Advances in Additive Manufacturing: Materials, Processes and Applications

Frontmatter

Control of the Microstructure and Mechanical Properties of a Super Duplex SAF 2507 Steel Produced by Additive Manufacturing

Abstract

Two-phase duplex stainless steels are widely used in transport industry due to their good fatigue and corrosion properties. Although these steels are investigated when they are produced and/or shaped by conventional processes, few research works have characterized duplex steels obtained by additive processes.

This paper concerns the elaboration and characterization of super duplex steel SAF 2507 obtained by laser powder bed fusion (LPBF). Firstly, the printability of this steel is discussed by analyzing the impact of certain process parameters on the density and microstructure of the material. This as-built microstructure being ferritic and not very ductile, various heat treatments (HT) are, then, applied in order to obtain the typical two-phase microstructure and thus improve the ductility. Afterward, the impact of the different phases (austenite and ferrite) on its mechanical behavior is analyzed.

This work has shown the possibility of obtaining an austenitic-ferritic microstructure close to 50–50 with different grain morphologies with an appropriate post-fabrication TTH. The resulting mechanical properties are satisfactory compared to those of duplex steel obtained by conventional processes.

Maxime Piras, Anis Hor, Eric Charkaluk

Microstructure and Mechanical Properties of Hybrid LPBF-DED Inconel 625

Abstract

The hybridization of Laser Powder Bed Fusion and Direct Energy Deposition could increase the application range of additive manufacturing by benefiting from the resolution of LPBF and the flexibility of DED. However, the microstructures and mechanical properties obtained by these processes are very different. This causes the hybrid parts to be very heterogeneous. The mechanical behavior of hybrid LPBF-DED Inconel 625 parts are investigated under static and cyclic loading. Both as-built and heat-treated Inconel 625 are studied to investigate the role of the specific as-built microstructure. Tensile tests are performed using Digital Image Correlation, which allows the global behavior to be explained by the local behavior of the samples. Hybrid samples are also tested under high cycle fatigue, and fractographic observations permit to determine the initiation sites and mechanisms. The DED is found to be the limitation in both the static and the fatigue strengths of hybrid samples. Hybrid samples perform as well as or better than mono-process DED. In static loading, the local behavior of the hybrid samples and the yield tensile strength gap between LPBF and DED determine the global behavior. The heat-treatment is successful in reducing this gap, and improving the global behavior of the hybrid samples, especially the total elongation. In fatigue, the defects are preponderant compared to the mechanical heterogeneity of hybrid samples.

Noémie Martin, Anis Hor, Etienne Copin, Philippe Lours, Léon Ratsifandrihana

Manufacturability of CoCrFeNiMnzAlxCuy High Entropy Alloy by Laser Powder Bed Fusion

Abstract

Six pre-alloyed high entropy alloys powders from the CoCrFeNiMn_zAl_xCu_y family were used to manufacture samples through Laser Powder Bed Fusion technology. These samples were used to assess the manufacturability, microstructure and mechanical properties of the developed alloys. It was found that increasing the Al concentration promoted the formation of a BCC/B2 phase, increasing the hardness and having a direct positive impact on the tensile properties. However, adding more aluminium than what can be found in the Al_0.5CoCrFeNi alloy led to extensive manufacturability issues that hindered the tensile properties. On the other hand, the Cu concentration did not appear to yield any significant impact on the microstructures and mechanical properties of the alloys. The considered additively manufactured alloys presented an overall higher hardness than their conventionally manufactured counterparts, but a lower ductility. Thermal treatment led to the precipitation of a σ phase in Al-containing HEAs, and of a secondary FCC phase in Cu-containing alloys. Finally, this paper proves the potential of the CoCrFeNiAl_x alloy family compared to single-phase stainless steels such as 316L and two-phase stainless steels such as SAF 2507.

