Cihat Okan Arikan 1 , Samet Doğan 2 , Deja Muck 3 1 Ege Üniversitesi, Emel Akın Vocational School, 35100, Bornova/İzmir 2 Ege University, Faculty of Engineering, Textile Engineering, Erzene, 35100 Bornova/İzmir 3 University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Textiles, Graphic Arts, and Design, Snežniška 5, 1000 Ljubljana, Slovenia Geometric Structures in Textile Design Made with 3D Printing Geometrične strukture v tekstilnem oblikovanju, izdelane s 3-D tiskom Original scientific article/ Izvirni znanstveni članek Received/Prispelo 11-2022 • Accepted/Sprejeto 12-2022 Corresponding author/Korespondenčni avtor: Samet DOĞAN E-mail: sametdogan1299@gmail.com ORCID ID: 0000-0002-3988-6799 Abstract 3D printing is a well-known technology for producing 3D objects by depositing successive layers of material. Among its many applications, the fashion industry has taken advantage of this technology to revolutionize its brands. Due to the unique properties of textiles, such as comfort, flexibility, etc., attempts have been made to create textile-like structures. Structures with different geometries were designed and printed using different materials ranging from rigid to flexible. In this study, three different basic geometric structures were designed using the Blender program (a free open-source 3D modelling software). Each geometric structure was designed in two different sizes with smaller and larger basic structural elements. In this case, six different models were created. The aim of this study was to compare the textile-like surfaces of different basic geometric shapes pro- duced with 3D printers. It also aimed to investigate the use of surfaces designed with basic geometric shapes in the textile-like material for fashion industries. In the production phase, the fused deposition modelling (FDM) process was chosen, and ABS and TPU materials were used. Various tests were performed, such as mass tests, and tensile and flexural strength tests on models with different basic geometric shapes and sizes. An exami- nation of the test results showed that the different geometric shapes of the various basic structures and the different materials used have an overall effect on the final properties of the structures. It was concluded that the obtained results can be used as a reference and could be helpful for researchers in the use of 3D printers in the textile-like material and fashion material industries. Keywords: 3D printing, geometric structures, textile-like material design Izvleček 3-D tiskanje je že dobro poznana tehnologija za izdelavo 3-D objektov z nanosom zaporednih slojev materiala. Med številnimi aplikacijami je tudi modna industrija to tehnologijo izkoristila za revolucioniranje svojih blagovnih znamk. Zaradi edinstvenih lastnosti tekstilij, kot so udobje, fleksibilnost itd., se poskušajo ustvariti tekstilu podobne strukture. V raziskavi so bile oblikovane strukture z raznovrstnimi geometričnimi vzorci in natisnjene z uporabo različnih mate- rialov, od togih do fleksibilnih. S programom Blender (odprtokodna programska oprema za 3-D modeliranje) so bile modelirane tri različne osnovne geometrične strukture. Vsaka geometrična struktura je bila zasnovana v dveh različnih 307 Tekstilec, 2022, Vol. 65(4), 307–321 | DOI: 10.14502/tekstilec.65.2022092 Tekstilec, 2022, Vol. 65(4), 307–321 308 velikostih z manjšimi in večjimi osnovnimi konstrukcijskimi elementi. Tako je nastalo šest različnih modelov. Cilj študije je bil primerjati tekstilu podobne površine različnih osnovnih geometričnih oblik, izdelanih s 3-D tiskalniki. Prav tako študija želi raziskati uporabo površin, oblikovanih z osnovnimi geometrijskimi oblikami, v materialih za modno indu- strijo. Za izdelavo geometričnih struktur je bil izbran postopek modeliranja s spajanjem slojev (FDM) in uporabljena materiala ABS in TPU. Na modelih z različnimi geometričnimi oblikami in velikostmi so bile opravljene različne meritve, kot so meritve mase in meritve natezne in upogibne trdnosti. Analiza rezultatov testiranja je pokazala, da različne geometrijske oblike različnih osnovnih struktur in različni uporabljeni materiali močno vplivajo na končne lastnosti omenjenih struktur. Ocenjujemo, da so dobljeni rezultati lahko dobra referenca in pomoč raziskovalcem pri uporabi 3-D tiskalnikov na področju oblikovanja tekstilu podobnih materialov v modni industriji. Ključne besede: 3-D tisk, geometrične strukture, oblikovanje tekstilu podobnih materialov 1 Introduction The use of computer technologies in the design stages of the textile sector, as well as the use of new materials and production methods in design, bring a new approach to the design creation process. Textile surface designs have been developed by us- ing new developments in design and production ar- eas and materials developed for different purposes. 