Unidirectional Research Articles

Influence of asymmetric rolling paths on the microstructure, texture, mechanical behavior, and electrical conductivity of electrolytic tough-pitch copper

In this work, the influence of asymmetric rolling paths on the microstructure, texture, mechanical behavior, and electrical conductivity of electrolytic tough-pitch copper was studied. Four different asymmetric rolling paths including unidirectional (UD), rolling (RD), transverse (TD), and normal (ND) with a thickness reduction of 90% were applied. Based on simulation results, the uniformity of strain distribution in the UD path was less than the other paths, the RD and ND paths had a better distribution of strain along the thickness, and the TD path exhibited the best strain distribution. Because of this, the TD, ND, and RD samples revealed a better distribution of copper oxide particles compared to the UD sample. The homogeneity of texture through the sheet thickness for the RD, TD, and ND paths was more than that for the UD path due to the uniform strain distribution. Unlike the other samples, the UD sample exhibited {001}〈110〉 Rotated Cube and {001}〈100〉 Cube orientations in the areas close to the surface due to the formation of severe accumulated strain. The maximum yield strength (405.5 MPa) and tensile strength (419.0 MPa) belonged to the RD sample. The TD sample showed a lower strain hardening rate as a result of easier cross-slip. The highest electrical conductivity (85.2 %IACS) belonged to the TD sample due to its lower dislocation density. The presence of θ-fiber and γ-fiber improved the electron conductivity of copper.

Multi-scale numerical calculations for the interphase mechanical properties of carbon fiber reinforced thermoplastic composites

This study employs a multi-scale numerical calculations method based on molecular dynamics and finite element modeling to investigate the stress transfer mechanisms within the interphase of unidirectional (UD) carbon fiber reinforced thermoplastic polymers (CFRTP) composites, based on which exponential decay model (EDM) was developed to predict the interphase strength and modulus. Revealing that the interphase strength and modulus are approximately 0.5–0.7 times that of the fibre/interphase interface or 1.2 to 1.7 times matrix. The EDM was validated using a coupled experimental-representative volume element modeling method. By calibrating the interphase fracture energy, the mechanical properties predicted by the EDM aligned well with the experimental results of UD CFRTP composites. Finally, the damage evolution and failure modes were analyzed, revealing that the transverse failure of UD CFRTP composites is dominated by the interphase, while longitudinal failure is primarily governed by the fibers, consistent with scanning electron microscope observations. This confirms the accuracy of the EDM, and application this method can be used to quickly and accurately assess the strength and modulus of the interphase in CFRTP composites to significantly reduce the numerical analysis time.

Exploring synergies between GnP and fiber orientation in enhancing mechanical, thermomechanical, and shape memory properties of carbon fiber polymer composites

Abstract This research investigates the mechanical, thermomechanical, and shape memory properties across 12 configurations of shape memory hybrid composites, varying in carbon fiber orientation: uni-directional (UD), bi-directional-Twill (BDT), and bi-directional-Plain (BDP), and multi-walled carbon nanotube weight percentages of 0.4%, 0.6%, and 0.8% elucidate the synergistic effects of fiber architecture and nanomaterial reinforcement. The fabrication process involves initially preparing GnP-modified epoxy nanocomposites through ultrasonication followed by hand layup techniques to fabricate three-phase shape memory hybrid composites. Optimal tensile performance is observed in GnP-modified UD composites at a 0.6 wt% concentration, achieving a tensile strength of 728.32 MPa and a modulus of 71.29 GPa. Furthermore, enhancements in thermomechanical and shape memory properties are noted in GnP-modified BDT composites and are further improved in GnP-modified BDP composites configurations. These improvements are attributed to enhanced interfacial bonding between the polymer and fiber, with the maximum effect observed at the 0.6 wt% BDP composite, validated by morphological analysis using FESEM. The study demonstrates that despite polymer modification, all configurations maintain high shape recovery ratios, particularly notable at 97.54% for 0.6 wt% GnP modified BDP composite, exceeding 90% across all configurations, indicating robust performance in shape memory capabilities.

