Evaluation of the Mechanical Properties of Porous ...

Research ArticleEvaluation of theMechanical Properties of Porous ThermoplasticPolyurethane Obtained by 3D Printing for Protective Gear

Hyojeong Lee1 Ran-i Eom2 and Yejin Lee 3

1Department of Fashion Design amp Merchandising Kongju National University Gongju-si Chungcheongnam-do 32588Republic of Korea2Research Institute of Human Ecology Chungnam National University Daejeon 34134 Republic of Korea3Department of Clothing amp Textiles Chungnam National University Daejeon 34134 Republic of Korea

Correspondence should be addressed to Yejin Lee yejincnuackr

Received 30 May 2019 Revised 3 September 2019 Accepted 4 October 2019 Published 7 December 2019

Academic Editor MariaGabriella Santonicola

Copyright copy 2019 Hyojeong Lee et alis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

ree-dimensional (3D) printing is an efficient and sustainable technology useful in various manufacturing fields e aim of thisstudy was to investigate the applicability of thermoplastic polyurethane (TPU) as a 3D printingmaterial and the conditions relatedto the use of TPU as personal protective equipmente tensile strength shock absorption and compressibility were evaluated fordifferent infill and thickness conditions An increase in the infill rate led to an increase in the tensile strength regardless of thesample thickness Similarly the compression energy increased as the infill increased Both the shock absorption and compressionproperties increased as the thickness decreased under identical infill conditions e actual shock absorption test data werecompared to the results of structural analyses which confirmed the potential for predicting impact deformation through theanalysis of the tensile characteristics and the basic properties of a 3D printed material

1 Introduction

e advent of additive manufacturing (AM) has changed theface of product fabrication by supporting in-sourcing andpromoting personal manufacturing businesses [1] is hastransformed not only the manufacturing industry but alsothe medical and distribution industries Designing a solidproduct used to be a particularly time-consuming processwith many lengthy mock-ups molding and injection pro-cesses before a serviceable product could be made HoweverAM allows complete parts to be manufactured from three-dimensional (3D) models e first stage in AM is typicallythe fabrication of the basic geometric shape which is fol-lowed by a consolidation stage that enhances the funda-mental properties of the intended material [2] In addition3D printing has acted as an alternative process by which toreduce the time and cost needed to go through this process[3] is technology is actively applied in a variety of in-dustries (eg space science medical construction andmechanical industries) for products such as art toys tools

and household items Recent studies on RepRap devices haveinvestigated the mechanical properties of printed parts forengineering applications [4] In the fashion industry 3Dprinting has been used to design everything from accessoriesto clothing [5] however only a few studies have analyzed itsapplicability in depth New molding materials are contin-uously being developed but can largely be categorized aspolyamide polylactic acid (PLA) thermoplastic poly-urethane (TPU) metal ceramic wood and compositematerials eir initial shapes can be categorized as powdersolid filament or liquid However 3D printed productsoften have different physical properties to the originalpolymer hence when particular functions are required fromthe product a preceding examination is necessary to createthe desired product through 3D printing [6] Furthermoreas the physical and mechanical properties of the finalproduct differ depending on the printing conditions re-gardless of the initial material or shape verification is re-quired [7 8] e analysis of energy absorbing profiles forgrading the density through the structure in a model of a

HindawiAdvances in Materials Science and EngineeringVolume 2019 Article ID 5838361 10 pageshttpsdoiorg10115520195838361

lattice structure or a hexagonal array demonstrated that thewider range of compression energies exhibited a higherefficiency and a greater magnitude of efficiency peaks wasobserved at the higher density layers [9ndash11] Howeverstudies on the recent development of the novel materials andapplications in 3D printing are limited [12ndash14] Manystudies have dealt with density as a variable in the designerrsquosmodeling process However the infill conditions also need tobe examined during 3D printing because the 3D printinguser can adjust the density by varying the porosity with theinfill condition TPU is a common 3D printing material Itslinear polymer chains make it a straight line with flexibleand rigid chains connected through covalent bondingerefore it displays high flexibility elasticity and shockresistance like rubber as well as thermoplasticity Fur-thermore it has excellent abrasion and tear resistance as wellas high hardness [15ndash17] In addition TPU is easier todeform than PLA owing to its high elasticity [18] Otherresearchers have applied TPU to golf or other functionalshoes [19] as well as to baggage or flooring material becauseof its properties [20] Attempts to join textile fabrics and 3Dpolymer filaments have revealed that TPU exhibits the bestadhesion to fabrics [21] In this study we combined the rapidadvance of 3D printing and TPU and confirmed their ap-plicability for the production of hard shell personal pro-tective equipment

Currently sports or industrial protective equipmentthat protect the hip joints knees elbows and shin of thehuman body from shock damage mostly comprise hardshells with a soft interior ese are usually reinforcedplastic and polyurethane foam respectively e reinforcedplastic used in hard shells is strong light and durable butnot flexible thus it does not respond well to bodymovement is discomfort during movement is exacer-bated when the product is ill-fitting erefore substitutingthe hard shell with TPU which is flexible and can protectfrom shock is expected to create greater adherence andcomfort during movement It will also contribute to futurepart customization because TPU is easily combined withtechnologies such as 3D scanners printers and modelingamong others

e ultimate purpose of this study was to investigateTPUrsquos applicability for personal protective equipment andthe optimal conditions to make it using 3D printing tech-nology In addition TPU can be easily obtained in themarket and thus was chosen for this study to enable notonly an expert but anyone to create prototypes or customizepersonal protective equipment through 3D printing etensile strength shock absorption and compressibilityproperties were evaluated in relation to the conditions ofprinting (infillmdashthe filling of the inside during prin-tingmdashand specimen thickness) In addition we analyzed thepredictability of shock absorption (an important perfor-mance factor in personal protective equipment) with theanalysis tool SolidWorks Energy displacement and de-formation were calculated using the elastic modulus Pois-sonrsquos ratio and the shear factor of the 3D printedmaterial topropose an efficient model that can confirm the potential of anew material with regard to productivity quality and

stability without further experimentation In addition wetested prototype models on the human body (knee andcrotch protectors) with different thickness and infill con-ditions to confirm their applicability to actual use