3D printers are one of the innovative processes that are claimed to lead to the industry 4.0 revolution. 3D printers allow the production of objects with- out the use of tools [1]. Textile and apparel designs developed in recent years have been influenced by technology and all the developments in design and production and have been produced using many materials and techniques developed for different purposes [2]. Various 3D production methods can be used for printing textile-like materials in the fashion indus- try. The most preferred methods are SLA (stereo lithography), SLS (selective laser sintering), FDM (fused deposition modelling) and Polyjet 3D [3]. We focused primarily on FDM as the most frequent- ly used technology, as we found many interesting articles about the aforementioned process. It has been shown that the choice of pattern and material affects the properties of material surfaces. This study showed that the larger the pattern, the harder the textile-like surface becomes (Figure 1). The size of a repeating pattern also has a significant impact on the printing time of the pattern. The smaller the pattern, the longer the printing process will take. The flexi- bility of the surface can also be affected by the num- ber of layers and especially the number of connect- ing wires. The more connecting wires a structure contained, the harder the surface became (Figure 2 A−C), while the tensile strength of the structure in- creased. In this study, a good compromise between the flexibility, elasticity and tensile strength of the textile-like surface was identified with a compres- sion model consisting of 11 layers (Figure 2C) [4]. Figure 1: Illustration of various repeating patterns: A) polygon pattern, B) rectangle pattern, C) floral pattern, D) fabric- like curtain with polygon pattern, E) fabric-like curtain with rectangle pattern, F) curtain with large patterns [4] Geometric Structures in Textile Design Made with 3D Printing 309 An important aspect of this work was to ensure the comfort of use of the textile-like surfaces. These properties can be achieved with the flexible and elastic printing material LAY-FOMM 40. Since LAY-FOMM 40 is harmless and food-safe accord- ing to the manufacturer, four layers of LAY-FOMM 40 are printed on each model (Figure 3). Basically, this is a printed lining layer that is also incorporat- ed into conventional clothing. Special effects can be achieved by manually intervening in the Z-height of a layer during the printing process [4]. In collaboration with a PhD project at the University of Central Florida in Orlando, a glove with integrated sensors based on textile-like struc- tures was printed (Figure 4). Sewing patterns were developed for the glove that are also used in the textile industry to produce garments (Figure 4A). It was printed using a X400 3D printer and PLA and LAY-FOMM 40 materials. As Figures 4B and 4C show, the surface of the glove was partially printed with polygons [4]. Figure 2: Different flexibilities based on the number of layers: A) five layers (three layers of PLA, two layers of LAY-FOMM 40), B) seven layers (four layers of PLA, three layers of LAY-FOMM 40), C) 11 layers (six layers of PLA, fives layers of LAY-FOMM 40) [4] Figure 3: Printed lining: A) four layers of LAY-FOMM 40 on textile-like surface, B) and C) fusion of four layers[4] Figure 4: 3D printed glove: A) sewing pattern printed from two materials, B) surface design of the glove, C) flexible sewing pattern with inner lining, D) pattern parts sewn together to form a three-dimensional garment [4] Tekstilec, 2022, Vol. 65(4), 307–321 310 In the glove pattern, several layered structures were achieved using FDM technology [5]. Figure 5 shows a test structure used to investigate whether individ- ual strings can be applied to relatively open struc- tures without support structures [5]. The results of the FDM print in Figure 6 show that while this approach is mostly successful, the threads can sometimes