Prediction of Temperature Distribution and Residual Stress in SLM Printed Parts

2018 ◽  
Author(s):  
Hong-Seok Park ◽  
Ngoc-Hien Tran ◽  
Ansari Md Jonaet
Keyword(s):  
Residual Stress ◽  
Temperature Distribution ◽  
Laser Source ◽  
Powder Bed ◽  
Manufacturing Planning ◽  
System A ◽  
Physical Chemical ◽  
Fast Cooling ◽  
Metallic Parts

Selective laser melting (SLM) is a powder bed based additive manufacturing (AM) process to manufacture metallic parts. SLM is the complex thermal-physical-chemical process of the interaction between a laser source and metallic powders. The SLM printing method has been applied widely for fabricating the metallic parts. However, the high temperature in heating and fast cooling during SLM process result in the large residual stress which affects to the quality of the SLM printed parts such as distortion and cracks. This research proposes to develop a system for predicting the quality of the part from the manufacturing planning to remove the failures before carrying out the real printing process. For developing such system, a model for predicting the temperature distribution should be generated. From this model, an interrelationship between process parameters and temperature distribution should be derived out. Based on that, the deformation can be predicted by calculating residual stress along with the result of temperature distribution.

scholarly journals Review of Powder Bed Fusion Additive Manufacturing for Metals

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1391
Author(s):  
Leila Ladani ◽  
Maryam Sadeghilaridjani
Keyword(s):  
Additive Manufacturing ◽  
Three Dimensional ◽  
Disruptive Technology ◽  
Powder Bed ◽  
Powder Particles ◽  
Metallic Parts ◽  
The Cost ◽  
Scientific Questions ◽  
Metal Additive

Additive manufacturing (AM) as a disruptive technology has received much attention in recent years. In practice, however, much effort is focused on the AM of polymers. It is comparatively more expensive and more challenging to additively manufacture metallic parts due to their high temperature, the cost of producing powders, and capital outlays for metal additive manufacturing equipment. The main technology currently used by numerous companies in the aerospace and biomedical sectors to fabricate metallic parts is powder bed technology, in which either electron or laser beams are used to melt and fuse the powder particles line by line to make a three-dimensional part. Since this technology is new and also sought by manufacturers, many scientific questions have arisen that need to be answered. This manuscript gives an introduction to the technology and common materials and applications. Furthermore, the microstructure and quality of parts made using powder bed technology for several materials that are commonly fabricated using this technology are reviewed and the effects of several process parameters investigated in the literature are examined. New advances in fabricating highly conductive metals such as copper and aluminum are discussed and potential for future improvements is explored.

scholarly journals Scanning Strategies in the PBF Process: A Critical Review

2020 ◽  
Author(s):  
Ehsan Malekipour ◽  
Hazim El-Mounayri
Keyword(s):  
Residual Stress ◽  
Critical Review ◽  
Heat Accumulation ◽  
Scanning Strategy ◽  
Homogeneous Microstructure ◽  
Powder Bed ◽  
Pros And Cons ◽  
Scanning Strategies ◽  
Metallic Parts ◽  
Powder Fusion

Abstract The powder-bed fusion (PBF) process is capable of producing near-fully dense metallic parts; however, various defects — particularly thermal abnormalities — can still be observed during the process. Some of these thermal defects — cracks, distortion, delamination of layers, and microporosity — cannot be removed by post-processing operations. The majority of these abnormalities are the result of residual stress, heat accumulation, lack of inter-track /inter-layer bonding, lack of powder fusion, or a combination of these factors. Modifying the scanning strategy (the topology of scanning tracks) can efficiently mitigate these abnormalities by adjusting the process parameters and adopting proper scanning patterns. The implementation of different scanning strategies significantly changes the ultimate quality of printed parts and manufacturing process lead time. Choosing a proper scanning strategy minimizes the residual stress and internal porosity, generates homogeneous microstructure, and avoids heat accumulation throughout the part during the printing process. In this work, we conducted a critical review of different scanning strategies, their pros and cons, limitations, and influence on the resulting properties of fabricated parts. Furthermore, we report the latest efforts for improvement of the current scanning strategies and introduce the-state-of-the-art strategies in the multi-laser PBF (ML-PBF) process. The insights provided here can assist scholars in evaluating existing scanning strategies and scanning patterns, and in identifying ways both to overcome scanning limitations and to modify them. On the other hand, it can assist manufacturers in selecting the best scanning strategies for their products based on their designs, demands, and resources.

