Tape Layup Research Articles

Advancements in Fiber-Reinforced Polymer Composites: A Comprehensive Analysis.

Composites made from fiber-reinforced polymers (FRPs) are a crucial and highly adaptable category of materials widely utilized in numerous fields. Their flexibility and the range of criteria for classification enable the creation of tailored solutions to address distinct requirements in sectors such as civil engineering, aerospace, automotive, and marine, among others. The distinguishing characteristics of FRP composites include the type of reinforcing fiber used, the composition of the matrix material, the employed manufacturing process, the orientation of the fibers, and the specific end-use application. These classification variables offer engineers a versatile structure to determine and select the most appropriate materials and production techniques for their specific needs. Furthermore, the present study aims to reunite the criteria of classification for FRPs and specific manufacturing technologies of FRPs, such as conventional ones (matched die molding, contact molding), automated ones (filament winding, tape lay-up, and fiber placement), and advanced ones (electrospinning and additive manufacturing),with the chronological development of FRPs, insights on material characteristics, and comprehensive design guidelines based on their behavior in different environments of use.

In-line and off-line NDT defect monitoring for thermoplastic automated tape layup

Automated tape layup (ATL), is susceptible to a variety of manufacturing defects that affect productivity and mechanical performance of the final part. To increase process efficiency an inline monitoring tool is developed, which detects defects during manufacturing in a ply-by-ply manner. The presented work details the capability analysis of inline non-destructive testing (NDT) by means of thermography compared to industry approved NDT methods, namely, active infrared thermography and ultrasonic testing, which are performed subsequently. Two sets of samples were made, with foreign object and debris (FOD) and without any artificial defects. These in-situ consolidated samples were then checked for FOD and bond inhomogeneity via all three NDT methods. Quantitative and qualitative analysis of research finding was performed. Inline thermography results conform to established industry standards in recognizing FOD defects. These defects can be localized and rectified immediately, increasing process reliability. Inline thermography can be used effectively for inline process control.

Inline tape width control for thermoplastic automated tape layup

Automated tape layup, is predisposed to positioning defects like gaps and overlaps which are detrimental to the structural integrity of the part. This work investigates the details of the design of inline width control concept, a technique for inline control of consolidated tape width to eliminate gaps. Continuous inline width variation is achieved by online control of the compaction force, during the layup process. Successful calibration and benchmarking tests using standard pressure measurement sensors are presented. Performance assessment tests are performed which demonstrate online variation of force from 50 N to 1000 N, having a standard deviation of 10 N. Correlation models for width control are obtained and it is shown that a width increase of 5–50 % of initial width is achievable using the prototype. An example of linearly varying force resulting in a trapezium shaped consolidated tape is also shown as a part of the feasibility study.

In‐line residual strain monitoring for thermoplastic automated tape layup using fiber Bragg grating sensors

AbstractAutomated tape layup (ATL) has been used extensively for manufacturing composites laminates using unidirectional prepregs for high‐performance industries like aerospace. Residual stress is one of the defects that adversely affect the layup quality. These stresses affect geometrical tolerances in the form of distortion of the final product and are found to have a detrimental impact on the mechanical properties. In‐line monitoring of such defects will help in productivity increase and achieving a reliable process control. The aim of the present work is to demonstrate the feasibility of fiber Bragg grating sensors for monitoring residual strains. FBGs are embedded inside a thermoplastic UD laminate. Temperature and strain discrimination is performed to recognize intermittent residual strains during the layup. Finally, intermittent residual strain is used to develop an understanding of the global residual strain. Effect of selective process parameter on residual stress formation and the evolution of the same is also analyzed.

