Thermoplastic Matrix Composites Research Articles

Modelling the time-dependent mechanical properties of thermoplastic and thermosetting polymers with Gumbel distribution functions

In this paper, we propose a simple modelling method that accurately describes the time-dependent viscoelastic behaviour of thermoplastic and thermosetting solid polymers. We performed short-term creep and stress relaxation tests on representative samples of three major classes of polymers: an amorphous, a semi-crystalline thermoplastic and a thermosetting polymer. Then, to investigate the relationship between the model parameters and the material composition, we also tested thermoplastic matrix composites with different plasticiser contents. From the short-term tests, master curves were constructed with the use of the time–temperature superposition principle. Then, the temperature dependence of the obtained shift factors was described using the Arrhenius model. The resulting creep compliance and relaxation modulus master curves were normalised and modelled with a two-parameter cumulative Gumbel distribution function (CDF) and its complementary distribution function (CCDF). For the creep and stress relaxation master curves, the median error of modelling was less than 16 % and 16.5 % in all cases, respectively. Furthermore, it was less than 2 % for the thermosetting polymer, making this model an excellent tool for describing the creep and stress relaxation behaviour of thermosetting systems. In the case of the plasticised composites, we found a strong relationship between the material composition and the location parameter of the Gumbel model. Based on this, we developed a method that can be used to estimate the evolution of the creep compliance curve for any arbitrary OLA content (between 0 wt% and 16 wt%) at any desired temperature (between 22 °C and 70 °C).

Testing Protocol Development for the Fracture Toughness of Parts Built with Big Area Additive Manufacturing.

The mechanical testing of additively manufactured parts has largely relied on the existing standards developed for traditional manufacturing. While this approach leverages the investment made in current standards development, it inaccurately assumes that the mechanical response of additive manufacturing (AM) parts is identical to that of parts manufactured through traditional processes. When considering thermoplastic, material extrusion AM, the differences in response can be attributed to an AM part's inherent inhomogeneity caused by porosity, interlayer zones, and surface texture. Additionally, the interlayer bonding of parts printed with large-scale AM is difficult to adequately assess, as much testing is performed such that stress is distributed across many layer interfaces; therefore, the lack of AM-specific standards to assess interlayer bonding is a significant research gap. To quantify interlayer bonding via fracture toughness, double cantilever beam (DCB) testing has been used for some AM materials, and DCB has been generally used for a variety of materials including metal, wood, and laminates. Mode I DCB testing was performed on thermoplastic matrix composites printed with Big Area Additive Manufacturing (BAAM). Of particular interest was the notch shape and deflection speed during testing. The results examine the differences when using two notch types and three deflection speeds. The testing method introduced by the following paper differentiates itself from the ones described in the standards used by modernizing the methodology. This was conducted with the introduction of Digital Image Correlation (DIC) to gather displacement and load data simultaneously without human intervention.

Assessing Intra-Bundle Impregnation in Partially Impregnated Glass Fiber-Reinforced Polypropylene Composites Using a 2D Extended-Field and Multimodal Imaging Approach.

This study evaluates multimodal imaging for characterizing microstructures in partially impregnated thermoplastic matrix composites made of woven glass fiber and polypropylene. The research quantifies the impregnation degree of fiber bundles within composite plates manufactured through a simplified compression resin transfer molding process. For comparison, a reference plate was produced using compression molding of film stacks. An original surface polishing procedure was introduced to minimize surface defects while polishing partially impregnated samples. Extended-field 2D imaging techniques, including polarized light, fluorescence, and scanning electron microscopies, were used to generate images of the same microstructure at fiber-scale resolutions throughout the plate. Post-processing workflows at the macro-scale involved stitching, rigid registration, and pixel classification of FM and SEM images. Meso-scale workflows focused on 0°-oriented fiber bundles extracted from extended-field images to conduct quantitative analyses of glass fiber and porosity area fractions. A one-way ANOVA analysis confirmed the reliability of the statistical data within the 95% confidence interval. Porosity quantification based on the conducted multimodal approach indicated the sensitivity of the impregnation degree according to the layer distance from the pool of melted polypropylene in the context of simplified-CRTM. The findings underscore the potential of multimodal imaging for quantitative analysis in composite material production.

