bluuebunny/crossref_metadata_2025 huggingface dataset:
Extracellular vesicles derived from human ESC–MSCs target macrophage and promote anti-inflammation process, angiogenesis, and functional recovery in ACS-induced severe skeletal muscle injury
Authors: Jiang Xiangkang , Yang Jingyuan , Lin Yao , Liu Fei , Tao Jiawei , Zhang Wenbin , Xu Jiefeng , Zhang Mao
Published: November 2023

Background

Acute compartment syndrome (ACS) is one of the most common complications of musculoskeletal injury, leading to the necrosis and demise of skeletal muscle cells. Our previous study showed that embryonic stem cells-derived mesenchymal stem cells (ESC–MSCs) are novel therapeutics in ACS treatment. As extracellular vesicles (EVs) are rapidly gaining attention as cell-free therapeutics that have advantages over parental stem cells, the therapeutic potential and mechanisms of EVs from ESC–MSCs on ACS need to be explored.

Method

In the present study, we examined the protective effects in the experimental ACS rat model and investigated the role of macrophages in mediating these effects. Next, we used transcriptome sequencing to explore the mechanisms by which ESC–MSC-EVs regulate macrophage polarization. Furthermore, miRNA sequencing was performed on ESC–MSC-EVs to identify miRNA candidates associated with macrophage polarization.

Results

We found that intravenous administration of ESC–MSC-EVs, given at the time of fasciotomy, significantly promotes the anti-inflammation process, angiogenesis, and functional recovery of muscle in ACS. The beneficial effects were associated with ESC–MSC-EVs affecting macrophage polarization by delivering various miRNAs which regulate NF-κB, JAK/STAT, and PI3K/AKT pathways. Our data further illustrate that ESC–MSC-EVs mainly modulate macrophage polarization via the miR-21/PTEN, miR-320a/PTEN, miR-423/NLRP3, miR-100/mTOR, and miR-26a/TLR3 axes.

Conclusion

Together, our results demonstrated the beneficial effects of ESC–MSC-EVs in ACS, wherein the miRNAs present in ESC–MSC-EVs regulate the polarization of macrophages.
On the global existence and analyticity of the mild solution for the fractional Porous medium equation
Authors: Abidin Muhammad Zainul , Marwan Muhammad
Published: November 2023

In this research article we focus on the study of existence of global solution for a three-dimensional fractional Porous medium equation. The main objectives of studying the fractional porous medium equation in the corresponding critical function spaces are to show the existence of unique global mild solution under the condition of small initial data. Applying Fourier transform methods gives an equivalent integral equation of the model equation. The linear and nonlinear terms are then estimated in the corresponding Lei and Lin spaces. Further, the analyticity of solution to the fractional Porous medium equation is also obtained.
Ozonated water soaking improves the flower growth, antioxidant activity, and bioactive compound accumulation in Agastache rugosa
Authors: Lam Vu Phong , Loi Dao Nhan , Kim Sunwoo , Shin Juhyung , Park Jongseok
Published: November 2023

Ozonated water (OW) is now being recognized as an innovative and eco-friendly solution for managing plant growth while also promoting the production of bioactive compounds and essential plant metabolites. This study aimed to identify the most effective duration of OW treatment to promote plant growth and accumulation of antioxidant activity and bioactive compounds in Agastache rugosa in a plant factory. Whole plants were subjected to OW soaking treatments for varying durations (0, 1, 10, 20, 40, and 80 s) at a concentration of 1 µmol·mol−1, once per week, at 0, 1, 2, 3, and 4 weeks after transplantation. Five weeks after transplantation, plant samples were collected for the analysis of their plant growth parameters, photosynthetic pigments and parameters, total flavonoid, antioxidant activity, and bioactive compounds. Stem length was decreased in all OW treatments, while the number of flower branches, the flower fresh and dry weights were significantly increased under 20, 40, and 80 s OW treatments than in the control group. The net photosynthetic rate decreased significantly in 20, 40, and 80 s OW treatments compared with the control. Chlorophyll a concentration was the highest in the 20-s OW treatment, and chlorophyll b concentration was the highest in the 10-s OW treatment. Total flavonoid levels in plants increased significantly under 20-, 40-, and 80-s OW treatments, and their antioxidant activity (superoxide dismutase, catalase, and peroxidase) were significantly higher under 40- and 80-s OW treatments than in the control. Rosmarinic acid content increased significantly under the 10- and 40-s OW treatments, whereas the tilianin and acacetin contents increased significantly under the 20-, 40-, and 80-s OW treatments compared to those in the control. Our results suggest that soaking whole plants in OW for 20–80 s enhances the flower growth and bioactive compounds in A. rugosa for medicinal use.

Graphical Abstract
Artificial ecosystem optimized neural network controlled unified power quality conditioner for microgrid application
Authors: Ratnakaran Rajeev , Rajagopalan Gomathi Bhavani , Fathima Asma
Published: November 2023

Unified power quality conditioner is chiefly employed to offer power quality improvement, especially in grid connected mode of operation in microgrid applications. This article proposes an artificial ecosystem optimized neural network for control of photovoltaic system and battery powered UPQC for microgrid applications. The intelligent routine implemented by the proposed controller helps tune parameters such as the error between load voltage references and measured load voltage signals so that the optimal performance of the system can be reached as its exploratory and exploitation capabilities are leveraged in controller design. A prototype of a three-phase system with a dually powered conditioner is tested and validated in MATLAB-Simulink environment in a variety of dynamic scenarios that are commonly present in a contemporary distribution network, such as grid voltage changes, grid inaccessibility, variation in photovoltaic power output, and nonlinear load. It is shown that the proposed controller, being aware of the instantaneous values of grid voltages, was able to adequately compensate in magnitude and phase under all dynamic scenarios to maintain the load voltage constant at the nominal value and sinusoidal. When the system switches automatically from grid-connected mode to islanded mode due to a grid fault, it was observed that the controller prioritizes delivering uninterrupted power to critical loads and enables fast discharge from the battery. The total harmonic distortion percentages of grid currents and load voltages are found to be within the limits as per IEEE-519 standards.
Fibroblast Growth Factor 23 Neutralizing Antibody Ameliorates Abnormal Renal Phosphate Handling in Sickle Cell Disease Mice
Authors: Xiao Liping , Clarke Kai , Hurley Marja M
Published: November 2023

