38 research outputs found
Forming of complex-shaped composite tubes using optimized bladder-assisted resin transfer molding
No full textRTMsim - A Julia module for filling simulations in Resin Transfer Moulding with the Finite Area Method
No full textResin Transfer Moulding (RTM) is a manufacturing process for producing thin-walled fiber reinforced polymer composites where dry fibers are placed inside a mould and resin is injected under pressure into the fibrous preform. During mould design, filling simulations can study different manufacturing concepts (i.e. placement of inlet ports and vents) to guarantee complete filling of the part and avoid air entrapment where flow fronts converge.
RTMsim is a new software tool for RTM filling simulations. The porous cavity is fully described by a mesh file with triangular cells on the part’s mid-surface and cell set definitions. The latter can be used for specifying the location of the pressure injection ports and regions with different preforms by assigning different thickness, porosity and permeability values. Additional equations (e.g. for modeling the degree-of-cure) can either be added with equations of the same type or modifications of existing equations (e.g. for variable cavity thickness as needed for vacuum assisted resin infusion simulations). Several test cases were used for successfully validating the implemented model
Novel test-rig for compaction behaviour analysis of textile reinforcements for improved RTM-process replication
No full textAbstractThis paper presents a novel testing method for evaluating the compaction behaviour of textile reinforcements in the context of liquid composite moulding processes. The existing testing approach utilizing pre-saturated samples (ex-ante) fails to accurately represent the unsaturated state of samples during vacuum infusion or resin transfer moulding (RTM) processes, leading to unreliable results and potential discrepancies with simulation. To address this limitation, a newly designed test-rig is introduced in this study, enabling compressibility testing based on real process specifications. The proposed method allows for the measurement of both dry and wet compression characteristics using a single specimen through in-situ impregnation of the materials under compressive load. Moreover, the test-rig enables tests according to ex-ante specifications, facilitating direct comparison with the proposed in-situ method. Finally, the test-rig allows for compressibility tests at elevated temperatures up to 200 °C. This is of particular relevance for studying the compaction behaviour of bindered technical fabrics. Preliminary comparative tests demonstrate excellent agreement between the results obtained using the ex-ante method under the 2020 international benchmark exercise and the novel in-situ impregnation method. This confirms the validity and reliability of the results obtained through the proposed testing method. By providing a more realistic representation of the compaction behaviour of textile reinforcements, the novel approach presented in this study offers valuable insights for optimizing liquid composite moulding processes and improving the accuracy of simulation models
Effect of Flashlamp Heating System Parameters on the Wedge Peel Strength of Thermoplastic Carbon Fiber Tape in the Automated Tape Placement Process
No full textLaser-assisted automated tape placement systems are currently the state of the art regarding thermoplastic tape placement. Flashlamp heating systems are rather new in this field of application and offer high energy density with low safety requirements and moderate costs compared to laser-assisted automated tape placement systems. In this study, the effect of processing parameters on interlaminar bonding of carbon fiber-reinforced polyamide 6 tapes is investigated using a flashlamp heating system. The temperature during placement is monitored using an infrared camera, and the bonding strength is characterized by a wedge peel test. The bonding quality of the tapes placed between 210 °C and 330 °C at a lay-up speed of 50 mm/s is investigated. Thermogravimetric analysis, differential scanning calorimetry, and micrographs are used to investigate the material properties and effects of the processing conditions on the thermophysical properties and geometric properties of the tape. No significant changes in the thermophysical or geometric properties were found. Moisture within the tapes and staining of the quartz guides of the flashlamp system have significant influence on the bonding strength. The highest wedge peel strength of dried tapes was found at around 330 °C
Methods of statistical uncertainty analysis applied to evaluation algorithms of a video-extensometer system
No full textExperimental validation of a new adaptable LCM mold filling software
No full textResin Transfer Molding (RTM) is a manufacturing process for fiber reinforced polymer composites where dry fibers are placed inside a mold and resin is injected under pressure. During mold design, filling simulations can study different manufacturing concepts (i.e. placement of injection gates and vents) to guarantee complete filling of the part and avoid air entrapment where flow fronts converge. In this work, a novel software tool LCMsim, which was implemented by the authors, is benchmarked against other tools and real-world flow experiments. Its development was driven by two ideas: Easy-of-use for the mold engineer and maximum flexibility for the researcher. Two experiments were used for validation. In the first, zones with different preform properties were present and in the second, race-tracking was enforced. Flow fronts from LCMsim and experiment agree with 7% error and simulated flow fronts from LCMsim and the commercially available software PAM-RTM agree with 3% error
A methodology for determining preform compaction in bladder-assisted resin transfer molding with elastomeric bladders for tubular composite parts
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An experimental method for characterizing unsaturated 1D flow in tubular braided preforms during bladder‐assisted resin transfer molding
No full textInfluence of process pressures on filling behavior of tubular fabrics in bladder-assisted resin transfer molding
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