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

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Abstract

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.

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... In a thesis by Weitao [21], detailed industry cost data was obtained from surveys of several composite aircraft part manufacturers, including key cost drivers and detailed breakdowns of mate-rial, tool, machine, labour, and indirect/fixed costs. Hagnell et al. [18] presented a cost model for several methods used for the manufacture of composite aircraft parts, and demonstrated this model with an aircraft wing. Hagnell et al. [17] later presented a detailed study of the costs associated with the full production of a composite aircraft wing box, including layup, bagging, curing, Non-Destructive Testing (NDT), and assembly. ...
... It is expected that there will be some material waste during the manufacturing process. Previous research studies concerning the bottom-up cost modelling of composites have considered waste percentages between 10-30% [16,18,21,25]. Therefore, an average waste percentage of 20% is used for all the materials in this work. ...
... _ in equation (14) is the total machine time required for the ℎ machine of the ℎ activity per load. For autoclaves, this time can vary depending on the size of the load, but is typically 7-10 hours [18,[23][24][25]. Therefore, a time of 8 hours is used in this work for _ and ℎ _ ℎ for the autoclave ( _ = ℎ _ ℎ = 8), so that there can be three shifts per day ( ℎ = 3). ...
Article
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A novel methodology is presented for the reliability-based manufacturing cost optimisation of composite aircraft structures. A comprehensive bottom-up costing approach is employed, enabling precise manufacturing cost estimation in terms of material, machine, labour, tooling, and indirect costs. This approach splits the manufacturing process into many individual activities, which can be combined in many different ways, allowing the proposed optimisation methodology to be applied to a wide range of composite aircraft structures. A genetic algorithm (GA) is coupled with a deep neural network (DNN) to efficiently determine the optimal composite ply stacking sequence for every part of an assembled structure. A numerical example featuring a composite-stiffened aircraft fuselage panel is investigated. The reliability of the panel is measured in terms of its buckling resistance, and its manufacturing cost is estimated based on the individual costs of over 20 activities. The labour times for each activity were estimated based on data collected from an aerospace company specialising in the manufacture of advanced composite aircraft structures. Results indicate that material, machine, labour, and tool costs can vary significantly depending on the level of structural reliability required, demonstrating the importance of accounting for non-material costs when designing composite aircraft structures.
... Here, predictive means that the methodology is aimed for use in an early conceptual design stage, in which it can identify general trends that supports holistic design decision while demanding a low amount of user input. Involved production costs are estimated through implementing a previously developed predictive technical cost model by [12,23]. ...
... However, as the quality of EAF produced steel is affected if fed by a scrap steel mix containing to many impurities [27], a retrieval rate of 80% is assumed. The material and production costs of a studied component is estimated using a previously developed predictive technical cost model [12,23], while the use phase and end-of-life phase costs are evaluated separately. Simplified lifecycle applied within the scope of this paper. ...
... To estimate material and production costs of studied component, a previously developed predictive technical cost model [12,23,28] is applied. The model is developed as a stand-alone package in Python [29] and estimates cost through connecting specified production flow to component geometry and complexity [12,23], see Figure 3. ...
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Fatigue strength dictates life and cost of welded structures and is often a direct result of initial manufacturing variations and defects. This paper addresses this coupling through proposing and applying the methodology of predictive life-cycle costing (PLCC) to evaluate a welded structure exhibiting manufacturing-induced variations in penetration depth. It is found that if a full-width crack is a fact, a 50% thicker design can result in life-cycle cost reductions of 60% due to reduced repair costs. The paper demonstrates the importance of incorporating manufacturing variations in an early design stage to ensure an overall minimized life-cycle cost.
... M.K. Hagnell et al. used Python to develop a manufacturing cost estimating software, established a linear relationship between selected size value and fabrication time, and used a complexity factor to modify the result [20,21], but it is assumed that all equipment are newly procured and must be amortized over every product. The result includes parts of the Non-Recurring Cost and Recurring Cost. ...
... Layup/weave Cure Assembly Final Product Specifically, for manual lay-up, the part is laid up layer by layer using prepreg. The price of pre-preg is 54 USD/kg, and the scrap rate is 25-30% [20]. The model selects 30%; hence, Eq. (7) can be converted to the EWH form: ...
... The process time of ATL/AFP can be expressed in the linearized form [20,27]: ...
Article
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As applications of composite material increasingly increase in the aviation sector, its manufacturing cost is now identified as a bottle neck, which limits the market competitiveness in terms of cost-performance efficiency. To estimate the manufacturing cost of composite structures at the early design stage, this research proposes a manufacturing cost model based on process simulation and represents the cost in the form of “Equivalent Working Hour” (EWH). The research also introduces the “Structural Complexity Element” (SCE) and “Hourly Rate Factor” (HRF) to ensure and improve the accuracy of the model. Then, the model is applied on a composite wing structure to calculate and analyze the manufacturing costs of two structure designs to be manufactured through manual lay-up, automated tape lay-up/fiber placement, autoclave or out-of-autoclave curing, mechanical assembly, and co-cure or adhesive bonding. The results verified the effectiveness of the model.
... costly [8,9]. The material cost of the reinforcing fibres in themselves is also often an issue. ...
... Carbon fibre for example, are available at high prices of 20-60 e/kg [10] depending on stiffness grade. Furthermore, production cost studies have shown that material cost becomes a dominating cost driver when producing CFRP components either at high production rates or in large structural adaptions [8,9,11,12]. ...
... In addition, a few LCA-studies [26,50] defines a methodology connecting material selection to lightweight design. Furthermore, the authors have previously shown that quantitative production cost studies including the identification of production cost drivers and cost reduction strategies can be used to identify non-value adding processes [8,51] and propose design guidelines [9,23]. For early conceptual development however, aforementioned cost studies does not provide overarching design guidance spanning application, performance and material system. ...
