Effect of section thickness on fatigue performance of laser sintered nylon 12

Amel, Hoda; Rongong, J.A.; Moztarzadeh, Hadi; Hopkinson, Neil

doi:10.1016/j.polymertesting.2016.05.027

Cited by 18 publications

(11 citation statements)

References 13 publications

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“…Munguia and Dalgarno (2015) obtained the LS PA12 fatigue behaviour in both reversed and rotating bending showing an isotropic response in terms of fatigue behaviour for both test configurations. Amel et al (2016) investigated the effect of the geometry (thickness) on the fatigue behaviour obtained under displacement controlled tension-tension and force-controlled fully reverse fatigue loading. Blattmeier et al (2012) studied the effect of the surface treatment on the fatigue behaviour determined through a load increase method of LS specimens.…”

Section: Introductionmentioning

confidence: 99%

Effect of the orientation on the fatigue crack growth of polyamide 12 manufactured by selective laser sintering

Cano

Salazar

Rodrı́guez

2019

RPJ

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Purpose Polyamide 12 (PA12) properties meet specific requirements for various applications in the automotive and aerospace industries. Bulk specimens made of PA12 and processed via the additive manufacturing technique such as selective laser sintering (SLS) present a layered structure. In case of structural applications, the fatigue performance of SLS PA12 parts is of vital importance and fatigue response studies in these type of materials are still scarce. Therefore, the purpose of this paper is to analyse the effect of the applied load orientation on the fatigue crack propagation behaviour of the layered structure of SLS PA12. Design/methodology/approach With the aim of understanding the effect of the applied load with respect to the layer orientation on the fatigue crack growth of SLS PA12, fatigue crack growth tests were carried out at two orientations. The specimens called PARA were orientated in such a way that the applied force direction belongs to the layer plane while in the group called PERP, the tensile force direction is coincident with the build direction, that is, perpendicular to the slice. Besides, special attention has been paid to the analysis of the fracture surfaces of the specimens, linking the micromechanisms of failure with the microstructure of the material. Findings The SLS PA12 specimens tested with the load applied parallel to the layered structure show a little better fatigue response than those tested at perpendicular orientation. The fracture surfaces of the specimens tested at perpendicular orientation are slightly smoother than those tested at parallel orientation. Crazes are the main micromechanism of failure with a crater size of 50 microns, which coincide with the spherulite size. This indicates that the void nucleation of the crazes takes places between lamellae inside the spherulites, and consequently, the craze growth and rupture occurs mainly in a transspherulitic mode. Originality/value PA12 parts manufactured via SLS are becoming more valuable in structural elements in the automative and aeronatical fields. In such applications, fatigue performance is vital for design. Fatigue studies are scarce in literature and even more when dealing with fatigue crack growth behaviour. The value of this work is the analysis of the fatigue crack growth response of these materials taking into account the anisotropic microstructure and to get a better understanding, this behaviour is explained taking into account the micromechanisms of failure and the microstructure of the material.

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Section: Introductionmentioning

confidence: 99%

Effect of the orientation on the fatigue crack growth of polyamide 12 manufactured by selective laser sintering

Cano

Salazar

Rodrı́guez

2019

RPJ

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“…There is no clear trend between the normalised specimen depth and the deviation from the logarithmic model. This is consistent with the findings of Amel et al (2016) who determined no correlation between specimen depth and fatigue life. The result is likely due to the fact that the depth is considered when calculating the stress experienced by the specimen (as outlined above), whereas the density is not.…”

Section: Specimen Depthsupporting

confidence: 92%

“…As such the results of this study provide a broad baseline for the nylon 12 material, however fall well short of covering the same territory as this investigation. A separate study by Amel, et al (2016) examined the effect of specimen thickness on the fatigue characteristics of SLS nylon 12. The results displayed a large discrepancy in the number of cycles to failure for identical samples under the same conditions.…”

Section: Nylon 12 Fatiguementioning

confidence: 99%

UQ eSpace

Fitzpatrick¹

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A local podiatry company has recently purchased a state-of-the-art 3D printer for manufacturing orthotic insoles. The HP Jet Fusion will replace the existing manufacturing techniques which are time consuming and labour intensive. However, due to the innovative printing process, the long-term durability of the material produced by the device is currently unknown. Fatigue is a significant concern in the design of orthotics due to the constant cyclic loading experienced during walking or running. As such, this thesis set out to determine the suitability of the Jet Fusion printer for producing orthotics from a fatigue perspective. Following an extensive literature review, flexural fatigue testing was conducted using the ASTM D7774 standard. The tests compared the Jet Fusion samples to the performance of specimens produced through fused deposition modelling (FDM). The results indicated that the Jet Fusion and FDM samples had fatigue limits of 22.4 MPa and 7.7 MPa respectively. The number of cycles to failure and flexural stress levels were found to be logarithmically correlated for both materials. With the maximum stress experienced by orthotic insoles being in the order of 1 MPa, it was found that both materials had sufficient properties to avoid failure due to fatigue. As such, it has been concluded that from a fatigue perspective, the HP Jet Fusion Printer is suitable for use in manufacturing orthotic insoles. ii ACKNOWLEDGEMENTS I would firstly like to thank my supervisor Dr Gui Wang for taking me on at such short notice. His expertise and guidance throughout this project have been of tremendous help and I am sincerely thankful for his assistance. I would also like to acknowledge: Daniel Graham for his assistance with setting up the testing machines; the UQ Workshop for producing the mounting rig; and iOrthotics for the inspiration for the topic and provision of testing samples. Finally, my heartfelt thanks go to my wonderful family and friends for their endless support and encouragement.

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“…10. The results of [68], indicating that as part density increases so does the number of cycles that the specimen is able to withstand. rectilinear boxes (35 × 5×1.4 mm 3 ) of polycaprolactone (PCL).…”

Section: Bending Fatiguementioning

confidence: 96%

“…In [68], the effects of geometry on the fatigue life was investigated by varying the section thickness (2, 4, and 6 mm) in dog bone PA12 specimens under tension-tension and tension-compression uniaxial loading. In both cases, the fatigue life increased with the section thickness, but these results were not statistically significant for tensiontension loading.…”

Section: Axial Loading Fatiguementioning

confidence: 99%

A review of the fatigue behavior of 3D printed polymers

Safai

Cuellar

Smit

et al. 2019

Additive Manufacturing

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As additive manufacturing of polymeric materials is becoming more prevalent throughout industry and research communities, it is important to ensure that 3D printed parts are able to withstand mechanical and environmental stresses that occur when in use, including the sub-critical cyclic loads that could result in fatigue crack propagation and material failure. There has so far been only limited research on the fatigue behavior of 3D printed polymers to determine which printing or material parameters result in the most favorable fatigue behavior. To better understand the effects of the printing technique, printing materials, and printing parameters on the fatigue behavior of 3D printed materials, we present here an overview of the data currently available in the literature including fatigue testing protocols and a quantitative analysis of the available fatigue data per type of the AM technology. The results of our literature review clearly show that, due to the synergism between printing parameters and the properties of the printed material, it is challenging to determine the best combination of variables for fatigue resistance. There is therefore a need for more experimental and computational fatigue studies to understand how the above-mentioned material and printing parameters affect the fatigue behavior.

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Effect of section thickness on fatigue performance of laser sintered nylon 12

Cited by 18 publications

References 13 publications

Effect of the orientation on the fatigue crack growth of polyamide 12 manufactured by selective laser sintering

Effect of the orientation on the fatigue crack growth of polyamide 12 manufactured by selective laser sintering

UQ eSpace

A review of the fatigue behavior of 3D printed polymers

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