Residual Stress and Deformation After Finishing of a Shell Structure Fabricated by Direct Metal Lamination Using Arc Discharge

2012 ◽  
Vol 6 (5) ◽  
pp. 611-617 ◽  
Author(s):  
Takeyuki Abe ◽  
◽  
Hiroyuki Sasahara
Keyword(s):  
Residual Stress ◽  
Temperature Distribution ◽  
Shell Structure ◽  
Arc Discharge ◽  
Three Dimensional ◽  
Local Maximum ◽  
Stress Release ◽  
Stress And Deformation ◽  
Metallic Parts ◽  
The Relationship

Arc welding technology has been used to melt metal, and a fabrication system for three-dimensional metallic parts has been developed around it: direct metal lamination using arc discharge. Here, the relationship between residual stress in the shell structure and temperature distribution in the shell structure after lamination are explored. Deformation caused by residual stress release is also measured. The results clarify that the local maximum value of the residual stress is small when the temperature in the shell structure is high. It is also found that the temperature distribution can be controlled through heat-input conditions and a cooling method using water. The residual stress distribution is formed by a non-uniform compressive plastic strain distribution. Plastic deformation is caused by the temperature distribution. No significant deformation due to residual stress release is observed when the lateral surface is finished.

scholarly journals Two-Step Laser Post-Processing for the Surface Functionalization of Additively Manufactured Ti-6Al-4V Parts

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4872
Author(s):  
Juliana S. Solheid ◽  
Torsten Wunsch ◽  
Vanessa Trouillet ◽  
Simone Weigel ◽  
Tim Scharnweber ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Contact Angles ◽  
Process Chain ◽  
Ultrashort Pulse Laser ◽  
Powder Bed ◽  
Post Process ◽  
Functionalized Surfaces ◽  
Processing Step ◽  
Metallic Parts

Laser powder bed fusion (LPBF) is one of the additive manufacturing methods used to build metallic parts. To achieve the design requirements, the LPBF process chain can become long and complex. This work aimed to use different laser techniques as alternatives to traditional post-processes, in order to add value and new perspectives on applications, while also simplifying the process chain. Laser polishing (LP) with a continuous wave laser was used for improving the surface quality of the parts, and an ultrashort pulse laser was applied to functionalize it. Each technique, individually and combined, was performed following distinct stages of the process chain. In addition to removing asperities, the samples after LP had contact angles within the hydrophilic range. In contrast, all functionalized surfaces presented hydrophobicity. Oxides were predominant on these samples, while prior to the second laser processing step, the presence of TiN and TiC was also observed. The cell growth viability study indicated that any post-process applied did not negatively affect the biocompatibility of the parts. The presented approach was considered a suitable post-process option for achieving different functionalities in localized areas of the parts, for replacing certain steps of the process chain, or a combination of both.

Technology and Hospital Information System: A Case of Implementation of Electronic Clinical Records in Hospital Maternity Irene Neto in Lubango, Angola

2019 ◽  
Vol 10 (11) ◽  
pp. 1131-1135
Author(s):  
Tomas Hambili Paulo Sanjuluca ◽  
◽  
Ricardo Correia ◽  
Anabela Antunes de Almeida ◽  
Ana Gloria Diaz Martinez ◽  
...  
Keyword(s):  
Maternity Hospital ◽  
Management Support ◽  
Retrospective Case ◽  
System A ◽  
Clinical Records ◽  
Retrospective Case Study ◽  
The Impact ◽  
And Child Health

Introduction: In order to have a good assessment of the quality of maternal and child health care, it is essential that there is up-to-date and reliable information. Objective: To evaluate the impact of the implementation of a computerized database of clinical processes in the admission, archive and medical statistics section, of Maternity hospital Irene Neto/Lubango-Angola. Methodology: A descriptive study with a quantitative and qualitative approach to carry out a retrospective case study deliveries and newborns, records from 2014 to 2017. Final considerations: The implementation of this project may contribute to the improvement of clinical management support management of the hospital as well as facilitating access to information for research and scientific production.