Eric Barth, Anis Hor

Mechanical Properties of Additively Manufactured 17-4PH SS: Heat Treatment

Abstract

The effects of the thermal post-treatments on the mechanical properties of SLMed 17-4PH stainless steel are studied. Three thermal post-treatments are carried out: (E0) as received state, (E1 and E2) solution annealing treatment and (E3) aging treatment. Microhardness, impact-strength, and wear tests are carried out to determine the effect of treatment on the mechanical properties of SLMed 17-4PH. The results showed that the hardness of 17-4PH at the E0 state is a greater than the hardness of the powder. This hardness decreases slightly from 418 HV to 384 HV after the solution annealing treatment E2 and increase again after E3 ageing treatment to around 447HV. A hardness difference between the two manufacturing directions was also observed. This difference almost disappears after the E3 ageing treatment. The impact strength results show a huge drop in impact strength for 17-4PH obtained by SLM. An improvement in wear behaviour following heat treatment, especially in the case of ageing.

Thabet A. M. Sghaier, Habib Sahlaoui, Tarek Mabrouki, Haifa Sallem, Joël Rech

Nitinol Stents Printed by Selective Laser Melting

Abstract

Nitinol alloys stents have been printed by Selective Laser Melting from a gas atomized powder with a composition of 50.8 at% Ni. The energy density has been adapted to set the austenite finish temperature just below the human body temperature, therefore the stent diameter can be reduced by plastic strain at lower temperature and recover its former expanded shape after being inserted in the artery. Several mesh geometries have been mechanically analyzed by finite elements modeling to ensure that the local strain will not exceed superelastic reversible capacity of 4% while squeezing the stent diameter by a factor of 4. The stent surface has been treated by electropolishing to reduce its roughness to Ra < 0.02 mm. After polishing, some samples have been coated by a 50 nm thick TiO₂ layer by Atomic Layer Deposition. Biocompatibility and hemocompatibility analysis demonstrated that the TiO2 coating significantly improved hemocompatibility. Nevertheless, uncoated stents are also biocompatible and hemocompatible according to ISO-10993–12 guidelines.

Jean Pralong, Livia Jerjen, Bruno Schnyder, Oksana Banakh, Tony Journot, Haifa Sallem, Samuel Rey-Mermet

Preliminary Study of Geometric Defects and Topography of Bio-Carriers Fabricated by the FDM Printing Process

Abstract

The Fused Deposition Modeling (FDM) process is one of the most widespread additive manufacturing technologies today. However, it still suffers from a great problem of anticipation of the quality of the manufactured product. Indeed, the quality of the output product is a key parameter in the acceptability of the end user. Many fields such as aeronautics, biomedical, food, pharmaceutical require many strict conditions for the acceptability of the product. In biological fields, and especially in the pharmaceutical field, the 3D printed product must meet the standards and requirements of the field to be accepted. In this context, our paper aims at analyzing the influence of some input parameters on the geometrical and topographical quality of samples dedicated to a biological application called bio-carrier. These bio-carriers are small structures used to capture phages when they are present at low titers. The 3D printed bio-carrier has also been used to enrich in vitro preparations for priming phage cultures to rapidly achieve high titers suitable for phage therapy applications. Phage therapy is used as a potential substitute for chemical antibacterial therapy.

A Design Of Experience was adopted, in which the size, thickness and filling rate of the bio-carrier were chosen as input parameters. The analysis of this design showed that the sample size is the key parameter that can improve or reduce the geometric effect. Increasing the sample size can reduce the geometric defect. The sample topography is influenced by the fill rate which is the most important factor.

Nada Ben Hariz, Atef Boulila, Mahfoudh Ayadi

Determination of Mechanical Parameters of 3D-Printed Parts: Experimental and Numerical Analyses

Abstract

Additive manufacturing process allows obtaining structured light parts widely desired by designers. The mechanical behavior of such materials is anisotropic and their mechanical parameters have to be precisely determined in order to obtain reliable numerical simulations. In this paper, the mechanical parameters of a grid pattern with an infill density of 60% are experimentally determined. The elasticity matrix is determined by considering a cubic anisotropy. In addition, the Hill48 criterion is adopted and rewritten in the case of the cubic anisotropy. For this end, the tensile and the shear tests are used in order to obtain the mechanical parameters in both elastic and plastic domains. For the sake of validation of the obtained parameters, flat-ring parts are additively manufactured by considering two raster orientations: 0°/90° and −45°/45°. These parts are subjected to the compression test and the applied load vs. the punch stroke is experimentally obtained showing the influence of the printing parameters on the mechanical responses. The effect of the raster orientation is then clearly observed showing that the raster orientation of −45°/45° leads to more resistant parts. Finally, the obtained numerical results are compared with experiment. It is found that the numerical simulations fit very well the experimental results.