We assessed the involvement of fibroblast growth factor 23 (FGF23) in phosphaturia in sickle cell disease (SCD) mice. Control and SCD mice were treated with FGF23 neutralizing antibody (FGF23Ab) for 24 hours. Serum ferritin was significantly increased in SCD mice and was significantly reduced in female but not male SCD mice by FGF23Ab. FGF23Ab significantly reduced increased erythropoietin in SCD kidneys. Serum intact FGF23 was significantly increased in SCD female mice and was markedly increased in SCD male mice; however, FGF23Ab significantly reduced serum intact FGF23 in both genotypes and sexes. Serum carboxy-terminal-fragment FGF23 (cFGF23) was significantly reduced in SCD IgG male mice and was markedly but not significantly reduced in SCD IgG female mice. FGF23Ab significantly increased cFGF23 in both sexes and genotypes. Serum 1,25-dihydroxyvitamin D3 was significantly increased in SCD IgG and was further significantly increased by FGF23Ab in both sexes and genotypes. Significantly increased blood urea nitrogen in SCD was not reduced by FGF23Ab. The urine phosphate (Pi)/creatinine ratio was significantly increased in SCD in both sexes and was significantly reduced by FGF23Ab. Increased SCD kidney damage marker kidney injury molecule 1 was rescued, but sclerotic glomeruli, increased macrophages, and lymphocytes were not rescued by short-term FGF23Ab. FGF23Ab significantly reduced increased phospho-fibroblast growth factor receptor 1, αKlotho, phosphorylated extracellular signal-regulated kinase, phosphorylated serum/glucocorticoid-regulated kinase 1, phosphorylated sodium-hydrogen exchanger regulatory factor-1, phosphorylated janus kinase 3, and phosphorylated transducer and activator of transcription-3 in SCD kidneys. The type II sodium Pi cotransporter (NPT2a) and sodium-dependent Pi transporter PiT-2 proteins were significantly reduced in SCD kidneys and were increased by FGF23Ab. We conclude that increased FGF23/FGF receptor 1/αKlotho signaling promotes Pi wasting in SCD by downregulating NPT2a and PIT2 via modulation of multiple signaling pathways that could be rescued by FGF23Ab.
Noising Creole Abroad: Chatting about Voice; Some Thoughts on Belinda Edmondson’s Creole Noise
Authors: Lalla Barbara
Published: November 2023

This essay reviews Belinda Edmondson’s literary yet cross-disciplinary study Creole Noise: Early Caribbean Dialect Literature and Performance (2022), which questions the Blackness of orality versus the Whiteness of narrative in the growth of Caribbean literature. Caribbean language history and discourse analysis have much to contribute to the exploration of ventriloquist beginnings of the regional narrative as well as to the nuancing of interpretation, and the review calls for such exchange across the relevant disciplines. The review also welcomes comparisons between literary developments of Black American and Caribbean literature that highlight the cross-cultural relevance of Edmondson’s analysis. Creole Noise is timely and useful in contributing positively to such matters as border disputes on Caribbeanness, with regard to regional and diasporic writing, and to challenges that face writers who are native speakers of Caribbean Creole as they convey local voices to foreign readers.
The Importance of Being (In)Authentic
Authors: Edmondson Belinda
Published: November 2023

In response to three discussions of the author’s Creole Noise: Early Caribbean Dialect Literature and Performance (2022), this essay raises questions about the meaning of authenticity in the production of literary Creole in the anglophone Caribbean from the eighteenth century to the present. It puts into conversation related progressive concepts of Creole, such as Kamau Brathwaite’s formulation of nation language, with early racist ventriloquist Creole narratives by White creoles in the eighteenth and nineteenth centuries. It does so as a way of disentangling what we mean when we identify an authentic Creole voice. This essay also examines the role of linguistics in affirming or disproving the authenticity of historical Creole narratives; distinguishes spoken Creole from written; and considers the importance, or lack of importance, in identifying authors when constructing a history of literary Creole. Authors discussed include Henry Garland Murray, Kamau Brathwaite, V. S. Naipaul, Cynric Williams, and Samuel Augustus Mathews.
La Caldosa: Afro-Lesbian Space-Making and Transnational Politics in Havana
Authors: White Kerry
Published: November 2023

This essay tells the story of a caldosa (both a stew and the gathering where it is served) hosted in 2016 by a network of Black lesbian activists in Havana, Cuba, that took place on the morning after the Pulse massacre in Orlando, Florida. The author explores the caldosa as both an example of and a metaphor for the transnational, coalitional, and space-making politics of Black lesbian activists in the island. Drawing on ethnographic fieldwork, interviews, and a participatory mapping project, the author shows how the work of making caldosa connects the local practice of space-making to a hemispheric and anticipatory Black lesbian politic. The essay builds on previous work on Black lesbian feminism in Cuba and provides insight into the type of activism that was happening in the island in the mid-2010s, which laid the groundwork for the growth in Afro-feminist and Afro-queer activism in the following years.
Μελέτη του λιπιδομικού αποτυπώματος ασθενών με μη αλκοολική λιπώδη νόσο του ήπατος
Authors: Καλοπήτας Γεώργιος
Published: November 2023

