A combined theoretical and experimental approach to model polyamide 12 degradation in selective laser sintering additive manufacturing

2021 ◽  
Vol 70 ◽  
pp. 271-289
Author(s):  
Feifei Yang ◽  
Xu Chen
Keyword(s):  
Additive Manufacturing ◽  
Experimental Approach ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Polyamide 12 ◽  
Sintering Additive

Fatigue life assessment of polyamide 12 processed by selective laser sintering. Damage modelling according to fracture mechanics

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alicia Salazar ◽  
Alberto Jesús Cano Aragón ◽  
Jesús Rodríguez
Keyword(s):  
Fatigue Life ◽  
Additive Manufacturing ◽  
Fracture Mechanics ◽  
Damage Evolution ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Load Direction ◽  
Content Type ◽  
Polyamide 12 ◽  
Fracture Parameters

Purpose Polyamide 12 (PA12) processed by the additive manufacturing technique of selective laser sintering (SLS) is acquiring a leading role in cutting-edge technological sectors pertaining to transport and biomedical among others. In many of these applications, design requirements must ensure fatigue structural integrity. One of the characteristic features of these SLS PA12 is the layer-wise structure that may influence the mechanical response. Therefore, this paper aims to assess the fatigue life behavior of PA12, focusing on the effect of the load direction with respect to the load orientation. Design/methodology/approach With the aim of analyzing the effect of the load direction with respect to the layer wise structure, fatigue tests on plain samples of SLS PA12 were carried out with the load applied parallel and perpendicular to the layer planes. The S-N stress life curves and the fatigue limit at 106 cycles were determined at room temperature and at a stress ratio of 0.1. The fracture surfaces were inspected to evaluate the damage evolution, modeled via the fracture mechanics methodology to obtain the fracture parameters. Findings The fatigue resistance was better when the load was applied parallel than when was applied perpendicularly to the layered structure. The analysis of the postmortem specimens evidenced three regions. The inspection of the fatigue macro crack growth region revealed that crazing was the mechanism responsible of nucleation and growth of damage till a macroscopic crack was generated, as well as of the consequent crack advancement. The calculated fracture parameters computed from the application of the fracture mechanics approach were similar to those obtained from standardized fracture tests, except when the stress levels were close to the yield strength. Originality/value The fatigue knowledge of polymers, and especially of polymers processed via additive manufacturing techniques, is still scarce. Therefore, the value of this investigation is not only to obtain fatigue data that could be used for structural design with SLS PA12 materials but also to advance in the knowledge of damage evolution during the fatigue process.

scholarly journals Review on the modeling of the laser sintering process for Polyamide 12

2021 ◽  
Vol 234 ◽  
pp. 00006
Author(s):  
Hanane YAAGOUBI ◽  
Hamid ABOUCHADI ◽  
Mourad TAHA JANAN
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Sintering ◽  
Experimental Studies ◽  
Laser Sintering ◽  
Sintering Process ◽  
Polyamide 12 ◽  
Manufacturing Techniques

One of the most promising additive manufacturing techniques is selective laser sintering (SLS) of thermoplastic materials. However, the materials successfully applicable to laser sintering (LS) are very limited today. In this study the exceptional position of polyamide 12 powders is underlined. Several numerical and experimental studies have been carried out to make comparisons between the use of powdered materials for polyamide 12 and other types of polymers during the SLS process. The complexity of this process and the interaction between the different phenomena involved has not been fully understood. In this work we highlight the different models of the selective laser sintering of polyamide 12 as well as their different results in order to better understand the functioning of this process.

scholarly journals Mode I Fracture Toughness of Polyamide and Alumide Samples obtained by Selective Laser Sintering Additive Process

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 640 ◽  
Author(s):  
Dan Ioan Stoia ◽  
Liviu Marsavina ◽  
Emanoil Linul
Keyword(s):  
Fracture Toughness ◽  
Additive Manufacturing ◽  
Selective Laser Sintering ◽  
Dimensional Accuracy ◽  
Laser Sintering ◽  
Mode I ◽  
Additive Process ◽  
Mode I Fracture ◽  
Mode I Fracture Toughness ◽  
Sintering Additive

