{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,6]],"date-time":"2026-06-06T00:21:28Z","timestamp":1780705288614,"version":"3.54.1"},"reference-count":38,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2020,3,19]],"date-time":"2020-03-19T00:00:00Z","timestamp":1584576000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>The Fused-Deposition Modelling (FDM) technique has transformed the manufacturing discipline by simplifying operational processes and costs associated with conventional technologies, with polymeric materials being indispensable for the development of this technology. A lack of quantification of viscoelastic\/plastic behavior has been noted when addressing FDM parts with Polyetherimide (PEI), which is currently being investigated as a potential material to produce functional end-products for the aerospace and health industry. Primary and secondary creep along with stress relaxation tests have been conducted on FDM PEI specimens by applying stresses from 10 to 40 MPa for 100 to 1000 min. Specimens were 3D printed by varying the part build orientation, namely XY, YZ, and XZ. Creep results were fitted to the Generalized Time Hardening equation (GTH), and then this model was used to predict stress relaxation behavior. FDM PEI parts presented an isotropic creep and stress relaxation performance. The GTH model was proven to have a significant capacity to fit viscoelastic\/plastic performances for each single build orientation (r &gt; 0.907, p &lt; 0.001), as well as a tight prediction of the stress relaxation behavior (r &gt; 0.998, p &lt; 0.001). Averaged-orientation coefficients for GTH were also closely correlated with experimental creep data (r &gt; 0.958, p &lt; 0.001) and relaxation results data (r &gt; 0.999, p &lt; 0.001). FDM PEI parts showed an isotropic time-dependent behavior, which contrasts with previous publications arguing the significant effect of part build orientation on the mechanical properties of FDM parts. These findings are strengthened by the high correlation obtained between the experimental data and the averaged-coefficient GTH model, which has been proven to be a reliable tool to predict time-dependent performance in FDM parts.<\/jats:p>","DOI":"10.3390\/polym12030678","type":"journal-article","created":{"date-parts":[[2020,3,19]],"date-time":"2020-03-19T10:01:35Z","timestamp":1584612095000},"page":"678","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Time-Dependent Mechanical Properties in Polyetherimide 3D-Printed Parts Are Dictated by Isotropic Performance Being Accurately Predicted by the Generalized Time Hardening Model"],"prefix":"10.3390","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9769-8788","authenticated-orcid":false,"given":"A. G.","family":"Salazar-Mart\u00edn","sequence":"first","affiliation":[{"name":"Grup d\u2019Enginyeria en Producte Industrial, (GEPI), Institut Qu\u00edmic de Sarri\u00e0, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6271-2594","authenticated-orcid":false,"given":"A. A.","family":"Garc\u00eda-Granada","sequence":"additional","affiliation":[{"name":"Grup d\u2019Enginyeria en Producte Industrial, (GEPI), Institut Qu\u00edmic de Sarri\u00e0, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8951-1135","authenticated-orcid":false,"given":"G.","family":"Reyes","sequence":"additional","affiliation":[{"name":"Grup d\u2019Enginyeria en Producte Industrial, (GEPI), Institut Qu\u00edmic de Sarri\u00e0, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1407-6394","authenticated-orcid":false,"given":"G.","family":"Gomez-Gras","sequence":"additional","affiliation":[{"name":"Grup d\u2019Enginyeria en Producte Industrial, (GEPI), Institut Qu\u00edmic de Sarri\u00e0, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7569-4711","authenticated-orcid":false,"given":"J. M.","family":"Puigoriol-Forcada","sequence":"additional","affiliation":[{"name":"Grup d\u2019Enginyeria en Producte Industrial, (GEPI), Institut Qu\u00edmic de Sarri\u00e0, Universitat Ramon Llull, Via Augusta 390, 08017 Barcelona, Spain"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2020,3,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1016\/j.ajme.2017.09.003","article-title":"Additive manufacturing applications in medical cases: A literature based review","volume":"54","author":"Javaid","year":"2018","journal-title":"Alexandria J. Med."},{"key":"ref_2","unstructured":"Perez, M., Block, M., Espalin, D., Winker, R., Hoppe, T., Medina, F., and Wicker, R.L. (2012, January 7\u20139). Sterilization of FDM-manufactured parts. Proceedings of the 23rd Annual International Solid Freeform Fabrication Symposium\u2014An Additive Manufacturing Conference, Austin, TX, USA."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"140","DOI":"10.1016\/j.ast.2016.12.019","article-title":"Additive manufacturing in unmanned aerial vehicles (UAVs): Challenges and potential","volume":"63","author":"Goh","year":"2017","journal-title":"Aerosp. Sci. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"393","DOI":"10.1108\/13552541111156522","article-title":"Enhancing aerospace engineering students\u2019 learning with 3D printing wind tunnel models","volume":"17","author":"Kroll","year":"2011","journal-title":"Rapid Prototyp. J."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Gibson, I., Rosen, D., and Stucker, B. (2014). Additive Manufacturing Technologies: 3D Printing, Rapid Prototyping and Direct Digital Manufacturing, Springer.","DOI":"10.1007\/978-1-4939-2113-3"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"176","DOI":"10.1108\/RPJ-04-2019-0106","article-title":"Fused deposition modelling: A review","volume":"26","author":"Vyavahare","year":"2020","journal-title":"Rapid Prototyp. J."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"670","DOI":"10.1016\/j.matdes.2015.06.074","article-title":"Mechanical property characterization and simulation of fused deposition modeling Polycarbonate parts","volume":"83","author":"Lluma","year":"2015","journal-title":"Mater. Des."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"506","DOI":"10.1016\/j.commatsci.2013.06.041","article-title":"Experimental characterization and analytical modelling of the mechanical behaviour of fused deposition processed parts made of ABS-M30","volume":"19","author":"Croccolo","year":"2013","journal-title":"Comput. Mater. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Galeja, M., Hejna, A., and Kosmela, P. (2020). Static and dynamic mechanical properties of 3D printed ABS as a function of raster angle. Materials, 13.","DOI":"10.3390\/ma13020297"},{"key":"ref_10","unstructured":"Ziemian, C., Cipoletti, D., Ziemian, S., Okwara, M., and Haile, K. (2014, January 4\u20138). Monotonic and Cyclic Tensile Properties of ABS Components Fabricated by Additive Manufacturing. Proceedings of the 25th International Solid Freeform Fabrication Symposium, Austin, TX, USA."},{"key":"ref_11","first-page":"159","article-title":"Anisotropic mechanical properties of ABS parts fabricated by fused deposition modelling","volume":"23","author":"Ziemian","year":"2012","journal-title":"Mech. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"129","DOI":"10.1016\/S1526-6125(02)70139-4","article-title":"Composite Modeling and Analysis for Fabrication of FDM Prototypes with Locally Controlled Properties","volume":"4","author":"Li","year":"2002","journal-title":"J. Manuf. Processes."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"287","DOI":"10.1016\/j.matdes.2009.06.016","article-title":"Parametric appraisal of mechanical property of fused deposition modelling processed parts","volume":"31","author":"Sood","year":"2010","journal-title":"Mater. Des."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"248","DOI":"10.1108\/13552540210441166","article-title":"Anisotropic material properties of fused deposition modeling ABS","volume":"8","author":"Ahn","year":"2002","journal-title":"Rapid Prototyp. J."},{"key":"ref_15","first-page":"1","article-title":"Material characterization of fused deposition modeling (FDM) ABS by designed experiments","volume":"10","author":"Montero","year":"2001","journal-title":"Soc. Manuf. Eng."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"39","DOI":"10.1016\/j.jmapro.2015.11.002","article-title":"Mechanical behaviour of ABS: an experimental study using FDM and injection moulding techniques","volume":"21","author":"Dawoud","year":"2016","journal-title":"J. Manuf. Processes"},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Mohamed, O.A., Masood, S.H., and Bhowmik, J.L. (2016). Optimisation of Dynamic Mechanical Thermal Properties of PC-ABS Parts Manufactured by FDM Process Using IV Optimal Design. Reference Module in Materials Science and Materials Engineering, Elsevier.","DOI":"10.1016\/B978-0-12-803581-8.04025-X"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"978","DOI":"10.1007\/s11665-010-9740-z","article-title":"The effect of layer orientation on the mechanical properties and microstructure of a polymer","volume":"20","author":"Vega","year":"2011","journal-title":"J. Mater. Eng. Perform."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.jmatprotec.2005.02.259","article-title":"Optimization of rapid prototyping parameters for production of flexible ABS object","volume":"169","author":"Lee","year":"2005","journal-title":"J. Mater. Process Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"219","DOI":"10.1108\/13552540310489604","article-title":"Mechanical behavior of acrylonitrile butadiene styrene fused deposition materials modeling","volume":"9","author":"Thomas","year":"2003","journal-title":"Rapid Prototyping J."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"414","DOI":"10.1016\/j.matdes.2018.06.018","article-title":"Flexural fatigue properties of polycarbonate fused-deposition modelling specimens","volume":"155","author":"Alsina","year":"2018","journal-title":"Mater. Des."