Οι ασθενείς με μη αλκοολική στεατοηπατίτιδα (NASH) παρουσιάζουν μια σημαντικά ταχύτερη πρόοδο στα στάδια της ίνωσης σε σύγκριση με τους ασθενείς που πάσχουν από απλή στεάτωση (NAFL). Παρόλα αυτά, η μη επεμβατική διάγνωση της NASH παραμένει μια ανεκπλήρωτη κλινική ανάγκη στις μέρες μας, με αποτέλεσμα η βιοψία ήπατος να είναι ο μόνος τρόπος διάγνωσης της NASH. Προκαταρκτικά δεδομένα έχουν δείξει ότι τα σφιγγολιπίδια/κηραμίδια, τα λιπαρά οξέα και άλλες κατηγορίες λιπιδίων μπορεί να σχετίζονται με την παρουσία και την ιστολογική δραστηριότητα της NASH. H παρούσα μελέτη είχε ως στόχο να εξετάσει εάν οι ασθενείς με NASH είχαν ένα διακριτό λιπιδομικό προφίλ πλάσματος σε σύγκριση με ασθενείς με NAFL και υγιείς μάρτυρες. Επίσης η μελέτη αυτή είχε ως στόχο την αξιολόγηση της ύπαρξης συσχέτισης μεταξύ του προφίλ των λιπιδίων του πλάσματος και των ιστολογικών ευρημάτων σε ασθενείς µε μη αλκοολική λιπώδη νόσο του ήπατος (NAFLD). Η μελέτη περιελάµβανε τρεις ομάδες: ασθενείς µε NASH (N=12), NAFL (N=10) και υγιείς μάρτυρες με φυσιολογικό ήπαρ (N=15). Στο σύνολο του πληθυσμού της μελέτης πραγματοποιήθηκαν στοχευμένες λιπιδομικές αναλύσεις για λιπαρά οξέα, ακυλοκαρνιτίνες και κηραμίδια μετά από ολονύκτια νηστεία και ομοιογενή δίαιτα με χαμηλή περιεκτικότητα σε λιπαρά το προηγούμενο 24ωρο. Ακόμη, στο σύνολο του πληθυσμού έγινε καταγραφή των βασικών ανθρωπομετρικών και δημογραφικών χαρακτηριστικών και πραγματοποιήθηκε λεπτομερής εργαστηριακός έλεγχος. Για τη στατιστική ανάλυση των δεδομένων και τη διερεύνηση ύπαρξης πιθανών συσχετίσεων χρησιμοποιήθηκαν σύγχρονες στατιστικές μέθοδοι μηχανικής μάθησης. Οι ασθενείς με NASH δε διέφεραν ως προς τα βασικά χαρακτηριστικά τους από τους ασθενείς με NAFL. Παρόλα αυτά, οι ασθενείς με NASH είχαν ένα διακριτό λιπιδομικό προφίλ πλάσματος σε σχέση με τους ασθενείς με απλή στεάτωση. Συγκεκριμένα, οι ασθενείς με NASH είχαν αυξημένα επίπεδα συγκεκριμένων ειδών λιπιδίων του πλάσματος, συμπεριλαμβανομένων μεταξύ άλλων, των λιπαρών οξέων (FA) 14:0, FA 15:0, FA 18:0, FA 18:3n3, καθώς και του κηραμίδιου Cer(d18:1/16:0), σε σύγκριση με τους ασθενείς με NAFL. Ακόμη, το λιπιδομικό αυτό προφίλ δείχνει να συσχετίζεται σημαντικά με την ιστολογική ενεργότητα της νόσου και να έχει υψηλή διαγνωστική απόδοση στη πρόβλεψη της NASH σε σύγκριση με τη NAFL. Αντιθέτως οι ασθενείς με NAFL αν και διέφεραν σημαντικά από τους υγιείς μάρτυρες ως προς τα βασικά χαρακτηριστικά τους, δεν παρουσίασαν αξιοσημείωτες διαφορές ως προς το λιπιδομικό προφίλ του πλάσματος. Συμπερασματικά, στην παρούσα μελέτη οι ασθενείς με NASH παρουσίαζαν ένα διακριτό λιπιδομικό αποτύπωμα πλάσματος το οποίο μπορεί να τους διαφοροποιήσει από τους ασθενείς με NAFL και τους υγιείς μάρτυρες με φυσιολογικό ήπαρ. Απαιτούνται περαιτέρω δεδομένα από μελλοντικές μελέτες με μεγαλύτερο μέγεθος δείγματος για την επικύρωση των ευρημάτων της παρούσας μελέτης και τη μελέτη πιθανών εφαρμογών των ευρημάτων αυτών στις στρατηγικές διάγνωσης και διαχείρισης της νόσου.
INTEGRATED PROXY MICROMECHANICAL MODELS IN MULTISCALE ANALYSIS USING DEEP LEARNING FOR LAMINATED COMPOSITES SUBJECT TO LOW-VELOCITY IMPACT
Authors: HOCHSTER HADAS , LIN SHIYAO , RANATUNGA VIPUL , SHEMESH NOAM N. Y. , HAJ-ALI RAMI
Published: November 2023