2 Materials and Methods

21 Samples and Output Conditions TPU (HyVISIONSouth Korea) samples were 3D printed under differentconditions to form test pieces for tensile impact andcompressibility tests based on the appropriate standards(ISO 527-2 [22] ISO 6603-2 [23] and ISO 2039-2 [24]respectively) TPU filament type used for filling detailedspecifications are as follows melt flow index 14ndash28 g10min tensile yield strength 21ndash36MPa elongation atbreak 26ndash60 flexural strength 60ndash97MPa flexuralmodulus 18ndash30 GPa impact strength 120 kJm2 andfilament diameter 175mm (plusmn005mm) Specimens weremodeled using Geomagic Design X software (3D SystemsUSA) Each bit of data had sliced G-codes appropriate for3D printing using Cubicreator 25 R3 software (HyVI-SION South Korea) and the specimens were 3D printedusing a Cubicon Style desktop 3D printer (HyVISIONSouth Korea) at a printing speed of 10mms floor tem-perature of 65degC chamber temperature of 50degC and dis-charge rod temperature of 230degC is printer is one of themost commonly used low-cost techniques in the field of3D printing e sample thickness and infill printingcondition were varied (5 or 10mm thickness 10 50 or100 infill) providing six types of samples Four copies ofeach sample were made so that four trials could be per-formed for each evaluation category to derive the averageand standard deviation Detailed conditions of 3D printingare shown in Table 1 e symbol of the sample was de-termined based on the thickness and infill condition andthe final name was determined based on the sample weightmeasurement value which is shown in Table 2 e ma-terial consumption of the sample was 4524 g for 10T1002769 g for 10T50 1364 g for 10T10 2265 for 5T1001580 g for 5T50 and 1032 g for 5T10 As a result ofverifying the morphological properties of the output ofTPU printing in the previous study [25] no particles werefound in the smooth surface when 100 TPU was sup-plied and the release kinetic was maintained at higherpurity (39 plusmn 09) in the X-ray tomography image Basedon the result of the previous study this study also premisedthat porosity would not occur during the printing processis assumption was addressed by utilizing the SEMimages presented in Table 1 for examination and only thepercentage indicated by the weight measurement wasconsidered On the contrary before printing the functionof leveling the bed was performed by auto leveling and thesample was placed in a lower position of the Z-axis for thebottom surface to be horizontal is minimized the effectof load during the output In addition when outputtingprotective equipment larger than the sample in this studyplacing the wide surface of the modeling sample hori-zontally can provide a more stable 3D printing and is lesslikely to fail

2 Advances in Materials Science and Engineering

22 Property Analysis

221 Tensile Testing e tensile properties of the TPUsamples were measured according to ISO 527-2 [22]e testpiece had 75mm gauge marks and the test was performed ata tensile velocity of 50mmmin

222 Impact Testing Impact tests were carried out to an-alyze the shock absorption properties of the TPU specimensfor application as personal protective equipment e RollerSports Protective Equipment [26] testing method from theKorea Products Safety Association was followed which is adrop test commonly used in industry to determine the abilityof a material to cushion impacts [27] A shock striker with127mm diameter and 5 kg mass was dropped from a heightof 10 cm applying a force of 50N e maximum impactforce and peak energy were measured e shock absorptionresults were statistically analyzed with one-way ANOVAusing SPSS 240 (IBM soft USA) e posttest performedwas the Duncan test

223 Compression Testing With reference to ISO 604 [28]for plastic compression testing the compressibility wasmeasured at a compressive velocity of 1mmin using a30000N rod cell and a 24000N proof load using a universaltester (WITHLAB WL2100 South Korea)

Table 3 shows the modeled specimen shapes for eachexperiment e temperature and the relative humidity forall experiments were 22plusmn 1degC and (400plusmn 3) respectively

emodel produced for the experiment in this study wasdesigned in compliance with the standard specification forproperty analysis However the thickness was generally50sim100mm which is the thickness of the protective hardshell and the shock absorbing foam

23 Structural Analysis Using the SolidWorks 2016 pro-gram (Dassault Systemes South Korea) a structural analysiswas performed for 3D models of the square TPU samplesused for shock absorption and compression tests For theanalysis the materialrsquos properties were provided by theSolidWorks program TPU had the following propertieselastic modulus 2410Nmm2 Poissonrsquos ratio 03897 andshear factor 8622Nmm2 A 127mm diameter circle wasdrawn at the center of the surface of each model to set thearea of the vertical load to mimic the actual tests e loadon each sample was set to 50N as in the shock absorptiontests After the analysis conditions were set a mesh of themodeling data was created and the simulation was executedFigure 1 shows the modeling dimensions as well as theanalysis conditions and procedure e peak force dis-placement and deformation were then compared and an-alyzed to investigate the possibility of predicting shockabsorption results by simulation To compare the simulationand actual experimental results the shape of the center of the10T samples deformed by the shock striker after the impacttests was observed as depicted in Figure 2 using the SEMimages and a three-dimensional scan coordinate measuringmachine (CONTURA G2 ZEISS Oberkochen Germany)