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"278","DOI":"10.1016\/j.matdes.2017.11.072","article-title":"Fatigue performance of fused filament fabrication (PLA) specimens","volume":"140","year":"2018","journal-title":"Mater. Des."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/j.matlet.2017.01.104","article-title":"Experimental investigation of time-dependent mechanical properties of PC-ABS prototypes processed by FDM additive manufacturing process","volume":"193","author":"Mohamed","year":"2017","journal-title":"Mater. Lett."},{"key":"ref_24","first-page":"164","article-title":"Experimental investigation of creep deformation of part processed by fused deposition modeling using definitive screening design","volume":"18","author":"Mohamed","year":"2017","journal-title":"Addit. Manuf."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"463","DOI":"10.1016\/j.proeng.2017.06.080","article-title":"Evaluation of the Influence of Parameters of FDM Technology on the Selected Mechanical Properties of Models","volume":"192","author":"Kozior","year":"2017","journal-title":"Procedia Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"256","DOI":"10.1016\/j.matdes.2017.01.050","article-title":"Mechanical characterization of 3D printed polymers for fiber reinforced polymers processing","volume":"118","author":"Brenni","year":"2017","journal-title":"Mater. Des."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"414","DOI":"10.1016\/j.matdes.2018.01.008","article-title":"A study of creep in polycarbonate fused deposition modelling parts","volume":"141","author":"Reyes","year":"2018","journal-title":"Mater. Des."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/j.polymertesting.2017.01.003","article-title":"Residual stress measurement in Fused Deposition Modelling parts A study of creep in polycarbonate fused deposition modelling parts","volume":"58","author":"Casavola","year":"2017","journal-title":"Polym. Test."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1642","DOI":"10.1016\/j.ijplas.2008.03.009","article-title":"A review of some plasticity and viscoplasticity constitutive theories","volume":"24","author":"Chaboche","year":"2008","journal-title":"Int. J. Plast."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1140\/epjst\/e2011-01387-1","article-title":"Creep, relaxation and viscosity properties for basic fractional models in rheology","volume":"193","author":"Mainardi","year":"2011","journal-title":"Eur. Phys. J. Spec. Top."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1555","DOI":"10.1007\/s12206-016-0310-7","article-title":"Creep simulation of adhesively bonded joints using modified generalized time hardening model","volume":"30","author":"Sadigh","year":"2016","journal-title":"J. Mech. Sci. Technol."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"4","DOI":"10.1177\/0309324714554965","article-title":"Modified creep constitutive equation for an epoxy-based adhesive with nonlinear viscoelastic behavior","volume":"50","author":"Zehsaz","year":"2015","journal-title":"J. Strain Anal. Eng. Des."},{"key":"ref_33","unstructured":"Garcia-Granada, A.A. (2000). The Effect of Creep and Mechanical Load on Cold Expanded Fastener Holes. [Ph.D. Thesis, University of Bristol]."},{"key":"ref_34","unstructured":"ASTM International, ASTM D638 - 02a (2013). Standard Test Method for Tensile Properties of Plastics 08. ASTM, 1, 1\u201316."},{"key":"ref_35","unstructured":"(2019, November 20). Stratasys, ULTEM 9085: Production-Grade Thermoplastic for Fortus 3D Printers. Available online: http:\/\/www.stratasys.com\/materials\/search\/ultem9085."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"4243","DOI":"10.1016\/j.matdes.2009.04.030","article-title":"Improving dimensional accuracy of Fused Deposition Modelling processed part using grey Taguchi method","volume":"30","author":"Sood","year":"2009","journal-title":"Mater. Des."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"81","DOI":"10.1016\/j.jare.2011.05.001","article-title":"Experimental investigation and empirical modelling of FDM process for compressive strength improvement","volume":"3","author":"Sood","year":"2012","journal-title":"J. Adv. Res."},{"key":"ref_38","unstructured":"ASTM International, ASTM D2990\u201317 (2017). Standard Test Methods for Tensile, Compressive, and Flexural Creep and Creep-Rupture of Plastics 08. ASTM, 1, 1\u201318."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/12\/3\/678\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T09:07:53Z","timestamp":1760173673000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/12\/3\/678"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,3,19]]},"references-count":38,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2020,3]]}},"alternative-id":["polym12030678"],"URL":"https:\/\/doi.org\/10.3390\/polym12030678","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,3,19]]}}}