Multiscale nonlinear micromechanical approaches can analyze laminated composite structures. In contrast, current classical macromechanical modeling approaches depict composite materials as anisotropic homogenized media. This research proposes alternative refined micromechanics that can generate the local mechanical behavior of fiber and matrix constituents and accurately depict the microstructure. The parametric high-fidelity generalized method of cells (PHFGMC) is an advanced micromechanical method that can be used for the nonlinear and failure analysis of different composite material systems. The computational effort required for generating the nonlinear multiaxial behavior is relatively small, depending on the size of the discretized repeating unit cell (RUC). However, it is computationally challenging, if not impossible, to integrate refined nonlinear micromechanical models within a multiscale finite element (FE) analysis of composite structures. To that end, we propose a new artificial neural network (ANN) based micromechanical modeling framework, termed ANN-PHFGMC, for depicting the nonlinear behavior of fiber-reinforced polymeric (FRP) materials. Pre-simulated mechanical stress-strain responses and behaviors are determined using the PHFGMC to generate a multiaxial training database for the ANN micromodel. The PHFGMC effective stress-strain responses for different applied multiaxial strain paths are divided into two sets of data; one for the training and the other for verifying the trained ANN-PHFGMC model. The resulting trained ANN-PHFGMC is accurate, with less than a 5% error in the verified predictions. Next, the ANN-PHFGMC model can be integrated within a commercial explicit FE code for multiscale low-velocity impact (LVI) analysis of laminated composite plates.
DEVELOPMENT OF SIMPLIFIED METHODS TO CHARACTERIZE PLASTICITY PARAMETERS FOR LS-DYNA MAT213
Authors: . GOLDBERG ROBERT K. , RICKS TRENTON M.
Published: November 2023

A material model which incorporates several key capabilities which have been identified as lacking in currently available composite material models has been developed. The material model utilizes experimentally based tabulated input to define the evolution of plasticity, damage, and failure as opposed to specifying discrete input parameters (such as modulus and strength). It has been implemented into the commercially available transient dynamic finite element code LS-DYNA® as MAT 213. The model can simulate the nonlinear deformation, damage and failure that take place in a composite under dynamic loading conditions. One challenge that has been encountered by users of MAT 213 is that several of the parameters in the orthotropic plasticity model are extremely difficult to characterize experimentally or data may not be available to characterize them. To simplify this process, a toolset and methodology are being developed which can be implemented as a stand-alone in MATLAB® application. A key part of this toolset will utilize a simplified version of the orthotropic plasticity model. Specifically, the orthotropic plasticity model utilized in MAT 213 has been simplified to simulate the stress-strain response of a composite ply with an arbitrary fiber orientation subjected to uniaxial loading or the shear response of a composite ply subject to pure shear loading. These simplified models will allow a user to simultaneously simulate the longitudinal and transverse tensile and compressive stress-strain responses, the shear stress-shear strain responses, and the off-axis tensile (or compressive) stress-strain responses of a composite ply in a highly efficient manner. By using this toolset, particularly when combined with a suitable optimizer, a user can quickly determine the required plasticity model parameters required for a MAT 213 analysis.
THERMOMECHANICAL PROPERTY PREDICTION OF A BISMALEIMIDE RESIN USING MOLECULAR DYNAMICS
Authors: WAVRUNEK TREVOR , PATIL SAGAR , BAMANE SWAPNIL , KEMPPAINEN JOSHUA , MAIARRU MARIANNA , ODEGARD GREGORY
Published: November 2023

Bismaleimide (BMI) resins have seen increased use as a thermoset polymer matrix material in structural aerospace composites as a result of their excellent thermomechanical properties and low specific weight that arise from the complex structural features of the BMI matrix. Since the development of high-performance composites has increasingly relied on molecular modeling to predict polymer processing characteristics, the ability to effectively model these materials is imperative. Molecular models offer insights into residual stresses and bulk properties of the composite matrix polymer, which directly impact the laminate’s durability and performance when subject to thermal and mechanical loads. Unfortunately, its complex crosslink structure has limited the structure-property understanding of BMI at the molecular level, complicating modeling attempts at all length scales. This study utilizes molecular-scale simulations to model a BMI thermoset resin commonly used in aerospace composites at the nanoscale to predict the properties of the bulk thermoset. Molecular dynamics (MD) simulations using the interface force field (IFF) are performed on BMI resins to describe a likely crosslink structure and to evaluate thermomechanical properties as a function of temperature and crosslink density. These properties are then validated against experimental data to ascertain the model accuracy and demonstrate that molecular modeling methods can be successfully used to predict the evolution of properties in the BMI resin during its curing.
DEEP LEARNING-BASED AUTOMATED SEGMENTATION OF FIBER BREAKS IN ADVANCED COMPOSITES
Authors: JAIN SUDHIR , LI CARINA  XIAOCHEN , VUONG DANIEL , MCGLLICK MATTHEW , SAIFAEE SAEED , FURTADO CAROLINA , KOPP REED , JOSEPH JOSHUA , ADJODAH DHAVAL , ROSINI SEBASTIAN , SINCLAIR IAN , SPEARING S. MARK , WARDLE BRIAN L.
Published: November 2023

