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Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer.
Thesis (PhD)--Stellenbosch University, 2023.
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| Format: | Thesis |
| Language: | en_ZA en_ZA |
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Stellenbosch : Stellenbosch University
2023
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| _version_ | 1867613912559517696 |
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| access_status_str | Open Access |
| author | Kirkman, Daniel Mark |
| author2 | Van der Merwe, André Francois |
| author_browse | Kirkman, Daniel Mark Van der Merwe, André Francois |
| author_facet | Van der Merwe, André Francois Kirkman, Daniel Mark |
| author_sort | Kirkman, Daniel Mark |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhD)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/127122 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:43:40.919Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/127122 Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. Kirkman, Daniel Mark Van der Merwe, André Francois Campbell, Robert Ian Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering. Additive manufacturing Metals -- Extrusion Fibrous composites Photopolymerization Thesis (PhD)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Continuous reinforcement fibres have been shown to drastically increase the strength of polymer components produced by additive manufacturing (AM). Material extrusion (MEX) methods of AM are particularly suited to the inclusion of continuous fibres. However, MEX methods are limited to planar, layer-wise build strategies. Fibre reinforced MEX processes will therefore still show some of the mechanical strength limitations of conventional MEX processes. Consequently, the improvements in mechanical properties promised by the inclusion of continuous fibres cannot be fully realized except for simple geometries and load cases. The aim of the study presented in this dissertation was to develop an AM system capable of the support-free deposition of continuous fibre reinforced polymer along freeform toolpaths. It was theorized that such an approach to AM could circumvent the limitations of layer-based AM methods to enable the AM of structurally optimized parts with load path aligned reinforcement fibres. A photopolymer resin and E-glass fibres were selected as respective matrix and reinforcement materials. The first extruder iterations were designed to extrude only a photopolymer gel, while the final iteration made use of inline impregnation for combining the matrix and reinforcement materials. Estimated fibre volume fractions of 35 % were achieved. Ultraviolet lasers were used to cure the matrix as it exited the extruder nozzle. Toolpath planning and generation algorithms, which facilitated the semi-automatic generation of 5-axis toolpaths for simple geometries, were implemented using MATLAB. Toolpaths were executed by a moving build platform attached to a robotic arm. Preliminary testing demonstrated the AM process for simple geometries. Results from preliminary tests were used for motivating improvements to the extruder design, and for the development of improved toolpath planning approaches. A series of tests was conducted using the final extruder iteration to determine suitable values of the critical process parameters identified during preliminary testing. Toolpaths were then generated for a more complex geometry resulting from a topology optimization considering continuous fibre reinforcement. Mechanical testing of this part verified that its strength and stiffness were significantly higher than that of a similar unreinforced part manufactured using a SLA 3D printer. Micro-CT scan and microscope analyses were performed on this part to assess the microstructure and to identify defects. Although the system which was developed was restricted with respect to the achievable geometric complexity, the continuous fibre reinforced support-free AM of a simple optimized part, using freeform toolpaths and load path aligned reinforcement fibres, was demonstrated. Suggestions for future research include the development of improved matrix and reinforcement materials, the automation of the freeform toolpath generation process for complex geometries, and further optimization of process parameters for improved geometric accuracy and mechanical