3 Results and Discussion

31 Tensile Properties It is often necessary to design pro-tective equipment that will provide ample protection againsthazards such as impact penetration and compression estress-strain graphs generated from tensile testing of thesamples are given in Figure 3 Unlike regular fabrics theTPU samples did not fracture because of their rubber-liketraits In general fabrics are woven from fibers whosestrength of a fiber is defined as the force or tensile strength inthe longitudinal direction divided by the fiber thicknessUsing the gd unit silk nylon and polyester fibers were

Table 1 Detailed conditions of 3D printing

Fill pattern Number of layersOverlap with outer wall

()Height of layer

(mm)10 (14x) 50 (24x) 100 (24x) 5T 10T Top(ea)

Bottom(ea)

25 50 6 3 15 02

Table 2 Variables for experimental samples and properties tested

ickness InfillCondition 5mm 10mm 10 50 100Naming 5T 10T 10 50 100

darrSample names (p porosity ) 5T10 (p 45) 5T50 (p 70) 5T100 (p 100)

10T10 (p 30) 10T50 (p 61) 10T100 (p 100)Property tested Tensile strength shock absorption and compressibility tests

Advances in Materials Science and Engineering 3

found to have a tenacity of gt06 gd while cotton rayon flaxand acetate fibers had tenacities of 02 gd or less [29] As theTPU fabric is printed directly (ie it is not made of wovenfibers) the tensile strength is measured in MPa and the

property is different from general fibers An increase in theTPU infill rate led to an increase in stress regardless of thesample thickness is makes the infill ratio an importantfactor for determining the tensile strength

Load area

5mm or 10mm

60mm 60mm

127mm

10 50 or 100

(a)

Load area

(b) (c)

Figure 1 Location and dimensions of load area for the structural analysis (a) Modeling (b) Load value input (c) Mesh creation

Materials

Sensor

CONTURA G2

Center line measurementrepeat 4 times

Figure 2 3D coordinate scan method for results after impact testing

Table 3 3D modeling specification

Test items Tensile property Shock absorption Compressibility

Modeling specification

170mm

10mm

80mm

20mm

24mm

60mm

60mm

60mm

60mm

Modeling


When viewing the initial modulus (ie the slope of thestress-strain curve close to the origin) there was no dif-ference between the two thicknesses when the infill was100 but a discrepancy was observed as the percentage ofinfill decreased with the thinner samples having a lowerinitial modulus In other words the thicker samplesstretched faster under a lower tensile stress at an infill of10 or 50 Various plastic materials have tensilestrengths ranging from 155 to 150MPa when measuredusing the ASTM D638 test method [30] In addition theproperties of plastics can be altered through processing andmixing For example the stress to failure of pure PLA is5433MPa [31] but when TPU is added the elongation rateincreases while the stress to failure decreases to approx-imately 20ndash24MPa Tymrak et al [32] found that theaverage tensile strengths for ABS and PLA were 285 and566MPa respectively with average elastic moduli of 1807and 3368MPa respectively e addition of TPU which isa rubbery material increased flexibility but decreasedhardness e current results also show that with 100infill the stress on the TPU sample was approximately10MPa when stretched to 200mm regardless of thethickness us its tensile strength was much lower thanthat of other plastic materials

32 Shock Absorption Properties e shock absorption ca-pabilities of the TPU samples were evaluated in relation tothe thickness and infill conditions with the results depictedin Figure 4 Table 4 shows the peak force (N) and totalabsorbed energy (J) on impact e peak force value in-creased as the infill ratio increased for samples of the samethickness At 100 infill the peak force increased withthickness (plt 0001) with the 5 and 10mm samples (100infill) having peak forces of 9381 and 13253N respecti-velymdashan increase of 380N In contrast the peak force wasnot heavily affected by the thickness when the infill ratio was10 or 50

e total energy tended to decrease with increasing infill(plt 0001) 10T10 and 5T10 samples with low p showedthe highest energy absorption but all the samples absorbedmost of the 5 J initial load with no fractures erefore thisindicates that their cushioning abilities were similarHowever among them the 100 infill samples can beinterpreted as having better resistance to impact force owingto their high peak force is supports the polynomialfunction proposed in Verstraetersquos study [25] wherein theinternal lattice structure of a printed sample is compressed atthe same strain rate however high porosity is likely to causethe material deformation

Fprop 1 minus emptyg1113872 11138733

emptyg 1 minusρρs

(1)

where ρ and ρs are densitiesAs shown by equation (1) the peak force decreases with

increasing porosity and the energy absorption is inverselycorrelated with p e materials used for personalequipment to protect the body from impact are mainlyrubber aluminum steel fiber or plastic [33] Among thesematerials plastics and foams are frequently used for pro-tective equipment in our daily lives but rarely as personal

0 5 15 20 2510

1400

1200

1000

800

600

400

200

0

Forc

e (N

)

Time (ms)

5T105T505T100

10T1010T5010T100

Figure 4 5T10 5T50 5T100 10T10 10T50 and 10T100 shockabsorption in relation to the printing conditions

Table 4 Peak force and total energy of absorption

Sample Peak force (N) Total energy (J)Mean (SD) Mean (SD)

5T10 6909 (609) 58 (007)5T50 8328 (703) 45 (004)5T100 9381 (703) 40 (006)10T10 6269 (580) 57 (001)10T50 8948 (132) 51 (004)10T100 13253 (845) 45 (004)

10

8

6

4

2

0

Tens

ile st

reng

th (M

Pa)

0 50 100 150 200Strain (mm)

