| 1. |
- Dutta, Abhik, et al.
(författare)
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FORMING OF HYBRID (UD-ASMC) COMPOSITES
- 2022
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Ingår i: ECCM 2022. - : Composite Construction Laboratory (CCLab), Ecole Polytechnique Federale de Lausanne (EPFL). ; , s. 446-453
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Konferensbidrag (refereegranskat)abstract
- Combining short and long fibre reinforcement in the same component, enables establishing an optimum combination between cost and production efficiency while still maintaining good structural characteristics of the produced component. This can be done in a single compression molding step. However, producing defect free hybrid components require a good understanding of the deformation mechanisms during manufacturing. Traditionally, unidirectional (UD)-prepreg forming models involve the study of mechanisms such as shear and ply bending. On the other hand, manufacturing of advanced SMC (ASMC) relies on enabling a significant amount of squeeze flow. However, little is known about the interaction of these mechanism. This study aims to look at the interaction between long, aligned fibres and short fibre composite material during the first phase, forming, of a compression molding process. A two-stage modelling approach consisting of draping and squeeze flow respectively, is suggested and material properties for the first stage of modelling the UD-ASMC hybrid stack is presented. The material system studied consists of a combination of UD “snap-cure” prepreg and ASMC, both having fibre volume fraction greater than 50% and are suitable for use in serial production.
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| 2. |
- Eliasson, Sara, et al.
(författare)
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A life cycle energy and weight comparison of a carbon fibercomposite versus metallic component in a commercial vehicle
- 2021
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Ingår i: A life cycle energy and weight comparison of a carbon fibercomposite versus metallic component in a commercialvehicle.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Lightweight design is important for Battery Electric Vehicles (BEVs), to minimize the effects from the added weight of the batteries. The study looks at the benefits and disadvantages of choosing a Carbon Fiber Reinforced Polymer (CFRP) material in comparison to metallic material for a specific battery electric commercial vehicle component. A Life Cycle Energy (LCE) and weight analysis are the basis for the comparison. Other aspects that could be considered important for the industrial implementation, such as cost, are also discussed. The LCE is assessed using a combination of engineering process modelling, available data from industrial partners, and data available in the literature. The analysis is aimed to support a holistic comparison, which means the modelling is performed on an overarching level of detail.
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| 3. |
- Eliasson, Sara, et al.
(författare)
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A Statistical Porosity Characterization Approach of Carbon-Fiber-Reinforced Polymer Material Using Optical Microscopy and Neural Network
- 2022
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 15:19
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Tidskriftsartikel (refereegranskat)abstract
- The intensified pursuit for lightweight solutions in the commercial vehicle industry increases the demand for method development of more advanced lightweight materials such as Carbon-Fiber-Reinforced Composites (CFRP). The behavior of these anisotropic materials is challenging to understand and manufacturing defects could dramatically change the mechanical properties. Voids are one of the most common manufacturing defects; they can affect mechanical properties and work as initiation sites for damage. It is essential to know the micromechanical composition of the material to understand the material behavior. Void characterization is commonly conducted using optical microscopy, which is a reliable technique. In the current study, an approach based on optical microscopy, statistically characterizing a CFRP laminate with regard to porosity, is proposed. A neural network is implemented to efficiently segment micrographs and label the constituents: void, matrix, and fiber. A neural network minimizes the manual labor automating the process and shows great potential to be implemented in repetitive tasks in a design process to save time. The constituent fractions are determined and they show that constituent characterization can be performed with high accuracy for a very low number of training images. The extracted data are statistically analyzed. If significant differences are found, they can reveal and explain differences in the material behavior. The global and local void fraction show significant differences for the material used in this study and are good candidates to explain differences in material behavior. © 2022 by the authors.
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| 4. |
- Eliasson, Sara, et al.
(författare)
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An Experimentally Based Micromechanical Framework Exploring Effects of Void Shape on Macromechanical Properties
- 2022
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Ingår i: Materials. - : MDPI. - 1996-1944. ; 15:12
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Tidskriftsartikel (refereegranskat)abstract
- A micromechanical simulation approach in a Multi-Scale Modeling (MSM) framework with the ability to consider manufacturing defects is proposed. The study includes a case study where the framework is implemented exploring a cross-ply laminate. The proposed framework highlights the importance of correct input regarding micromechanical geometry and void characteristics. A Representative Volume Element (RVE) model is developed utilizing true micromechanical geometry extracted from micrographs. Voids, based on statistical experimental data, are implemented in the RVE model, and the effects on the fiber distribution and effective macromechanical properties are evaluated. The RVE algorithm is robust and maintains a good surrounding fiber distribution around the implemented void. The local void fraction, void size, and void shape affect the effective micromechanical properties, and it is important to consider the phenomena of the effective mechanical properties with regard to the overall void fraction of an RVE and the actual laminate. The proposed framework has a good prediction of the macromechanical properties and shows great potential to be used in an industrial implementation. For an industrial implementation, weak spots and critical areas for a laminate on a macro-level are found through combining local RVEs. © 2022 by the authors.