properties. AFRIKAANS OPSOMMING: Deurlopende versterkingsvesels verbeter die sterkte van polimeer laagvervaardigde (LV) komponente. Materiaal ekstruderingsmetodes (MEX) van LV is besonder geskik vir die insluiting van versterkingsvesels. MEX is egter beperk to vlak- en laagvervaardiging-strategieë. Veselversterkte MEX prosesse sal dus steeds sommige van die gebreke van konvensionele MEX prosesse toon. Behalwe in eenvoudige geometrieë en belastings, sal die verbeterde meganiese eienskappe wat die insluiting van veselversterking bied, nie altyd bereik word nie. Die doel van hierdie proefskrif was om ‘n LV proses te ontwikkel vir die deponering van ‘n deurlopende veselversterkte polimeer in ‘n vrye vorm. Die aanname was dat so ‘n benadering ‘n aantal van die beperkings van laag-gebaseerde metodes sou oorkom, juis dan om struktureel optimeerde komponente moontlik te maak waar versterkingsvesels met vryvorm lasrigtings oriënteer is. ‘n Fotopolimeerhars en E-glas vesels is geselekteer as die onderskeie matriks en versterkings materiale. Die eerste weergawes van die ekstrudeerder is ontwerp om slegs ‘n fotopolimeer-gel te ekstrudeer. Die finale weergawe het van ‘n inlyn proses gebruik gemaak om die matriks en versterkings materiale te kombineer. Geskatte vesel tot volume verhoudings in die omgewing van 35 % is bereik. Ultraviolet lasers is gebruik om die matriks materiaal te verhard sodra dit uit die ekstrudeerder tuit kom. Gereedkapsroete beplanning en generasie algoritmes, wat die semi-outomatiese generasie van 5-vryheidsgraad-gereedskaproetes vir eenvoudige geometrieë gefasiliteer het, is geïmplementeer deur die gebruik van MATLAB. ‘n Werksplatvorm aan die robot arm gemonteer het die gereedskapsroetes gevolg terwyl die ekstrudeerder staties is. Aanvanklike toetslopies het die LV proses vir eenvoudige geometrieë demonstreer. Resultate van hierdie toetslopies is gebruik om die ekstrudeerder ontwerp te verbeter en gereedskapsroetes te ontwikkel. ‘n Reeks toetslopies is met die finale weergawe van die ekstrudeerder uitgevoer om geskikte waardes vir kritiese proses parameters, wat gedurende die aanvanklike toetslopies identifiseer is, te bepaal. Daarna is gereedskapsroetes vir ‘n meer komplekse geometrie genereer, wat vanaf ‘n topologie ontwikkel is wat vir deurlopende veselversterking optimeer is. Die meganiese toetse van hierdie komponent het bevestig dat die sterkte en onbuigsaamheid aansienlik hoër was as soortgelyke onversterkte komponente wat vervaardig was deur die gebruik van ‘n SLA 3D-drukker. CT-skandering en mikroskoop-analise is op hierdie komponent uitgevoer om mikrostrukture te evalueer en om gebreke te identifiseer. Alhoewel die stelsel beperk was ten opsigte van die bereikbare kompleksiteit van geometrieë, is die deurlopende veselversterkte LV van ‘n eenvoudige optimeerde komponent deur die gebruik van vrye-vorm gereedskapsroetes en lasrigtingbelynde versterkingsvesels demonstreer. Toekomstige navorsingsmoontlikhede sluit in die ontwikkeling van verbeterde matriks en versterkings materiale, die outomatisering van die vryvorm gereedskaproete generasie proses vir komplekse geometrieë, en verdere optimering van proses parameters vir verbeterde geometriese akkuraatheid en meganiese eienskappe. Doctorate 2023-02-03T07:59:46Z 2023-05-18T07:05:23Z 2023-02-03T07:59:46Z 2023-05-18T07:05:23Z 2023-03 Thesis http://hdl.handle.net/10019.1/127122 en_ZA en_ZA Stellenbosch University 297 pages : illustrations. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Additive manufacturing Metals -- Extrusion Fibrous composites Photopolymerization Kirkman, Daniel Mark Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. |
| title | Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. |
| title_full | Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. |
| title_fullStr | Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. |
| title_full_unstemmed | Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. |
| title_short | Freeform support-free additive manufacturing with continuous fiber reinforced photopolymer. |
| title_sort | freeform support free additive manufacturing with continuous fiber reinforced photopolymer |
| topic | Additive manufacturing Metals -- Extrusion Fibrous composites Photopolymerization |
| url | http://hdl.handle.net/10019.1/127122 |
| work_keys_str_mv | AT kirkmandanielmark freeformsupportfreeadditivemanufacturingwithcontinuousfiberreinforcedphotopolymer |