5T105T505T100

10T1010T5010T100

Figure 3 5T10 5T50 5T100 10T10 10T50 and 10T100 stress-strain curves


protective equipment in industrial uses [20] In previousstudies [4 6] the absorption rate of impact energy wasevaluated in relation to the thickness of the plastic it wasconcluded that thickness is a highly influential factor Al-though greater thickness meant a lower impact absorptionrate considering the increase in weight the optimal con-ditions for the human body still had to be investigated Inother words even if the impact absorption rate is maximal ifit requires more weight to be applied to the body discomfortand thermal stress may occur leading to ineffective pro-tection However in this study it was found that 3D printedTPU equipment that can protect against peak forces of lessthan 800N could be thin (light) and still have a high shockabsorption rate However if more than 1000N of peak forcehad to be absorbed the thickness would be a highly sig-nificant factor

33 Compressibility Properties Figure 5 shows the results ofcompressive testing on samples with different thicknessesfor each of the infill conditions e compressive strengthshowed large changes according to the infill ratio similar tothe tensile and shock absorption properties Relative analysisof the energy required to compress each sample to a certainload showed that the compression energies of both the 5 and10mm thick samples increased as the infill ratio increasede compression energy also increased as the thicknessdecreased under identical infill conditions Clear inflectionpoints were observed in the compression energy-straingraphs for samples with 10 and 50 infill but not for thosewith 100 infill regardless of the thickness For the sampleswith 10 infill the compression energy quickly increased forthe first 10mmof strain with an inflection point observed atapproximately 10mm On the contrary the samples with50 infill initially compressed linearly and displayed aninflection point at approximately 15mm strain Howeverthe samples with 100 infill compressed almost linearlythroughout the whole test

Despite these differences all the samples were capable ofretaining their shape for a certain amount of time after themaximum compressive stress was reached rather thanshowing a sudden decrease in strength or fracturingMoreover the gradual increase of pressure near the de-formation point upon initial compression demonstrates thatthe material provided soft cushioning is is likely to berelated to TPUrsquos characteristic flexibility For equipment thatrequires better protection from compression the infillcondition should be set to 100 Furthermore as changingthe thickness does not considerably change the compressiveproperties using thinner equipment may be beneficial whenconsidering weight With comprehensive assessment of theshock absorption results it is necessary to find the optimalprocessing conditions to bestow a particular piece of pro-tective equipment with the required properties

34 Structural Analysis For the structural analysis thematerialrsquos properties were provided by the SolidWorksprogram and the tensile strength was input as the averagetensile strength of each specimen from the experimental

analyses e elastic modulus was obtained from equation(2) based on the measured tensile strengths [34] (5T1001935Nm2 5T50 02819Nm2 5T100 04656 Nm210T10 01470 Nm2 10T50 02214 Nm2 and 10T10004658 Nm2) where E is Youngrsquos modulus (Pa) σ is theuniaxial stress or uniaxial force per unit surface (Pa) andε is the strain or proportional deformation In prac-tice Youngrsquos modulus is given in megapascals (MPa orNmm2)

E σε (2)

Table 5 shows the structural analysis of each modelHere the energy is calculated from the force (N) and dis-placement (m) by the following equation where the forcewas calculated bymultiplying pressure (Pa) and area of circlefor vertical load (m2)

energy of absorption (J) pressure (Pa) times unit area m21113872 11138731113960 1113961

times displacement (m)

force (N) times displacement (m)

(3)

e energy level decreased as the percentage infill in-creased However the thicker samples had greater peakforce is tendency is similar to the data from actualmeasurements in Table 4 suggesting that it can be pre-dicted using structural analysis Nevertheless a correctioncoefficient is required to ensure the actual measurementdata completely match the calculated values and furtherresearch is needed Based on this result an image of thedisplacement during shock absorption is shown in Figure 6In this figure 10T10 and 10T50 have the stress focused atthe center where the load is applied suggesting the pos-sibility of plastic deformation when a physical load isapplied Figure 7 shows the result of scanning the shape ofthe sample after actual impact testing through 3D co-ordinate scan analysis and SEM images for 10T10 10T50and 10T100 samples It was difficult to distinguish thesamples based on the SEM images that is the amountpressed by the impact was found to be very smallerefore it can be interpreted that these samples aresuitable as a protective material in terms of wearing du-rability and aesthetics However an additional 3D co-ordinate scan analysis was performed to quantitativelyobserve the differences between each sample 10T10 was thelargest deformation of minus 01222mm 10T50 and 10T100were minus 005223mm and minus 005083mm respectively and thedifference between the two samples was insignificant10T10 showed similar analysis and experimental valuesand the lower the filling ratio the greater the deformationcaused by impact In terms of deformation fill rates 50(p 60sim70) and 100 (p 100) are expected to be favorableand exhibit the desired even stress distribution and lowdeformation for crafting protective equipment On thecontrary since output with 10 (p 30sim40) is high inflexibility and energy absorption it can be considered as aprotective device for clothing that is not exposed to verystrong impacts


35Application forProtectiveGear e results of this studydemonstrate that for moderate protective gear (ie

absorbs lt1000 N impact energy and protects from weakcompression) the higher the infill condition the higherthe strength but the lower the flexibility erefore wemodeled various crotch [35] and knee protectors [36] tobe worn on the human body to demonstrate the potentialapplications Table 6 shows the modeling and output ofthe crotch and knee protectors We also investigatedwhether the product is practical to use when 3D printingwith 10 infill and 5mm thickness e reason for this isthat the thickness of the form of the crotch or kneeprotective gear is generally sold in the market in therange of 5ndash10mm and the consumer complaints re-garding the current products include lack of flexibilityand less comfort when worn e production of sampleswas printed to examine the applicability of the results ofthis study and 10 infill condition was found to havesuitable comfort for wearing owing to its moderateflexibility

