Assessing Micro-Void Formation at the Tips of Fibers within the Microstructure of Additively Manufactured Polymer Composite Bead

Assessing Micro-Void Formation at the Tips of Fibers within the Microstructure of Additively Manufactured Polymer Composite Bead | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Assessing Micro-Void Formation at the Tips of Fibers within the Microstructure of Additively Manufactured Polymer Composite Bead Aigbe Awenlimobor, Neshat Sayah, Douglas E. Smith This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7190667/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Jan, 2026 Read the published version in Applied Composite Materials → Version 1 posted 12 You are reading this latest preprint version Abstract Micro-voids within the bead microstructure of additively manufactured short carbon fiber- reinforced polymer composites are known to compromise the material performance. Unfortunately, a comprehensive understanding of the formation mechanisms of micro-voids during polymer processing is currently lacking. The present study considers micro-void nucleation at fiber interfaces, particularly those occurring at the end of suspended fibers. Micro-computed tomography (µCT) image acquisition techniques are used to characterize microstructural features of a 13wt% carbon fiber reinforced ABS composite bead manufactured via Large Area Additive Manufacturing (LAAM). The results reveal a significant collection of micro-voids at the tips of fibers approaching 80% of the total micro-void volume fraction. In addition, fiber tip micro-voids are relatively larger and less spherical than micro-voids isolated within the ABS matrix. Theoretical formulations of several known mechanisms for micro-void nucleation during LAAM material processing indicate that localized fluid pressure likely plays a pivotal role in micro-void formation. To better expose this mechanism, we simulate the hydrostatic flow-field pressure distribution surrounding a single rigid fiber suspended in simple shear flow using finite element analysis (FEA). Computed results demonstrate that the polymer matrix pressure decreases significantly at the fiber ends where micro-void nucleation is experimentally observed to occur. Our approach provides the fiber surface pressure distribution in simple shear flow that typifies nozzle regions with extreme flow conditions, enhancing our understanding of micro-void development mechanisms as the polymer melt flows through the nozzle. Additive Manufacturing Voids Microstructure Polymer Composites Fiber Reinforcement Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 23 Jan, 2026 Read the published version in Applied Composite Materials → Version 1 posted Editorial decision: Revision requested 12 Sep, 2025 Reviews received at journal 09 Sep, 2025 Reviews received at journal 24 Aug, 2025 Reviewers agreed at journal 22 Aug, 2025 Reviewers agreed at journal 20 Aug, 2025 Reviews received at journal 18 Aug, 2025 Reviewers agreed at journal 28 Jul, 2025 Reviewers agreed at journal 26 Jul, 2025 Reviewers invited by journal 25 Jul, 2025 Editor assigned by journal 24 Jul, 2025 Submission checks completed at journal 24 Jul, 2025 First submitted to journal 22 Jul, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-7190667","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":491382426,"identity":"259998cb-8022-45b5-ba90-ecb7f1d259ec","order_by":0,"name":"Aigbe Awenlimobor","email":"data:image/png;base64,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","orcid":"","institution":"Baylor University","correspondingAuthor":true,"prefix":"","firstName":"Aigbe","middleName":"","lastName":"Awenlimobor","suffix":""},{"id":491382427,"identity":"5a439e48-69cf-4429-a7c6-3eb309093003","order_by":1,"name":"Neshat Sayah","email":"","orcid":"","institution":"Baylor University","correspondingAuthor":false,"prefix":"","firstName":"Neshat","middleName":"","lastName":"Sayah","suffix":""},{"id":491382428,"identity":"4af093c4-8b0c-43ef-8ea1-32c4285eb3e5","order_by":2,"name":"Douglas E. 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Unfortunately, a comprehensive understanding of the formation mechanisms of micro-voids during polymer processing is currently lacking. The present study considers micro-void nucleation at fiber interfaces, particularly those occurring at the end of suspended fibers. Micro-computed tomography (\u0026micro;CT) image acquisition techniques are used to characterize microstructural features of a 13wt% carbon fiber reinforced ABS composite bead manufactured via Large Area Additive Manufacturing (LAAM). The results reveal a significant collection of micro-voids at the tips of fibers approaching 80% of the total micro-void volume fraction. In addition, fiber tip micro-voids are relatively larger and less spherical than micro-voids isolated within the ABS matrix. Theoretical formulations of several known mechanisms for micro-void nucleation during LAAM material processing indicate that localized fluid pressure likely plays a pivotal role in micro-void formation. 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