Muhannad Ahmed Obeidi

• Professor
• Dublin City University

Is additive manufacturing (AM) a sustainable process? Can the process be optimised to produce sustainable AM parts and production techniques? Additive manufacturing offers the production of parts made of different types of materials in addition to the complex geometry that is difficult or impossible to produce by using the traditional subtractive m...

The properties of nitinol, an alloy of nickel and titanium, include its good biocompatibility, corrosion resistance, damping capacity, fatigue strength, superelasticity, and shape memory characteristics. With other conventional methods, it has been challenging to achieve high precision and accuracy of the produced parts; however, laser powder bed f...

Most research to date in the field of L-PBF of nitinol has been with near equiatomic nickel-titanium binary pre-alloyed powders. Significant understanding over the last 10 years has been gained in relation to aspects such as microstructural evolution, control of elemental composition, phase transformation behaviour, control of defects and mechanica...

The realm of Additive Manufacturing (AM), often referred to as 3D printing, encompasses a broad spectrum of applications and methodologies, each contributing distinctively to the progress of this dynamic field [...]

Additively manufactured synthetic bone scaffolds have emerged as promising candidates for the replacement and regeneration of damaged and diseased bones. By employing optimal pore architecture, including pore morphology, sizes, and porosities, 3D-printed scaffolds can closely mimic the mechanical properties of natural bone and withstand external lo...

An impressed current cathodic protection system (ICCP) requires measurements of extremely low-level quantities of its electrical characteristics. The current experimental work utilized the Adafruit INA219 sensor module for acquiring the values for voltage, current, and power of a default load, which consumes quite low power and simulates an ICCP sy...

The microhardness of low carbon mild steel was analysed after surface treatment by using carbon dioxide CO₂ and Fibre laser for comparison. Identical input parameters were used to compare the increase between the as-supplied material hardness and the treated surface. Microhardness testing was used to measure the surface hardness and a scanning elec...

The effect of various solution heat treatment temperatures (i.e., 1120, 1160, 1200 and 1240 °C) on the microstructure, grain morphology and crystallographic texture of IN939 fabricated by powder bed fusion-laser beam (PBF-LB) was investigated. Microstructural analyses showed that the high-temperature gradient and rapid solidification of the PBF-LB...

It is believed that the best parts’ design and performance is that which mimics the creation of nature. Palm is a very good example of an extra ordinary tree which must attract the attention of engineers and designers. In contrast with other types of trees, palms have a vascular, jumble, and spongy tissue stem instead of a wooden one. This is the r...

Owing to the increasing demand for bone repair strategies, several biomaterials have been developed. Among the materials available for this purpose, hydroxyapatite stands out for its osteoinduction capacity, since it possesses a chemical composition similar to that of inorganic bone constituents. In comparison to bones, the mechanical properties of...

Additive manufacturing is growing rapidly in the last decades due to the significant development in the laser technology and metal powder manufacturing. It offers a way to rapidly create near-net-shape engineered parts starting from a digital CAD file without the need for dies or molding. It also offers the ability to manufacture parts designed in...

Recent decades seen the success of Additive Manufacturing (AM) in many industrial applications including aerospace, biomedical, automotive, and tooling. In the manufacturing of metallic parts, AM technology has the ability to produce parts with complex geometries which are difficult or impossible to produce using the conventional fabrication method...

The recrystallization and grain growth behaviour of IN718 alloy additively manufactured by laser powder bed fusion (L-PBF) is presented herein. The effects of three different temperatures (1050, 1150 and 1250 °C) and holding times (15, 45 and 90 min) were investigated. The texture evolution of the samples was recorded via electron backscatter diffr...

This study evaluates the phase and microstructural evolution of additively manufactured (AM) Nickel Titanium (NiTi) alloy, across the interface with 316L stainless steel build plate, in order to understand the processing parameter (input power, layer thickness and scan speed), composition, and microstructure interrelationships necessary to achieve...

Functionally grading material composition in laser-powder bed fusion grants the potential for manufacturing complex components with tailored properties. The challenge in achieving this is that the current laser-powder bed fusion machine technology is designed to process only powdered feedstock materials. This study presents a multi-feedstock materi...

Laser powder bed fusion (L-PBF) success in the industrial scenario strongly depends on the ability to manufacture components without defects and with high building rates, but also on the ability to effectively control the microstructure to gain the required properties in the final component. In this regard, the recently developed numerical simulati...

Functionalised holograms are important for applications utilising smart diffractive optical elements for light redirection, shaping and in the development of sensors/indicators. This paper reports on holographic recording in novel magnetic nanocomposites and the observed temperature change in dry layers and liquid samples exposed to alternating mag...