The heterogeneity of the microstructure and the anisotropy of the mechanical properties of carbon fiber reinforced polymer composites (CFRP) are associated with complex damage mechanisms that make failure prediction highly challenging. Typical damage mechanisms for CFRP include: (i) interlaminar cracking (delamination), (ii) matrix cracking, and (iii) fiber breakage. X-ray computed tomography (CT) has been utilized recently to identify the complex damage in progressive failure of CFRP in 3D and 4D (3D spatial and 1D temporal). However, these scans contain a large amount of data (≈10 GB/mm3), which makes it challenging to extract mechanistic insights in a reasonable time frame. In previous work, we presented the first deep learning (DL) convolutional neural network (CNN) segmentation of multiclass microscale matrix damage in CFRP. The trained CNN segments complex and sparse composite matrix damage mechanism to ≈ 99.99% agreement, with nearly 100% of human time eliminated, providing higher accuracy compared to human segmentation. In this work, we developed CNN-based method for the automated segmentation of fiber breaks using synchrotron radiation-based CT (SRCT) scans that have been human-labeled. The model employed a U-Net full CNN as the high-level encoder (feature extraction)-decoder (feature localization) structure, and VGG16 as the deep CNN backbone via the publicly available Segmentation Models GitHub repository. An unbiased evaluation was performed comparing the machine vs. the human-labeled ground truth. Finally, active learning was presented for the machine-assisted relabeling of datasets containing fiber breaks. The deep learning-based automated segmentation method demonstrated accurate identification (> 90%) of fiber breakage for CFRP.
CHARACTERIZATION OF LOW-VELOCITY IMPACT DAMAGE IN THERMOPLASTIC LAMINATED COMPOSITESThe impact damage response of two thermoplastic material systems were compared over a range of impact energies. Eight-inch-square impact specimens with a 24-ply quasi-isotropic layup were manufactured from TC1225 LMPAEK T700G from Toray Industries and APC AS4D/PEKK-FC from Solvay. The effect of the degree of crystallinity (DOC) on the damage response was also investigated using a third set of specimens from the Toray material manufactured with reduced crystallinity. Using a combination of data obtained from X-ray computed tomography (CT) scans and ultrasonic testing (UT), detailed damage maps were created for every interface and ply for selected specimens. Using these damage maps, the delamination size, shape, and area were evaluated at each interface. The presence of fractured fibers was also identified on each ply. The LMPAEK material was found to have fewer and smaller delaminations than the PEKK specimens for impacts at the same energy. However, the LMPAEK specimens contained a larger number of fiber breaks. A similar trend was observed when comparing the baseline LMPAEK specimens with the low-crystallinity LMPAEK specimens. The low-crystallinity specimens had very little delamination but had a large number of plies with fiber breaks. In addition, the LMPAEK specimens often contained lines of fiber fractures in near-surface plies emanating from the contact region that were not present in the PEKK specimens.
Authors: JACKSON WADE , ROSE CHERYL , LEONE FRANK
Published: November 2023

The impact damage response of two thermoplastic material systems were compared over a range of impact energies. Eight-inch-square impact specimens with a 24-ply quasi-isotropic layup were manufactured from TC1225 LMPAEK T700G from Toray Industries and APC AS4D/PEKK-FC from Solvay. The effect of the degree of crystallinity (DOC) on the damage response was also investigated using a third set of specimens from the Toray material manufactured with reduced crystallinity. Using a combination of data obtained from X-ray computed tomography (CT) scans and ultrasonic testing (UT), detailed damage maps were created for every interface and ply for selected specimens. Using these damage maps, the delamination size, shape, and area were evaluated at each interface. The presence of fractured fibers was also identified on each ply. The LMPAEK material was found to have fewer and smaller delaminations than the PEKK specimens for impacts at the same energy. However, the LMPAEK specimens contained a larger number of fiber breaks. A similar trend was observed when comparing the baseline LMPAEK specimens with the low-crystallinity LMPAEK specimens. The low-crystallinity specimens had very little delamination but had a large number of plies with fiber breaks. In addition, the LMPAEK specimens often contained lines of fiber fractures in near-surface plies emanating from the contact region that were not present in the PEKK specimens.
MULTISCALE THERMAL-MECHANICAL ANALYSIS OF TOW-STEERED COMPOSITE PLATE STRUCTURES USING A MIXED-FIDELITY NEURAL NETWORK MODEL
Authors: LIU XIN , LIU BANGDE , TIAN SU , YU WENBIN
Published: November 2023

One challenge of design optimization of tow-steered composites is the significantly increased computational cost with more design variables in realistic structures. Emerging machine learning models, such as artificial neural network (ANN) models, offer an efficient alternative to expensive finite element analysis (FEA). However, the requirement for extensive training data can limit the application of ANN models in structural design using tow-steered composites. In this paper, we will utilize a recently developed Design Tool for Advanced Tailorable Composites (DATC) to generate training data. Single-fidelity ANN models will be developed to take design parameters of tow-steered composites and predict the critical buckling load of structures. The accuracy and efficiency of the ANN models will be validated with high-fidelity FEA. To reduce the cost of generating training data, we propose a composite ANN model to take mixed-fidelity data from simulations at different mesh densities. Two examples of tow-steered composite structures will be employed to develop the single-fidelity and mixed-fidelity ANN models. The results show that the proposed mixed-fidelity ANN model delivers accuracy comparable to high-fidelity FEA, while also significantly enhancing efficiency in comparison to the single-fidelity ANN model.
LOW VELOCITY IMPACT OF WOVEN GFRP/ CFRP COMPOSITES: NUMERICAL ANALYSIS AND EXPERIMENTATION
Authors: SOMMER DREW E. , WERNER BRIAN T. , SKULBORSTAD ALYSSA J. , LONG KEVIN N.
Published: November 2023

Low-velocity impact (LVI) of laminated composites is commonly used in aerospace industry certification as part of a durability and damage tolerance assessment (e.g., barely visible impact damage, compression after impact, etc.). In certain situations, the puncture resistance of an impacted composite structure is of interest. To study the behavior of composite plates near perforation, this work focusses on LVI of composites at relatively high impact energies. An experimental test campaign was conducted wherein composite laminates composed of layers of woven glass fiber-reinforced polymer (GFRP) and woven carbon fiber-reinforced polymer (CFRP) plies were impacted in a drop tower using a standard LVI setup with a hemispherical indenter tip. The stacking sequence contained blocked plies of the same material, yielding a glass-carbon-glass layup. A range of impact energies were selected to produce widespread damage, including delamination, fiber fracture, and shear failure, and to fully perforate the panels in some instances. These tests are distinguished from other such impact experiments in that substantial damage and perforation are observed at low velocities. The interface between dissimilar materials showed large delaminations, which could propagate to the edge of the plate at the highest tested impact energies. Numerical modelling was performed using the explicit transient dynamics solver of Sierra/Solid Mechanics, a finite element code developed at Sandia National Laboratories. Continuum damage mechanics (CDM) and cohesive zone modelling (CZM) were utilized for the intra- and interlaminar failure, respectively. Pseudo-ply-by-ply meshing with one element through the thickness of every two blocked plies was used, and delamination planes were modelled with cohesive zone elements (CZE) inserted between every two layers. The main quantities of interest, including the energy dissipation, force-displacement curve, peak force, and damage patterns, were used to compare the numerical simulations with the experiments. These data are useful for validating computational simulations and provide insight into the impact resistance and energy dissipation capability of hybrid GFRP/CFRP composites.
IMPACT DAMAGE AND FAILURE MECHANISMS OF HYBRID FACESHEET SANDWICH COMPOSITES UNDER LOW TEMPERATURE CONDITIONS
Authors: MACK JASON P. , MIRZA FAIZAN , BANIK ARNOB , KHAN M.H. , TAN K.T.
Published: November 2023