In future studies more complex samples will be de-veloped and evaluated for stability as well as subjectrsquos wearcomfort When evaluating the impact and energy absorp-tion it is expected that if the evaluation is performed notonly on a plane but also on various areas of the complexcurved surface then it will be possible to obtain a highlypractical application result

5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)

Figure 5 Compressibility property in relation to thickness with 10 50 and 100 infill rates

Table 5 Structural analysis results of absorption energy

Sample Energy (kJ)5T10 235T50 165T100 1010T10 6310T50 4110T100 19

01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000

Figure 6 3D simulation of displacement


4 Conclusions

Overall TPU does not fracture like regular fiber Its strengthis proportional to the infill rate during printing regardless ofthe sample thickness making the infill rate an importantfactor in determining the strength of the resultant materiale maximum impact values also increased as the infillincreased when samples of identical thicknesses werecompared However although the peak force was not heavilyaffected by the thickness when the infill rate was 10 or 50

the greater thickness greatly assisted shock absorption whenthe infill rate was 100 erefore when the impact ab-sorption conditions are below 800N the thickness is in-significant so it is beneficial to use a thinmaterial that lowersthe weight and retains high shock absorption Howeverwhen absorbing over 1000N of shock energy the thicknessbecomes a key factor All the specimens absorbed a totalenergy of at least 5 J erefore it was confirmed that TPUmaterial created using 3D printing could be used as personalprotective equipment e compression energy also

10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)

3D coordinateanalysis

(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)

Figure 7 3D coordinate analysis and SEM photos of shock absorption after impact testing (a) 10T10 (b) 10T50 (c) 10T100

Table 6 Modeling and printout of crotch and knee protectors as example applications

Crotch protector for cycling

3D modeling

3D printing

Knee protector for sports activity

3D modeling

3D printing


increased as the infill rate increased regardless of thethickness e increase was more drastic when the infill ratewas 100 than for 10 or 50 If the part was required toprotect from high compression the infill rate needed to be100in materials should also be chosen when weight is aconsideration because the thickness was relatively in-significant Structural analyses showed that the thinner thematerial the less deformation was caused by the impactregardless of the infill condition In addition it was con-firmed that the same tendency as the experimental results ofthe actual impact testing was shown In the future exper-iments are expected to be performed by simulating theproperties of newmaterials as well as different thickness andinfill conditions us when 3D printing the TPU materialover the hard shell of protective equipment the infillcondition must be set to 100 to achieve the desired shockabsorption and compression properties However thethickness must be set considering the importance of theprotective function Moreover the tensile strength wasmuch lower than general plastic even when the infill con-dition was 100 Hence it should be very comfortable towear because of the low level of constraint on the bodyHowever it will be advantageous to apply reinforced plasticinstead of TPU if extreme protection is required in whichcase a morphologic approach for comfort such as structuralincisions or holes will be necessary erefore selecting theoptimal conditions and conducting modeling to preciselydetermine the desired protective conditions are consideredvery important We examined the effectiveness of the samplewith 10 infill and 5mm thickness in two example appli-cations (crotch protector and knee protector) which areworn on the human body It was found that the product wassuitable in terms of wearing comfort stability and flexibility

Although this study was restricted to the use of TPUfurther studies will be conducted with the addition of newlydeveloped materials to produce a continuously developeddatabase is can be applied as a fundamental basis fordeveloping protective materials Actual protective devicescould also be produced to conduct wearing tests

Data Availability

e data used to support the findings of this study are in-cluded within the article

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the National Research Foun-dation of Korea (NRF) grant funded by the Korea Gov-ernment (MSIT) (no 2016-1956)

References

[1] J C Glenn T J Gordon and E Florescu State of the Futuree Millennium Project Washington DC USA 2014

[2] International Organization for Standardization AdditiveManufacturingmdashGeneral PrinciplesmdashTerminology ISOASTM 52900 Geneva Switzerland 2015

[3] H Lee ldquoA study of the production of textiles using 3Dprinting technologyrdquo Masterrsquos Degree Hanyang UniversitySeoul Republic of Korea 2017

[4] N G Tanikella B Wittbrodt and J M Pearce ldquoTensilestrength of commercial polymer materials for fused filamentfabrication 3D printingrdquo Additive Manufacturing vol 15pp 40ndash47 2017

[5] H S Kim and I A Kang ldquoStudy on status of utilizing 3Dprinting in fashion fieldrdquo Journal of the Korea Fashion andCostume Design Association vol 17 no 2 pp 125ndash1432015

[6] F S Senatov K V Niaza M Y ZadorozhnyyA V Maksimkin S D Kaloshkin and Y Z EstrinldquoMechanical properties and shape memory effect of 3D-printed PLA-based porous scaffoldsrdquo Journal of the Me-chanical Behavior of Biomedical Materials vol 57pp 139ndash148 2016

[7] E Mikołajewska M Macko Ł Ziarnecki et al ldquo3D printingtechnologies in rehabilitation engineeringrdquo Health ScienceJournal vol 4 no 12 pp 78ndash83 2014

[8] J W Stansbury and M J Idacavage ldquo3D printing withpolymers challenges among expanding options and oppor-tunitiesrdquo Dental Materials vol 32 no 1 pp 54ndash64 2016

[9] F Shen S Yuan Y Guo et al ldquoEnergy absorption of ther-moplastic polyurethane lattice structures via 3D printingmodeling and predictionrdquo International Journal of AppliedMechanics vol 8 no 7 2016

[10] S R Bates I R Farrow and R S Trask ldquo3D printed elastichoneycombs with graded density for tailorable energy ab-sorptionrdquo in Active and Passive Smart Structures and In-tegrated Systems vol 9799 International Society for Opticsand Photonics Washington DC USA 2016