Article
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The design of a composite material structure is often challenging as it is driven by the trade-off between lightweight performance and production costs. In this paper, the boundaries of this design trade-off and its implications on material selection, geometrical design and manufacturability are analysed for a number of design strategies and composite material systems. The analysis is founded on a methodology that couples weight-optimization and technical cost modelling through an application-bound design cost. Each design strategy is evaluated for three levels of bending and torsional stiffness. The resulting stiffness-versus cost-range together constructs the design envelope and provides guidelines on the suitability and improvement potential of each case. Design strategies researched include monolithic, u-beam-, sandwich-insert- and sandwich-stiffened plates. Considered material systems include carbon-, glass, recycled carbon-, lignin- and hemp-fibre reinforced composites. Optimized sandwich designs are shown to have lowest design cost. Glass-, recycled carbon-, lignin- and hemp-fibre reinforced composite materials are all shown to reduce costs but at lower stiffness performance. Ultimately, the case study demonstrates the importance of early structural design trade-off studies and material selection and justifies introducing novel fibre systems in low-cost applications of moderate stiffness levels.
... Also, Schubel (2012) compared various composites processing techniques using Technical Cost Modelling (TCM), determining that automated processes can reduce manufacturing costs by up to 8% in a 40 m wind turbine blade. Highlighting the influence of production volumes, Hagnell and Åkermo (2015) developed a cost model with part complexity factors which compared Hand Layup, ATL with Hot Drape Forming (ATL + HDF), and AFP, and concluded that, for their test case, Hand Layup was the most cost-effective up to 150 parts with ATL + HDF taking over from there. However, these cost models are simplified and tend to use only case-specific empirical relations that may, especially regarding material costs, fail to identify the range of components where ATL and AFP are more cost-effective. ...
... As mentioned in Campbell (2004) and in Hagnell and Åkermo (2015), the layup rate has a significant decrease in efficiency as part size decreases, since the tape is rarely being laid at the optimum speed, with the machine having to decelerate, cut the prepeg, and accelerate many times, making it unviable in terms of time and cost. The higher layup rate can only be achieved, according to Hagnell and Åkermo (2015), for parts larger than 288 m 2 . ...
... As mentioned in Campbell (2004) and in Hagnell and Åkermo (2015), the layup rate has a significant decrease in efficiency as part size decreases, since the tape is rarely being laid at the optimum speed, with the machine having to decelerate, cut the prepeg, and accelerate many times, making it unviable in terms of time and cost. The higher layup rate can only be achieved, according to Hagnell and Åkermo (2015), for parts larger than 288 m 2 . ...
Article
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.
... This scenario obliges one to reconsider the whole cost chain in the manufacturing process of components, and studies have addressed large fuselage parts [2]. In recent years, the traditionally high-cost composite parts are have been revealed to be cost-effective in different industry fields [3,4], mostly driven by the reduction of the manufacturing cycle time by automating the processes, despite the costs of both the associated equipment and the raw material. ...
... The end-effector assembly design and prototype are shown in Figure 5. A single hollow cask, 230 × 145 × 145 mm 3 , made of aluminium 6061 T6, is directly fastened to the arm flange to provide a rigid frame to hold both the milling head and gauge, with a total weight of 27 kg. The end-effector requires the gauge power, signal, and pneumatic lines, and includes a vacuum nozzle to remove fibre debris, which are very damaging to all the equipment. ...
Article
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Structural potting is used to prepare honeycomb panels to fix metallic elements, typical in aircraft doors. In this paper, a full procedure for structural potting using robotic arms is presented for the first time. Automating this procedure requires the integration of, first, machining operations to remove the skin layers and prepare the potting points and, then, resin injection into the honeycomb cells. The paper describes the design, prototyping, and testing of specific end-effectors. Different end-effectors were explored to ensure efficient injection. The results obtained with the prototypes show that the potting quality is adequate to accomplish the required process checks for industrial manufacturing. The injection process time can be reduced by a factor greater than 3.5, together with the extra assets associated with the automation of complex tasks. Therefore, structural potting automation is demonstrated to be feasible with the end-effectors proposed for milling and injection, which are ready for use with conventional robotic arms in manufacturing lines.
... The review of literature uncovered that cost estimation is used in automotive, aerospace and renewable energy industries and the main reasons for process cost estimation are, supporting business cases [3,4,10], process benchmarking [5,6,7], product design [2] and design vs. manufacturing process trade-offs [8,9]. ...
... Shehab [5] x x x x x x 6 Hagnell and Akermo [6] x x x x 4 Haffner [8] x ...
Chapter
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Cost estimation helps build confidence in the feasibility of the development of novel manufacturing processes. This paper focuses on the exploration of the cost estimation for novel manufacturing processes for decision support. One of the aspects of estimation is building credibility around the analysis, especially, in the early stages of planning. Cost estimating guidelines provide a good overview of the cost estimation steps but there is a requirement for guidelines for cost estimation model development. Through building on an understanding of the cost estimation principles, as well as cost estimation modelling, a high-level generic approach for process cost estimation is proposed. Further, a demonstration of a cost estimation modelling approach used for composites manufacturing in the automotive sector is provided, outlining the steps in cost estimation model development.
... The review of literature uncovered that cost estimation is used in automotive, aerospace and renewable energy industries and the main reasons for process cost estimation are, supporting business cases [3,4,10], process benchmarking [5,6,7], product design [2] and design vs. manufacturing process trade-offs [8,9]. ...
... Shehab [5] x x x x x x 6 Hagnell and Akermo [6] x x x x 4 Haffner [8] x x x x x 5 Fuchs [3] x x x x x 5 Cheung [10] x x x 3 Curran [11] x ...