Experimental and numerical studies of the open hole tensile strength of drilled‐ and molded‐hole unidirectional laminates

AbstractIn this paper, we created a new molded‐hole process to manufacture holes instead of drilling in unidirectional (UD) carbon fiber reinforced plastics avoid fiber discontinuity. Several open hole tensile (OHT) tests were carried out on specimens with Cross ply (CP) and Quasi‐isotropic (QI) stacking sequence with drilled holes and molded holes. At the same time, we established finite element analysis (FEA) models of drilled‐hole laminate and molded‐hole laminate to characterize the stress field around the hole. The numerical analysis results reveals that the max principal strain distribution around the molded hole has much higher coincidence with fiber axial direction than that in drilled‐hole laminate. Moreover, the OHT strength results of QI specimens indicate that the plates with molded holes were more 50% higher than those with drilled holes. This process will provide reference for molded UD CFRP structure holes. And the numerical model can help engineering designer make OHT strength prediction.Highlights A new molded‐hole process for unidirectional prepreg was created. Molded‐hole specimens have higher open hole tensile strength than drilled‐hole pieces. The simulation results were close to the experimental results.

A multi-linear constitutive relation considering the temperature effect on quasi-static mode I delamination in UD/MD laminates

In this study, a multi-linear constitutive relation taking into account temperature and fiber bridging is proposed for characterizing delamination behavior in composite laminates under various temperature conditions. An approach combining analytical solution and J-integral is also established for determining the cohesive parameters in the multi-linear constitutive relation. To validate the proposed constitutive relation, mode I quasi-static delamination experiments of unidirectional (UD) and multidirectional (MD) carbon/bismaleimide laminates are carried out at 25 ℃ (room temperature), 80 °C and 130 ℃. The experimental results show that the increasing temperature resulted in a monotonic increase in the fracture toughness of the UD laminates while affect the fracture toughness of MD laminates slightly. A FE model is established with the implementation of the proposed multi-linear constitutive relation using UMAT subroutine. Good agreements between the experimental and simulated results demonstrate the validity of the proposed constitutive relation, with the relative difference of peak load between predicted and experimental values less than 8.2 % and the relative difference of initial and steady-state fracture toughness between predicted and tested results less than 15 %. This study provides the possibility to numerically study the temperature effect on the delamination behavior of laminates and has promising applications in the damage tolerance design of composite structures.

Harnessing nanostructures and fiber architecture: A synergistic leap in shape memory polymer composites

This research investigates the synergistic effects of carbon fiber orientation and nanostructure reinforcement across 21 configurations of shape memory polymer composites. It examines uni-directional (UD), bi-directional Twill (BDT), and bi-directional Plain (BDP) fiber architectures, along with varying concentrations of MWCNT and GnP at 0.4%, 0.6%, and 0.8%. The fabrication process involves initially preparing nanostructure-modified epoxy nanocomposites through ultrasonication followed by hand layup techniques to fabricate three-phase shape memory polymer composites. Optimal tensile performance is observed in GnP-modified UD composites at a 0.6 wt% concentration, achieving a tensile strength of 728.32 MPa and a modulus of 71.29 GPa. Furthermore, enhancements in thermomechanical and shape memory properties are noted in GnP-modified BDT composites and are further improved in GnP-modified BDP composite configurations. GnP-modified composites outperform MWCNT ones due to GnP’s sheet structure aligning parallel to the load and its larger surface area, which facilitate enhanced interaction with the matrix. These improvements, supported by FESEM analysis, highlight enhanced interfacial bonding and result in high shape recovery ratios, with all configurations exceeding 90%, despite polymer modification.

A novel continuum damage evolution model based on the concept of damage driving force for unidirectional composites

A novel damage evolution model for unidirectional (UD) composites is established in this paper in the context of continuum damage mechanics (CDM). It addresses matrix cracking and it is to be applied along with the damage representation established previously. The concept of damage driving force is employed based on the Helmholtz free energy. It is shown that the damage driving force can be partitioned into three parts, resembling closely three conventional modes of fracture, respectively. A damage evolution law is derived accordingly based on the newly obtained expressions of the damage driving force. The fully rationalised Tsai-Wu criterion is employed in the model for predicting the initiation of matrix cracking damage and fibre failure, assisted with the rationalised maximum stress criterion for identifying the damage modes. A mechanism is introduced to describe the unloading behaviour as a part of the proposed model. The predictions were validated against experimental results, showing good agreement with the experiments and demonstrating the capability and effectiveness of the proposed model.