[11] S R G Bates I R Farrow and R S Trask ldquo3D printedpolyurethane honeycombs for repeated tailored energy ab-sorptionrdquo Materials amp Design vol 112 pp 172ndash183 2016

[12] J-Y Lee J An and C K Chua ldquoFundamentals and appli-cations of 3D printing for novel materialsrdquo Applied MaterialsToday vol 7 pp 120ndash133 2017

[13] B C Gross J L Erkal S Y Lockwood C Chen andD M Spence ldquoEvaluation of 3D printing and its potentialimpact on biotechnology and the chemical sciencesrdquo Ana-lytical Chemistry vol 86 no 7 pp 3240ndash3253 2014

[14] J-F Xing M-L Zheng and X-M Duan ldquoTwo-photonpolymerization microfabrication of hydrogels an advanced3D printing technology for tissue engineering and drug de-liveryrdquo Chemical Society Reviews vol 44 no 15pp 5031ndash5039 2015

[15] T Hentschel and H Munstedt ldquoermoplastic poly-urethanemdashthe material used for the erlanger silver catheterrdquoInfection vol 27 no 1 pp S43ndashS45 1999

[16] A Burke and N Hasirci ldquoPolyurethanes in biomedical ap-plicationsrdquo Biomaterials vol 553 pp 83ndash101 2004

[17] H-Y Mi M R Salick X Jing et al ldquoCharacterization ofthermoplastic polyurethanepolylactic acid (TPUPLA) tissueengineering scaffolds fabricated by microcellular injectionmoldingrdquoMaterials Science and Engineering C vol 33 no 8pp 4767ndash4776 2013

[18] Y Han and J Kim ldquoA study on the mechanical properties ofknit fabric using 3D printing-Focused on PLA TPU Fila-mentrdquo Journal of Fashion Bus vol 22 no 4 pp 93ndash105 2018


[19] S H Jang T H Oh and S H Kim ldquoEffects of heat treatmenttemperature on various properties of thermoplastic poly-urethane composite fabricsrdquo Textile Science and Engineeringvol 54 no 1 pp 22ndash27 2017

[20] J-H Kim and G-H Kim ldquoermoplastic polyurethane(TPU)ethylene-propylene-diene monomer rubber (EPDM)and TPUpolybutadiene rubber (BR) blends for the appli-cation of footwear outsole materialsrdquo Elastomers and Com-posites vol 48 no 3 pp 195ndash200 2013

[21] Y Han and J Kim ldquoStudy on peel strength measurement of3D printing composite fabric by using FDMrdquo Journal ofFashion Bus vol 23 no 2 pp 77ndash88 2019

[22] International Organization for Standardization Plas-ticsmdashDetermination of Tensile PropertiesmdashPart 2 Test Con-ditions for Moulding and Extrusion Plastics ISO 527-22012Geneva Switzerland 2017

[23] European Standard PlasticsmdashDetermination of PunctureImpact Behaviour of Rigid PlasticsmdashPart 2 InstrumentedImpact Testing ISO 6603-22000 Europe 2002

[24] International Organization for Standardization Plas-ticsmdashDetermination of HardnessmdashPart 2 Rockwell HardnessISO 2039-21987 Geneva Switzerland 2015

[25] G Verstraete A Samaro W Grymonpre et al ldquo3D printingof high drug loaded dosage forms using thermoplasticpolyurethanesrdquo International Journal of Pharmaceuticsvol 536 no 1 pp 318ndash325 2018

[26] Korean Agency for Technology and Standards Shock Ab-sorption Performance Test Method Korea Department ofMinistry of Knowledge Economy Sejong City Republic ofKorea 2009

[27] R M Silva J L Rodrigues V V Pinto M J FerreiraR Russo and C M Pereira ldquoEvaluation of shock absorptionproperties of rubber materials regarding footwear applica-tionsrdquo Polymer Testing vol 28 no 6 pp 642ndash647 2009

[28] International Organization for Standardization Plas-ticsmdashDetermination of Compressive Properties ISO 604 Ge-neva Switzerland 2002

[29] S Kim Cloth Materials Gyeonggi-do GyoMoon PublishersGyeonggi-do Republic of Korea 2000

[30] K Van de Velde and P Kiekens ldquoBiopolymers overview ofseveral properties and consequences on their applicationsrdquoPolymer Testing vol 21 no 4 pp 433ndash442 2002

[31] E S Park ldquoermal mechanical and rheological properties ofpoly(lactic)acidthermoplastic poly(ester)urethanecaco3compositesrdquo Masterrsquos esis Hanyang University SeoulRepublic of Korea 2009

[32] B M Tymrak M Kreiger and J M Pearce ldquoMechanicalproperties of components fabricated with open-source 3-Dprinters under realistic environmental conditionsrdquo Materialsamp Design vol 58 pp 242ndash246 2014

[33] P G Georgopoulos P Fedele P Shade et al ldquoHospital re-sponse to chemical terrorism personal protective equipmenttraining and operations planningrdquo American Journal of In-dustrial Medicine vol 46 no 5 pp 432ndash445 2004

[34] IUPAC Compendium of Chemical Terminology BlackwellScience Oxford UK 1997

[35] S Park H Lee and Y Lee ldquoSuggestion of crotch prototype forcyclewear based on 3D modeling and printingrdquo Journal ofHuman Ecology vol 28 no 2 pp 67ndash80 2019

[36] H Lee and Y Lee ldquoSegmental hard shell design of kneeprotector for children using 3D printingrdquo Journal of FashionBus vol 21 no 4 pp 116ndash126 2017