Conference Paper
Cost estimation helps build confidence in the feasibility of the development of novel manufacturing processes. This paper focuses on the exploration of the cost estimation for novel manufacturing processes for decision support. One of the aspects of estimation is building credibility around the analysis, especially, in the early stages of planning. Cost estimating guidelines provide a good overview of the cost estimation steps but there is a requirement for guidelines for cost estimation model development. Through building on an understanding of the cost estimation principles, as well as cost estimation modelling, a high-level generic approach for process cost estimation is proposed. Further, a demonstration of a cost estimation modelling approach used for composites manufacturing in the automotive sector is provided, outlining the steps in cost estimation model development.
... Since one of the purposes to combine composite laminates consist of Carbon or Glass fiber with metal layers is to reach economic benefits, the cost analysis of the manufacturing process of fiber composite and hybrid laminates is a crucial factor [20][21][22][23][24]. In the CFRP manufacturing process, the study from Nunna et al. [24] shows that raw material costs still the influential factors related to the overall cost. ...
... By increase the tow size from 3 k to 50 k, the cost can be reduced from 76.6% to 49.6%. For more complex structures, Hagnell and Akermo [21] studied the cost analysis using a case study in the aerospace industry with a focus on aeronautical wings. The costs were evaluated in different methods of wing production. ...
Article
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The present study evaluated CFRP and SPCC hybrid laminates by combined experimental and simulation analysis. The results showed that the strength of hybrid laminate [SPCC/[0] n ] S increased more than 100% from 1000 MPa (0.5 mm thickness) compared to 2000 MPa (2 mm thickness). Moreover, by setting the volume fraction of hybrid laminates, the strength can increase from under 500 MPa to more than 3000 MPa with a minimum changed in strain performance. In other results, the effect of temperature differences during the manufacturing process is investigated. The analysis related to the operational temperature that used different material combinations was also evaluated. The band of temperature is varying from as high as 45°C to as low as −45°C. The outcomes demonstrate that the range of maximum strain of laminate from 45°C to −45°C can up to 0.1% of strain. Further analysis with a comparison regarding the angle effect of hybrid laminates with residual compressive stress and the curing temperature was also evaluated. The waviness trend shows higher when the temperature is set higher, and vice versa. The experimental results indicate good agreement with simulation results. Moreover, the analysis based on cost assessment was included and compared with other mechanical properties.
... The high anisotropy of CFRP Materials and Design 198 (2021) 109302 require diverse and complex layups, which are designed depending on the load case of the structure and usually exhibit a multi-directional fibre directions. To achieve these orientations in a cost effective manner, automated manufacturing methods such as tape laying, pultrusion or resin transfer moulding (RTM) are used to build the laminates and to create sub-components that are then joined together [2]. However, the relatively low bearing strength of CFRPs means that the laminate has to be thickened in order to have sufficient joint strength. ...
... Based on Fig. 10 we can hypothesise that maximum laminate ductility can be achieved by choosing a combination of ply thicknesses that would fall below the ultimate stress criterion; bearing in mind that t CFRP in Eqs. (1) and (2) refers to the thickness of the total ply block of CFRP plies between two steel layers, not to the individual ply thickness. This implies that to achieve maximum ductility, one would have to use steel layers that are an order of magnitude thicker than the CFRP plies. ...
Article
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The effect of ply thickness on the notch sensitivity and bearing properties on carbon fibre reinforced polymer composites and their hybrid laminates with steel foils were studied. Laminates with ply thicknesses of 0.3 mm and 0.03 mm comprising of CFRP and hybrid laminates were manufactured and characterized using tension, open hole tension and double lap bearing tests. A 25% ply substitution was found to double the bearing load with extensive plastic deformation in the joint while maintaining high stress and maintaining constant cross-sectional thickness in the laminate. With a good agreement between the finite element predicted values and failure behaviour, the damage initiation and progression behaviour could be observed experimentally. We numerically captured (i) rapid failure of 0° plies in the thin ply CFRP hybrid and (ii) continuous delamination with significant plastic deformation for the thick ply CFRP hybrid. The numerical results significantly reduce future experimental work when designing hybrid laminates and could allow the laminate lay-up to be tailored for load cases. Both the experiments and numerical models underline the distinct size effects occurring with respect to the ply thicknesses when hybridising a very ductile metal with a brittle yet strong composite material.
... At the end of each track, the tapes are cut by a cutting unit (7). As each tape can be cut individually, making a near-net-shape lay-up with low scrap rates in a range of 2 % to 6 % possible [4,[14][15][16]. The distance from the cutting unit to the nip point defines the minimum cut length (MCL). ...
... Even though resource efficiency has been the goal for aerospace manufacturing for several decades (Argüelles et al., 2001), the two biggest aircraft manufacturers, Airbus and Boeing, and their supply chain generate about 1000 t of cured and uncured carbon fiber prepreg waste each year (Biron and Kidlington, 2020). To maximize the resource efficiency, manufacturing processes with a low scrap rate like automated fiber placement (AFP) should be used preferably (Hagnell and Åkermo 2015). Yet, larger amounts of uncured prepreg might be scrapped as the material properties change during processing due to storage at elevated temperatures (outtime). ...
Article
Full-text available
In automated fiber placement (AFP), knowledge about the interaction between material properties and process parameters is essential to achieve cost-efficient manufacturing. Both, lay-up rate and defects are dependent on the properties of the uncured prepreg tapes which are out-time dependent. However, information thereof is not given in data sheets and there are no standardized test methods. To quantify the changes of the material properties, we conducted experiments on mechanical properties and tack with IM7/8552 up to 15 days out-time using previously evaluated test methods. Furthermore, we carried out AFP lay-up trials to quantify the effects on steering defects. The results for the mechanical properties reveal a non-linear increase of the shear modulus and the transverse tensile modulus and a strong correlation to the test temperature. Results from the probe tack tests show a strong dependence on out-time at 20°C and a weak dependence at 40°C. Results from a novel peel tack test method and the lay-up trials revealed a monotonous change as a function of out-time. In both cases, we identified the lay-up rate and the infrared (IR) emitter power as the process parameters with the largest influence. The obtained results present an overall view of the material behavior depending on different test and process parameters as a function of out-time. By this, they help optimize the AFP process parameters and serve as input for material models and AFP defect models.