break, even when a minimum diam- eter of 0.4 mm is maintained. Therefore, lace-like structures were created that also start with a par- tially open base layer but do not contain free-float- ing regions as the next approach to creating tex- tile-based 3D printed patterns [5]. Based on the well-known Plauen lace, lace patterns were designed, usually containing floral and circu- lar elements on a base layer connecting these parts. One such pattern is shown in Figure 7a. Since there are no free-floating areas, printing using the FDM process is not problematic if all connecting lines have a sufficiently large diameter (Figure 7b) [5]. In addition to soft PLA, which was used for most of the lace patterns to avoid potential mechanical problems with harder material that could cause base joints to break, an experimental polymer was used: Lay Tekkks, one of four different types of porous filament from the PORO-Lay line. Lay Tekkks is a hard filament manufactured by Kai Parthy of CC- Products (Cologne, Germany) that can be trans- ported to the nozzle without the transport prob- lems that too-soft filaments can cause in some FDM printers. However, after printing is complete, it can be placed in warm water for a period of minutes to hours, which causes the hard part of the material to dissolve. The resulting sample thus becomes in- creasingly softer the longer it is immersed in water (Figure 8) [5]. Figure 5: Test pattern for a layered structure consisting of three superimposed layers [5] Figure 7: Multi-layer lace pattern shown in ‘netfabb’ (a), and the resulting 3D print (b). Detail size ~ 4 cm × 7 cm [5] a) b) Figure 6: Results of the 3-layer structure printed using FDM (size 8 cm × 8 cm) [5] Geometric Structures in Textile Design Made with 3D Printing 311 The aim of this study was to print textile-like sur- faces with different geometric structures using 3D printing technologies based on thermoplastic ex- trusion. A fused deposition modelling (FDM) was used as the 3D production method. In this study, 6 different models were designed using 3 different ba- sic geometric structures. These are small size hole square, large size hole square, small size hole trian- gle, large size hole triangle, small size hole hexagon, large size hole hexagon. All of the modeled samples were printed in the same size. Only the hole sizes and shapes of the models were different. These 6 dif - ferent models were printed with ABS and TPU ma- terial. Three different tests were applied to total 72 samples. The effects of these basic geometric shapes on textile-like surfaces were investigated using mass, tensile and flexural strength measurements. In the study, it was also investigated which basic geometric shape is more useful and flexible in tex- tile-like materials; which basic geometric structure could be more durable and what could affect the test results; and which thermoplastic material and basic geometrical structure can exhibit properties like a textile-like fabric. 2 Materials and methods 2.1 Sample preparation 2.1.1 ABS and TPU ABS (also known as acrylonitrile-butadiene-sty- rene) has high hardness, good impact strength even at low temperatures, good insulating properties, good wear and tensile strength, high dimensional stability, and high surface gloss [6, 7]. Thermoplastic polyurethane (TPU) is a melt-pro- cessable thermoplastic elastomer with high du- rability and flexibility. TPU offers a wide range of physical and chemical property combinations for the most demanding applications, e.g., automotive, wire and cable, breathable films for leisure, sports and textile coatings, wearable non-yellowing films, etc. Its properties are between the characteristics of plastic and rubber. Thanks to its thermoplastic characteristic, it has several advantages that oth- er elastomers cannot offer, such as excellent ten- sile strength, high elongation at break and good load-bearing capacity [8, 9]. 2.1.2 Modelling of geometric structures In this study, textile-like surfaces were printed based on three different basic geometric shapes: square, triangle and hexagon. 