in order to link the energy dissipated at the failure location to the fatigue lifetime and to predict the fatigue curve from the thermomechanical response of one single sample. The predictions obtained for the three cases are compared successfully to the Wohler curves obtained with classic fatigue tests. Finally, a discussion is proposed to compare results for the three samples in terms of dissipation fields and fatigue lifetime. This comparison illustrates that, if the approach is leading to a very relevant diagnosis on each case, the dissipated energy field is not giving a straightforward access to the lifetime cartography as the relation between fatigue failure and dissipated energy seems to be dependent on the local mechanical and microstructural state.

Tailoring the heat transfer on the injection moulding cavity by plasma sprayed ceramic coatings

Inhomogeneous material shrinkage in injection moulding can cause warpage in thermoplastic components. To minimise the deformations of the injection moulding parts, the heat transfer during the cooling phase can be adjusted according to the local cooling demand on the surface of the mould cavity by means of plasma sprayed coatings with locally variable thermal resistance over the surface of the mould. Thermal resistance is a function of thermal conductivity and thickness of the coatings, where thermal conductivity of thermal barrier coatings can be adjusted by altering the chemical composition and the microstructure, which is depending on the thickness. This work evaluates the application of plasma sprayed coatings with variable thickness as thermal barrier coatings in the mould cavity. The thermal resistance of the coating and thereby the heat transfer from the melt into the mould will be influenced locally by varying the coating thickness over the cavity area according to the local cooling demand. Using the laser flash method, the thermal conduction of coatings with different thicknesses will be determined. On the basis of the experimentally determined thermal conduction, the effect of the coatings on the temperature field of the mould cavity will be numerically calculated and the required thickness distribution of the coating for an optimal temperature gradient will be determined.

Study on Utilization of Palm Frond for Wood Plastic Composite

Palm frond waste is a lignoselulose material that is abundant availability in Indonesia. The material has potential to be used as raw material for wood plastic composite material (WPC). The purpose of this reseach was to study the effect of levels of treated palm frond (TPF) and maleated polypropylene (MAPP) compatibilizer to the properties and morphology of the palm frond-based WPC. As thermoplastic component was used polypropylene (PP). Extractable components from palm fronds removed with water washing and drying. The WPC samples were prepared by mixing PP, TPF, MAPP and paraffin in the internal mixer at temperature of 170°C and rotor speed of 80 rpm for 15 minutes. The mass ratio of PP/TPF was varied with 50/50, 60/40 and 70/30 w/w. The MAPP levels was varied with 0%, 4% and 5% w/w. Paraffin was used as a palsticizer with a level of 2% w/w. The testing included tensile and flexural properties by using universal testing machine (UTM) according to ASTM D-678 and ASTM D-790 standards, respectively. Other testing also conducted for morphology by using scanning electron microscope (SEM) and water adsorption test. The result indicate that the best properties of the WPC sample obtained at PP/TPF mass ratio of 60/40 w/w and MAPP level of 5% w/w, with tensile strength of 156 kgf/cm2 and flexural strength of 598 kgf/cm2 with water adsorption of 1.4% w/w.

Building Block Approach’ for Structural Analysis of Thermoplastic Composite Components for Automotive Applications

Advanced thermoplastic prepreg composite materials stand out with regard to their ability to allow complex designs with high specific strength and stiffness. This makes them an excellent choice for lightweight automotive components to reduce mass and increase fuel efficiency, while maintaining the functionality of traditional thermosetting prepreg (and mechanical characteristics) and with a production cycle time and recyclability suited to mass production manufacturing. Currently, the aerospace and automotive sectors struggle to carry out accurate Finite Elements (FE) component analyses and in some cases are unable to validate the obtained results. In this study, structural Finite Elements Analysis (FEA) has been done on a thermoplastic fiber reinforced component designed and manufactured through an integrated injection molding process, which consists in thermoforming the prepreg laminate and overmolding the other parts. This process is usually referred to as hybrid molding, and has the provision to reinforce the zones subjected to additional stresses with thermoformed themoplastic prepreg as required and overmolded with a shortfiber thermoplastic resin in single process. This paper aims to establish an accurate predictive model on a rational basis and an innovative methodology for the structural analysis of thermoplastic composite components by comparison with the experimental tests results.

Characterization of a thermoforming composite material made from hemp fibers and polypropylene

The paper refers to a composite material developed for manufacturing thermoformed products with applications in furniture making, automotive industry etc., a method and machinery for manufacturing the material in unwoven form. From this material, Research and Development Department of TAPARO SA has designed and built a series of furniture components. The composite material made of a thermoplastic fibrous component and hemp fibre component, the way of obtaining and the properties of the thermoformed material presented in the paper are necessary in the process of designing and optimizing the parts.