In this study, we experimentally investigate the impact damage and failure mechanisms of foam-core sandwich composites with carbon fiber reinforced polymer (CFRP) and/or glass fiber reinforced polymer (GFRP) face sheets. Specimens are conditioned and impacted over a wide temperature range (from room temperature of 23°C down to -70°C) using Instron CEAST 9350 impact test machine. This work also explores the use of hybrid composite face sheets, with various configurations of layering CFRP and GFRP in the face sheets of foam-core sandwich composites. Results show that exposure to low temperature causes more severe damage, particularly in specimens with CFRP face sheets, due to their extreme brittleness. GFRP face sheet specimens are able to achieve larger deformation and absorb greater impact energy even at low temperature conditions. There is a significant benefit in using hybrid configurations, by striking a balance between brittle (CFRP) and ductile (GFRP) materials and harnessing their mechanical advantages of high strength and high fracture toughness, respectively. Results also demonstrate that hybridization is a solution to reduce temperature effects in impact deformation. Careful placement of CFRP and GFRP in layup order can harness the best impact performance. X-ray micro-computed tomography (μCT) images reveal substantial delamination at the interfaces between CFRP and GFRP layers. It is also observed that CFRP layers fail by brittle fracture, while delamination is the major damage mode within GFRP layers. Other complex failure mechanisms in the composite face sheets (such as matrix crack and fiber breakage) and foam core (core crushing, core shearing and interfacial debonding) are also presented.
REACTIVE MOLECULAR DYNAMICS SIMULATIONS OF THE FURAN PYROLYSIS PROCESS FOR CARBON- CARBON COMPOSITE FABRICATION
Authors: KEMPPAINEN JOSH , GALLEGOS IVAN , GISSINGER JACOB R. , WISE KRISTOPHER E. , KOWALIK MALGORZATA , ODEGARD GREGORY M.
Published: November 2023

Carbon-Carbon composites (C/C composites) are an excellent thermal protection system for aerospace vehicles. The matrix material of most C/C composites, glassy carbon (GC), demonstrates excellent thermal stability and mechanical response with low mass densities. Although GC materials have been in development and use for decades, molecular simulation protocols need to be developed to accelerate the optimization of processing cycles and to drive the development of the next generation of C/C composites. This research aims to establish molecular dynamics (MD) simulation protocols to accurately predict the evolution of the molecular structure and properties of furan resin during the pyrolysis processes that convert the polymer into a GC material. MD workflows are developed using a reactive force field to simulate the evolution of the molecular structure, mass density, and elastic properties of furan resin-derived GC. MD simulation parameters are optimized, and the predicted structures and properties are shown to agree with experimental measurements from the literature. The modeling methodology established in this work can provide guidance in driving the development of the next-generation C/C composite precursor chemistries.
EXPERIMENTAL AND COMPUTATIONAL INVESTIGATION INTO THE USE OF DISCONTINUOUS FIBER COMPOSITES TO MANUFACTURE A BRACKET
Authors: NAKAGAWA TROY , KO SEUNGHYUN , CHEN ZHISONG , LARSON MICHAEL H. , ADAMS EBONNI J. , SOJA MATTHEW R. , JAMES SCOTT , YANG JINKYU , SALVIATO MARCO , AVERY WILLIAM B.
Published: November 2023

In this study, Discontinuous Fiber Composites (DFCs) are used to manufacture a bracket with two platelet sizes, a narrow and square platelet. X-ray CT scans were performed in order to obtain the exact mesostructure of the bracket. From this, areas of low and high flow of platelets are observed and the effects of this are studied. The exact orientations are obtained and mapped onto a digital twin of the bracket for Finite Element (FE) simulations. The model is validated against uniaxial tension experiments. The FE model can precisely predict the apparent stiffness, strength, and match the failure locations seen in experiments. By making a one-to-one copy of the brackets, a better understanding of the failure mechanisms of complex DFC systems can be obtained.
INVESTIGATION OF CARBON BLACK/ULTRA-HIGH- MOLECULAR-WEIGHT-POLYETHYLENE NANOCOMPOSITES MANUFACTURED BY COMPRESSION MOLDING AND EQUAL CHANNEL ANGULAR EXTRUSION
Authors: MIROSHNICHENKO KATERYNA , BUKLOVSKYI STANISLAV , TSUKROV IGOR , THOMSON REBECCA J. , SOLBERG PEDER C. , LIMBERG AFTON K. , CITTERS DOUGLAS W. VAN
Published: November 2023

