Exploiting the optical reflectance behaviour of carbon fibre composites for low-cost inspection and orientations analysis

Pierce, Robert S.; Liu, Xiaoling

doi:10.1177/0731684420934868

Cited by 4 publications

(7 citation statements)

References 21 publications

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“…This study improves upon the previous fibre orientation analysis 26 by excluding any results that are calculated from 'indistinct' peaks, leading to greater confidence in the fibre orientation measurements. A peak is classified as 'indistinct' when its reflectance value lies within the standard deviation of the remaining (non-peak) reflectance values, as shown in Figure 1.…”

Section: Improved Fibre Orientation Analysismentioning

confidence: 63%

“…[23][24][25] However, previous research by the authors has demonstrated a fibre orientation measurement technique based on optical reflectance that can be performed quickly across very large surfaces at a low cost. 26 As an extension of this approach, the current work improves its reliability and applies the technique to the evaluation of flow-induced fibre alignment in panels manufactured from high flow charges, presented in Experimental testing.…”

Section: Fibre Orientation Analysismentioning

confidence: 99%

“…Previous work has demonstrated the use of an optical reflectance method to measure fibre orientations across the surface of carbon fibre composites, and SMCs in particular. 26 This approach relies on taking a series of images under different lighting conditions (i.e. from 16 different directions at regular angular intervals) and identifying the opposite pair of conditions that produces the peak reflectance intensity for each pixel.…”

Section: Improved Fibre Orientation Analysismentioning

confidence: 99%

“…Here, a novel method for assessing fibre alignment in the flow direction is developed as a further extension of the existing fibre orientation analysis technique. 26 This is done by comparing the measured fibre orientation against the expected theoretical flow direction and can be evaluated in terms of an 'alignment factor' across any subset, or the entirety, of a panel. This alignment factor is determined for a case of radial flow as follows.…”

Section: Assessing Flow Alignmentmentioning

confidence: 99%

“…23–25 However, previous research by the authors has demonstrated a fibre orientation measurement technique based on optical reflectance that can be performed quickly across very large surfaces at a low cost. 26…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Fibre alignment and mechanical performance of carbon fibre Sheet Moulding Compounds under different preform compaction

Nega

Pierce

Liu

et al. 2022

Journal of Reinforced Plastics and Composites

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This work investigates the effect of preform compaction on the mechanical performance and flow-induced fibre alignment of carbon fibre reinforced Sheet Moulding Compounds (SMCs). Two groups of panels have been compression moulded from reclaimed carbon fibre tows in vinyl-ester resin with low (0.5 MPa) and high (10 MPa) preform compaction pressure Additionally, a low-cost fibre orientation analysis method has been further improved in terms of reliability, and a novel flow assessment method has been developed for carbon fibre SMCs. This approach revealed greater fibre alignment with the flow direction in the lower faces of panels as a result of greater contact time with the heated mould and a lower charge viscosity at the time of pressing. As expected, greater fibre alignment in the flow direction was observed outside the initial charge coverage area in both types of panels, where the flow was greatest. Due to additional fibre flow during the high-pressure compaction stage, the mean degree of flow alignment in the high compaction panel was 47% higher than that of the low compaction panel. Improvements in the tensile stiffness (8%) and strength (32%) were also observed as a result of the high-pressure compaction stage and associated flow alignment.

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Section: Improved Fibre Orientation Analysismentioning

confidence: 63%

Section: Fibre Orientation Analysismentioning

confidence: 99%

Section: Improved Fibre Orientation Analysismentioning

confidence: 99%

Section: Assessing Flow Alignmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Fibre alignment and mechanical performance of carbon fibre Sheet Moulding Compounds under different preform compaction

Nega

Pierce

Liu

et al. 2022

Journal of Reinforced Plastics and Composites

Self Cite

View full text Add to dashboard Cite

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Full‐field effect of flow‐induced fiber orientation during compression molding of carbon fiber sheet molding compounds

Nega,

Pierce,

et al. 2024

Polymer Composites

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An image‐based fiber orientation analysis technique has been employed to study the effect of initial charge coverage and preferential fiber alignment on the flow‐induced fiber orientations in carbon fiber sheet molding compounds (SMCs). The initial charge coverage area exhibited minimal fiber reorientation while significant fiber alignment in the flow direction was observed in the regions of greatest flow. Novel subsurface analysis using the same full‐field orientation analysis technique also showed the presence of a skin‐core structure with greater flow‐induced fiber alignment at the mold surfaces, while the core retained more of the initial fiber orientation distribution. Edge effects were also revealed by this analysis at the mold walls. Tensile testing from two orthogonal directions showed that panels molded from lower charge coverage resulted in better mechanical performance and lower anisotropy. Moreover, by encouraging charge flow in the preform's preferential alignment direction, high tensile stiffness and strength in the preferred direction were achieved (56.7 GPa and 238.9 MPa, respectively) at 30% fiber volume fraction. This provides a practical demonstration of the value in controlling fiber orientation, with respect to charge positioning and mold flow, to maximize and tailor the composite performance of SMCs typically used for automotive applications.Highlights Low‐cost scanning technique is extended to assess internal fiber orientations Full‐field orientations are measured before and after molding Investigation of how charge size and shape can affect orientations Combining effects of flow and initial orientation to tailor SMC performance Circular statistics provides a thorough analysis of orientation distributions

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Sensor-guided machining of large-scale CFRP components based on resin transfer molded features

Muth,

Carstensen,

Hintze

et al. 2023

Optical Measurement Systems for Industrial Inspection XIII

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Carbon fiber-reinforced Plastics (CFRP) are a key factor for achieving a carbon-neutral mobility sector due to their lightweight properties. Despite their near-net-shape manufacturing subsequent precision machining is required. In case of large-scale CFRP components, which are characterized by small quantities and low machining volumes, such processes are difficult to operate economically with conventional systems. Robotic systems offer a suitable solution. Their use in machining, however, requires additional measures to compensate for structural system limitations. In addition, individual deviations of the blanks require time-consuming measuring for referencing the machining system.To enable the use of cost-efficient robotic systems and to eliminate unproductive downtime for measuring, the intended manufacturing of CFRP components by Resin Transfer Molding (RTM) offers a new opportunity. RTM allows for the integration of defined features into the molding tool, which are reproduced inverted on the component and can be referenced by subsequent processes. This is utilized with adapted strategies for time-efficient measuring and high-precision machining.Fundamentals for the corresponding feature design as well as the selection of a suitable measuring device are presented. Focusing on laser-based sensors, the relationship between wavelength and (semi-)transparent surfaces is discussed and validated. Besides the metrological detection, production-specific aspects are also taken into account. Based on the gained knowledge, the main aspects of a proper sensor-feature combination are elaborated and prototypically realized. Finally, an outlook is provided on the challenges involved when implementing a robust algorithm for feature detection.

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Exploiting the optical reflectance behaviour of carbon fibre composites for low-cost inspection and orientations analysis

Cited by 4 publications

References 21 publications

Fibre alignment and mechanical performance of carbon fibre Sheet Moulding Compounds under different preform compaction

Fibre alignment and mechanical performance of carbon fibre Sheet Moulding Compounds under different preform compaction

Full‐field effect of flow‐induced fiber orientation during compression molding of carbon fiber sheet molding compounds

Sensor-guided machining of large-scale CFRP components based on resin transfer molded features

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