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| 5. |
- Hagnell, Mathilda Karlsson, et al.
(författare)
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Cost modelling of composite structures
- 2015
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Ingår i: JEC Composites Magazine. - 1639-965X. ; 52:96, s. 28-29
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Tidskriftsartikel (refereegranskat)abstract
- In aeronautics, composite materials are weight-efficient but difficult and often costly to produce. To study this contrast, the authors are working on a methodology where the costs of composite manufacture and assembly are estimated as a function of structure geometry, complexity and manufacturing approach.
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| 6. |
- Iyer, Kaushik, et al.
(författare)
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The multi-objective optimization framework: A step towards minimizing life-cycle costs and energy consumption of carbon fibre automotive structures
- 2024
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Ingår i: Composites Part B. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 271
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Tidskriftsartikel (refereegranskat)abstract
- Design of a sustainable and economical composite structure is challenging due to the often contradicting design drivers such as energy consumption and cost. Therefore, predicting the environmental and economic impact in the early stages of product design results in the significant reduction of energy consumption and cost. Consequently, the impact of contrasting objectives on an optimized carbon fibre reinforced polymer (CFRP) demonstrator is evaluated in this study. This evaluation is performed by integrating a predictive life-cycle assessment and costing framework in a multi-objective optimization methodology. The varying design configurations include designs with and without stiffeners. Furthermore, the impact of end-of-life allocation on the optimized design is also evaluated in this study. The results show a marked difference between the energy consumption of the various optimized designs with energy optimization producing the most efficient solution. However, the mass of the demonstrator increases by 7–9 kg across the different design configurations when the closed loop allocation model is implemented. Consequently, the results show the importance of selecting an appropriate EOL allocation methodology in evaluating the energy consumption of a product. The results also show that the parameters driving the energy consumption (mass and material configuration) and cost (complexity and manufacturability) are varied and often contrasting. The differences in mass, cost, and energy optimized designs further reinforces the importance of coupling cost and energy evaluation in design of sustainable products. Finally, the study demonstrates the need for a holistic life-cycle based assessment in early stage sustainable product design.
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| 7. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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A composite cost model for the aeronautical industry : Methodology and case study
- 2015
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Ingår i: Composites Part B. - : Elsevier BV. - 1359-8368 .- 1879-1069. ; 79, s. 254-261
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Tidskriftsartikel (refereegranskat)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 (All) followed by hot drape forming (HDF) is the most cost-effective choice.
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| 8. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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Cost and weight efficient assembly of aeronautical composite structures
- 2015
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Ingår i: ICCM International Conferences on Composite Materials. - : International Committee on Composite Materials.
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Konferensbidrag (refereegranskat)abstract
- Composite materials and integrated structures are weight-efficient, but not necessarily cost-efficient. In order to compare weight benefits with production cost penalties, the influence of each must be studied simultaneously. Production costs are challenging to estimate as they depend on production method choice as well as involved process variables such as annual production volume. In order to enable simultaneous analysis of cost and weight it is therefore necessary to develop tools that assist in production cost estimation. This paper presents the continuation of previous work, where the manufacturing costs of a composite structure is studied using a novel cost estimation tool, here extended to include that of assembly costs. Focus of this paper is assembly of aeronautical structures. The model is finally applied and discussed through estimating the assembly costs of two cases; that of a co-cured structure and that of a mechanically joined structure. The case study shows that the co-cured wing box is more cost-efficient than that of the mechanically joined wing box. Regarding weight, the mechanically joined structure increases the structural weight by about 1 kg, which corresponds to a weight increase of 1 %. Important cost drivers for the mechanically joined wing box are fastening, drilling and shimming costs, each representing about 20 % of the total cost as the annual production volume increases to 1000 produced structures per year. Important cost drivers for the co-cured wing box is the cost of part positioning and autoclave curing, representing about 40 % of the total cost each as the annual production volume increases to 1000 produced structures per year.
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| 9. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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Design implications and opportunities of considering fatigue strength, manufacturing variations and predictive lcc in welds
- 2021
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Ingår i: Metals. - : MDPI. - 2075-4701. ; 11:10
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Tidskriftsartikel (refereegranskat)abstract
- 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. © 2021 by the authors.
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| 10. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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From aviation to automotive - a study on material selection and its implication on cost and weight efficient structural composite and sandwich designs
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The structural design of composite materials is often challenging as its driven by a trade-off between lightweight structural performance and production costs. Addressing this design trade-off, this paper presents a methodology and case study that compares the weight- and production cost-potential of different composite materials and structural designs solutions through the use of a proposed application-bound design cost. Representative design solutions; monolithic, u-beam-, sandwich-insert- and sandwich-stiffened, are each optimized with respect to bending and torsional stiffness of increased severity to chart an extrapolated application map with respect to cost and stiffness. Optimized sandwich designs are shown to have lowest design cost where full stiffness is achieved. Alternative fibre materials researched; glass fibre, recycled carbon fibre, lignin-based fibres and hemp fibres, all reduce costs but at compromised stiffness. Ultimately, the case study demonstrates the impact of early design and material selection and justifies introducing novel fibre systems to reduce design cost.