CorrosionInternational Journal of

Hindawiwwwhindawicom Volume 2018

Advances in

Materials Science and EngineeringHindawiwwwhindawicom Volume 2018


Journal of

Chemistry

Analytical ChemistryInternational Journal of


ScienticaHindawiwwwhindawicom Volume 2018

Polymer ScienceInternational Journal of



Advances in Condensed Matter Physics


International Journal of

BiomaterialsHindawiwwwhindawicom

Journal ofEngineeringVolume 2018

Applied ChemistryJournal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of


High Energy PhysicsAdvances in

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

TribologyAdvances in



ChemistryAdvances in


Advances inPhysical Chemistry


BioMed Research InternationalMaterials

Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

lattice structure or a hexagonal array demonstrated that thewider range of compression energies exhibited a higherefficiency and a greater magnitude of efficiency peaks wasobserved at the higher density layers [9ndash11] Howeverstudies on the recent development of the novel materials andapplications in 3D printing are limited [12ndash14] Manystudies have dealt with density as a variable in the designerrsquosmodeling process However the infill conditions also need tobe examined during 3D printing because the 3D printinguser can adjust the density by varying the porosity with theinfill condition TPU is a common 3D printing material Itslinear polymer chains make it a straight line with flexibleand rigid chains connected through covalent bondingerefore it displays high flexibility elasticity and shockresistance like rubber as well as thermoplasticity Fur-thermore it has excellent abrasion and tear resistance as wellas high hardness [15ndash17] In addition TPU is easier todeform than PLA owing to its high elasticity [18] Otherresearchers have applied TPU to golf or other functionalshoes [19] as well as to baggage or flooring material becauseof its properties [20] Attempts to join textile fabrics and 3Dpolymer filaments have revealed that TPU exhibits the bestadhesion to fabrics [21] In this study we combined the rapidadvance of 3D printing and TPU and confirmed their ap-plicability for the production of hard shell personal pro-tective equipment

Currently sports or industrial protective equipmentthat protect the hip joints knees elbows and shin of thehuman body from shock damage mostly comprise hardshells with a soft interior ese are usually reinforcedplastic and polyurethane foam respectively e reinforcedplastic used in hard shells is strong light and durable butnot flexible thus it does not respond well to bodymovement is discomfort during movement is exacer-bated when the product is ill-fitting erefore substitutingthe hard shell with TPU which is flexible and can protectfrom shock is expected to create greater adherence andcomfort during movement It will also contribute to futurepart customization because TPU is easily combined withtechnologies such as 3D scanners printers and modelingamong others

e ultimate purpose of this study was to investigateTPUrsquos applicability for personal protective equipment andthe optimal conditions to make it using 3D printing tech-nology In addition TPU can be easily obtained in themarket and thus was chosen for this study to enable notonly an expert but anyone to create prototypes or customizepersonal protective equipment through 3D printing etensile strength shock absorption and compressibilityproperties were evaluated in relation to the conditions ofprinting (infillmdashthe filling of the inside during prin-tingmdashand specimen thickness) In addition we analyzed thepredictability of shock absorption (an important perfor-mance factor in personal protective equipment) with theanalysis tool SolidWorks Energy displacement and de-formation were calculated using the elastic modulus Pois-sonrsquos ratio and the shear factor of the 3D printedmaterial topropose an efficient model that can confirm the potential of anew material with regard to productivity quality and

stability without further experimentation In addition wetested prototype models on the human body (knee andcrotch protectors) with different thickness and infill con-ditions to confirm their applicability to actual use

2 Materials and Methods

21 Samples and Output Conditions TPU (HyVISIONSouth Korea) samples were 3D printed under differentconditions to form test pieces for tensile impact andcompressibility tests based on the appropriate standards(ISO 527-2 [22] ISO 6603-2 [23] and ISO 2039-2 [24]respectively) TPU filament type used for filling detailedspecifications are as follows melt flow index 14ndash28 g10min tensile yield strength 21ndash36MPa elongation atbreak 26ndash60 flexural strength 60ndash97MPa flexuralmodulus 18ndash30 GPa impact strength 120 kJm2 andfilament diameter 175mm (plusmn005mm) Specimens weremodeled using Geomagic Design X software (3D SystemsUSA) Each bit of data had sliced G-codes appropriate for3D printing using Cubicreator 25 R3 software (HyVI-SION South Korea) and the specimens were 3D printedusing a Cubicon Style desktop 3D printer (HyVISIONSouth Korea) at a printing speed of 10mms floor tem-perature of 65degC chamber temperature of 50degC and dis-charge rod temperature of 230degC is printer is one of themost commonly used low-cost techniques in the field of3D printing e sample thickness and infill printingcondition were varied (5 or 10mm thickness 10 50 or100 infill) providing six types of samples Four copies ofeach sample were made so that four trials could be per-formed for each evaluation category to derive the averageand standard deviation Detailed conditions of 3D printingare shown in Table 1 e symbol of the sample was de-termined based on the thickness and infill condition andthe final name was determined based on the sample weightmeasurement value which is shown in Table 2 e ma-terial consumption of the sample was 4524 g for 10T1002769 g for 10T50 1364 g for 10T10 2265 for 5T1001580 g for 5T50 and 1032 g for 5T10 As a result ofverifying the morphological properties of the output ofTPU printing in the previous study [25] no particles werefound in the smooth surface when 100 TPU was sup-plied and the release kinetic was maintained at higherpurity (39 plusmn 09) in the X-ray tomography image Basedon the result of the previous study this study also premisedthat porosity would not occur during the printing processis assumption was addressed by utilizing the SEMimages presented in Table 1 for examination and only thepercentage indicated by the weight measurement wasconsidered On the contrary before printing the functionof leveling the bed was performed by auto leveling and thesample was placed in a lower position of the Z-axis for thebottom surface to be horizontal is minimized the effectof load during the output In addition when outputtingprotective equipment larger than the sample in this studyplacing the wide surface of the modeling sample hori-zontally can provide a more stable 3D printing and is lesslikely to fail