Research on the thermal conductivity and mechanical properties of carbon fiber reinforced thermoplastic composites doped with different sizes carbon nanotubes: A combination of experiments, numerical simulations and multi‐objective optimization

AbstractWhile improving the thermal conductivity of composites, single‐size carbon nanotubes (CNT) often degrade their mechanical properties due to the agglomerates. To overcome this limitation, this study reported thermoplastic resin matrix composites synergistically reinforced with small, medium, and large‐size carbon nanotubes (S‐CNT, M‐CNT, and L‐CNT). Using the thermal conductivity (λ) and mechanical properties (flexural strength [F], compressive strength [C] and tensile strength [T]) as the response values, we conducted 21 sets of mixing design experiments and developed the associated quadratic term models. Further multi‐objective optimization was carried out for the above response values. Optimized multiscale CNT synergistically modified composites (S‐CNT, M‐CNT, and L‐CNT contents of 1.25, 7.02, and 2.56 wt%) exhibited a λ value of 1.168 W/mK, which was 121% higher than that of pure composite and also superior to the same content of S‐CNT‐ (1.031 W/mK), M‐CNT‐ (1.016 W/mK), and L‐CNT‐modified composites (0.983 W/mK). Additionally, the optimized composite demonstrated excellent mechanical properties (F = 1482 MPa, C = 848 MPa, and T = 1759 MPa), which were 13%, 11%, and 13% higher than those of the pure composites, respectively, and also surpassed those of the S‐CNT‐, M‐CNT‐and L‐CNT‐modified composites.Highlights Using three different scales of carbon nanotubes modified CF/PPBESK composites. Polynomial modeling of composite's thermal conductivity and mechanical properties. Synergistic interactions between carbon nanotubes to improve the composite's thermal conductivity and mechanical properties.

Experimental study of the importance of fiber breakage on the strength of thermoplastic matrix composites subjected to compression after impact

Post-impact strength and damage tolerance of composite structures stands as a paramount design consideration in the aeronautical industry. In the event of a low velocity impact, a set of damage manifestations within laminated structures are induced, including matrix cracking, delamination and fiber breakage. Despite the critical importance of discerning the influence of each damage type on post-impact compression strength, only a limited number of studies have endeavored to quantify these effects comprehensively. In response to this research gap, we have developed a novel methodology capable of mimicking damage extension and shape caused by a low-velocity impact, while preserving fiber integrity. This innovation is achieved through the application of induced electrical currents, thereby facilitating controlled damage simulation without compromising fiber structural integrity. Our investigation compares the residual stiffness and strength of AS4/PEEK laminates subjected to low velocity impacts and induction currents, under conditions of equivalent damage. Our findings reveal that fiber breakage significantly influences the loss of stiffness in the laminate, but not its strength. Moreover, our results confirm the role of delamination as the primary determinant of strength degradation in the damaged material.

Microstructural evolution of highly aligned discontinuous fiber composites during longitudinal extension in forming

The longitudinal extensional viscosity of a highly aligned discontinuous fiber (ADF) thermoplastic matrix composite is investigated to develop a model and validate microstructural evolutionary mechanisms. Samples stretched at constant temperature and strain rate are shown to exhibit a strain softening behavior. X-ray CT analysis and optical micrographs show that the composite microstructure deconsolidates before forming and evolves with deformation. The conventional unit cell micromechanical model includes the effects of matrix viscosity, fiber aspect ratio and fiber volume fraction. This model is modified to include the stiffening effect of fiber spacing variability, and the softening effects of porosity and decreasing fiber overlap length with elongation. Calibration of the model reveals that matrix shear strain rate is an order of magnitude higher than previously predicted due to local fiber spacing. This effect is captured by a fiber spacing variability parameter which scales average spacing down by an order of magnitude. The observed strain softening behavior is described and a combinations of fiber overlap length reduction and local fiber spacing increase.

Thermoplastic and thermoset polymer matrix composites reinforced with bismuth oxide as radiation shielding materials