Selective Laser Sintering is a flexible additive manufacturing technology that can be used for the fabrication of high-resolution parts. Alongside the shape and dimension of the parts, the mechanical properties are essential for the majority of applications. Therefore, this paper investigates dimensional accuracy and mode I fracture toughness (KIC) of Single Edge Notch Bending samples under a Three Point Bending fixture, according to the ASTM D5045-14 standard. The work focuses on the influence of two major aspects of additive manufacturing: material type (Polyamide PA2200 and Alumide) and part orientation in the building environment (orientations of 0°, 45° and 90° are considered). The rest of the controllable parameters remains constant for all samples. The results reveal a direct link between the sample densities and the dimensional accuracy with orientation. The dimensional accuracy of the samples is also material dependent. For both materials, the angular orientation leads to significant anisotropic behavior in terms of KIC. Moreover, the type of material fundamentally influences the KIC values and the fracture mode. The obtained results can be used in the development of additive manufactured parts in order to obtain predictable dimensional tolerances and fracture properties.

scholarly journals Characterization of Polymer Powders and Effects of Powder Reuse in Selective Laser Sintering

2021 ◽  
Vol 33 (3) ◽  
pp. 658-664
Author(s):  
H. Chiririwa
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Sintering ◽  
Polymeric Materials ◽  
Cost Effective ◽  
Laser Sintering ◽  
Polyamide 12 ◽  
Extensive Range ◽  
The Many ◽  
Selection Of

Selective laser sintering (SLS) had been recognized as production expertise (additive manufacturing). The complication restricting the use of SLS in additive manufacturing in an extensive range of industrial scope is the limited selection of usable polymers as it is only limited to polyamide 12. Other polymeric materials such as polypropylene and polyethylene are needed to establish pristine market avenues in industry. In selective laser sintering, the powder is reused in consecutive cycles of the route for the reason that it is sustainable and cost effective. Characterization procedures, including the many available techniques has been proposed to determine changes in chemical microstructures, morphology along with flowability. Subtle disimilarities linking virgin and used powder have been identified through characterization.

scholarly journals Modeling crystallization kinetics for selective laser sintering of polyamide 12

2021 ◽  
Author(s):  
Dominic Soldner ◽  
Paul Steinmann ◽  
Julia Mergheim
Keyword(s):  
Crystallization Kinetics ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Polyamide 12

Study in performance and morphology of polyamide 12 produced by selective laser sintering technology

2018 ◽  
Vol 24 (5) ◽  
pp. 813-820 ◽  
Author(s):  
Junjie Wu ◽  
Xiang Xu ◽  
Zhihao Zhao ◽  
Minjie Wang ◽  
Jie Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Polarized Light ◽  
Chain Scission ◽  
High Energy ◽  
Laser Sintering ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Content Type ◽  
X Ray ◽  
Polyamide 12

Purpose The purpose of this paper is to investigate the effect of selective laser sintering (SLS) method on morphology and performance of polyamide 12. Design/methodology/approach Crystallization behavior is critical to the properties of semi-crystalline polymers. The crystallization condition of SLS process is much different from others. The morphology of polyamide 12 produced by SLS technology was investigated using scanning electron microscopy, polarized light microscopy, differential scanning calorimetry, X-ray diffraction and wide-angle X-ray diffraction. Findings Too low fill laser power brought about bad fusion of powders, while too high energy input resulted in bad performance due to chain scission of macromolecules. There were three types of crystal in the raw powder material, denoted as overgrowth crystal, ring-banded spherulite and normal spherulite. Originality/value In this work, SLS samples with different sintering parameters, as well as compression molding sample for the purpose of comparison, were made to study the morphology and crystal structure of sintered PA12 in detail.

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