()Height of layer

(mm)10 (14x) 50 (24x) 100 (24x) 5T 10T Top(ea)

Bottom(ea)

25 50 6 3 15 02








Load area

5mm or 10mm

60mm 60mm

127mm

10 50 or 100

(a)

Load area

(b) (c)


Materials

Sensor

CONTURA G2






170mm

10mm

80mm

20mm

24mm

60mm

60mm

60mm

60mm

Modeling






emptyg 1 minusρρs

(1)



0 5 15 20 2510

1400

1200

1000

800

600

400

200

0

Forc

e (N

)

Time (ms)

5T105T505T100

10T1010T5010T100




5T10 6909 (609) 58 (007)5T50 8328 (703) 45 (004)5T100 9381 (703) 40 (006)10T10 6269 (580) 57 (001)10T50 8948 (132) 51 (004)10T100 13253 (845) 45 (004)

10

8

6

4

2

0

Tens

ile st

reng

th (M

Pa)

0 50 100 150 200Strain (mm)

5T105T505T100

10T1010T5010T100








E σε (2)





(3)






5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)




01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000



4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls















()Height of layer

(mm)10 (14x) 50 (24x) 100 (24x) 5T 10T Top(ea)

Bottom(ea)

25 50 6 3 15 02








Load area

5mm or 10mm

60mm 60mm

127mm

10 50 or 100

(a)

Load area

(b) (c)


Materials

Sensor

CONTURA G2






170mm

10mm

80mm

20mm

24mm

60mm

60mm

60mm

60mm

Modeling






emptyg 1 minusρρs

(1)



0 5 15 20 2510

1400

1200

1000

800

600

400

200

0

Forc

e (N

)

Time (ms)

5T105T505T100

10T1010T5010T100




5T10 6909 (609) 58 (007)5T50 8328 (703) 45 (004)5T100 9381 (703) 40 (006)10T10 6269 (580) 57 (001)10T50 8948 (132) 51 (004)10T100 13253 (845) 45 (004)

10

8

6

4

2

0

Tens

ile st

reng

th (M

Pa)

0 50 100 150 200Strain (mm)

5T105T505T100

10T1010T5010T100








E σε (2)





(3)






5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)




01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000



4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Load area

5mm or 10mm

60mm 60mm

127mm

10 50 or 100

(a)

Load area

(b) (c)


Materials

Sensor

CONTURA G2






170mm

10mm

80mm

20mm

24mm

60mm

60mm

60mm

60mm

Modeling






emptyg 1 minusρρs

(1)



0 5 15 20 2510

1400

1200

1000

800

600

400

200

0

Forc

e (N

)

Time (ms)

5T105T505T100

10T1010T5010T100




5T10 6909 (609) 58 (007)5T50 8328 (703) 45 (004)5T100 9381 (703) 40 (006)10T10 6269 (580) 57 (001)10T50 8948 (132) 51 (004)10T100 13253 (845) 45 (004)

10

8

6

4

2

0

Tens

ile st

reng

th (M

Pa)

0 50 100 150 200Strain (mm)

5T105T505T100

10T1010T5010T100








E σε (2)





(3)






5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)




01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000



4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls








emptyg 1 minusρρs

(1)



0 5 15 20 2510

1400

1200

1000

800

600

400

200

0

Forc

e (N

)

Time (ms)

5T105T505T100

10T1010T5010T100




5T10 6909 (609) 58 (007)5T50 8328 (703) 45 (004)5T100 9381 (703) 40 (006)10T10 6269 (580) 57 (001)10T50 8948 (132) 51 (004)10T100 13253 (845) 45 (004)

10

8

6

4

2

0

Tens

ile st

reng

th (M

Pa)

0 50 100 150 200Strain (mm)

5T105T505T100

10T1010T5010T100








E σε (2)





(3)






5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)




01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000



4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls









E σε (2)





(3)






5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)




01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000



4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls







5T105T505T100

10T1010T5010T100

0 1 2Strain (mm)

Com

pres

sion

ener

gy (M

Pa)

30

25

20

15

10

5

0

(a)

Com

pres

sion

ener

gy(M

Pa)

5T1010T10

002040608

112

05 1 15 2 250Strain (mm)

(b)

Com

pres

sion

ener

gy(M

Pa)

5T5010T50

02468

05 1 15 2 250Strain (mm)

(c)

Com

pres

sion

ener

gy(M

Pa)

5T10010T100

05

1015202530

05 1 15 2 250Strain (mm)

(d)




01

005

0

5T10 5T50 5T100

10T10 10T50 10T100

mm

10T10T0 10100 10T10T0 505050 10T10T0 10010000



4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




4 Conclusions



10T10001mmsec

X (mm)

Z

150

200

250

300

350

400

450

SEM images(12x)


(a)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T50Z

(b)

001mmsec

X (mm)

150

200

250

300

350

400

450

10T100Z

(c)




3D modeling

3D printing


3D modeling

3D printing




Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls






Data Availability




Acknowledgments


References









































Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls

























Advances in



Journal of

Chemistry















Journal of





Volume 2018









Journal of


Na

nom

ate

ria

ls




Evaluation of the Mechanical Properties of Porous ...

Documents

Transcript of Evaluation of the Mechanical Properties of Porous ...