Level of automation (LOA) in aerospace composite manufacturing: Present status and future directions towards industry 4.0

Composites have become the go-to material of the aerospace industry during the past decades and a significant uptake in composite materials for aerospace applications was evident in recent years. Both expert academics and industry practitioners believe, to meet the future demand, the level of automation in the aerospace composite manufacturing process chains must be improved. The main focus of automation in composites so far has been given to automate siloed operations but limited attention has been paid to end-to-end integration of the process chains leading to inefficiencies, rising operational costs, and low productivity. This paper intends to compare and contrast the level of automation (LOA) in different aerospace composite manufacturing process chains to identify where the LOA triumphs and lacks. For this purpose, core-process and sub-process tasks involved in commonly used manufacturing process chains (i.e. Filament Winding, Automated Tape Layup, Automated Fiber Placement, Resin Transfer Molding, and Pultrusion) are identified by conducting a detailed literature review and verified by the experts. Then, the process chains are mapped and visualized to understand the workflow. Later, these tasks are evaluated based on an established LOA taxonomy developed for manufacturing processes. The study reveals that even the popular ‘automated’ processes are developed in silos and do not show consistent higher LOA throughout their process chain. While core-process tasks show intermediate LOA (Level 5–6), most non-value-added activities show poor LOA (Level 1–4). Most importantly, none of the tasks involved in the existing composite manufacturing process chains have reached a higher LOA (Level 7). The paper reveals that focusing on sub-process tasks, and tasks that lack automation should be the next step towards achieving fully automated composite manufacturing and presents a two-pronged approach to realize Industry 4.0.

Ply-by-ply inline thermography inspection for thermoplastic automated tape layup

Automated tape layup (ATL) largely employs post manufacturing manual visual inspection techniques for defect detection, which severely affects the productivity. Inline monitoring and defect prediction can help in making the process faster and more reliable. The presented work details the use of thermography as an inspection tool for thermoplastic tape material. A new online monitoring system is developed containing Infrared camera integrated on a purpose build ATL test rig. The capability of the tool to identify various defects is analyzed. Moreover, detailed temperature and cooling behavior analysis is done for defect prediction.

Automated manufacturing of bio-inspired carbon-fibre reinforced polymers

Carbon-fibre reinforced polymers (CFRPs) present outstanding mechanical performance per unit of mass; however, they also fail in a brittle manner, with little or no warning of their forthcoming catastrophic failure. In this study, a ‘brick-and-mortar’ design inspired by the structure of nacre was implemented by automated tape lay-up for the first time with the aim of changing the failure response of CFRPs. Standard procedures and materials already implemented in the aerospace industry have been used to produce bio-inspired CFRPs laminates, providing the first example of bio-inspired concepts scaled-up to industrial level. The effects of the proposed automated manufacturing process on the morphology and tensile properties of the laminates were investigated. A non-linear response was observed when the bio-inspired laminates were subjected to tensile forces. This type of response agrees with those of previous studies on lab-scale manufactured aligned discontinuous CFRPs.

Cost analysis of alternative automated technologies for composite parts production

Composite material usage in aircraft has been rising since the 1990s, with significant increases in manufacturing productivity and repeatability due to automation in the production of aeronautic parts made of composite materials, becoming a strong driver for widespread adoption of composites in this industry. Automated Tape Layup (ATL) and Automated Fibre Placement (AFP) are two of the most important automated manufacturing technologies within aeronautics composites, although their cost implications and economic comparison have not been widely studied. This paper presents an economic evaluation of ATL and AFP technologies. Using process-based cost models, the manufacturing process of a horizontal stabiliser is modelled, determining for each technology the associated consumption and use of resources and their implications towards the part final cost. Results show that ATL is less expensive than AFP, due to lower material costs, although with less material efficiency and slower cycle time.

Behaviors of carbon fiber reinforced thermoplastic prepreg tape layup molding by infrared heating.

Behaviors of carbon fiber reinforced thermoplastic prepreg tape layup molding by infrared heating.