Concurrent experimental testing and computational micromechanical modeling of a UD NCF GFRP composite ply

The current research work presents a detailed and thoroughly validated computational micromechanical modeling methodology to study the damage initiation and propagation in a uni-directional (UD) glass fiber-reinforced non-crimp fabric (NCF) composite ply. Under the applied transverse tension and compression loads, the effect of various microscale material and geometrical parameters on the ply level stress–strain behavior is studied. To this end, along with the distinctly modeled individual microscale constituents of the UD NCF composite ply (axial fibers, backing fibers, and matrix), the generated RVE (Representative Volume Element) model consists of manufacturing-induced defects and variabilities such as voids as well as the backing fiber’s out-of-plane waviness. The fiber/matrix interface failure behavior in the generated RVE model is simulated using cohesive zone formulations that follow bi-linear traction-separation law. Whereas the hydrostatic pressure-dependent non-linear stress–strain response followed by the fracture of the epoxy matrix is captured using the linear Drucker-Prager plasticity model coupled with the stress triaxiality-based failure criterion. The backing fibers stress–strain and failure behavior is modeled using the linear elastic and isotropic material model in conjunction with the maximum stress criterion.The proposed numerical methodology is thoroughly validated both qualitatively and quantitatively by conducting detailed experiments on a neat epoxy as well as at the composite laminate level. Upon comparing the experimental and computational results, the observed knee or slope change in the bi-linear stress–strain response of the UD NCF composite ply under transverse tension is attributed to the loss of the load-carrying ability of the axial fiber bundle due to fiber/matrix interface debonding followed by the ply splitting. Under the application of transverse compression load, the composite ply failure behavior is governed by the formation of a dominant matrix plastic shear band in the axial fiber bundles, which is in turn triggered by the fiber/matrix interface failure. Under the applied loads in the matrix-dominated direction, the presented research work provides a detailed insight into the microscale damage initiation and propagation in a UD NCF composite ply and its consequent influence on the macroscale stress–strain response.

Investigating the role of fibre-matrix interfacial degradation on the ageing process of carbon fibre-reinforced polymer under hydrothermal conditions

The aqueous environment can deteriorate the fibre-matrix interface of carbon fibre-reinforced polymer (CFRP), significantly impairing the non-fibre-dominated mechanical properties. Thus, this study aimed to quantitatively analyse the impact of interfacial degradation on the hydrothermal ageing mechanism and process of the CFRP. Firstly, entire water absorption process of the CFRP under hydrothermal conditions was divided into three stages according to experimental measurement of its water content. Based on this division of stages, a novel water diffusion model was established for the hydrothermally aged CFRP. To measure the mechanical degradation, tensile tests were conducted on unaged, aged, and redried neat epoxy and transversely positioned unidirectional (UD) CFRP specimens. It was found that the transverse tensile strength degradation of UD CFRP was irreversible due to the permanent interfacial debonding between the fibres and matrix, in contrast to the reversible ageing of the epoxy matrix. To further quantify the fibre-matrix interfacial ageing, physically-based models were established for the degraded interfacial strength of CFRP subjected to hydrothermal conditions. After the characterization of the modelling coefficients, the physically-based models can be employed to predict interfacial strength inside the aged CFRP for various ageing durations. The prediction error was only 4.57 % for the transverse tensile strength of degraded UD CFRP with various ageing durations from the representative volume element (RVE) simulation with its interfacial strength provided by the physically-based models, validating the effectiveness of the proposed physically-based models for degraded fibre-matrix interface under various ageing conditions.

Enhancement of pin‐bearing behavior of pultruded FRP profiles by multi‐directional fiber architecture design

AbstractThe low resistance of bolted joints in pultruded unidirectional (UD) fiber‐reinforced polymer (FRP) profiles limits the load grade of truss bridges due to shear damage along UD fibers. To address this issue, this study proposes multi‐directional (MD) fiber architecture in FRP profiles to improve the ultimate bearing strength of bolted joints. The digital image correlation shows that the addition of off‐axis fibers in MD FRP profiles prevents shear failure in the UD FRP profile. As a result, the ultimate bearing strengths of MD FRP profiles are enhanced attributed to “off‐axis fiber tie action”. Micro‐computed tomography shows that fiber damage in MD FRP profiles emerged from outer plies, including fiber breakage in 90° and ±45° fibers and fiber kinking in 0° and ±45° fibers. The off‐axis fibers break due to tension when resisting the bearing load in MD FRP profiles. The fiber kinking indicated strength contribution from 0° to ±45° fibers. The fiber breakage and fiber kinking in each ply are dominant in bearing failure instead of delamination, which increases the bearing strength of the pultruded MD FRP profiles. These findings facilitate controlling damage evolution in the pultruded MD FRP profiles and designing high‐resistance bolted joints.Highlights Multi‐directional fibers improved bearing strengths of FRP profiles by 28.5%–33%. Off‐axis fibers bent under pin‐bearing, forming a tie action until breakage. Fiber breakage and kinking in each ply contributed to the bearing failure. Strain localization and redistribution were observed using DIC.