Sami Chatti, Amina Remadi

3D Printed Educational Robotic Arm

Abstract

This paper presents an exploration concerning the employment of the additive manufacturing process in the fabrication of educational robot prototypes that mimic the technical qualities and operating characteristics of industrial robotic arms. Specifically, we present the 3D printing process of an open-source model called the EEZYbotARM MK2, using Fused Deposition Modeling (FDM). This model shares the kinematic structure of the industrial ABB IRB 460 robot. The 3D printed is proposed as an educational robot for the Higher Institute of Applied Sciences and Technology of Sousse (ISSAT-So). The 3D printing process involves the use of PLA filament and the RAISE3D N2 printer. We present the proposal printing parameters applied to achieve an efficient quality of the printed parts, within a minimum amount of printing time. Finally, we present the assembled EEZYbotARM MK2 and its potential applications for educational purposes in the field of robotics. The results demonstrate the potential of 3D printing in the development of educational robot prototypes, and the importance of open-source models for the circularity and the availability of robotics education.

Mohamed Slim, Mohamed Ali Terres

Topological Optimization of Ti-6Al-4V Knee Prostheses Through Lattice Structures for Enhanced Mechanical Performance

Abstract

In this study, we performed a topological optimization on a knee prosthesis made of Ti-6Al-4V titanium super alloy using metallic additive manufacturing. The optimization was done using nTopology software, wherein lattice structures were incorporated within the femoral component to reduce its weight while maintaining adequate mechanical strength. A comparative analysis of the prosthesis’ mechanical strength with and without optimization was conducted. Our simulation results, obtained through ANSYS, reveal the advantages of topological optimization in the medical industry.

M. Frija, A. Toumi, M. Khodja

Manufacturing of Cranial Implant Using SPIF and 3D Printing

Abstract

The single-point incremental forming (SPIF) and fused deposition modelling 3D printing (FDM) are used in the manufacture of parts for small series and prototypes in various sectors such as aeronautics, biomedical field, and art pieces. In this sense, recent published results have revealed an increasing interest in shaping components for biomedical uses. This work aims to study the geometric precision of the two methods during the development of a cranial implant and to compare the fidelity of the parts to be developed to the CAD part

Sofiene Marzouki, Slim Bouzidi, Atef Boulila

New Horizons in Engineering Education: From Additive Manufacturing to Immersive Learning

Abstract

Additive Manufacturing (AM) has now become a fully-functional production process, which is becoming more and more widespread in various industrial sectors. Besides, AM has the potential to enhance learning by providing engineering students with hands-on, experiential and interactive learning experience. In the same line, higher education’s focus on immersive learning has gained significant traction, thanks to the rise of digital technologies. In this context, this work reports the project conducted in the learning factory developed at the Industry 4.0 laboratory of the National Engineering School of Tunis (ENIT). Current projects are presented and challenges are pointed out.

Safa Bhar Layeb, Amel Jaoua, Mikel Noomen

Exploring Human-Cyber-Physical Systems in Additive Manufacturing: Insights into Human-Machine Collaboration

Abstract

The technology known as additive manufacturing, or 3D printing, has swiftly emerged as a revolutionary force that could transform the process of product design and manufacturing. This convergence of the physical and digital worlds has given rise to human-cyber-physical systems (HCPS) within additive manufacturing. HCPS involves seamless collaboration and interaction between humans, machines, and software, creating new possibilities for designing and producing products. Consequently, comprehending the intricacies of human-machine collaboration within HCPS becomes essential for unlocking the complete potential of additive manufacturing. Building upon our previous work, we aim to leverage our expertise in human-machine interaction to explore its application within the realm of additive manufacturing. This paper aims to investigate HCPS in Additive Manufacturing (AM) by providing valuable insights into the factors that contribute to effective collaboration between humans and machines. Through a comprehensive analysis of existing literature and case studies, we intend to shed light on the challenges and opportunities in this field, as well as identify key areas for future research and development.