UGR CALCULATION BASED ON THE LUMINANCE SPATIAL-ANGULAR DISTRIBUTION

2020 ◽  
Vol 2020 (4) ◽  
pp. 25-32
Author(s):  
Viktor Zheltov ◽  
Viktor Chembaev
Keyword(s):  
Monte Carlo ◽  
Angular Distribution ◽  
Monte Carlo Method ◽  
Visual Task ◽  
New Method ◽  
Lighting System ◽  
Preliminary Assessment ◽  
System A ◽  
The Monte Carlo Method

The article has considered the calculation of the unified glare rating (UGR) based on the luminance spatial-angular distribution (LSAD). The method of local estimations of the Monte Carlo method is proposed as a method for modeling LSAD. On the basis of LSAD, it becomes possible to evaluate the quality of lighting by many criteria, including the generally accepted UGR. UGR allows preliminary assessment of the level of comfort for performing a visual task in a lighting system. A new method of "pixel-by-pixel" calculation of UGR based on LSAD is proposed.

The real concept of substitution in Ayurveda literature and adulteration the misleading concept of modern era

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Ashashri Shinde ◽  
Pankaj Gupta ◽  
Sudipt Rath
Keyword(s):  
Medicinal Plant ◽  
Plant Material ◽  
Genetic Parameters ◽  
Herbal Drugs ◽  
Material Identification ◽  
The Real ◽  
Physical Chemical ◽  
Unfair Trade ◽  
Modern Era

A quality drug is central to the success of any therapeutic plan. The quality of drug is determined right from the collection to delivery to the patients. The commonest problem involving the medicinal plant stating materials is intentional or unintentional substitution and adulteration owing to multiple reasons like unavailability, higher costs, unfair trade etc. This trend was also present in the olden days, as evident from the concept of substitute drugs (Pratinidhi Dravya) as available in Yogratanakara, Bhavaprakasha and Bhaishajyaratnawali. Therefore, Charka and later Acharyas also have dealt with authentication and standardization of herbal drugs and formulations in detail by using four Pramanas (tools of knowledge) Ch.Vi.8/87. Nowadays the concept of substitution is entirely converted into intentional and unintentional malpractices of adulteration. The established authenticity parameters for plant material identification and standardization like organoleptic, physical, chemical and genetic parameters are relatively inaccessible for routine use. Not withstanding the accuracy and usefulness of these lab parameters and delay in the development of easy to perform parameters for reasonable drug authentication. These adulteration malpractices spoils the market of herbal industries. In this article we discuss about concept of substitution in ancient Ayurveda and at present intentional and unintentional adulteration practices.

Evaluation of the microbiological and physical-chemical quality of salted bovine meat marketed in establishments and free fairs in the north zone of Rio de Janeiro

2018 ◽  
Vol 6 (4) ◽  
pp. 65
Author(s):  
Julio Cesar Queiroz Penha ◽  
Robson Maia Franco ◽  
Maria Carmela Kasnowski Holanda Duarte ◽  
Katia Christina Leandro
Keyword(s):  
Rio De Janeiro ◽  
Chemical Quality ◽  
The North ◽  
Physical Chemical

scholarly journals Smoothing additive manufactured parts using ns-pulsed laser radiation

2021 ◽  
Author(s):  
Florian Kuisat ◽  
Fernando Lasagni ◽  
Andrés Fabián Lasagni
Keyword(s):  
Surface Roughness ◽  
Mechanical Performance ◽  
State Of The Art ◽  
Pulsed Laser ◽  
Industrial Applications ◽  
Laser Source ◽  
Pulsed Laser Radiation ◽  
Current State ◽  
The Impact

AbstractIt is well known that the surface topography of a part can affect its mechanical performance, which is typical in additive manufacturing. In this context, we report about the surface modification of additive manufactured components made of Titanium 64 (Ti64) and Scalmalloy®, using a pulsed laser, with the aim of reducing their surface roughness. In our experiments, a nanosecond-pulsed infrared laser source with variable pulse durations between 8 and 200 ns was applied. The impact of varying a large number of parameters on the surface quality of the smoothed areas was investigated. The results demonstrated a reduction of surface roughness Sa by more than 80% for Titanium 64 and by 65% for Scalmalloy® samples. This allows to extend the applicability of additive manufactured components beyond the current state of the art and break new ground for the application in various industrial applications such as in aerospace.

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