2.1.3 Printing The printed models in this project were made us- ing a Zmorph FAB 3D printer (Zmorph, Poland) (Figure 9), which uses the fused deposition model- ling process. This high-quality semi-professional 3D printer processes thermoplastic filaments by melt- ing them in the extruder immediately before print- ing. The maximum operating temperature at the ex - truder tip is 260 °C, while the maximum extrusion volume is 40 mm/s. The maximum working volume of the printer is 235 mm ×250 mm ×165 mm. The printer uses Voxelizer printing software. A file in Voxelizer format is transferred to the printer via a a) b) Figure 8: Lace pattern from Lay Teks before (a) and after dissolving the hard material in warm water for three hours (b). The size of the pattern is 8 cm × 8 cm [5] Tekstilec, 2022, Vol. 65(4), 307–321 312 USB memory stick or Wi-Fi. FDM is a process based on the formation of a new layer on another layer by melting the fibrous thermoplastic material. The printing material used in this project was an ABS (acrylonitrile butadiene styrene) filament (AzureFilm, Slovenia), which is a lightweight, high-impact and high-creep polymer [10]. TPU (thermoplastic polyurethane) (AzureFilm, Slovenia) with high tensile strength was also used. This system is based on the principle of extruding molten plastic from a heated injector onto a heated moving bed [11]. To obtain the model after print- ing from the pressure bed, the temperature of the bed must be lowered to a minimum temperature of 30 °C degrees. The parameters used to print the models in this study on the Zmorph 3D printer are shown in Table 1 for ABS material and Table 2 for TPU material. Figure 9: Photo during printing Table 1: Printing parameters for printing with ABS material Settings Value Extruder settings Default print speed 24 mm/s Travel speed 90 mm/s Layer settings First layer speed 40% First layer height 0.42 mm Maximum adhesion ratio 2.5 Height minimum multiplier 0.4 Height maximum multiplier 0.75 Temperature Hotbed temperature 100 °C Extruder temperature 255 °C Fan speed 40% Other Filament diameter 1.75 mm Extrusion diameter m Table 2: Printing parameters for printing with TPU material Settings Value Extruder settings Default print speed 20 mm/s Travel speed 120 mm/s Layer settings First layer speed 100 % First layer height 0.25 mm Maximum adhesion ratio 2.25 Height minimum multiplier 0.3 Height maximum multiplier 0.85 Temperature Hotbed temperature 60 °C Extruder temperature 250 °C Fan speed 30 % Other Filament diameter 1.75 mm Extrusion diameter m Geometric Structures in Textile Design Made with 3D Printing 313 2.1.4 Software The models created in this study were modelled using the 3D Blender program. The modelled pat - terns are saved as *.stl files and transferred to the Voxelizer software for 3D printing. A *.stl file is easy to use for printing with this program. A G-code file is also created to transfer the models to the print- er with the Voxelizer program for special head and print movements. 2.1.5 Models printed with ABS and TPU To ensure the comparability of the test results, the sizes of the models were designed in basic geomet- ric shapes that were most similar to each other. The models were designed on the basis of the dimen- sions 50 mm × 150 mm × 2 mm, so that they could be easily tested in a tensile and bending testing ma- chine. The width of the lines forming the geometric shapes was 0.8 mm. 2.2 Samples Sample 1 (a) Small size hole square The width of all lines forming the figures in the pat - terns was 0.8 mm. The dimensions of this pattern, created in the form of small squares of horizontal and vertical lines, were 49.4 mm × 151.42 mm × 2 mm. The inner dimension of each square was 4.5 mm × 4.5 mm. A real, printed ‘small size hole square’ example is shown in Figure 10, while the 3D model drawing made using Blender software is shown in Figure 11. (b) Large size hole square The size of this model was 49.4 mm × 153.9 mm × 2 mm. However, in this example, the dimensions of the square holes were larger than in the previous model. In this model, the x and y length of the inner square was 8.8 mm × 8.8 mm. A real ‘large size hole square’ exam- ple is shown in Figure 12, while a 3D model drawing made using Blender software is shown in Figure 13. Figure 10: Structures printed with ABS small size hole square Figure 11: Screenshot of the 3D modelled square structure with small holes in Blender software Figure 12: Structure printed with ABS large size hole square Figure 13: Screenshot of the 3D modelled large size hole square structure in Blender software. Tekstilec, 2022, Vol. 65(4), 307–321 314 Sample 2 (a) Small size hole triangle In this model, small triangles with only one