Papers by Keyword: Pultrusion

Abstract: Process speed in pultrusion is significantly influenced by the exothermic reactions of the matrix materials used. The main reaction zone (gel zone) is a key indicator to describe and interpret the reaction behavior in pultrusion. It can be easily observed by elevated temperatures in the die, particularly for highly exothermic thermoset matrices like vinyl ester, epoxy, and polyurethane. However, this effect is not as pronounced in reactive thermoplastics. The exothermic reactions contribute to a reduction in power consumption of the heating plates within the different heating zones, each with its individual temperature. Analyzing the power consumption of the individual heating zones across different process parameter settings allows to determine the position of the gel zone. This information is foundational for pultrusion process optimization, as it allows for more efficient utilization of the die length, ultimately increasing the pull speeds and enabling higher production rates. In this study, a comparative analysis of the power consumption across the heating zones was performed. To validate the findings obtained from the power measurements, thermocouples were drawn through the die at the same process parameters to accurately measure the temperature evolution within the pultruded profile throughout the die length.

Abstract: This work focuses on the pultrusion of pre-consolidated tapes made of virgin polypropylene reinforced with glass fiber. A specially designed laboratory-scale pultrusion line was used, consisting of a heating/forming mold, a cooling mold, and the pulling system. A life cycle assessment was conducted to evaluate the environmental impact of producing a pultruded composite material with a constant cross-section of 100 mm² and a length of one meter. The cradle-to-gate approach was chosen to model the pultrusion process, which involves the three stages mentioned above. The analysis was performed using the CML 2016 method in the LCA for Experts (Sphera) software. The data used in this work to model the cradle-to-gate scenario are mainly derived from experimental measurements taken during the pultrusion process using sensors and from the literature. The specific Energy Consumption (SEC) was calculated for both operational conditions (1.41 MJ/m at v120 to 0.905 MJ/m at v180). Despite the defects found, the samples taken from the pultruded profile showed significant interlaminar shear strength (120 mm/min of 83.7 ± 9.6 MPa compared to 63.5 ± 17.3 MPa at 180 mm/min).

Abstract: This work develops and validates thermo-chemical models for pultrusion of glass fiber–reinforced polyurethane composites on an industrial PulFlex production line. A reduced one-dimensional model combining a calibrated Kamal–Sourour (KS) cure law with an Arrhenius type chemo-rheological viscosity formulation is cross-validated against a three-dimensional ANSYS Composite Cure Simulation using identical material inputs along a three-zone, 0.9144 m heated die. Embedded thermocouples provide in-die temperature histories at 50.8 cm·min⁻¹ for calibration, while additional differential scanning calorimetry (DSC) measurements supply degree of cure (DoC) profiles for independent validation. At the industrial operating speed of 50.8 cm·min⁻¹, the mathematical and ANSYS models both reproduce the measured temperature peak location and exit temperature within a few degrees Celsius and predict a die-exit DoC of approximately 0.95, confirming near-complete curing. Using these calibrated fields as inputs to an analytical pulling-resistance formulation, both models predict comparable pulling force magnitudes and plateau behavior, demonstrating that the simplified 1D framework can capture not only thermo-chemical evolution but also process resistance trends over a range of pulling speeds. The validated 1D model therefore enables efficient exploration of speed–temperature–force tradeoffs for process window design, while the 3D ANSYS model provides a higher-fidelity reference for local gradients and future thermo–chemo–mechanical extensions.

Abstract: For an effectiveness improvement of conventional pultrusion processes, new optimization methodology is developed by using the design of experiments and response surface technique. An application of this methodology with two objective functions describing the minimum electrical energy spent for a curing and maximum pull speed is successfully demonstrated for the pultrusion process producing thin-walled-rectangular profile.

Abstract: Structural performance and buckling behaviors of pultruded fiber-reinforced polymer (PFRP) angle profile beams under three-point bending tests are presented in this paper. The angle specimens were evaluated to investigate the effect of unbraced length of the beams on the buckling responses and critical buckling loads. In total, sixteen specimens, including eight span-to-width ratios (L/b) were tested. The dimension of the angle profile was commercially available 76x6.4 mm. The span-to-width ratios of the specimens were in the range of approximately 13 to 59. The constituent materials used for the angle profiles consist of unidirectional E-glass fibers and polyester resin. From the bending tests, the load-deformation relationships and failure modes of angle beams were reported. The experimental results indicated that the critical buckling load decreases as the span-to-width ratio increases. The degree of flexural-torsional buckling is directly related to span-to-width ratio. Furthermore, the comparison between the critical buckling loads obtained from experimental study and prediction using methods provided in AISC-LRFD design equation for PFRP angle profile beams showed an unsatisfactory correlation of the critical buckling loads.