... Carbon fibre-reinforced polymers offer excellent physical and mechanical properties, making them a more attractive choice of material in the field of aircraft manufacturing, facilitating emissions reduction and long fight times [1,2]. The amount of composite application in recent aircraft has reached 50% of their weight [3][4][5]. Therefore, the use of joints is impossible to avoid, and bolts become the most extensively used assembly mode employed for transferring large loads and aircraft maintenance [6,7]. In fact, the most common bolting scenario in modern aircraft is that with a composite and titanium to constitute a hybrid joint [8][9][10][11]. ...
Article
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Thin-ply composites have attracted increasing attention from researchers due to their higher damage tolerance and delamination suppression. This paper presents a detailed investigation of the fatigue behaviour and damage mechanism of symmetrical thin/thick hybrid design laminate-titanium joints under tension-tension loading. Laminates with four different configurations, thick, thick-thin-thick, thin-thick-thin and thin, were designed. According to the quasi-static bearing limit of the thick-ply laminates joints, fatigue testing of each hybrid joint was carried out at two load levels for a certain number of cycles. The deformation and damage of the hybrid joint were characterized by scanning electron microscopy (SEM). With thick plies and the addition of a number of thin plies, the hybrid design laminates can significantly improve the fatigue performance. Stacking thin-ply on the outermost layers of the laminate is more meaningful for double-lap joints than the use of thin-ply joints in the middle. Under an identical number of cycles, the deformation around a hole in the thin-ply laminate is only approximately 50% of that of the thick ply. The damage is delayed, and the propagation of inter- and intralaminar cracks is suppressed in the thin-ply laminates, resulting in the best fatigue resistance and less delamination under the two fatigue loads.
... Hagnell and Akermo [15] describe a TCM for a generic aeronautical wing in which costs scale with part features for a given production method. An integrated top-down and bottom-up approach was employed, depending on available cost data. ...
Article
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Lack of cost information is a barrier to acceptance of 3D woven preforms as reinforcements for composite materials, compared with 2D preforms. A parametric, resource-based technical cost model (TCM) was developed for 3D woven preforms based on a novel relationship equating manufacturing time and 3D preform complexity. Manufacturing time, and therefore cost, was found to scale with complexity for seventeen bespoke manufactured 3D preforms. Two sub-models were derived for a Weavebird loom and a Jacquard loom. For each loom, there was a strong correlation between preform complexity and manufacturing time. For a large, highly complex preform, the Jacquard loom is more efficient, so preform cost will be much lower than for the Weavebird. Provided production is continuous, learning, either by human agency or an autonomous loom control algorithm, can reduce preform cost for one or both looms to a commercially acceptable level. The TCM cost model framework could incorporate appropriate learning curves with digital twin/multi-variate analysis so that cost per preform of bespoke 3D woven fabrics for customised products with low production rates may be predicted with greater accuracy. A more accurate model could highlight resources such as tooling, labour and material for targeted cost reduction.
... Approaches for economic assessment generally focus on full-surfaced fabrics and not local reinforcements. Furthermore, the overall manufacturing process is considered, requiring a comprehensive set of input data [22,23]. Usually, the production planning, during which detailed manufacturing parameters are defined, is conducted in the later stages of the product development process [24]. ...
Article
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Locally load-optimized fiber-based composites, the so-called tailored textiles (TT), offer the potential to reduce weight and cost compared to conventional fiber-reinforced plastics (FRP). However, the design of TT has a higher complexity compared to FRP. Current approaches, focusing on solving this complexity for multiple objectives (cost, weight, stiffness), require great effort and calculation time, which makes them unsuitable for serial applications. Therefore, in this paper, an approach for the efficient creation of simplified TT concept designs is presented. By combining simplified models for structural design and cost estimation, the most promising concepts, regarding the cost, weight, and stiffness of TT parts, can be identified. By performing a parameter study, the cost, weight, and stiffness optima of a sample part compared to a conventional FRP component can be determined. The cost and weight were reduced by 30% for the same stiffness. Applying this approach at an early stage of product development reduces the initial complexity of the subsequent detailed engineering design, e.g., by applying methods from the state of the art.
... Clear consensus is missing on how waste processing cost should be calculated, but most used method seems to be V/ton, which was also used in this study. A more accurate product specific cost calculation can be done by taking into consideration the geometrical complexity of a part for which production time and tooling costs for a given quantity of products can be estimated (Hagnell and Åkermo, 2015). The manufacturing cost also depend on the used material heating method isothermal (heating the tool and the surroundings) or non-isothermal (heating the material directly) (Pantelakis et al., 2009). ...
Article
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The use of waste is often justified by the economic and environmental benefits of their use. This study compares the use of waste materials derived from construction and demolition waste—namely wood waste, mineral wool waste, gypsum board waste, and stone cutting dust—as alternative fillers in the production of thermoplastic composites using recycled high-density polyethylene as a matrix material. In total, nine alternative composites were studied in terms of their production costs, as well as their climate change impacts in three distinct product applications. Compared with the plastic matrix, the wood fiber achieved a cheaper price of €0.8–1.2/kg and the best properties in relation to weight. The price of mineral-based fillers varied between €0.5–1.1/kg, but the effect of the higher density on the weight increased the total price of the products. The unfilled recycled plastic was the cheapest solution in the application where the covered volume was important. The impact of using recycled high-density polyethylene in composites production totals at −1.24 kg CO2-eq./kg, out of where 1.75 kg CO2-eq. is the avoided impact from avoided waste disposal and 0.51 kg CO2-eq. is induced impact from producing the composites. When also accounting for the avoided impact from the substitution of virgin high-density polyethylene with the recycled high-density polyethylene composites, the avoided impact further increases to −3.17 kg CO2-eq./kg. The mineral fillers with were preferable in the application where mass was important, however, had lower avoided impacts than unfilled polyethylene ranging between −2.06 kg CO2-eq. and −2.47 kg CO2-eq. Wood fiber filler was the preferred filler option in the application where the material properties were taken into account in the amount of required material, but resulted in the lowest cumulative avoided impacts ranging between −1.79 and −2.25 kg CO2-eq., with most of the avoided impact originating from the replacement of virgin high-density polyethylene.