Anis Hamza, Noureddine Ben Yahia

Simplification of an Additive Manufacturing Machine Implementation Using Its CAD Model and Mixed-Reality

Abstract

This study presents the development and evaluation of a Mixed Reality (MR) tool called HoloPrint, designed to assist students in learning how to use a Filament Deposition Machine (FDM) for 3D printing. The HoloPrint tool combines a MR headset with a pedagogical scenario based on teacher feedback and is tailored to the expected competency profiles of students. The proof of concept phase focuses on understanding how users adopt this novel way of interacting with a combined virtual and real environment while accomplishing the scenario's objectives. A homogenous population of 81 first-year engineering students at INSA Toulouse was selected to participate in the study. The experiment was conducted during practical work sessions with 8 classes, each consisting of 10 students. The study evaluated the success rate of students using HoloPrint and assessed the tool's usability and usefulness through the System Usability Scale (SUS) questionnaire. Results indicate a high success rate of 98.8% for students using HoloPrint to print objects without assistance. The average SUS score for the tool was 79.69, indicating “Good” acceptability and nearing “Excellent.” Furthermore, prior experience with 3D printers or VR headsets did not significantly impact the success rate or SUS scores, suggesting the tool's effectiveness in aiding both novice and experienced students. In conclusion, the study demonstrates the potential of Mixed Reality as an effective and user-friendly tool for training students on a simple additive manufacturing machines, it enables the researchers to conduct further experimentation on more complex additive manufacturing machines.

Mina Ghobrial, Philippe Seitier, Michel Galaup, Pierre Lagarrigue, Patrick Gilles

A CAD-Based Method for the Measurement of AM Parts Accuracy Considering the Build Orientation

Abstract

In Additive Manufacturing (AM), several printing processes such as Fused Deposition Modelling (FDM) can deliver complex parts and shapes in short building time using different types of materials. However, the quality and the accuracy of the printed parts might vary according to several print input parameters. In this regard, the present paper aims to study and quantify the effect of the build orientation parameter on the dimensional accuracy of printed parts in FDM 3D printing. An example of a part prototype is manufactured based on the FDM technique and considering different build orientations. Points cloud of the printed prototype is extracted using the 3D scan method. The realistic CAD models of parts features are determined considering the point clouds resulting from the scan process. The dimensional accuracies of the reconstructed parts features are computed according to different build orientations. The developed method can be considered a preliminary decision support tool that assists designers and 3D printing manufacturers in the investigation of the build orientation impact on the accuracy of the printed parts features.

Ahmed Elayeb, Anis Korbi, Riadh Bahloul, Farhat Zemzemi, Mehdi Tlija, Borhen Louhichi

Thermal Study for Optimization of the Thermomechanical Welding Butt Fusion Process of the PEHD Tubes (PE100)

Abstract

Today, high-density polyethylene (HDPE) is the frequently used polymer in the world for public water and gas distribution, and also for the disposal of wastewater. The welding butt fusion technique of polyethylene tubes (HDPE) is that most chosen in the thermoplastic industry given its efficiency and advantages over other processes and through which the mechanical behavior of the welding can approach that of the original materials. We focus our study in this document on the study of distribution and the effect of temperature at the welding juncture, modified welding parameters: heating temperature, heating time and welding force (for fixing the other welding parameters). The issue of this article is the control of the temperature and the thickness of the molten zone allows a partial improvement in a technical origin of the welding joint’s quality.

Awadi Walid, Zidi Mondher

Additive Manufacturing and Investment Casting Comparison of Superalloys: Aerospace industry

Abstract

Investment casting is one of the oldest technologies used in the world. Recently, metal additive manufacturing (AM) has been evolving rapidly. Indeed, AM is defined as a process of shaping a part by adding a layer-over-layer. However, AM is limited to the production of parts in small and medium series. This paper consists of a review of the AM versus the Investment casting technology of super alloys such as Nickel and Cobalt based alloys. Moreover, it shows a comparison between processes complexity, advantages, disadvantages, product quality, production cycle time and production costs.