di- agonal were formed on the small squares of the first example (Figure 14). The dimensions of this model were 49.4 mm × 151.2 mm × 2 mm. The 3D model prepared using Blender software is shown at Figure 15. (b) Large size hole triangle The size of this model was 49.4 mm × 153.9 mm × 2 mm. This model is similar to the small size hole tri- angle model. The model size was made larger and is shown in Figure 16, while 3D the drawing model using Blender software is shown in Figure 17, The difference in size and triangular area was obtained by adding a diagonal to each square. Figure 14: Structure printed with ABS small size hole triangle Figure 15: Screenshot of the 3D modelled small size hole triangle structure in Blender software Figure 16: Structure printed with ABS large size hole triangle Figure 17: Screenshot of the 3D modelled large size hole triangle structure in Blender CAD software Sample 3 (a) Small size hole hexagon This model had a large diagonal dimension of 6.11 mm. The dimensions of this model were 51.8 mm × 147.7 mm × 2 mm. The real structure is shown in Figure 18, while the 3D model prepared using Blender software is shown in Figure 19. (b) Large size hole hexagon This model was designed with large hexagonal shapes with a large diagonal length of 12.22 mm. The di- mensions of this model were 54.7 mm × 150.7 mm × 2 mm. This is similar to the small size hole hexagon model, but with larger sized holes. The real structure is shown in Figure 20, while the 3D model prepared using Blender software is shown in Figure 21. Geometric Structures in Textile Design Made with 3D Printing 315 2.3 Methods A mass of samples that were designed in similar di- mensions was tested to understand effects of print- ed ABS and TPU materials in six different ways. The mass of the samples was measured with precision balance Mettler Toledo AE 200. Mechanical properties have been tested on a dy- namometer Instron 5567 (Instron, GB) (Figure 22a). The distance between the clamps was 5 cm. Tensile test applied to the samples with six different tex- tile-like surfaces with three different basic geometric structures produced using ABS and TPU materials to investigate which basic geometric surface and which material would be more suitable for textile-like mate- rials in the fashion industry. This test was performed to measure the wearability of a fabric or surface. The aim of the flexural strength (Figure 22b) test was to examine the drape on the human body when a textile-like surface is worn. In this test, six different samples were printed with ABS and TPU materials using three different basic geometric pat- terns, followed by the relevant research. While applying these tests, the dimensions of spec- imens of 150 mm × 50 mm × 2 mm were accept- ed as adequate for testing on the dynamometer. Therefore, all samples were designed to be closest to these dimensions. Laboratory values of ambient temperature was 23 °C ± 2 °C and relative humidity of 45% ± 10%. Measurements were made according to the ISO 13934-1 test standard. 3 Results and discussion In this study, mass, tensile stress and flexural strength of samples with different geometric sur- faces produced in the same dimensions with ABS and TPU materials was analyzed, compared and interpreted. Figure 18: Structure printed with ABS small size hole hexagonal Figure 19: Screenshot of the 3D modelled small size hole hexagonal structure in Blender software Figure 20: Structure printed with ABS large size hole hexagonal Figure 21: Screenshot of the 3D modelled large size hole hexagonal structure in Blender software Tekstilec, 2022, Vol. 65(4), 307–321 316 72 printed textile-like surfaces were obtained from 12 different models for tensile strength testing. The obtained surfaces were compared in two different ways with different geometric surfaces and different materials. 