A process planning framework and virtual representation for bead-based additive manufacturing processes

CNC-based hybrid manufacturing systems capable of additive manufacturing (AM) and machining have been developed for metal and large thermoplastic components. Currently, there are no CAD/CAM systems that seamlessly integrate additive and machining tool paths and simulation, as required for a complete hybrid manufacturing solution. Tool paths for bead-based AM cannot be generated by simply reversing the Z processing order of waterline machining tool paths. AM process planning modules are significantly different than those for machining. Unique AM process planning challenges related to geometry, establishing relevant process-specific settings, thermodynamics, tool path planning and realistic virtual process simulation are discussed. To support hybrid manufacturing, the output from the additive manufacturing simulation must be employed as a stock model for subsequent machining. This paper discusses the architecture, process and data flows for a bead-based AM processes, with results being presented primarily for laser cladding.

Effect of Plug Temperature on the Strain and Thickness Distribution of Components Made by Plug Assist Thermoforming

Abstract Plug temperature is a key parameter affecting the thickness distribution of thermoplastic components made by plug assist thermoforming. For a specified pair of plug and plastic sheet, the variation in plug temperature can alter the coefficient of friction (COF) between the pair. We show here how the temperature dependence of COF influences the nature and extent of biaxial stretching of the sheet and consequently the thickness distribution of the thermoformed component. In the present study, high impact polystyrene (HIPS) sheets were thermoformed into axisymmetric cups using a plug-assist process in which the aluminum plug temperature (Tplug) was varied from ambient to above the glass transition temperature of HIPS (∼100 °C). Biaxial strain maps on the surfaces of the formed cups were measured and quantified using Grid Strain Analysis (GSA). Thickness distributions of the cups were also measured. Temperature dependent COF between HIPS and aluminum was determined independently using a rotational rheometer. The measured COF was low for T < 100 °C, whereas it increased appreciably at and above 100 °C. We conclude that when Tplug < 100 °C the HIPS sheet slips on the plug during forming, and this results in biaxial stretching of the base and walls of the formed cup. In contrast for Tplug > 100 °C, a significant reduction in the magnitude of slip is expected. Here the sheet is gripped at the clamp and by the plug during forming which causes reduced biaxial stretching of the base and increased uniaxial stretching of the walls of the cup. Simulations of plug-assist thermoforming using a temperature dependent COF showed qualitative agreement with the GSA data thereby supporting our inferences.

Fatigue behavior enhancement of short fiber glass reinforced polyamide by adding phase change materials

Abstract High responsibility thermoplastic components subjected to dynamic forces show serious in-service thermal limitations. This paper shows that adding the adequate material with a phase-change, PCM, to a thermoplastic matrix component significantly increases its fatigue life. To do this, the fatigue resistance of short fibre-glass reinforced polyamide is analysed by means of monotonous fatigue tests on tensile specimens. Next, the design of the pieces of this material, used in high-speed rail fastenings, is optimised for fatigue efforts by means of accelerated single-piece tests. Finally, it is verified that the fatigue resistance of these pieces endowed with hydrated salt, Na2S2O3·5H2O, which acts as a PCM, increases by a surprising 400% with respect to the reference pieces without PCM.

Deformation behavior of FRP-metal composites locally reinforced with carbon fibers

This study investigates variations of hybrid laminates, consisting of one aluminum sheet and a unidirectional glass fiber (GF) reinforced polyamide 6 (PA6) basic structure with partial carbon fiber (CF) reinforcement. To create these heterogeneous FRP laminates, it is necessary to design and produce semi-finished textile-based products. Moreover, a warp knitting machine in conjunction with a warp thread offset unit was used to generate bionic inspired compounds. By the variation of stacking prior to the consolidation process of the hybrid laminate, an oriented CF reinforcement at the top and middle layer of the FRP is realized. In both cases the GFRP layer prevents contact between the aluminum and carbon fibers. In so doing, the high strength of carbon fibers can be transferred to the hybrid laminate in load directions with an active prevention of contact corrosion. The interface strength between thermoplastic and metal component was improved by a thermal spray coating on the aluminum sheet. Because of the high surface roughness and porosity, mechanical interlock was used to provide high interface strength without bonding agents between both components. The resulting mechanical properties of the hybrid laminates are evaluated by three point bending tests in different load directions. The effect of local fiber orientation and layer positioning on failure and deformation mechanism is additionally investigated by digital image correlation (DIC).

Process chain for serial manufacture of polymer components with micro- and nano-scale features: Optimisation issues

This article reports a follow-up research to investigate further the component technologies of a cost-effective manufacturing route designed to achieve function and length scale integration in products. The route employs a viable master-making process chain that integrates compatible and at the same time complementary, structuring and replication technologies to fabricate Zr-based bulk metallic glass inserts. To validate them, they are subsequently integrated into a micro-injection moulding machine, and polymer structures incorporating both micro- and nano-scale features are replicated. Especially, the masters and/or replicas after each processing step were analysed and the factors affecting its overall performance were identified. The research demonstrated that the master-making process chain can be a viable fabrication route for both fully amorphous and partially crystalline Zr-based bulk metallic glass inserts that incorporate different length scale features. The results also showed that relatively good fidelity of the different scale features can be achieved with the micro-injection moulding process, and thus, it can enable function and length scale integration in thermoplastic components.