Polymer composites reinforced with heavy metals have wide applications in the nuclear industry as radiation shielding materials against emitted radiation from nuclear equipment. In this study, considering bismuth oxide as reinforcement, various polymers including thermoplastic polymers, such as high-density polyethylene, low-density polyethylene, polypropylene, polyvinyl acetate, polymethyl methacrylate, and thermosetting epoxy resin have been considered as matrices. After preparing various samples of polymer composites loaded with 60 % by weight of bismuth oxide, some physical, mechanical, and radiation shielding properties (neutron and gamma attenuation coefficients) of these polymer composites have been measured and compared with each other. First, the density of the samples was measured, and the response of these samples to varying compressive force was investigated. The stress-strain diagrams of composites with different matrices were compared. Subsequently, the linear and mass attenuation coefficients of the composites were measured over a wide range of energies (32–1480 keV) against direct and collimated beams from various standard gamma-ray sources (134Cs, 60Co, 154Eu, 133Ba, and 22Na) using an HPGe detector. A collimated beam from an Am–Be source was utilized to measure and compare the attenuation properties of the composite samples against neutron flux. Furthermore, the properties of the composites against neutron and gamma radiation were calculated using the MCNP Monte Carlo code over a broad energy range, and the results were compared and validated with the experimental data. The comparison of the calculated and measured results shows reasonable agreement. The results indicate that in situations where high attenuation properties coupled with high strength are desired, polymeric composites with an epoxy matrix can be considered as radiation shielding materials. If the use of flexible and malleable material is required, such as for reactor piping shielding or the fabrication of protective gloves and clothing in a radiation environment, among the polymers studied, polyvinyl acetate is a more suitable matrix.

Cyclic creep strain rate criterion for short-fibre reinforced thermoplastics: Validation of creep and fatigue performance across a wide range of load ratios

The fatigue and creep responses of short-fibre reinforced thermoplastic matrix composites are influenced by numerous parameters such as load ratio for fatigue. Fatigue criteria, based solely on the evolution of the cyclic creep of the mean strain, are effective for load ratios greater than zero (tension/tension) but have limitations for negative load ratios (tension/compression).The aim of this study was to propose a unified creep and fatigue criterion, based on the evolution of the cyclic creep of the maximum strain, that allowed both load ratio domains to be covered. To investigate a wide range of load ratios (-1 to 0.8), an existing creep and fatigue database was augmented with purely alternated tension/compression tests. This database, which included 489 tests, considered the variations in parameters that influence the creep and fatigue responses, such as fibre orientation, water content and specifically for fatigue load ratio and frequency. This was used to validate a unified criterion based on the cyclic creep of the maximum strain. This criterion improved fatigue life prediction compared to existing criteria and allowed fatigue and creep results to be unified with 87% of estimated lifetimes within a scatter band of factor two.

Mechanical and thermal properties of short banana fiber reinforced polyoxymethylene composite materials dependent on alkali treatment

Abstract The present study aimed to develop a recyclable composite material based on a natural product, namely banana fiber, instead of synthetic reinforcement elements such as glass fiber or carbon fiber in thermoplastic matrix composites employed in many aspects of daily life. Polyoxymethylene (POM) thermoplastic was used as the matrix material. 3 %, 6 %, and 9 % by weight short natural banana fiber was used as reinforcement. Furthermore, the study improved the mechanical and thermal properties of the composite material with chemical improvements based on alkali treatment of banana fiber. Banana fiber and POM was initially mixed mechanically and then extruded at temperatures between 170 and 190 °C to obtain a homogeneous mixture. The mixture obtained by extrusion was initially cooled in the cooling pool and then passed through the crusher to obtain granules. These granules were pressed in plastic injection molds to obtain standard test samples. The ratio of reinforcement material and the variations in mechanical and thermal properties of the composites induced by the alkali treatment are presented in figures and tables. Furthermore, the changes in cross-sectional material images were examined with electron microscopy scans. The tensile and flexural strength of the material improved with alkali treatment.

Experimental and Numerical Study of Bearing Damage of a CF-LMPAEK Thermoplastic Composite

This study focuses on investigating the behavior of a thermoplastic matrix composite (Carbon Fiber-LMPAEK) under a bearing strength determination test. The specimens were subjected to a double-shear-bolted joint configuration tensile test, and the propagation of damage was monitored using extensometers. The research employs a technique that involves inelastic modelling and considers discrepancies in layer interfaces to better understand bearing damage propagation. In this context, cohesive modelling was utilized in all composite layers, and the Hashin damage propagation law was applied. The double-shear-bolted joint configuration chosen for the test revealed critical insights into the bearing strength determination of the Carbon Fiber-LMPAEK thermoplastic matrix composite. This comprehensive approach, combining inelastic modelling and considerations for layer interfaces, provided a nuanced understanding of the material’s response to bearing forces. The results of the study demonstrated that all specimens exhibited the desired type of bearing failure, characterized by severe delamination around the hole. Interestingly, the thermoplastic matrix composite showcased enhanced bearing properties compared to traditional thermoset materials. This observation underscores the potential advantages of thermoplastic composites in applications requiring robust bearing strength. One noteworthy aspect highlighted by the study is the inadequacy of current aerospace standards in prescribing the accumulation of bearing damage in thermoplastic composites. The research underscores the need for a more strategic modelling approach, particularly in cohesive modelling, to accurately capture the behavior of thermoplastic matrix composites under bearing forces. In summary, this investigation not only provides valuable insights into the bearing strength of Carbon Fiber-LMPAEK thermoplastic matrix composites, but also emphasizes the necessity for refining aerospace standards to address the specific characteristics and failure modes of these advanced materials.