Shell on shell bonding of composite heat shield

Heat shield of a guided rocket experiences severe thermo-structural loads during flight especially during its re-entry phase. To meet the above requirement, Carbon Fibre Reinforced Plastic (CFRP) composite is the ideal choice of material which not only has high specific strength, stiffness, good thermal properties and light weight but also exhibits these properties at elevated temperatures. Heat shield is a two layered CFRP composite structure. Carbon Phenolic (CP) layer is an outer thermal member realized by tape lay-up method taking advantage of better ablation characteristics and Carbon Epoxy (CE) is an inner structural load bearing member fabricated by wet filament winding process to get tailor made structure. Each layer (CE & CP) is designed to meet its unique and distinct role. Realization of heat shield needs special attention as it is an assembly of multiple composite sections and also it is process intensive. The aim of this paper is to provide an insight into the established bonding methodology of two layered heat shield structure viz. selection of bonding material , qualification at coupon level both with metal and composite as substrate, tools and fixture, detailed established process and parameters, non-destructive testing of bonded structures, acceptance and qualification. It can be concluded that the structure bonded with the above established process methodology exhibits good bond quality post testing

Getting to grips with automated prepreg handling

Automated manufacturing of composite parts based on prepreg material is receiving increased interest with the rising use of composite materials for high-performance applications. The two main automation alternatives for prepreg layup, automated tape layup and fiber placement, are not cost-effective for all types of products, and manual labor is common for the manufacturing of complex parts in low manufacturing volumes. Alternatives to the two dominant automation solutions have been pursued, but so far these have had a limited impact in industrial applications. This paper presents four different solutions for automated layup of prepreg plies to flat laminates that can be formed in a subsequent forming process, which decrease the system complexity. The solutions target products where the layup of flat laminates today is done manually due to technical limitations or cost considerations. The layup solutions must manage challenges caused by material properties such as low material rigidity and tack, and be able to handle a high number of ply shapes. All four solutions are designed for prepreg that is covered with a stiff backing paper. The aim of the paper is to analyze and compare the four solutions. It can be concluded that the most versatile solution is a dual-arm robot equipped with simple end effectors. The dual-arm solution presents a possibility to control the pick-up and lay-down motions that make peeling motions possible, which is advantageous when picking material that has tacked to the pickup surface.

Foam injection molding of glass fiber reinforced polypropylene composites with laminate skins

Sandwich panels which consist of discontinuous glass‐fiber reinforced polypropylene composite foam core and continuous glass‐fiber reinforced polypropylene laminate skins were manufactured using industry‐scale equipment in a streamlined manner. The streamlined process included two stages: (1) continuous glass‐fiber reinforced polypropylene laminates as the face skins were produced using an automated, rapid tape layup machine and a hydraulic press, and (2) discontinuous glass‐fiber reinforced polypropylene composite as the core was foam injection‐molded onto the laminate skins (i.e., overmolding), which eliminated bonding process of the foam core and laminate skins, with a physical blowing agent, nitrogen. Optical microscopy results suggested that the increase of void fraction by the core‐back (or mold opening) technique increased the average cell size and cell size distribution, but had little effect on the cell density of the foam core. Mechanical test results suggested that the addition of laminate skins increased the flexural modulus and flexural strength of the solid as well as foam composites significantly. In addition, the material indices were calculated for the sandwich panels manufactured in this study, and the results suggested that the addition of the laminate skins and foaming by the core‐back (or mold opening) technique can greatly reduce the weight of material needed to have the same bending stiffness and maximum bending force. COMPOS., 39:4322–4332, 2018. © 2017 Society of Plastics Engineers

Demonstration and Methodology of Structural Monitoring of Stringer Runs out Composite Areas by Embedded Optical Fiber Sensors and Connectors Integrated during Production in a Composite Plant.