Conductive carbon black (CCB) reinforced ultra-high molecular weight polyethylene (UHMWPE) polymers are investigated by micro-computed tomography, scanning electron microscope, and mechanical testing. The composites are manufactured by two techniques: compression molding (CM) and equal channel angular extrusion (ECAE). It is observed that electrical conductivity increases for the composites with the higher concentration of CCB inclusions without significant loss of tensile toughness. At the same time, ECAE procedure decreases the observed thickness of the CCB-rich layer and decreases electrical conductivity of the UHMWPE composites as compared to CM. Concentration of carbon inclusions in CCB-rich layer was evaluated for different weight fractions of CCB in the overall composite. Preliminary studies indicate that ECAE doesn’t change the orientation and elongation of UHMWPE particles in the CM consolidated composites.
SHAPE CONTROL FOR THERMOPLASTIC COMPOSITES MADE BY AUTOMATED FIBER PLACEMENT USING ANNEALING
Authors: SCATTOLIN CLARA , HOA SUONG VAN
Published: November 2023

The goal of this research is to undo the visible warping and relieve the residual stresses of thermoplastic composite parts manufactured using automated fiber placement (AFP) technology by designing an annealing cycle. AFP is an automated process that allows for the manufacturing of flat and round parts from various materials, including thermoplastic composites. The samples were made from carbon fiber reinforced polyether ether ketone (PEEK) tape and were manufactured on a 6- axis AFP system with a hot gas torch. The residual stresses arise due to the large temperature gradients in manufacturing and the subsequent uneven cooling. The warping is problematic because finished parts vary significantly from their intended geometry. The curvature of samples with 4, 12, and 15 layers were measured using a laser measuring system that is comprised of a platen that allows users to pinpoint x-y coordinates and a laser to provide the elevation. MATLAB was used to compute the second order polynomial that best represents this surface. The curvature at any point on this surface can be calculated using partial derivatives. Annealing in an oven and using a heat blanket were explored as out-of-autoclave options. A reduction in the mean curvature of 86%-90% was observed in unidirectional samples with an annealing cycle comprised of a three-hour hold at 200°C and vacuum pressure of 15 torr. The sample with a symmetric unbalanced layup sequence only had a 17%-19% improvement to its mean curvature.
ANALYSIS OF THE INFLUENCE OF DRILLING PARAMETERS AND MONITORING OF THE DELAMINATION PHENOMENON IN THERMOPLASTIC CFRP MACHINING
Authors: KONDO MARCEL YUZO , CALLISAYA EMANUELE SCHNEIDER , BOTELHO EDSON COCCHIERI , COSTA MICHELLI LEALI , ALVES MANOEL CLÉBER DE SAMPAIO , RIBEIRO MARCOS VALÉRIO
Published: November 2023

Carbon fiber reinforced Polyamide 6 (Nylon 6) composites have a high potential for use in the aerospace, automotive, and energy industries. Parts of polymeric composites are generally manufactured in dimensions close to those used by the hot compression molding process. However, the assembly of these components in manufacturing a product occurs by riveting or screwing, which makes it necessary to drill holes. The central hole quality problem during the machining of carbon fiber-reinforced polymeric composites (CFRP) is the delamination phenomenon. Separating the composite layers at the entrance of the cutting tool (peel-up delamination) and exit (push-out delamination) harms the resistance, stiffness, and reliability of the components. Many strategies are used to suppress the occurrence of delamination, including the selection of suitable machining parameters, the use of specific tool geometries, and the use of different materials for making drills. Ways of monitoring the drilling process to prevent delamination are also researched. The present study aimed to analyze the drilling process of a thermoplastic polymeric composite reinforced with carbon fibers, verifying the influence of the variation in the drilling parameters of cutting speed and feed rate in the thrust force and push-out delamination factor. It was carried out through two different 32 full factorial matrices, testing cutting speed from 35.95 to 133.12 m/min and feed rate from 0.018 to 0.118 mm/rev. It also investigated the potential use of thrust force signals for monitoring delamination formation during the drilling process.
EFFECT OF FIBER-MATRIX INTERFACE ON FIBER-DIRECTION COMPRESSIVE STRENGTH OF CARBON FIBER COMPOSITES
Authors: GHAFFARI SARVENAZ , SEON GUILLAUME , MAKEEV ANDREW
Published: November 2023

The rotorcraft industry has shown a strong interest in High-modulus (HM) carbon fiber-reinforced polymers (CFRPs) due to their potential to create lightweight airframes and rotor components, resulting in significant weight reduction. However, a major drawback of HM CFRPs has been their very low compressive strength in the fiber direction compared to the currently used intermediate-modulus (IM) CFRPs in primary structures. This weakness has been delaying the implementation of HM CFRPs in aircraft structures. Microstructural tailoring may provide an innovative means for breaking through the fiber-direction compressive strength barrier of the HM CFRPs. The primary failure mechanism in both HM and IM CFRPs under fiber-direction compression is shear microbucking, which is significantly influenced by fiber-matrix interface strength. In-depth analysis using in-situ scanning electron microscopy (SEM) experiments has revealed significant differences in the surface characteristics of the carbon fibers, leading to a much stronger interface for IM fibers compared to HM fibers. These findings have prompted a microstructural tailoring strategy involving the reinforcement of HM fibers with IM fibers, which enhances the overall stability of the microstructure governing the fiber-direction compressive strength performance of the material. A laboratory-scale production-quality manufacturing system has been delivered, and promising experimental results enabling HM CFRPs with adequate fiber-direction compressive strength have been achieved through hybridization of IM and HM fibers at the filament level in HM CFRP toughened with nano-silica. This new material solution not only approaches the compressive strength of IM CFRPs but also provides more than 30% higher axial modulus.
EXTRACTING DAMAGE MODE AND DEPTH IN COMPOSITE PANELS THROUGH MEASURED WAVE CHARACTERISTICS USING A NOVEL MINI-IMPACTOR EXCITATION SOURCE
Authors: CUEVA JANELLE COLEEN DELA , KIM HYONNY
Published: November 2023