Laser In Situ Joining as a Novel Approach for Joining Large‐Scale Thermoplastic Carbon Fiber‐Reinforced Polymer Aircraft Structures

Thermoplastic matrix composites are a viable option to reduce the carbon footprint during the life of an aircraft due to their ability to be molten and resolidified again. Tape‐based layup processes, such as automated tape placement, are well‐examined but have not seen extensive use in large‐scale joining applications, since they have to be processed layer‐by‐layer. In contrast, the advanced laser in situ joining method (CONTIjoin) utilizes fully consolidated and cut‐to‐size multilayered laminates, enabling the continuous layup of tailored laminates aligned with the mechanical application requirements. Herein, sample joints are manufactured using CONTIjoin technology, describing the general process principle, and are compared with samples produced using a standard heat press process. The base material, carbon fiber‐reinforced LMPAEK (low‐melt polyaryletherketone) is characterized using infrared spectroscopy. Using a 3.5 kW carbon dioxide (CO2) laser (10.6 μm wavelength) coupled with highly dynamic beam deflection, multidirectional reinforced laminates with up to six plies are processed to produce 24‐ply plates. The influence of joining temperatures up to 400 °C on the joint quality is investigated. Cross‐cuts are examined and interlaminar shear strength tests are conducted. With CONTIjoin, maximum strengths of 48.5 MPa are observed, reaching over 90% of the heat press reference.

Thermal aging effect on mechanical properties of polyamide 6 matrix composites produced by TFP and compression molding

AbstractTailored Fiber Placement is an innovative manufacturing technique that precisely positions continuous fibers in critical areas of fiber preforms for optimal structural performance. This study focuses on producing glass fiber‐reinforced polyamide composites using TFP technology and compression molding to address the durability concerns of thermoplastic matrix composites in automotive parts. The production process involved a constant temperature of 300°C, 16 bar pressure, and holding times of 270, 300, and 330 s. Short‐term thermal aging cycles were applied to simulate automotive part acclimatization. Tensile and 3‐point bending tests were conducted to evaluate mechanical properties. Statistical analysis using response surface methodology provided insights into the relationship between production parameters and mechanical properties. Differential Scanning Calorimetry characterized the composite material, and macroscopic damage analysis was performed. Results showed a potential 10% decrease in tensile strength due to short‐term thermal aging. Aging had the most significant impact on elastic modulus and tensile strength according to the Pareto chart. Flexural modulus increased, while flexural strength decreased with thermal aging. Holding time had no effect on flexural modulus but reduced flexural strength.Highlights Glass/polyamide composites were produced by compression molding with TFP technology. Short‐term thermal aging cycles were applied on the GF‐PA6 composite material. Mechanical properties were analyzed statistically according to the RSM. TFP technique can assist OEM companies in lowering desired target cost per vehicle.

Polyphenylene sulfide for high-rate composite manufacturing: Impacts of processing parameters on chain architecture, rheology, and crystallinity

High performance semi-crystalline thermoplastics necessitate high temperature processing to form useful structures, but the effects of repeated exposure to these extreme environments on key polymer properties are not well understood. This work investigates the influence of degradation-driven structural changes resulting from exposure to standard melt processing conditions in oxygen rich environments on the rheological properties, crystallization behavior, and crystal structure of polyphenylene sulfide (PPS). Melt processing temperatures (300°C, 320°C, and 340°C) and hold times (up to 60 min) are varied to probe the effects of thermal exposure on polymer properties. Extended melt-state exposure causes an increase in PPS melt viscosity due to the formation of complex branched/crosslinked structures where increasing temperature causes this process to occur more rapidly. Dynamic isothermal rheology of PPS displays a 70x increase in the complex viscosity at 10 rad/s after 60 minutes at 340°C. Frequency sweep rheological experiments reveal a notable deviation from linearity (terminal slope = 2) with slopes as low as 0.14 after thermal exposure. Stress recovery experiments indicate thermally processed PPS requires more time to relax stress under an applied strain. Imperfections along the polymer backbone in the form of branches/crosslinks decrease overall crystallinity and reduce lamellar thickness, with no changes to the unit cell structure. For semi-crystalline high performance thermoplastic matrix composites relying on high degrees of crystallinity to provide solvent resistance and strength, these results have serious implications for the need to tightly control melt processing steps and understand the final material state. Furthermore, viscoelastic properties of post-processed PPS polymers should be considered for recycling and reuse strategies.