3.1 Production times of models and mass measurement results For all 3D-printed geometric structures presented, the manufacturing time and mass of the structures were first analyzed. Table 3 shows that the printing times of the de- signed models vary depending on the model and material. This is because ABS and TPU materials have different printing parameters. For this reason, an exact comparison of the printing times is not possible. Table 4 and Figure 23 clearly show that all models printed with TPU are heavier than those printed with ABS. Although the models with TPU and ABS materials are all made in the same dimensions, the reason why the models printed with TPU are heav- ier is that TPU and ABS materials have different specific densities. TPU material has a higher spe- a) b) Figure 22: Photos of a) tensile test and b) flexural test Table 3: Production times of models Geometric structure Marked as Production time with ABS (min) Production time with TPU (min) Small size hole square SS 173 141 Large size hole square LS 77 87 Small size hole triangle ST 111 306 Large size hole triangle LT 163 139 Small size hole hexagon SH 164 126 Large size hole hexagon LH 99 129 Figure 23: Average mass of models 5 3,1 7,55 4,85 4,35 3,4 5,3 3,45 8,15 5,05 4,8 5,2 0 1 2 3 4 5 6 7 8 9 SS LS ST LT SH LH Average weights of models (g) Printed models ABS TPU Geometric Structures in Textile Design Made with 3D Printing 317 cific gravity than ABS material. The density of TPU material is 1.15−1.17 g/cm 3 , while the density of ABS material is 1.03−1.10 g/cm 3 [12, 13]. It is clearly seen that the large size hole square is the lightest and the small size hole triangle is the heavi- est of samples produced using both materials. Mass determination results provide important in- formation on many performance properties, such as the strength, density, and softness of the mate- rial. At the same time, mass determination tests provide information about the density of textile surfaces [14]. 3.2 Tensile strength test results Maximum force applied to the samples, percentage of tensile strain (displacement) at maximum force and amount of displacement at maximum force are given in the Table 5 and 6, and Figures 24−26. The tensile stress test results of six different sam - ples printed with TPU material and created based on three different basic geometric patterns clearly shows that under maximum strength, hexagonal structure specimens have higher tensile stress per- formance than specimens produced in other struc- tures. This is the same for hexagonal structures produced using both TPU and ABS materials. Since TPU material is more flexible than ABS material, the displacement percentages of the samples pro- duced using TPU material under maximum force are quite high compared to ABS material. In the samples produced using TPU material, the highest displacement percentage was 317.53% under maxi- mum force, while the highest value was obtained for ABS material, at 6.212%. The displacement of the specimens at maximum force, tensile strain (displacement) at maximum force and maximum force at tensile stress were measured in this test. The speed of the measuring device was 025 mm/s. Tensile strength results vary according to materials and sample structures. Since the material and ba- sic geometric surface structure were investigated in this study, the samples were produced in the same dimensions and on the same model surfaces. The test results clearly show that the tensile stress (dis- placement) of TPU material at maximum strength demonstrated much higher values than ABS material. Moreover, Figure 26 shows that the maximum force applied to ABS material is much higher than the maximum force applied to TPU material, since ABS material is much less flexible than TPU material. Comparison of tensile strength results of samples with basic geometric structures produced using ABS material: LH > SH > ST > SS > LS > LT (Table 5). Comparison of tensile strength results of samples with basic geometric structures produced using TPU material: LH > ST > SH > SS > LT > LS (Table 6). It is clear that the hexagonal specimens have the highest tensile strength at both materials. Table 4: Average weight of models Geometric structure Average weight and STDV of ABS models (g) Average weight and STDV of TPU models (g) SS 5.0 ± 0.21 5.3 ± 0.20 LS 3.1 ± 0.25 3.45 ± 0.21 ST 7.55 ± 0.28 8.15 ± 0.17 LT 4.85 ± 0.23 5.05 ± 0.20 SH 4.35 ± 0.27 4.8 ± 0.04 LH 3.4 ± 0.19 5.2 ± 0.26 Figure 24: Displacement at maximum force 262,64 234,09 317,45 241,21 304,26 317,53 2,284 2,083 2,801 2,62 6,148 6,212 0 50 100 150 200 250 300 350 0 1 2 3 4 5 6 7 8 9 10 SS LS ST LT SH LH Displacement at maximum force (mm) Displacement at maximum force (mm) Printed models TPU ABS Tekstilec, 2022, Vol. 65(4), 307–321 318 Table 6: Tensile strain test results applied to models produced using TPU TPU models Maximum force (N) Tensile strain (displacement) at maximum force (%) Displacement at