... Different coating alternatives of carbon steel can be found in the literature: stainless steel [8,9] organic coatings [10,11] ceramic coatings [12,13] and cermets [14,15]. In recent years, sprayed aluminum alloys are used in a high technology of aeronautics, e.g., as bond coats for thermal barrier coatings on turbine components, as restorative layers for machine parts, for corrosion under pressure, in numerous other applications requiring wear, high temperature and corrosion-resistant surfaces [16][17][18][19][20][21]. The purpose of coatings is to protect the surface of the machine element from attacks. ...
Article
This work focuses on the experimental characterization and mechanical behavior modeling of aeronautical alloy based composite to simulate tension test by finite element method and experimental test. The numerical finite element simulation allowed us to understand and manage a number of phenomena encountered during the mechanical behavior of our composites. Tensile tests applied have shown large changes in mechanical properties of the base alloy after coating, which are possibly related to the very different nature of the assembled materials and conditions of application. We note a strong decrease of the elastic limit of AG3 coated compared to AU4G. The high ductility of this alloy is the cause which engenders during the gritting process a large penetration of the granule particles in the substrate and the creation of plastic zones. Thus, a radial compression is exerted on the section which causes a plastification process. The decrease of the average section of the substrate after sandblasting, the stress concentration at the cavity and / or the compressive residual stress created when sandblasting are responsible for the decrease in breaking strength of the AU4G compared to the AG3. The material becomes hard and fragile. The experimental results obtained during our study are consistent with those of the simulation. Indeed, it was noted that the concentration of stresses during the tensile tests was located at the ends of the useful length of the test specimen. Keywords: Aeronautical, Coatings, Aluminum, Mechanical Behavior
... Generally, the high pressure levels can be applied using an autoclave [26,27] or hot press [28,29] both of which require high capital investment and energy consumption. Therefore, the composite industry has been frequently faced with a trade-off between the quality of composite parts and production cost [30]. ...
Article
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This study presents a novel method to fabricate high-quality, large composite parts which can be used in a wet lay-up/vacuum bag (WLVB) process. The new method utilizes a commercial lifting magnet, which is commonly used for transporting ferrous plates, to apply a magnetic consolidation pressure on the WLVB composite lay-up. The pressure is applied on a large area of the laminate by slowly sliding the magnet over the vacuum bag surface, which leads to an improved laminate quality. When further improvement is desirable, multiple passes of the magnet can be performed, where each pass successively compacts the lay-up. To explore the feasibility of implementing this technique, random mat and plain weave glass/epoxy laminates were fabricated, and their properties compared to conventional WLVB laminates. The effects of the number of moving passes of the lifting magnet on the laminate microstructure and properties are also investigated. As a result of multiple passes, the fiber volume fraction in random mat and plain weave laminates increases to 34% and 53%, representing 80% and 16% improvements, respectively. In addition, the void volume fraction reduces almost by 60% to a very low level of 0.7% and 1.1%, respectively. Consequently, the flexural properties considerably enhance by 20–81%, which demonstrates the potential of the proposed method to produce WLVB parts with substantially higher quality. It is also shown that there exists an optimal number of passes, depending on the fabric type where additional passes induce new voids as a result of excessive resin removal.
... Weiterhin lassen sich vor allem großflächige Bauteile, wie z. B. Flügelschalen und Rumpfsegmente, bei Stückzahlen größer 150 Stück pro Jahr kosteneffizient fertigen [HAG15]. ...
Book
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Production processes such as Automated Fiber Placement (AFP) gain in importance due to increasing consumption of fiber-reinforced plastics (CFRP) especially in aero-space applications. A manual inspection in the quality control of the AFP Process is time consuming and inefficient because of the low contrast between the different CFRP plys. In this dissertation, a new monitoring method is presented and investigated which is based on an infrared camera mounted behind the compaction roller of the AFP head. The system evaluates the thermal contrast between the surface and the just placed tows as well as the general temperature disturbance. Due to a detection of the tow edges, positioning faults can be identified. Connection faults and foreign bodies result in temperature anomalies which can be detected by evaluating the surface tempera-tures. A prototype monitoring system is developed to analysis the system boundaries and through an example process the general functionality is demonstrated.
... Different coating alternatives of carbon steel can be found in the literature: stainless steel [8,9] organic coatings [10,11] ceramic coatings [12,13] and cermets [14,15]. In recent years, sprayed aluminum alloys are used in a high technology of aeronautics, e.g., as bond coats for thermal barrier coatings on turbine components, as restorative layers for machine parts, for corrosion under pressure, in numerous other applications requiring wear, high temperature and corrosion-resistant surfaces [16][17][18][19][20][21]. The purpose of coatings is to protect the surface of the machine element from attacks. ...
Article
Full-text available
This work focuses on the experimental characterization and mechanical behavior modeling of aeronautical alloy based composite to simulate tension test by finite element method and experimental test. The numerical finite element simulation allowed us to understand and manage a number of phenomena encountered during the mechanical behavior of our composites. Tensile tests applied have shown large changes in mechanical properties of the base alloy after coating, which are possibly related to the very different nature of the assembled materials and conditions of application. We note a strong decrease of the elastic limit of AG3 coated compared to AU4G. The high ductility of this alloy is the cause which engenders during the gritting process a large penetration of the granule particles in the substrate and the creation of plastic zones. Thus, a radial compression is exerted on the section which causes a plastification process. The decrease of the average section of the substrate after sandblasting, the stress concentration at the cavity and / or the compressive residual stress created when sandblasting are responsible for the decrease in breaking strength of the AU4G compared to the AG3. The material becomes hard and fragile. The experimental results obtained during our study are consistent with those of the simulation. Indeed, it was noted that the concentration of stresses during the tensile tests was located at the ends of the useful length of the test specimen.