Seawater ageing of thermoplastic acrylic hybrid matrix composites for marine applications

Increasing usage of polymer composite materials necessitates the development of recyclable alternatives to traditional thermoset matrices or new techniques for recycling these materials. One family of promising recyclable matrices are the room temperature infusible acrylic resins, known commercially as Elium®. If these new materials are to be used in the tidal stream energy and shipping sectors, they must be able to withstand long-term immersion in seawater without significant losses in mechanical properties. In this study, accelerated seawater ageing is applied to acrylic/glass fibre and modified acrylic/glass fibre composites along with a traditional epoxy/glass fibre baseline. The mechanical properties (tensile, flexural, and short beam) are compared before and after ageing, and electron microscopy is used to examine fracture surfaces to determine the effects of water ingress on fracture propagation. In addition, the diffusion coefficients of the composites in seawater are compared and the changes in glass transition temperatures are used to determine the effects of plasticisation.

Correlation of surface and interfacial temperature during differential ultrasonic spot welding

Ultrasonic spot welding (USW) has become an attractive joining method for thermoplastic polymers (TP) and thermoplastic matrix composites (TPMC). In the USW process, the material to be joined is subjected to mechanical vibrations of high frequency, causing intermolecular and surface friction which heat and melt the material at the joint interface. The interface resolidifies, resulting in a joint between two materials. In USW, it is necessary to focus the mechanical vibrations at the required weld location. A common method to accomplish this is to incorporate an energy director (ED) at the interface between materials to melt preferentially. However, incorporating EDs complicates the manufacturing process, particularly for large constant thickness polymer sheets. In this work, differential ultrasonic spot welding (DUS) is used which employs a flat horn and anvil of different diameters to initiate frictional heating between laminates at the desired joint location. This work investigates the effectiveness of DUS compared to a more traditional USW setup. Additionally, by measuring temperature at both the surface and the interface during DUS using infrared imaging and a thermocouple (TC), respectively, the driving factors behind the thermal profile of the welding process are examined. The goal of coupling the thermal profile to physical attributes of the DUS process is to eventually determine if variability present in the thermal profile may be tied to well-known joint area and strength variabilities.

Online characterization of moisture transport in a high-performance carbon fiber-reinforced thermoplastic composite at high temperatures: Identification of diffusion kinetics

Prior to processing, high-performance fiber-reinforced ThermoPlastic matrix Composites (TPC) are usually stored in ambient conditions, thus causing moisture sorption. During processing at high temperature, the stored moisture induces defects that deteriorate the mechanical properties of the produced parts. In order to understand these effects, it is necessary to study water (de)sorption phenomena in TPC, which was only characterized at low temperatures up to now (<100°C). Thus, we characterized online moisture (de)sorption mechanisms at high temperatures (up to 300 °C) on large and representative samples of a high-performance carbon-fiber (CF) reinforced PolyEtherKetoneKetone (PEKK) laminates. This characterization was performed thanks to a new thermogravimetric device named OMICHA (Online Moisture Ingress CHAracterization) that we developed purposely. This new device allows to continuously measure weight variation of large composite samples under controlled and high temperature and/or humid environment. Sorption and desorption tests allowed to determine macroscopic moisture diffusion coefficient of CF/PEKK at several temperatures, highlighting a complex dual stage macroscopic diffusive behavior which is also modeled and discussed.

State of Knowledge on Starch as an Alternative Solution to Petrochemical Resources—A Review

The use of plastics from petrochemical resources poses environmental impacts, and one of the alternative solutions is the use of starch. The objective of this present work has been to present the literature on starch, and to highlight the debate in the development of composite films. The approach adopted was to present the state of the art on starch and thermoplastic starch matrix composites. The work shows that starch is available worldwide and can be used in the manufacture of biodegradable plastics; the debate remains on the reinforcement of thermoplastic starch to improve its physical and mechanical properties poor; then researchers must diversify the reinforcements to see the impact on the properties of thermoplastic starch.