B. Aouadi, S. Ghannem, B. Ben Fathallah, M. A. Yallese

The Impact of the Adaptive Slicing Integration on the AM Cost

Abstract

The manufacturing industry has been revolutionized by additive manufacturing (AM) by allowing the creation of complex geometries that were once impossible to manufacture using traditional methods. However, the layer-by-layer approach of additive manufacturing can result in dimensional and geometric errors due to the staircase effect, particularly in parts with complex shapes. Hence, achieving a balance between the quality and the cost is one of the most AM challenges. In this context, Design for Additive Manufacturing (DFAM) and adaptive slicing have emerged as promising approaches to reduce these errors while establishing a balance between the AM quality and cost. This work focuses on the importance of the adaptive slicing in minimizing the AM time and cost during the DFAM phase. A method for adaptive slicing is proposed based on minimizing errors due to the staircase effect caused by shape curvatures in the part. The results demonstrate that the proposed method can in some cases significantly save more than 80% of building time and cost in order to obtain the same surface quality comparing to the standard slicing method. Moreover, this slicing technique also improves the parts dimensional and geometrical tolerances, hence, reduces errors and improves the overall quality. The presented approach has the potential to enhance the capabilities of additive manufacturing, allowing the creation of parts with higher accuracy and precision, and reducing the need for post-processing.

Ahmed Elayeb, Farhat Zemzemi, Mehdi Tlija, Borhen Louhichi

In-Situ Monitoring of Selective Laser Melted Ti–6Al–4V Parts Using Eddy Current Testing and Machine Learning

Abstract

Metal laser powder bed fusion (L-BPF) technology is one of the most common and evolved additive manufacturing technologies to fabricate metal components. However, the control of defects generated during the SLM process remains an essential technological challenge for its implementation in production lines. In this work, based on the combination of eddy current testing (ECT) and machine learning (ML) approach, we propose a methodology allowing the in-situ monitoring of LPBF process porosity defects of Ti-6AL-4V components. The present empirical approach is achieved by setting up trained AI algorithms for the in-situ detection of porosity defects generated during the part fabrication. The algorithms are fed with data collected layer by layer using a specific experimental set up composed of an ECT system mounted on the machine recoater of the SLM machine. Comparison between predicted and experimental outcomes shows the effectiveness of the proposed framework which allows the prediction of porosity defects layer by layer with a mean absolute error (MAE) of 0.1% for CNN2D algorithm and 0.11% for LSTM one. The framework developed in this study can be effectively applied to quality control in additive manufacturing.

Haifa Sallem, Hatem Ghorbel, Edouard Goffinet, Adeline Cinna, Jean Pralong, Jonatan Wicht, Bernard Revaz

Non-conformities and Scrap Costs Reduction in a 3D Printing Workshop

Abstract

The aim of this study is to reduce non-conformities and scrap costs in a Tunisian 3D printing workshop. Therefore, we performed a resolution of problems methodology. We started by defining the problem. According to a preliminary diagnosis of the 3D printing workshop, it was impossible to conduct a numerical analysis due to the lack of indicators and non-conformities registration. So, we began our work by establishing key performance indicators to gain insights into the different machines of this workshop. Then, we developed a non-conformities registration document. This document was essential to realize the Pareto Analysis which revealed that” low extrusion density” is the main non-conformity. After identifying its main causes through a root cause analysis, we implemented improvement actions consisting principally of the optimization of printing parameters. In the last step ‘‘review of results’’, we noticed an average of 15% reduction in the non-conformity rate and scrap cost. We showed also, through this article, that low extrusion density non-conformity exists regardless of the generation of the machine and that key performance indicators are essential and can be adapted to reflect the real state of 3D printing workshops in a Tunisian industry.