Embedding optical fibers sensors into composite structures for Structural Health Monitoring purposes is not just one of the most attractive solutions contributing to smart structures, but also the optimum integration approach that insures maximum protection and integrity of the fibers. Nevertheless this intended integration level still remains an industrial challenge since today there is no mature integration process in composite plants matching all necessary requirements. This article describes the process developed to integrate optical fiber sensors in the Production cycle of a test specimen. The sensors, Bragg gratings, were integrated into the laminate during automatic tape lay-up and also by a secondary bonding process, both in the Airbus Composite Plant. The test specimen, completely representative of the root joint of the lower wing cover of a real aircraft, is comprised of a structural skin panel with the associated stringer run out. The ingress-egress was achieved through the precise design and integration of miniaturized optical connectors compatible with the manufacturing conditions and operational test requirements. After production, the specimen was trimmed, assembled and bolted to metallic plates to represent the real triform and buttstrap, and eventually installed into the structural test rig. The interrogation of the sensors proves the effectiveness of the integration process; the analysis of the strain results demonstrate the good correlation between fiber sensors and electrical gauges in those locations where they are installed nearby, and the curvature and load transfer analysis in the bolted stringer run out area enable demonstration of the consistency of the fiber sensors measurements. In conclusion, this work presents strong evidence of the performance of embedded optical sensors for structural health monitoring purposes, where in addition and most importantly, the fibers were integrated in a real production environment and the ingress-egress issue was solved by the design and integration of miniaturized connectors compatible with the manufacturing and structural test phases.

Effect of Fibre Orientation on the Properties and Functional Performance of Ablative Materials for Solid Rocket Motors

Ablative materials are polymeric composites where the reinforcement is generally a fibre with high melting point like Carbon or Silica and the matrix is a high char yielding resin like phenolics. These composites are used as thermal protection systems in Solid rocket motor nozzles, liquid engine throats, control thrusters, re-entry nose caps etc. They encounter extremely hostile conditions during their service conditions. The high temperature, pressure, velocity of hot exhaust gases, heat flux, particle impingement of the solid propellant particles etc. contribute to harsh environment inside the nozzle. These high performance composites are synthesised using specially developed processes using sophisticated equipments. In this paper, the process of ablation, the physical and chemical changes and the process of synthesis of ablatives are clearly elaborated. In the present work, the factors affecting the thermo-mechanical properties and functional performance of ablatives are investigated. Based on the selected parameters, detailed study was done on a few key factors. The fiber orientation in the reinforcement and the process of orienting the fibers during the prepreg tape layup were chosen for detailed study. Composites were processed under carefully controlled conditions and detailed characterisation was done. The details of processing operations, characterisation and Non-destructive evaluation have been explained in this paper. The critical process parameters and the special processing conditions needed to realise a defect-free composite have also been addressed. The details of these tests, the post test evaluation and analysis etc. are explained in this paper.

Auto Tape Layup of Carbon Fiber Reinforced Thermoplastic Prepreg Tape using Near Infrared Heating

Auto Tape Layup of Carbon Fiber Reinforced Thermoplastic Prepreg Tape using Near Infrared Heating

熱可塑性CFRPテープ連続積層成形における近赤外線および高周波誘導ロール加熱の影響

Automated thermoplastic tape laying (ATL) and automated fiber placement (AFP) are high-potential manufacturing methods for continuous carbon fiber reinforced thermoplastic (CFRTP) composites which can ensure operational safety even in highly loaded components such as aircraft wing skins and fuselages or construction large scaled structures. This study aimed to reveal the heating behavior of CFRTP in continuous tape layup molding. The material used for the experiment was unidirectional carbon fiber reinforced polyamide 6 (CF/PA6) prepreg tape. The effects of processing conditions such as output of infrared heater, feed speed of prepreg tapes and heating temperature of pressure rollers on the tape laying behavior of prepreg tape were investigated. In the case of only near infrared heating, it was revealed that the difference in temperature between the upside and downside prepreg tape was increased significantly. Then, the joining strength was decreased significantly compared with using the infrared heater, because the moisture in the prepreg tapes was not removed completely. On the other hand, when the near infrared heater and heating roller were used, the difference in temperature between the upside and downside prepreg tape was decreased considerably. It was also revealed that the surface temperature of CF/PA6 prepreg tape and singe lap tensile strength tends to increase with decreasing the feed speed of prepreg tapes.