Abstract: This study examined the optimal abrasive wear performance of kenaf-reinforced polymer composite under different sliding conditions. Three different fiber loadings i.e. 43.05, 49.30 and 55.33 vol.% of kenaf fiber was reinforced into a polyester resin using the pultrusion technique. Optimal responses of wear rate and average coefficient of friction (COF) for kenaf fiber-reinforced polyester composites, based on different levels of control factors (fiber loading, applied load, counterface roughness and sliding speed) were determined by the Taguchi Design of experiment (DOE) with L₉ (3⁴) orthogonal array and Analysis of variance (ANOVA) methods. The wear behaviour of kenaf fiber-reinforced composites were investigated using DUCOM pin-on-disc tester with three levels of applied loads (10-30 N), sliding speeds (0.42-1.3 m/s) against different grit sizes of silicon carbide abrasive papers (average grain size~2.2-25.2 μm) under dry sliding condition. The optimization of S/N ratio and degree of significance of the control variables to minimize the wear rate and average COF of kenaf fiber-reinforced polyester composites was carry out. The results showed that the counterface roughness is the most significant factor in affecting the wear rate, followed by applied load, sliding speed, and fiber loading. For average COF, the fiber loading is the most significant factor followed by applied load, sliding speed and counterface roughness.

Abstract: Pultrusion is a composite manufacturing technique for processing continuous composite profiles with a constant cross section. In such system, energy and mass balances are used to model the thermal and kinetic behavior of the material during processing. This work aims to compare the results obtained in the recent literature, regarding thermal optimization of pultrusion. In the present analysis, an alternative thermal configuration has been suggested, with the objective of maximizing the mean degree of cure. A general-purpose FE software, ANSYS-CFX^®, has been used to perform a three-dimensional (3D) conductive heat transfer analysis. Several case studies were conducted where the degree of cure was analyzed for varying heating scenarios. Results have shown that it is possible to get a higher cure in less process time if the die is isolated from the environment.

Abstract: The present article focuses on manufacturing of metal powder filled pultrusion profiles for electro-technical applications. Herein a set of test material has been reviewed, which was prepared with the aim to present an optimized composite structure with high metal powder content for magnetic slot wedge production, outperforming the products currently available by alternative technology – compression moulding.This article gives a short overview of incorporating fine metal powders as fillers into pultrusion process (including the technical challenges) and the experimental work done in the project. The selection and analysis of components have been briefly discussed along with the results of material tests conducted on prepared composite samples. Mechanical, dielectric and magnetic properties of the samples were studied at different filler loadings and compared to the properties of iron powder filled compressed laminates.Several application specific material properties were determined, including flexural strength according to ISO 178, volume and surface resistivity similarly to IEC 93, and relative permeability using vibrating sample magnetometer (VSM). Scanning Electron Microscope (SEM) and various image processing software were used to analyse the composition and microstructure of the material samples. Material test results are presented at different iron powder loadings from 20 to 55 wt% and recommendations given for optimal materials selection.

Abstract: Since literature on the machinability of non laminated composites is scarce, an investigation was extended away to study the machinability of thick non laminated Glass Fiber Reinforced Plastic (GFRP) composites and to compare the above with machinability of thick laminated composites. The composites with high fiber weight fraction were drilled with a special geometry coated carbide drill (Ratio drill). Taguchi’s orthogonal array and analysis of variance (ANOVA) were used to examine the influence of process parameters (feed and spindle speed) on quality characteristics (thrust force and torque). The optimum degree of process parameters towards aperture quality was obtained.

Abstract: Structural health monitoring is an important research topic in the field of fiber reinforced plastics (FRP). An effective way to detect defects or overloads in these FRP has still not been found. One way to monitor the actual state of FRP components is via integrated sensors. Integrating current standard sensors negatively affects the flux of force. Therefore investigations about integration methods of sensors in FRP components have been made. The integration of an optical fiber sensor into FRP profiles via a pultrusion process was investigated. It could be shown that the pultrusion process is suitable method for the integration of fiber optic sensors for strain measurements. Another investigated sensor principle was the integration of piezoelectric polyvinylidene fluoride (PVDF) fibers via a vacuum assisted process. The PVDF fibers were integrated into 3-point bending specimen and the piezoelectric effect was tested with and without polarization. The investigation showed that it is possible to measure the piezoelectric effect of PVDF fibers integrated into a 3-point bending test specimen. It could also be shown that carbon fibers can be used as textile electrodes for the measurement of the generated charge on the PVDF surface.