maximum force (mm) SS 382.696 ± 10.966 525.280 ± 10.448 262.640 ± 5.224 LS 231.116 ± 37.769 468.180 ± 76.292 234.090 ± 38.146 ST 556.948 ± 54.403 601.900 ± 69.924 300.450 ± 34.962 LT 273.418 ± 34.962 482.420 ± 4.052 241.210 ± 2.026 SH 331.192 ± 7.305 608.520 ± 25.904 304.260 ± 12.952 LH 355.691 ± 25.423 635.060 ± 16.080 317.530 ± 8.040 Table 5: Tensile strain test results applied to models produced using ABS ABS models Maximum force (N) Tensile strain (displacement) at maximum force (%) Displacement at maximum force (mm) SS 674.858 ± 35.448 4.569 ± 0.704 2.284 ± 0.352 LS 435.340 ± 35.922 4.165 ± 0.407 2.083 ± 0.204 ST 766.462 ± 17.023 5.601 ± 0.402 2.801 ± 0.201 LT 437.367 ± 15.954 4.125 ± 0.448 2.062 ± 0.224 SH 310.827 ± 6.015 12.296 ± 1.824 6.148 ± 0.912 LH 194.244 ± 12.765 12.424 ± 1.872 6.212 ± 0.936 Figure 25: Tensile strain (displacement) at maximum force Figure 26: Maximum force at tensile stress test 525,28 468,18 601,9 482,42 608,52 635,06 4,569 4,165 5,601 4,925 12,296 12,424 0 5 10 15 20 0 100 200 300 400 500 600 700 SS LS ST LT SH LH Tensile strain (displacement) at maximum force (%) Tensile strain (displacement) at maximum force (%) Printed models TPU ABS 674,858 435,34 766,462 437,367 310,827 194,244 382,696 231,116 556,948 273,418 331,192 355,691 0 100 200 300 400 500 600 700 800 900 SS LS ST LT SH LH Maximum force at tensilestresstest (N) Printed models ABS TPU Textile-like surfaces produced using different ge- ometric shapes According to Tables 5 and 6, the smaller the repeat- ing pattern units on printed textile-like surfaces, the higher the tensile strength and vice versa: the larger the pattern, the harder the textile-like surface pro- duced. If the patterns were printed in small repeat units, the mass of the models increased (Table 4). As a result of the tests conducted in this study, the order of tensile strength of different geometric models made with both ABS and TPU materials is as follows: SH > ST > SS, LH > LT>LS. Tables 5 and 6 clearly show that textile-like surfaces printed with a hexagonal pattern have a much high- er tensile strength. Geometric Structures in Textile Design Made with 3D Printing 319 Hexagons are ubiquitous in nature, from the larg- est planets to microscopic compounds. The reason for this prevalence, however, is not because hexa- gons have a special edge, but because the simplest shape that can be created in nature is the circle, and flexible circles spontaneously transform into hex- agons under pressure. From honeycombs to giant clouds on planets, from geological formations to snowflakes, every hexagon can be illuminated using purely scientific explanations. For millennia, sci- entists and philosophers thought the hexagon was the shape that would most efficiently fill a plane. However, this idea was discussed earlier. Moreover, at the end of the 19 th century, the Belgian physicist Joseph Plateau was able to calculate that the forces on 120-degree foils are all in equilibrium and that this geometry is the most mechanically stable ar- rangement [15]. 3.3 Flexural strength test results Flexural strength test results are given in Tables 7 and 8, and on Figures 27−29. TPU material has a higher flexibility than ABS ma- terial. For this reason, Figure 28 clearly shows that TPU material requires much less force to bend than ABS material. When evaluating the flexural strength of models made using the two different materials, no direct correlation can be established between the flexural strengths of different shapes. 19,772 27,042 26,138 28,154 28,358 25,124 27,042 29,25 30 27,656 24,3822 25,536 0 5 10 15 20 25 30 35 SS LS ST LT SH LH Compressive displacement at maximum force (mm) Printed models ABS TPU Figure 27: Compressive displacement at maximum force Table 7: Flexural strength test results applied to models produced using ABS material Models of ABS Maximum force (N) Compressive displacement at maximum force (mm) Force at break (Standard) (N) SS 9.112 ± 0.19 24.208 ± 2.24 8.364 ± 0.28 LS 5.341 ± 0.17 27.042 ± 3.96 5.140 ± 0.31 ST 12.743 ± 0.53 26.138 ± 2.83 11.933 ± 0.68 LT 8.386 ± 0.42 28.154 ± 0.72 7.438 ± 0.37 SH 5.744 ± 0.15 28.358 ± 3.84 5.297 ± 0.16 LH 4.786 ± 0.10 25.124 ± 1.09 4.537 ± 0.23 Table 8: Flexural strength test results applied to models produced using TPU material Models of TPU Maximum force (N) Compressive displacement at Maximum Force (mm) Force at break (Standard) (N) SS 0.185 ± 0.01 27.042 ± 3.07 0.159 ± 0.01 LS 0.135 ± 0.01 29.250 ± 1.47 0.119 ± 0.00 ST 0.274 ± 0.01 30.000 ± 3.86 0.272 ± 0.03 LT 0.141 ± 0.00 27.656 ± 2.46 0.125 ± 0.01 SH 0.109 ± 0.01 24.822 ± 1.86 0.100 ± 0.01 LH 0.133 ± 0.01 25.536 ± 2.03 0.118 ± 2.03 Tekstilec, 2022, Vol. 65(4), 307–321 320 4 Conclusion 3D printers are appearing in all aspects of our lives, including the textile and fashion industries. 