Strength and its variability in 3D printing of polymer composites with continuous fibers

Additive manufacturing (AM) of polymer composites with continuous fibers could play a major role in the future of aerospace and beyond but will require printed materials to achieve new levels of reliability. This study characterized the strength distribution of selected thermoplastic matrix composites as a function of printing via fused filament fabrication (FFF). Experimental and commercial composite filaments of continuous carbon or Kevlar fibers were printed with volume fraction (Vf) ranging from approximately 28 to 56 %. The strength was evaluated under uniaxial tension after specific stages of printing and Weibull statistics were applied to characterize the strength distribution. There was a significant reduction in strength of the printed material with respect to the unprinted condition, regardless of reinforcement type, fiber volume fraction or printer used. Damage introduced by feed extrusion of the filament, and fiber failures induced at material deposition were most detrimental. For carbon fiber filaments, the reduction ranged from approximately 10 % for an experimental material to over 60 % for a commercial filament. There was no correlation in the strength degradation or variability with Vf. The prevention of process-related fiber damage is key to advancing AM for continuous fiber composite and application to designs intended for stress-critical applications.

A review of the fabrication methods and mechanical behavior of continuous thermoplastic polymer fiber–thermoplastic polymer matrix composites

AbstractThermoplastic polymer fiber–thermoplastic polymer matrix composites (PPCs or PRFPs), often recognized as self‐reinforced or single polymer composites, are potential candidates for future advanced polymer composites because of various advantages(e.g., recyclability, formability, low‐cost, ultra‐lightweight, environmental friendliness, etc.). The manufacturability and mechanical behavior of these composites compared to conventional carbon‐/glass‐/aramid‐fiber‐reinforced polymers is of great interest to the composites community, but there are a limited number of studies in this area. To this end, this paper reviewed fabrication methods with different processing parameters and mechanical behavior of uni‐/multi‐directional thermoplastic PPCs featuring continuous thermoplastic polymer fibers from limited data in the literature. It was shown that most specific behaviors (normalized by density) of these materials in various loading conditions (e.g., quasi‐static tension/shear/flexure, tension‐tension fatigue, and out‐of‐plane impacting, etc.) are comparable to or better than glass‐/aramid‐fiber‐reinforced polymers. Particularly, the specific ductility in the foregoing conditions outperforms all the carbon‐/glass‐/aramid‐fiber‐reinforced polymers. Thermoplastic PPCs with remarkable performance can be achieved through several uncomplicated methods (e.g., film stacking, hot compaction, powder and solution impregnations, matrix infusion and injection molding, additive manufacturing, etc.), which have some similarities to the methods used for carbon‐/glass‐/aramid‐fiber‐reinforced polymers. Moreover, several opportunities and challenging problems of thermoplastic PPCs were summarized at the end of this review paper. Efficient solutions may require countless efforts in the composites community to further strengthen the performance and understanding of thermoplastic PPCs for wide applications in various engineering fields in the future.

Digital Manufacture of a Continuous Fiber Reinforced Thermoplastic Matrix Truss Core Structural Panel Using Off-the-Tool Consolidation

Sandwich panels are commonly used as structure, based on fiber reinforced composites, with the goal of high flexural stiffness and low mass. It is most common to separate two high performance composite facesheets with a low-density core, generally in the form of a foam or honeycomb. A recent concept has been to replace these traditional core materials with fiber reinforced truss-like structures, with the goal of further reducing mass. A system is described that can radically reduce the amount of tooling required for truss core sandwich panel manufacture. This system, which is a digital manufacturing platform for the extrusion of continuous fiber reinforced commingled glass fiber/PET tow, was developed to demonstrate the rigidization of composites both on, and off, a tool surface. Navtruss core panels were successfully manufactured using this digital manufacturing platform, without conventional tooling, and the resulting through thickness compression moduli and panel shear moduli were within 14.6% and 23% of the values baseline compression molded specimens. Thus, the results suggest that, with further development, complex truss core structures with performance approaching that of compression molded panels can be manufactured with radically reduced tooling requirements from high volume fraction, continuous fiber reinforced thermoplastic matrix composites.