Ultrahigh room and high − temperature mechanical properties of SiCf/SiC composites prepared by hybrid CVI and PIP methods: Effects of PIP temperature

Unidirectional (UD) SiCf/SiC composites were prepared using chemical vapor infiltration (CVI)-polymer infiltration and pyrolysis (PIP) hybrid procedure at different PIP temperatures of 1100 °C (1100PIP), 1300 °C (1300PIP), and 1500 °C (1500PIP). The effect of PIP temperature on the microstructure of each component was studied. Results showed that SiC fiber strength and interfacial shear strength (IFSS) were the main factors affecting the mechanical properties of the composite. At 1100 °C, the fiber was thermally stable and IFSS was high, due to which 1100PIP achieved ultrahigh mechanical performance with tensile strength of 901.0 ± 87.7 MPa, flexural strength of 2186.5 ± 192.5 MPa, and toughness of 80.6 ± 12.0 MPa·m1/2. At 1300 °C, IFSS decreased slightly, due to the crystallization of BN interphase. Hence, the mechanical performance of 1300PIP decreased slightly to 789.8 ± 42.9 MPa, 1935.9 ± 163.2 MPa, and 58.2 ± 4.0 MPa·m1/2, respectively. At 1500 °C, severe fiber ceramization and decrease in IFSS caused severe decline in mechanical performance to about half of that of 1100PIP. The crack could be deflected not only at the fiber/BN (F/B) interface, but also at the CVI SiC/PIP SiC (C/P) interface, due to the existence of free carbon layers at the C/P interface, which played an important role in improving the strength and toughness of the composite. 1300PIP also showed excellent strength at high − temperature. At 1350 °C and 1500 °C, its flexural strengths were as high as 1529.0 ± 73.0 MPa and 1223.1 ± 81.1 MPa, respectively. The thermal conductivity and thermal expansion coefficient were also tested. Their values were mainly affected by the grain size and thermal stabilities of the SiC fiber and PIP matrix.

Modeling and failure mechanism study of unidirectional GFRP corrugated sandwich sheet piles based on discrete element method

In this paper, a DEM model of a unidirectional glass fiber reinforced polymer composite sandwich sheet pile (UGFRP-CSSP) is developed to elucidate the damage mechanisms under longitudinal bending and axial compression at the mesoscale, in order to bridge the gap between existing knowledge and its potential applications as sheet pile walls. A series of four-point bending and axial compression tests are performed on UGFRP-CSSP to validate the DEM model, which is calibrated through a sensitivity analysis of the mesoscopic parameters. The failure behavior, crack progress, and initial crack formation of the UGFRP-CSSP are investigated by correlating the results from physical experiments and numerical simulations. The research reveals that the DEM model accurately depicts the failure behavior under bending and compression of unidirectional (UD) composite elements, offering a mesoscopic perspective on the failure origins. It is identified that the tensile shear strength of the resin is the weak point leading to initial failure, as it is lower than that of the glass fibers. Longitudinal bending failure typically initiates at the skin-core interface and around the central axis of core, with cracks propagating longitudinally due to compression shear failure between fibers. Axial compression failure also occurs predominantly at the skin-core interface, with similar longitudinal cracking attributed to tensile shear failure at the acute angle fiber connections in the long span side. Finally, a new viewpoint was proposed that the fiber modulus may have a decisive impact on the failure behavior of UD composite materials.

Micromechanical analyses of unidirectional (UD) discontinuous flax fiber reinforced composites

Prediction of the strength and damage behavior of natural fiber composites is a challenging task due to computational difficulties resulting from large fiber aspect ratio, non-uniform fiber length distribution, and interface modelling. A computational micromechanical model, which solves the above-mentioned challenges by incorporating a novel representative volume element (RVE) generation algorithm inspired by Lennard-Jones potential, is developed to predict the tensile behavior of unidirectional (UD) flax/epoxy composites. Effects of fiber aspect ratio, fiber spatial distribution, interfacial and matrix properties on longitudinal modulus, strength, and the damage behavior of the flax/epoxy composites are extensively studied using the numerical model. The modulus and strength predicted by numerical model were compared with both analytical models and experimental results, which not only validated the numerical model but identified the limitations of analytical model. The longitudinal strength of flax/epoxy composites initially increased with fiber aspect ratio. Upon reaching certain fiber aspect ratio (25 in this study), strength predicted by both RVE (RVEs with many fibers) and unit cell (unit cells with two fibers) are close to experimental value (240 MPa). This finding provides confidence and guidance on how to use simplified unit cells to predict the strength of natural fiber composites with acceptable accuracy and much lower computational cost.

