Numerical and Experimental Investigation of GMT Compression Molding and Fiber Displacement of UD-Tape Inserts

Behrens, Bernd‐Arno; Bohne, Florian; Lorenz, Ralph D.; Arndt, H.; Hübner, Sven; Micke-Camuz, Moritz

doi:10.1016/j.promfg.2020.04.109

Cited by 8 publications

(3 citation statements)

References 11 publications

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“…To gain this velocity profile a forming simulation is inevitable. Future work will concentrate on the flow simulation with a thermal model [15,21]. By optimizing the final temperature in the part or multiobjectives [22], this simulation can determine the exact parameters of the profile.…”

Section: Discussionmentioning

confidence: 99%

Path velocity planning for a forming process of fiber-reinforced thermoplastic with six degree of freedom

Wonnenberg

Dröder

2021

Prod. Eng. Res. Devel.

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By punch trajectory planning for a multi-axis forming press, it is possible to affect the local material properties in the workpiece. A multi-axis forming process can influence the material flow and thus the material properties via the punch path. During multi-axis forming processes, the velocity on a defined punch path affects the heat transfer between the punch and the forming material. An example for such forming materials is glass mat thermoplastics (GMT). Multi-axis forming can form these materials in a molten state. The materials cool down during forming due to contact-induced heat transfer between material and punch. The contact zone varies during the process and depends on the punch path. The punch velocity, however, influences the duration of the contact. In order to plan the punch velocity for required part properties, this paper presents an analytical model. The model bases on the geometrical description of the contact zone and gives different velocity profiles, which are tested in experiments. Finally, the paper discusses the analytical model, the velocity profiles and the requirements for the press.

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Section: Discussionmentioning

confidence: 99%

Path velocity planning for a forming process of fiber-reinforced thermoplastic with six degree of freedom

Wonnenberg

Dröder

2021

Prod. Eng. Res. Devel.

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“…In comparison to thermosetting plastics, shorter cycle times can be realised with FRP in manufacturing processes. Furthermore, the development of integrated manufacturing processes is advancing in order to use the potential of already established technologies to an optimum extent [8]. A promising solution that meets the growing demand for large-scale manufacturing of hybrid lightweight structures is injection moulding, which is already established for thermoplastics in various industries.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modelling of Bond Strength in Overmoulded Thermoplastic Composites

et al. 2021

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Overmoulding of thermoplastic composites combines the steps of thermoforming and injection moulding in an integrated manufacturing process. The combination of continuous fibre-reinforced thermoplastics with overmoulded polymer enables the manufacturing of highly functionally integrated structures with excellent mechanical properties. When performed as a one-shot process, an economically efficient manufacturing of geometrical complex lightweight parts within short cycle times is possible. However, a major challenge in the part and process design of overmoulded thermoplastic composites (OTC) is the assurance of sufficient bond strength between the composite and the overmoulded polymers. Within the framework of a simulation-based approach, this study aims to develop a methodology for predicting the bond strength in OTC using simulation data and a numerical model formulation of the bonding mechanisms. Therefore, a modelling approach for the determination of the bond strength depending on different process parameters is presented. In order to validate the bond strength model, specimens are manufactured with different process settings and mechanical tests are carried out. Overall, the results of the numerical computation are in good agreement with the experimentally determined bond strength. The proposed modelling approach enables the prediction of the local bond strength in OTC, considering the interface conditions and the processing history.

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“…As molding experiments using a compression mold and a compression molding machine, there are several reports discussing time-dependent changes in melt pressure and temperature for GMT under non-isothermal conditions through a compression mold with pressure and temperature sensors mounted at different positions. In these reports, the experimental data were compared with numerical simulation results [15], and melt pressure reductions, which are due to material shrinkage by temperature decrease after indicating maximum pressure, were discussed [16]. However, profile data on melted sheet transfer from a heating machine to a mold have not been measured, and measurement techniques for precise "compression waiting time" have not been sufficiently verified.…”

Section: Introductionmentioning

confidence: 99%

Study of Monitoring Method and Melt Flow Behavior in Compression Molding Process Using Thermoplastic Sheets Reinforced with Discontinuous Long-Fibers

Kobayashi

2021

J. Compos. Sci.

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In compression molding using glass-fiber-mat-reinforced thermoplastic (GMT) sheets, a slightly longer compression waiting time from sheet placement on a lower mold to the start of sheet compression by an upper mold can cause incomplete filling due to a decrease in the sheet temperature. However, precise measurement techniques for compression waiting time have not been sufficiently established. A monitoring system was produced that includes pressure—temperature sensors mounted in a compression mold that can simultaneously measure the pressure and temperature of one local surface. Two types of distance sensors were also used to measure upper mold motion widely and precisely. Determination of compression waiting time was attempted by measuring the moment when the lower mold temperature slightly increases in response to contact with the melted GMT sheet and the moment when the melt pressure increases in response to compression by an upper mold. The results showed that compression waiting time could be precisely calculated using the profile data obtained. Moreover, it was also possible to observe the melt pressure overshoot that occurs depending on sheet stacking patterns and mold cavity shape, although in some cases, the overshoot was not observed. In conclusion, this study has demonstrated that the system is effective in monitoring the compression molding process widely and precisely.

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Numerical and Experimental Investigation of GMT Compression Molding and Fiber Displacement of UD-Tape Inserts

Cited by 8 publications

References 11 publications

Path velocity planning for a forming process of fiber-reinforced thermoplastic with six degree of freedom

Path velocity planning for a forming process of fiber-reinforced thermoplastic with six degree of freedom

Numerical Modelling of Bond Strength in Overmoulded Thermoplastic Composites

Study of Monitoring Method and Melt Flow Behavior in Compression Molding Process Using Thermoplastic Sheets Reinforced with Discontinuous Long-Fibers

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