3D printers, which have the potential to facilitate per- sonalized production, are gaining momentum as the technology evolves. Manufacturing with 3D printers is an alternative to traditional manufactur- ing methods. Defined as the manufacturing method of the 21st century, 3D printers allow the body to be wrapped like fabric, weaving together different shapes in dif- ferent sizes. Textile designers can work with this technology as an alternative working method in- stead of traditional production methods. For this article, six different patterns were designed using three different basic geometric shapes. A total of 72 patterns were made using six different models with two different materials. These patterns were sub- jected to mass, tensile strength and flexural strength tests. From the results of the tensile strength tests, it was determined that different geometric shapes affect tensile strength. Hexagonal structures have high val- ues, while square structures have lower values. The hexagonal structures showed the highest resistance to the force applied to them when the tensile stress test was performed. This is due to the fact that the hexagons, because of their angle of 120°, were able to equally resist the force applied by all arms. Different models have an impact on the comfort of the prod- ucts used in the textile-like material in fashion indus- tries. The result in this case was that the hexagonal structures are more comfortable than others. The results show that the tensile strength of TPU material is much higher than that of ABS material. In addition, textile-like surfaces made using TPU material have more flexibility and drape than tex- tile-like surfaces made using ABS material. Textile-like surfaces printed using TPU material have a softer feel than those made using ABS mate- rial. Therefore, textile-like surfaces made using TPU material are more suitable in terms of wearability. ABS material’s hard handling, lower flexibility, and lack of drapability limit its use in the material in fashion industries. However, ABS material can be used in the manu- facture of accessories as an alternative material for the textile material and fashion industries, such as buckles, crown buttons, zippers, walking sticks, umbrella bags, fans, watch straps, etc. The order of bending strength of the models made using ABS material according to their values under compression displacement at maximum force was as follows: shapes with small holes and shapes with large holes; triangle with small holes > square with small holes > hexagon with small holes, square with large holes > triangle with large holes > hexagon with large holes. The order of bending strength of the models made using TPU material according to their values under compression displacement at maximum force was as follows: shapes with small holes and shapes with large holes; triangle with small holes > square with small holes > hexagon with small holes, square with large holes > triangle with large holes > hexagon with large holes. Figure 28: Maximum force at flexural strength test Figure 29: Force at break (standard) 8,778 5,341 12,743 8,386 5,744 4,786 0,185 0,135 0,274 0,141 0,109 0,133 0 0,2 0,4 0,6 0,8 1 0 2 4 6 8 10 12 14 SS LS ST LT SH LH Maximum force at flexural strength test (N) Printed models ABS TPU 8,364 5,14 11,933 7,438 4,974 4,537 0,159 0,119 0,272 0,125 0,1 0,118 0 2 4 6 8 10 12 14 SS LS ST LT SH LH Forc e at break (standard) (N) Printed models ABS TPU Geometric Structures in Textile Design Made with 3D Printing 321 No conclusion could be drawn from the results of the applied flexural strength tests, since the impact of shapes on flexural strength was not stable. However, comparing two different materials, the difference between the maximum forces can be clearly seen. According to the results of the bending strength test, we can conclude that the properties of the materials impact these test results rather than the moulds. 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