Safa Mathlouthi, Abd El Hedi Gabsi

Contribution to the Formulation of a Material Based on Marble Waste for Its Use in 3D Printing in Civil Engineering

Abstract

The objective of this research is to experimentally study the way of recovery and recycling of marble processing waste mixed with other materials for 3D printing in Civil Engineering. In this paper, we present the framework of this study and the approach to be followed in the feasibility study of the use of Tunisian marble powder in the formulation of a printable material in Civil Engineering. Local materials from Tunisia (marble rock processing waste), now considered as waste, will be recycled in the field of additive manufacturing. We propose an experimental protocol and the first results of the characterization of the raw materials used. In particular, the marble powder used is calcium-dominant and contains a low percentage of Quartz and Dolimite, It has a density of 1.22.

Habib Zargayouna, Essaieb Hamdi, Tarek Mabrouki

Easy Conversion of PET Bottles to Eco-Filament for 3D Printing and Process Characterization

Abstract

Due to the economic and ecological impact, material recycling technologies are increasingly privileged and preferred over to standard processes. In this article, we focus on the potential to recover polyethylene terephthalate (PET) from water and soft drink bottles that have been poorly stored, transported and used, as well as from bottles from different manufacturers. The process used is to convert the bottle into a 1.75 mm diameter filament without fragmentation or dissolving. It does not require any heavy or industrial equipment and can be easily made even by 3D printing enthusiasts. We then used an FDM (Fused Deposition Modeling) 3D printer to build the modeled shape using the resulting filament.

The results of the process were characterized (tensile strength and hardness) and compared with those of 3D printing with “polylactic acid” (PLA), the most commonly used material in this type of printing. It offers adequate properties for many applications (close mechanical properties: elasticity around 230 MPa, maximum mechanical strength around 29 MPa, hardness around 10 MPa).

Chokri Ben Aissa, Abd El Hedi Gabsi, Safa Mathlouthi, Abdelkarim Ghanem

Modeling and Optimization of Joint Condition Based Quality/Maintenance Strategy for an Additive Manufacturing Equipment

Abstract

In industrial plants, operations management encompasses three main functions: quality management, production scheduling, and maintenance planning. While these functions are interconnected in reality, they are often treated separately in practice. However, it is widely recognized that handling these parameters in isolation can lead to suboptimal solutions. To address this issue, this paper proposes an integrated approach for jointly controlling production, quality, and maintenance in the context of additive manufacturing. Specifically, we focus on an Additive Manufacturing Equipment that produces a single type of product and undergoes a degradation process, resulting in the production of non-conforming units. To make informed decisions regarding the maintenance plan, inspections are conducted to monitor product quality and machine degradation. Our strategy involves establishing a relationship between the state of the quality indicator and the level of machine degradation, thereby studying their collective impact on the maintenance plan. The objective is to minimize the average total cost per unit of time, taking into account maintenance costs, quality-related costs, and production costs. To achieve this, we develop a mathematical model and provide a numerical example to calculate optimal values for the decision variables. The proposed approach is applied to address the maintenance planning challenge for 3D printer machines.

Zeineb Boumallessa, Mounir Elleuch, Houssam Chouikhi, Hatem Bentaher

Experimental and Numerical Study of the Wire Arc Additive Manufacturing (WAAM) Process

Abstract

Wire Arc Additive Manufacturing (WAAM) is an additive manufacturing process that utilizes an electric arc to melt and deposit metal wire layer by layer, creating a three-dimensional component. This process offers several advantages, such as the ability to produce large-sized parts. It is increasingly being utilized in industries for the production of components for aerospace, automotive, shipbuilding, and other applications. However, it also comes with drawbacks, including low surface resolution and the need to manage deformations and residual stresses. Continuous research and development in this technology are crucial to optimize manufacturing parameters and enhance the mechanical properties and quality of produced parts. In this study, an experimental investigation was conducted to determine the optimal parameters of the WAAM process for producing complex parts. Simple and complex components were fabricated using this process. A numerical model of the WAAM process was developed using the LS-DYNA code. This numerical simulation can aid in understanding the material behavior during the welding process.