Chapter
Compression moulding is a well-established technique for processing polymer composite materials, using either thermoset or thermoplastic matrices. It is sometimes referred to as matched-die moulding, where the fibre reinforced composite material is forced to deform or flow within the mould cavity. Compression moulding is commonly associated with the forming of composite materials with discontinuous fibre reinforcements, at low (15%) to medium (50%) volume fractions. Compression moulding is used to process pre-impregnated intermediate products to produce semi-structural and structural composite components, for example thermoset Sheet Moulding Compounds (SMC), Glass Mat Thermoplastics (GMT) or Long Fibre Thermoplastics (LFT). Most recently, compression moulding has been used to process platelet-like materials, i.e. fibre strands or bundles pre-impregnated with a thermoset or a thermoplastic matrix, which are similar in nature to waste thermoset prepregs or recycled thermoplastic materials. This process is attractive because it is easily automated and can be used to produce very complex geometries without any waste, where the shape of the component can be used to significantly enhance the stiffness of the structure (e.g. ribs). Molding cycle times are typically dependent on part thickness, but range from 60 to 300 seconds, offering one of the fastest moulding processes for thermoset materials. The aim of this chapter is to give an overview of the various moulding compounds and their associated compression moulding processes, and to discuss the effect of processing conditions on the induced microstructure.
Article
Nondestructive testing of composite materials is important in aerospace applications, and mm-wave imaging has been increasingly used for this purpose. Imaging is traditionally performed using Fourier methods, with inverse methods being an alternative. This communication presents a mm-wave imaging method with an inverse approach intended for nondestructive testing of singly curved composite panels with sparsely distributed flaws. It builds on previous work which was limited to imaging on planar panels. The move from planar to singly curved panels increases the applicability of the method for aerospace applications. The imaging method is reference-free due to a numerical source separation algorithm and exploits sparsity in reconstruction of scatterers. It is demonstrated using near-field measurements at 60 GHz of an industrially manufactured composite panel with deliberate flaws. Compared to a more traditional Fourier imaging method, our method generates images with higher resolution and higher dynamic range. Flaw detection is also easier using our method as it generates images with less background clutter.
Article
Adhesive bonding technologies are widely used for the assembly of stiffened panels manufactured in advanced composites for structural applications in aeronautics. However, stiffened panels are prone to the occurrence of defects or damage in the skin/stiffener junction, which will reduce the damage tolerance properties and affect structural integrity. The presence of unstable irregularities in the bonding region contributes to the decrease in the level of adhesion, limiting the resistance of the adhesive/laminate interface when subjected to mechanical loads. This article presents an experimental fracture analysis of flat panels with a longitudinal T-stiffener integrated into the skin by secondary bonding. The panels were produced in quasi-isotropic carbon/epoxy laminates with an artificial insert film replacing the adhesive film in the center of the bonding, to induce the initial damage. The tests were performed under cyclic loading followed by static axial compression loading at room temperature up to collapse. The panel selected for visual and fractographic analysis reached buckling instability with 14% of the final load, in the time interval when the failure propagation induced slight reductions in stiffness. The results obtained from this work showed the influence of the failure mechanisms combined with the formation of the failure modes and fractographic aspects that characterized the complexity of the fracture morphology provided by debonding of the skin/stiffener junction. The information revealed was relevant to the understanding of the failure process resulting from a critical defect on secondary bonding joints, applied in the integration of composite stiffened panels for aeronautics applications.
Article
This paper presents a novel recyclate value model derived from the retained mechanical performance of retrieved fibres in fibre-reinforced composites. The proposed recyclate value model was used to perform an economic analysis for establishing the future closed-loop material usage of fibre-reinforced composite materials. State-of-the-art recycling of carbon and glass-reinforced thermosets was adopted and resulted in a proposed recycling hierarchy in order to achieve a more sustainable environment and raw material cost reduction. The recyclate value model showed that approximately 50% material cost reductions can be achieved at comparable mechanical performance by using recycled fibre instead of virgin fibre in appropriate applications. From the aspect of lightweight design this cost reduction provides the designer with new material choices, appropriate for lower cost and diverse stiffness designs. The proposed closed-loop hierarchy documents the importance of further improvement of fibrous material recycling, including sorting according to mechanical performance, in order to identify application areas previously not utilised and to maximise material sustainability and value throughout the material's lifetime.
Article
Purpose The purpose of this paper is to compare two different tools for tolerance analysis. Tolerance analysis is an important task to design and manufacture high-precision mechanical assemblies; it has received considerable attention in the literature. Many are the tools required to carry out a tolerance analysis, and may be divided into two categories: the analytical models and the statistical software packages. No comparison exists in the literature among these two categories. Design/methodology/approach This work presents a comparison between two different approaches to tolerance analysis: an analytical method, the variational model, and a statistical software, eM-Tolmate. The comparison has been developed on the same aeronautical case study that constitutes an actual product. Findings The proposed approach has been applied to an aeronautical case study. The results of the case study show how, when 2D tolerance analysis problems need to be solved, the two adopted tools give the same results. When the complexity of the tolerance analysis problems increases, the statistical software becomes the only choice to use. The new findings of the present paper are related to the fact that computer-aided tolerance analysis software packages remain the only choice to approach actual complex industrial products despite the extensive development of theoretical research. Research limitations/implications This paper deals with a unique case study. However, the two adopted approaches and the obtained results are general, that is, they may be applied to any assembly. Practical implications Tolerance analysis is a valid tool to foresee geometric interferences among the components of an assembly, before getting the physical assembly. It involves a decrease of the manufacturing costs. Originality/value Many are the tools for tolerance analysis, such as different analytical models and different commercial software packages. Some are the comparisons among the different tools in the literature, but they are not exhaustive. Therefore, when a user has to solve an assembly problem to foresee the geometric interferences during the design stage, he/she does not know what to choose. The original contribution of the paper is to address the user’s choice through a comparison between an analytical model and a statistical software to solve the tolerance analysis problems of an actual aeronautical assembly.