Thermomechanical and Viscoelastic Characterization of Continuous GF/PETG Tape for Extreme Environment Applications

The thermomechanical and viscoelastic properties of a glass fiber polyethylene terephthalate glycol (GF/PETG) continuous unidirectional (UD) tape were investigated using differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and dynamic mechanical analysis (DMA). This study identified five operational conditions based on the Army Regulation 70-38 Standard. The DSC results revealed a glass transition temperature of 78.0 ± 0.3 °C, guiding the selection of temperatures for TMA and DMA tests. TMA provided the coefficient of thermal expansion in three principal directions, consistent with known values for PETG and GF materials. DMA tests, including strain sweep, temperature ramp, frequency sweep, creep, and stress relaxation, defined the material’s linear viscoelastic region and temperature-dependent properties. The frequency sweep indicated an increased modulus with rising frequency, identifying several natural frequency modes. Creep and stress relaxation tests showed time-dependent behavior, with strain increasing under higher loads and stress decreasing over time for all tested input values. Viscoelastic models fitted to the data yielded R2 values of 0.99, demonstrating good agreement. The study successfully measured thermomechanical and viscoelastic properties across various conditions, providing insights into how temperature influences the material’s mechanical response under extreme conditions.

Atomic force microscopy-based nanoindentation technique for characterizing the transverse and shear moduli of flax fibers

Experimentally evaluating the elastic properties of flax fibers is challenging due to their complex hierarchical structure, and a standard test procedure for measuring their transverse and shear moduli is currently not reported in the literature. Hence, this study presents an atomic force microscopy (AFM) based nanoindentation technique to evaluate the transverse and shear moduli of flax fiber. A high-precision focused ion beam (FIB)-milling process was used to fabricate a flat surface for indentation along the longitudinal fiber cross-section of the fiber and transverse fiber cross-section by polishing the unidirectional (UD) lamina in order to evaluate the indentation modulus. Further, Swanson's numerical contour approach was adopted to evaluate the elastic properties of the fiber from the measured indentation modulus. The accuracy of the experimentally obtained fiber properties is verified by using it in a micromechanics model for predicting the elastic properties of the UD lamina and comparing it with experimental results reported in the literature.

Influence of Fiber Volume Fraction on the Predictability of UD FRP Ply Behavior: A Validated Micromechanical Virtual Testing Approach.

Enhancing the understanding of the behavior, optimizing the design, and improving the predictability and reliability of manufactured unidirectional (UD) FRP plies, which serve as primary building blocks for structural FRP laminates and components, are crucial to achieving a safe and cost-effective design. This research investigated the influence of fiber volume fraction (vf) on the predictability and reliability of the homogenized elastic properties and damage initiation strengths of two different types of UD FRP plies using validated micromechanical virtual testing for representative volume element (RVE) models. Several sources of uncertainties were included in the RVE models. This study also proposed a modified algorithm for microstructure generation and explored the effect of vf on the optimal sizes of the RVE in terms of fiber number. Virtual tests were systematically conducted using full factorial DOE coupled with Monte Carlo simulation. The modified algorithm demonstrated exceptional performance in terms of convergence speed and jamming limit, significantly reducing the time required to generate microstructures. The developed RVE models accurately predicted failure modes, loci, homogenized elastic properties, and damage initiation strengths with a mean error of less than 5%. Also, it was found that increasing vf led to a concurrent increase in the optimal size of the RVE. While it was found that the vf had a direct influence on homogenized elastic properties and damage initiation strengths, it did not significantly affect the reliability and predictability of these properties, as indicated by low correlation coefficients and fluctuations in the coefficient of variation of normalized properties.

An Insight into the Mechanical Properties of Unidirectional C/C Composites Considering the Effect of Pore Microstructures via Numerical Calculation.