Seddik Shiri, Mounir Rabhi, Ated Ben KhalifA, Khaled Boulahem, Fethi Aloui, Sami Chatti

Parameters Effect Study on Bead Geometry Deposited by CMT Technology Based Wire Additive Manufacturing (WAAM) Process

Abstract

Wire-Arc Additive Manufacturing has gained attention due to its ability to build high integrity metal parts. Nevertheless, some challenges persist in this technology, mostly in obtaining optimal deposition parameters that allow for obtaining parts with high geometry quality. The purpose of this study was to investigate the effect of process parameters on the quality of the welded bead made by WAAM deposition strategy based on CMT technology, for samples created using AISI 316L stainless steel welding wire, build up on an AISI 304L stainless steel substrate. A Multiple-Level Factorial Design was carried out, followed by an analysis of variances (ANOVA) to assess the effects of travel speed (TS), wire feed rate (WFR) as well as gas flow rate (GFR) on the beads geometry. The obtained results are promising to be used in future research, such as wall deposition strategy.

Oussama Trad, Ated Ben Khalifa, Farhat Zemzemi, Hédi Hamdi, Borhen Louhichi

Use of the RDPP-SF Method for Robust Design of Dynamic AM-Fused Deposition Modeling Process

Abstract

In manufacturing processes, dynamic systems are extensively used, and finding out the optimal setting of the signal and the operating parameters, which yields the least sensitive design solution about the process responses is a crucial issue. The article proposes a stochastic method (RDPP-SF), which can account for uncertainty in dynamic systems. The method determines the optimal design solution while providing estimates of the natural part-to-part and noise variation components. The virtue of the proposed method is finally demonstrated using an AM-FDM process to monitor the variability in the X, Y, and Z directions of part geometry about a hypothetic CAD model.

Marwan Amdouni, Atef Dhokkar, Ali Trabelsi, Mohamed-Ali Rezgui

Effect of Printing Process Parameters on the Tensile Behavior of FDM-Built Parts

Abstract

The present study deals with the qualification of the effect of polymer printing parameters on tensile mechanical properties of parts manufactured based on the fused filament deposition (FDM) process. Two types of polymers, namely PLA and PETG, were selected for this study. For that the influence of three key FDM parameters which are layer thickness, infill ratio and infill pattern on the mechanical behavior of precited parts were evaluated according a design of experiment. Particular attentions were taken to Young’s Modulus (E) and Ultimate Tensile Strength (UTS) evolutions. The results demonstrate that these three process parameters have an important influence on the variation of the tensile properties of FDM-manufactured parts. Furthermore, optimal printing parameters for PLA and PETG were determined resulting in higher mechanical properties than those obtained using parameters indicated in the filament technical datasheets.

Asma Belhadj, Salma Slama, Mouhamed Hichem Habouba, Tarek Mabrouki

Experimental Investigation of SLM Parameters Effects on Roughness of 316L Parts

Abstract

This work is an experimental parametric study that employs the design of experiments methodology to investigate the influence of printing parameters on the surface quality of 316L stainless steel parts manufactured through the SLM process. To achieve this objective, a full factorial plan consisting of three factors at three levels is used. The factors investigated are laser power (P), scanning speed (V) and hatching distance (HD). This study involves assessing the impact of these parameters on the roughness of SLM printed parts and determining the various combinations that result in a good surface condition.

Oussema Bouguerra, Salma Slama, Asma Belhadj, Noureddine Barka

Experimental Study of Morphological Defects Generated by SLM on 17-4PH Stainless Steel

Abstract

For cyclic loading applications and critical structural, the emergence of flaws in additively manufactured components is a key concern. This study highlighted the defects generated by selective laser melting (SLM) to the 17-4 PH stainless steel parts. The defects were quantified using an experimental study: Optical microscope and roughness meter to evaluate surface morphology (roughness and porosity) and microstructure. Tensile tests to evaluate the mechanical performance. The defects recorded take several forms, the most important of which are the rough and heterogeneous surface, prominent bumps on the outer surface in the shape of a hemisphere, cavities inside the spaced and adjacent parts of different shapes, internal cracks perpendicular to the printing direction, undissolved particles confined in the dissolving structure layers, brittle behaviour, non-resistant attractive and heterogeneous structure etc.

Thabet A. M. Sghaier, Habib Sahlaoui, Haifa Sallem, Tarek Mabrouki, Joël Rech

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