Thesis
Not at all like ordinary materials evacuation techniques, additive manufacturing (AM) depends on a novel materials incremental manufacturing logic. Additive manufacturing infers layer by layer forming and union of powder feedstock to discretionary designs, regularly utilizing a PC controlled laser. The present advancement center of AM is to deliver complex formed useful metallic segments, including metals, combinations and metal lattice composites (MMCs), to meet requesting prerequisites from aviation, barrier, car and biomedical ventures. Laser sintering (LS), laser softening (LM) and laser metal testimony (LMD) by viewed as the three most adaptable AM forms. Laser based AM forms for the most part have a complex non-balance physical and synthetic metallurgical nature, which is material and process subordinate. The impact of material qualities and preparing conditions on metallurgical instruments and resultant microstructural and mechanical properties of AM handled parts should be cleared up. This work is the eighth chapter out of 40 chapter collection discussing the high read and well-known publications in additive manufacturing and engineering. The statistical metadata and metric were extracted based on Google report and finding. The concentration of this thesis is mainly in the field of pump components in aerospace.
Article
This paper presents a cost-efficiency study of part integration with respect to reduced assembly effort within aeronautical composite structures. The study is performed through the use, and continuous improvement upon, a previously developed cost model. Focus are on the assembly and basic inspection a wing box, part of a section of a full wing, where involved parts are all considered to be manufactured from carbon fibre reinforced plastic (CFRP). Treated cases range from traditional, mechanical joining, to high integration either through co-curing or co-bonding of composite structures. The outcome of presented cost study shows that increased integration decreases the overall production cost of said considered wing box. In general it is shown that co-curing or co-bonding reduces a number of cost-expensive assembly steps in comparison to mechanical joining.
Article
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Top Level Aircraft Requirements for the down-selection process of advanced technologies for A380 are discussed in this article. The application of composite panels for the un-pressurized fuselage is taken as an example for the "best fit" of materials and manufacturing technologies with technology requirements.
Article
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A case study for the cost optimization of aircraft structures based on the operating cost as an objective function is presented. The proposed optimization framework contains modules for estimation of the weight, manufacturing cost, nondestructive inspection cost, and structural performance; the latter is enhanced by a kinematic draping model that allows the fiber angles to be simulated more realistically. The case study includes five material systems: aircraft-grade aluminum, two types of resin-transfer molded noncrimp fabric reinforcements, and two types of M21/T800 prepreg. The results are compared in relation to each other, and it is shown that (depending on the estimated fuel burn share of the component) a different material system is favorable when optimizing for low-operating cost.
Article
Full-text available
Tooling is an essential element of near net shape manufacturing processes such as injection molding and die casting, where it may account for over 25% of the total product cost and development time, especially when order quantity is small. Development of rapid and low cost tooling, combined with a scientific approach to mold cost estimation and control, has therefore become essential. This paper presents an integrated methodology for die and mold cost estimation, based on the concept of cost drivers and cost modifiers. Cost drivers include the geometric features of cavity and core, handled by analytical cost estimation approach to estimate the basic mold cost. Cost modifiers include tooling parameters such as parting line, presence of side core(s), surface texture, ejector mechanism and die material, contributing to the total mold cost. The methodology has been implemented and tested using 13 industrial examples. The average deviation was 0.40%. The model is flexible and can be easily implemented for estimating the cost of a variety of molds and dies by customizing the cost modifiers using quality function deployment approach, which is also described in this paper.
Article
The structural materials used in airframe and propulsion systems influence the cost, performance and safety of aircraft. This essential new book is intended for undergraduate students studying aerospace and aeronautical engineering, and is also a valuable resource for postgraduate students and practising aerospace engineers. The first three chapters of the book introduce the reader to aerospace materials. The next group of chapters go on to discuss the properties, production and metallurgy of materials for aerospace structures, followed by chapters on performance issues and recycling. The final chapter covers materials selection for aerospace structures and engines.
Article
: This paper outlines a new approach to determining the effect of part complexity on the cost of manufacturing a composite part. It also describes a methodology for predicting cost based on complexity that uses the techniques of Method Time Measurement (MTM). The proposed methodology offers a relatively simple method to predict the fabrication time of a complex component. It is based on the theory of acceleration and deceleration for every movement of action; therefore, the developed model has physical interpretations. In addition this paper describes a computer-based system for estimating time/cost to manufacture a complex composite part. The cost model has been implemented in a Relational Database Management System (RDBMS) with Access 97. The time estimated for hand lay-up compares very well with the industrial data. This concept of estimating fabrication time for a complex part appears to be applicable to many other composite manufacturing processes.
Article
Highly consistent quality and cost-effective manufacture of advanced composites can be achieved through automation. It may therefore open up new markets and applications for composite products in aerospace, automotive, renewable energy, and consumer goods. Automated Tape Laying (ATL) and Automated Fibre Placement (AFP) are the two main technologies used to automate the layup of prepreg. The historical development and past research of both technologies is reviewed; with an emphasis on past issues in application and capability as well as their solution, including both thermoset and thermoplastic material layup. It is shown that past developments have moved away from simply emulating manual layup into the now unique layup procedures for ATL, and into the current AFP technology base. The state of the art for both technologies is discussed and current gaps in the understanding of both processes highlighted. From this, future research needs and developments are derived and discussed.