Pores are common defects generated during fabrication, which restrict the application of carbon/carbon (C/C) composites. To quantitatively understand the effects of pores on mechanical strength, this paper proposes a representative volume element model of unidirectional (UD) C/C composites based on the finite element method. The Hashin criterion and exponential degraded rule are used as the failure initiation and evolution of pyrolytic carbon matrices, respectively. Interfacial zones are characterized using the cohesive constitutive. At the same time, periodic boundary conditions are employed to study transverse tensile, compressive, and shear deformations of UD C/C composites. Predicted results are compared with the experimental results, which shows that the proposed model can effectively simulate the transverse mechanical behaviors of UD C/C composites. Based on this model, the effects of microstructural parameters including porosity, pore locations, the distance between two pores, pore clustering, and pore shapes on the mechanical strength are investigated. The results show that porosity markedly reduces the strength as porosity increases. When the porosity increases from 4.59% to 12.5%, the transverse tensile, compressive, and shear strengths decrease by 35.91%, 37.52%, and 30.76%, respectively. Pore locations, the distance between two pores, and pore clustering have little effect on the shear strength of UD C/C composites. For pore shapes, irregular pores more easily lead to stress concentration and matrix failure, which greatly depresses the bearing capacity of UD C/C composites.

Development of sandwich test coupons with continuous protective layers for accurate determination of the tensile failure strain of unidirectional carbon fibre reinforced composites

Recently introduced unidirectional (UD) carbon fibre reinforced epoxy (CF/EP) tensile test coupons with continuous protective layers were developed further by comparing three coupon designs with different layer integration techniques. Consistent experimental data was generated with high sample number and low scatter. Thermal residual strains were considered in case of two coupon designs where the layers were integrated at elevated temperature. A curve-fitting-based strength evaluation method is proposed for the sandwich coupons since this parameter cannot be evaluated directly. The sandwich type coupons yielded statistically significant increase in their average failure strain compared to that of the baseline tabbed coupons. In contrast, the three sandwich coupon types did not show significant differences. Therefore, the sandwich coupon type made by bonding cured UD composite layers together at room temperature is proposed for further application as they allow for full delamination at CF/EP layer fracture and do not require thermal strain correction during the evaluation.

An experimental validation study of a numerical modeling approach to predicting post-consolidation dimensions of thermoplastic composites

Consolidation is an important step in the processing of thermoplastic unidirectional (UD) tapes, as it creates a bond between individual tapes to form a semi-finished sheet: The tape stack is first heated and then cooled, both while being subjected to pressure. If the material is in a soft or even molten state and its flow unrestricted, this compression can result in squeeze flow, the direction of which is determined by the fibers of the tapes. Extensive squeeze flow not only results in significant changes in part geometry to the point where it may fail to meet design and application specifications but can also lead to severe distortion and residual stresses. To address this, we developed a model that, given the process parameters and fiber orientation, predicts the effects of squeeze flow. Based on experimental data on UD polycarbonate tapes with 44% carbon fibers by volume consolidated at various process settings, this paper presents the validation of the model for industrial application. We found that at low heating temperatures, where the matrix viscosity is too high and prevents the material from flowing, the simulation results deviated markedly from the experimental data. With these temperatures excluded, however, the overall deviation of the model was 8.7% for thickness change and 5.3% for area change.

Applying optical coherence tomography to inline quality monitoring of unidirectional glass-fiber-reinforced thermoplastic tapes

Originally developed for biomedical applications and diagnosis, optical coherence tomography (OCT) has recently been demonstrated to be a powerful non-destructive and non-invasive measurement method for detecting defects in glass-fiber reinforced polymer composites. While previous studies have focused mainly on the use of OCT in the analysis of thermoset composites, we were able to show in offline experiments that OCT can be used to quickly detect typical defects (e.g., dry fiber regions, gaps and fiber breakage) in thermoplastic unidirectional (UD) tapes at high resolution. To investigate the applicability of OCT to inline monitoring, we advanced our previously published approach in two major steps: First, we incorporated the OCT system into an industrial-scale UD-tape production line, and derived optimal settings for inline detection of dry region defects from a comprehensive design of experiments (DoE) to find an optimal balance between accuracy and data size for a stationary tape sample by varying A-scan sampling rate, A-scan averaging and OCT transverse travel velocity. Second, using these optimal settings, we went on to investigate moving tapes over a range of industrially relevant take-off speeds. Microscopy was used for validation in both cases. We developed a fast and robust statistical analysis of B-scans that visualizes the quality of full cross-sections in an interpretable manner for potential use in a real-time setting. Within an industrially relevant production speed range of up to 15 m/min, we are thus now able to investigate 120 mm wide (and potentially wider) UD tapes inline at a transverse resolution of 22 µm, producing only 21 MB of data per measurement.