Development of a Novel Ablative Composite Tape Layup Technology for Solid Rocket Motor Nozzle and Liquid Engine Liners

Solid rocket motor nozzles and liquid engine throats use ablative composite materials to protect the structures from the extremely severe operating conditions of high temperature, pressure and particle impingement. These ablative nozzle liners are processed from carbon phenolic/silica phenolic prepregs using a complex processing cycle. The process starts from impregnating the fibres with phenolic resin followed by either moulding or wrapping/winding prepreg tapes over metallic mandrels followed by polymerization under pressure. Traditionally, prepreg is cut into straight tapes and wound on mandrels to form the divergents. For throats and convergents, prepreg patterns are cut and stacked for curing. Plies of shape conforming to the development of base cone are cut from the prepreg and wound on the mandrel. After polymerization, the final required configuration is machined from this cylindrical blank after the liners are cured. The new method, described in this paper, replaces the straight-cut prepreg tapes by bias-cut prepreg tapes. These can be used for ablative liners in which the plies are at an angle to the direction of the flow. Bias tapes are cut at 45° to the warp and weft directions of the fabric to the required width and formed to the required frustum of cone. Since the cone is formed from straight cut bias tape, the fibre construction will be uniform around the circumference unlike the pattern cut tape. The efficiency of this process depends on the wrapping ratio which is in turn a function of the diameter, ply angle and tape width. To get the best wrapping ratio, shaped mandrels are used which brings down the material wastage and machining allowances. This paper describes the attempts to develop the Bias wrapping technology for angle wound liners. The details of process trials, challenges faced and how they were overcome, advantages of the process over conventional process etc are explained. Exhaustive material characterization of the material was done. Property comparison and validation of performance in subscale tests and a full scale static test are also discussed. The analysis indicates that this new technology has good potential in replacing the traditional tape-winding technology for rocket motor nozzle liners.

A composite cost model for the aeronautical industry: Methodology and case study

This paper presents a novel composite production cost estimation model. The strength of the model is its modular construction, allowing for easy implementation of different production methods and case studies. The cost model is exemplified by evaluating the costs of a generic aeronautical wing, consisting of skin, stiffeners and rib feet. Several common aeronautical manufacturing methods are studied. For studied structure, hand layup is the most cost-effective method for annual volumes of less than 150 structures per year. For higher production volumes automatic tape layup (ATL) followed by hot drape forming (HDF) is the most cost-effective choice.

Tribological Study of Polymer Composite Forming Using Model Experiments and Real Composites

This experimental study is focused on identification of tribological mechanisms acting during forming of polymer composites. The range of relevant processes includes fibre placement, tape lay-up, moulding, draping, and RTM. Two types of tribological experiments, relying both on simultaneous application of compression and shear loadings, are carried out. Firstly, model macromechanical tests are undertaken on plastic rods of millimetric diameter immersed in a viscous liquid, representing composite fibres and matrix, respectively. By careful simulation of forming conditions, this experiment helps to identify the friction phenomena occurring in real composites. On the other hand, the micromechanics of forming processes is studied through a microscopic experiment on real carbon fabric. This material is clamped between two glass plates and pulled in opposing directions in the plane of the fabric. It is hypothesized that the evolution of contact area due to shearing that can be measured in this experiment is an essential feature of the tribology of forming processes, a topic which hitherto has not been investigated.

Dynamic finite element simulation and transient temperature field analysis in thermoplastic composite tape lay-up process

In the lay-up process of thermoplastic composite tape, the thermal conditions have great influence on the end quality and performance of composites. In the lay-up process of thermoplastic matrix composites, a semi-infinite solid model is used to analyse the heat transfer by simulating the heating of hot gas torch. Temperature of the control volume is calculated based on the model. A dynamic finite element model is developed to obtain the transient temperature field. The birth–death element strategy in ANSYS was used to simulate the movement of lay-up head during dynamic loading and laying-up prepreg onto the composite substrate. The simulation results of using the transient heat transfer model and the finite element model were compared well. The bonding temperature increases linearly with the heater temperature and is closely related to the moving speed of the roller. The bonding temperature changed slowly when the roller moved faster.