Article
Cost modelling is typically one of the first steps in the design and development of a new or existing product and can show clear avenues for effective manufacturing. This paper provides an overview of existing cost modelling techniques and details the process term technical cost modelling (TCM), which is a combined parametric and process flow simulation method used widely throughout the manufacturing industry where historical data is either not available or does not exist. A focus is drawn on the manufacture of a 40 m wind turbine blade with the effects of part size, production volume, materials costs and tooling being detailed. A case study is presented which investigates the cost effectiveness of a range of existing manual production methods (hand-lay prepreg, VI, LRTM) and compares this to automated manufacturing (ATL, AFP, overlay braiding). ATL and AFP are shown to reduce manufacturing costs by up to 8% despite the high capital costs associated with automated equipment. The cost centres are isolated and clearly indicate the dominance of materials and labour. Material deposition in the tool is only one of a string of labour intensive processes in the manufacture of a large wind turbine blades and a holistic automated blade manufacturing approach is perhaps required to see the true labour saving benefits.
Article
The primary intention of this paper is to review the current state of the art in engineering cost modelling as applied to aerospace. This is a topic of current interest and in addressing the literature, the presented work also sets out some of the recognised definitions of cost that relate to the engineering domain. The paper does not attempt to address the higher-level financial sector but rather focuses on the costing issues directly relevant to the engineering process, primarily those of design and manufacture. This is of more contemporary interest as there is now a shift towards the analysis of the influence of cost, as defined in more engineering related terms; in an attempt to link into integrated product and process development (IPPD) within a concurrent engineering environment. Consequently, the cost definitions are reviewed in the context of the nature of cost as applicable to the engineering process stages: from bidding through to design, to manufacture, to procurement and ultimately, to operation. The linkage and integration of design and manufacture is addressed in some detail. This leads naturally to the concept of engineers influencing and controlling cost within their own domain rather than trusting this to financers who have little control over the cause of cost. In terms of influence, the engineer creates the potential for cost and in a concurrent environment this requires models that integrate cost into the decision making process.
Article
Thermoplastic composite and sandwich materials offer a potential of reducing component weight and improving recyclability while at the same time enhancing process economy through reduced manufacturing cycle time. The economical aspects of compression moulding of three different thermoplastic composite and sandwich material systems are modelled herein and are compared to compression moulding of a thermoset sheet moulding compound and stamping of sheet metal. A program has been developed which predicts component cost for different component sizes and complexities. It is found that raw material cost strongly dominates component cost for compression moulding of composite components, while in sheet metal stamping component cost is dominated by equipment costs.The model shows that thermoplastic composites are cost competitive for small to medium sized components and short production series of large components. The sandwich concepts offers a potential of further reducing component cost compared to composites, thus making the concept interesting for larger components, but still for short to intermediate production series, which is illustrated by calculating component cost for compression moulding of a sandwich tailgate.
Article
Two resin transfer moulding (RTM) processes have been examined for automotive body-in-white (BIW) structures. An epoxy system was compared with a novel reactive polyamide 12 (PA12) system via characterisation of reaction kinetics and the production of carbon fibre floor pan quadrant demonstrators incorporating typical geometrical features. Cost modelling tools were used to compare the two RTM variants for full floor-pan production at volumes of 12,500–60,000 parts per year. A 22% increase occurred for the standard TP-RTM cycle versus the epoxy system, principally due to thermal cycling of the tool that dominated the in-mould cycle time. Study of alternate preforming strategies showed that a reduction in non-crimp fabric scrap yielded major cost savings.
Article
A study has been conducted to estimate the costs of manufacture of a simple component in a number of different composite materials and by different manufacturing routes. The materials and routes selected span the range of composites from those appropriate for general engineering applications to aerospace. A simple methodology is introduced for a comparison on the basis of cost-performance efficiency. It is demonstrated that more economic solutions may often be realised by choice of ‘expensive’ carbon rather than ‘cheaper’ E-glass as the reinforcing fibre.
Article
This paper presents the architecture of the knowledge based engineering system which has been developed for estimation of weight and cost. It mainly discusses knowledge implementation in the knowledge base and knowledge processing in the inference engine to obtain weight and cost estimates. The inference engine extracts geometric data from a geometric model in CATIA V5 and processes the knowledge using the geometric data. Fuzzy logic is used for indiscrete knowledge. It also recognizes the flanges of a part and measures part complexity. The system automates the design process of weight and cost estimation including structural analysis.
Article
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002. Includes bibliographical references. Experience shows that the majority of costs are committed during the early stages of the development process. Presently, many cost estimation methods are available to the public for metal processing, but there are almost none (excluding proprietary) for advanced composite materials. Therefore, the central objective of this thesis is to provide a comprehensive overview of the costs of common composite production technologies such as Hand Layup, Resin Transfer Molding, Automated Tow Placement, Pultrusion, Forming, and Assembly. The work includes information on investment costs for production equipment and tooling as well as estimation guidelines for labor and material. Designers are presented with Design for Manufacturing guidelines (DFM) explaining how process selection and part design can lead to potential cost saving opportunities. Process based or technical cost models are well suited to quantify manufacturing costs and relate them to part design features, such as size and shape complexity. These physically based scaling principles can be easily adapted to changes in process technology and thereby reducing data requirements. In order to identify all relevant cost drivers, a detailed process plan is compiled for each composite manufacturing method. These processes can include up to 50 process steps and a total of 270 cost equations are used to calculate the cost contribution of each. (cont.) A number of case studies conducted in concert with our industrial sponsors clearly identifies the best point of each production process and for example help to explain the economic benefits of co-curing versus mechanical assembly. Users can therefore study the economic consequences of design changes in detail and consequently highlight any favorable design/process combinations. To further facilitate the comparison of process performance and to promote the feedback from industry all of the models are available on the Internet at http://web.mit.edu/lmp/www/composites/costmodel/. by Sascha M. Haffner. Ph.D.
On prepreg and properties and manufacturability
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