Ultrasonic guided wave (UGW) is an established nondestructive evaluation method capable of assessing a wide area of the structure. A novel composite mini-impactor was used as a broadband excitation source for the UGW damage characterization of composite plates. Unlike the traditional impact hammers for composite structures which have an excitation frequency below 30 kHz, the unidirectional carbon/epoxy mini-impactor can excite between a range of 30-500 kHz. The excitation source was utilized to conduct basic studies on the effect of single-mode damage states such as: delamination, matrix crack, and fiber breakage. The single-mode damage states in AS4/977-3 prepreg composite plates are manufactured during layup by incorporating release film strips for delamination, and perpendicular cuts to create matrix or fiber breaks. Broadband air-coupled transducers (BATS) were used to measure the UGW structural response to the mini-impactor excitation through a pitch-catch setup. Two reception transducers are placed before and after the damage on the wave propagation path to assess the true structural transfer function (STF) through deconvolution between the signal output of both receivers. Comparisons of measured wave characteristics between pristine and damage types are conducted using extraction of damage-indicative signal features and by calculating Difference Signals. Additionally, double-sided UGW interrogations were conducted on the composite plates having non-centered flaws to determine different damage depths. Damage type and depth were distinguished based on STF statistical features and Difference Signals. STF of Damaged Signals farther from the surface of excitation were not indicative of damage but were identifiable through Difference Signals. Signals indicating fiber breakage produce a strong reduction in amplitude when breakage is closer to the surface of excitation.
ADDITIVE MANUFACTURING OF FRONTALLY- POLYMERIZABLE CONTINUOUS CARBON FIBER TOW-BASED COMPOSITES
Authors: HMEIDAT NADIM S. , ZAKOWOROTNY MICHAEL , PARIKH NIL A. , LE THIEN B. , AGRAWAL, PRANJAL , DEBRUN GAVIN , BAUR JEFFERY , GEUBELLE PHILIPPE H. , TAWFICK SAMEH H. , SOTTOS NANCY R.
Published: November 2023

Additive manufacturing (AM) of high-performance thermoset polymer-matrix composites has important applications in many fields, including the aerospace, energy and automotive industries. Current AM methods for thermoset composite often require a thermal post-cure or result in lower mechanical properties compared to conventional composite manufacturing techniques. Frontal polymerization (FP) presents an alternative curing strategy that utilizes a self-sustaining exothermic reaction that propagates through a monomer as a front to convert it to a hardened thermoset polymer. In this work, we develop an extrusion-based AM process to deposit dicyclopentadiene (DCPD)-impregnated carbon fiber tows which undergo FP. The tow is deposited on a thermally conductive, heated bed to supply the thermal energy required to initiate FP. We investigate the effect of bed temperature on the front speed, front temperature, and degree of cure of the printed composite tows. A finite-element model based on a homogenized thermo-chemical formulation is developed to capture the deposition of the tow on the substrate, the heat transfer in the tow, the cure kinetics of the matrix material, and the impact of key process parameters, including the fiber volume fraction, bed temperature and deposition speed. This numerical model is then used to predict the front properties and maximum degree of cure, and is compared to experimental results.
QUANTITATIVE EVALUATION OF FIBER DISTRIBUTION IN DISCONTINUOUS CFRP USING DARK-FIELD IMAGES DERIVED BY X-RAY TALBOT-LAU INTERFEROMETER
Authors: YOSHIMURA AKINORI , ASANO KEISUKE , GOTO KEITA , ARAI MASAHIRO , ARIMOTO TADASHI
Published: November 2023

This study proposes a new method which quantitatively evaluates distributions of carbon fiber content, mean fiber orientation, and variance of fiber orientation in CFRP. Dark-field images taken by Talbot-Lau interferometer are employed for the method. Talbot-Lau interferometer can measure X-ray scattering generated by carbon fibers in the optical path as a dark-field signal. Dark-field image visualizes the distribution of dark-field signal. The authors first describe a model that relates number of carbon fibers oriented in a certain orientation in CFRP and the dark-field signal. The model is then expanded so that it can calculate dark-field signal of CFRP laminates in which carbon fibers of different orientations are stacked in the thickness direction. Carbon fiber distribution, mean fiber orientation, and variance of fiber orientation in a given CFRP can be evaluated by using the model. The method is validated by comparing the results of the method to the results those are directly measured from the optical microscopic images. The authors believe that the proposed method has a potential to be a new nondestructive inspection method for CFRP.
RX-FEM MODELING OF FATIGUE DAMAGE GROWTH IN COMPOSITES WITH LOCAL R-RATIO BY USING STRENGTH TRACKING METHOD
Authors: LU WEI-TSEN , CURRY GRAYSON , ADLURU HARI , SENEVIRATNE WARUNA , IARVE ENDEL V.
Published: November 2023

A computationally efficient fatigue methodology is proposed that uses automatic cycle jump step selection algorithm within implicit framework to predict fatigue damage accumulation in laminated composites. Stress state scan within a specified load profile such as one or more cycles is performed to determine local stress ratio (R-ratio) in each integration point. S-N ply level-based strength criterion was applied for matrix Mesh Independent Crack (MIC) insertion in each ply as well as within respective Cohesive Zone Model (CZM) formulation at the damage initiation stage. Paris Law based propagation was utilized for MIC and delamination opening within CZM. The local R-ratio is implemented within CZM for initiation and propagation stages. In addition to the matrix failure modes fatigue degradation in the fiber direction under compression loading was implemented. The concept is based on shear strength degradation in the misalignment frame and LaRC failure criterion. Finite element simulations of [45/0/−45/90]3?? open hole laminate under tension-tension (T-T) and compression-compression (C-C) fatigue were performed. Fiber damage, delamination, and matrix cracks are seen to be the appropriate size and location compared with the experimental result.