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| 11. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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From aviation to automotive - a study on material selection and its implication on cost and weight efficient structural composite and sandwich designs
- 2020
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Ingår i: Heliyon. - : Elsevier. - 2405-8440. ; 6:3
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 12. |
- Karlsson Hagnell, Mathilda
(författare)
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Technical cost modelling and efficient design of lightweight composites in structural applications
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A lightweight transport design reduces fuel costs and emissions and can be achieved through the use of fibre-reinforced composite materials. Although lightweight, the composite raw material can be expensive and the sequential component production challenging and costly. To design weight- and cost-efficient composite structures and find ways to reduce production costs, technical cost modelling must be applied. In this thesis, a technical cost model for composite manufacture, assembly and basic inspection is proposed and implemented to identify cost drivers, evaluate trending design strategies and suggest appropriate composite design guidelines for transport and aeronautical applications. Among identified cost drivers, material costs dominates at 50-90 % of the total part cost also for low annual volumes. Tooling costs are second in importance for slow processes and large parts while the importance of investment and labour depends on degree of automation. Part integration is shown to only marginally reduce cost. Traditional composite assembly is in turn found to potentially reduce costs by 30 % through the elimination of non-value-adding processes such as shimming and part positioning. In comparison to part integration, sandwich design exhibits superior cost- and weight-efficiency for low-to-intermediate stiffness levels. Moreover, the industry impact of a sustainable, circular recycling flow of composite materials is estimated and shown to give up to halved raw material costs as well as cost returns also for virgin carbon fibre users. Low-cost fibres such as glass, lignin-based carbon, hemp and recycled carbon fibres are found to be highly cost-competitive also for structural adaptions.The technical cost model, method and results presented in this thesis provide important composite design conclusions and a foundation for further modelling work needed to reach that elusive weight- and cost-optimal composite design.
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| 13. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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The economic and mechanical potential of closed loop material usage and recycling of fibre-reinforced composite materials
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- 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.
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| 14. |
- Karlsson Hagnell, Mathilda, et al.
(författare)
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The economic and mechanical potential of closed loop material usage and recycling of fibre-reinforced composite materials
- 2019
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Ingår i: Journal of Cleaner Production. - : ELSEVIER SCI LTD. - 0959-6526 .- 1879-1786. ; 223, s. 957-968
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 15. |
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Proceedings of the Resource Efficient Vehicles Conference - 2021 (rev2021)
- 2021
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Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- rev2021 was the first edition of the conference on Resource Efficient Vehicles, held online on 14-16 June 2021. This vehicle-centric conference aims to bring together participants from academia, industry and public agencies to discuss research from all relevant fields connected to resource efficiency in all motorised modes of transport and interdependent surrounding systems. The theme of this multidisciplinary conference is Resolving Functional Conflicts in Vehicle Design, a theme explored through topics including modelling for multifunctional design; making trade-offs; efficient use of materials and space; integrating new solutions; transforming the product system; transforming the vehicle-transport system; sustainable design; and early-stage design. The 2021 edition of the conference consisted of 40 selected papers for presentation at the conference, complemented with four workshops, five keynote lectures from invited speakers, and a concluding panel discussion with four invited participants. It was organised by the Centre for ECO2 Vehicle Design at KTH Royal Institute of Technology in Stockholm.
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| 16. |
- Shetye, Nitish, et al.
(författare)
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Life-Cycle Energy Analysis of a High Strength Steel Heavy Vehicle Component Subjected to Fatigue Loading
- 2021
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Ingår i: Procedia Structural Integrity. - : Elsevier B.V.. - 2452-3216. ; , s. 538-545
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Konferensbidrag (refereegranskat)abstract
- This study focuses on comparing the life-cycle energy required for Conventional Steel and HYBRIT (Hydrogen Breakthrough Ironmaking Technology) Steel. The application chosen for this comparison was a bogie beam of Volvo's articulated hauler A30. HYBRIT is a new generation of a fossil-free steel technology developed by SSAB (Swedish Steel Company) which aims to replace coal with hydrogen during steel production to reduce CO2 emissions. The different phases analysed where; material extraction, steel production, component manufacturing, use and end of life phases. Where the use phase is predominantly fatigue loading. It is concluded that HYBRIT Steel consumed 8-10% less energy than Conventional Steel over the entire lifecycle. For applications with less dominant use phases, the percentage of energy saved by HYBRIT Steel would be even larger.
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