Laser-powder bed fusion was identified as a promising technique for manufacturing metal matrix composites. However, over a decade later, little progress has been made in addressing the persisting issues hindering the wider exploitation and industrial usage of metal matrix composites. Therefore, the present study proposes the implementation of a fea...

Nitinol alloys have great applications especially in the biomedical industry due to their unique super-elastic and shape memory properties which depends on the balance between the element composition Ni–Ti. For this reason, controlling the applied volumetric thermal energy (VED) during the manufacturing process is very essential in order to identif...

Powder Bed Fusion (PBF) has emerged as an important process in the additive manufacture of metals. However, PBF is sensitive to process parameters and careful management is required to ensure the high quality of parts produced. In PBF, a laser or electron beam is used to fuse powder to the part. It is recognised that the temperature of the melt poo...

Achieving good surface profile and low levels of porosity are prime challenges in the Laser-Powder Bed Fusion (L-PBF) additive manufacturing technique. In order to optimise these properties, post-processing is often required. However, the compression of powder spread on the build plate and re-melting of each build layer during the L-PBF process cou...

Demand for new Ti alloys for AM is immense. Ti–5Al–5Mo–5V–3Cr (wt.%), a β type Ti alloy is chosen for this study as it possesses excellent properties. Samples are manufactured using SLM technique. Relative density, surface morphologies and hardness of samples produced by varying laser processing parameters, e.g., laser scan speed and laser power, a...

Poor surface quality of Additively Manufactured (AM) components, can greatly increase the overall cost and lead time of high-performance components. Examples are medical devices where surfaces may contact the patient's skin and hence need to be smooth and aerospace components with high fatigue strength requirements where surface roughness could red...

Despite the accelerated growth of laser-powder bed fusion in recent years, there are still major obstacles to be overcome before the technology enjoys truly widespread adoption. These include inconsistent part quality and repeatability issues linked to variability in the properties of printed parts. Commonly, the print location across the build pla...

This study is focused on the 3D printing of NiTi shape memory alloy (SMA) in cuboidal shaped samples via the Laser Powder Bed Fusion (L-PBF) process using a dissimilar material build plate of 316L stainless steel. Four processing parameters were investigated at three levels for the optimization of the process. Those parameters were the laser beam p...

In this study, the printing capability of two different additive manufacturing (3D printing) techniques, namely PolyJet and micro-stereolithography (µSLA), are investigated regarding the fabrication of bone scaffolds. The 3D-printed scaffold structures are used as supports in replacing and repairing fractured bone tissue. Printed bone scaffolds wit...

Despite the recent progress in additive manufacturing (AM) process and technology, challenges in the repeatability and reproducibility of AM parts still hinders the adoption of this technique in many industries. This is particularly difficult when a part is qualified on a particular part on a certain machine using optimised parameters. If a manufac...

Poor surface quality represents an important issue that needs improvement for metal Additively Manufactured parts. Both short or long wavelength lasers have been applied for surface polishing in order to improve the surface finish. In this work, the possible use of a CO2 laser for the surface polishing of AlSi10Mg parts made by Laser-based Powder B...

Process monitoring and sensing is widely used across many industries for quality assurance, and for increasing machine uptime and reliability. Though still in the emergent stages, process monitoring is beginning to see strong adoption in the additive manufacturing community through the use of process sensors recording a wide range of optical, acous...

Powder spreading is a crucial step in the powder bed fusion process, which controls the quality of powder bed and consequently affects the quality of printed parts. To date, however, powder spreadability has received very little attention and substantial fundamental work is still needed, largely because of the lack of experimental studies. Therefor...

Additive Manufacturing presents a great application area for Machine Learning because of the vast volume of data generated and the potential to mine this data to control outcomes. In this paper we present preliminary work on classifying infrared time-series data representing melt-pool temperature in a metal 3D printing process. Our ultimate objecti...

This paper focuses on the effects of the laser surface texturing process and joint configuration of stainless steel adherends on the adhesive tensile bond strength. Two different sources, a CO2 and a fiber laser, were used and compared. In particular, proper choice of laser parameters was explored with the aim of producing different roughness and p...

Laser-powder interaction and meltpool dynamics govern the physics behind the selective laser melting process. Spattering is an unavoidable phenomenon taking place during the process which results in reconstituted particles falling within the powder bed. These are known to influence the interaction between the incident laser beam and the powder. The...

In this study, selective laser melting (SLM) was investigated for the manufacturing of 316L stainless steel press-fit joints. The accuracy of selective laser melting technique in fabrication of texture profile in shape, pitch and height of microsurface texturing was examined. The resulting insertion and removal forces achieved from the produced tex...

Additive Manufacturing presents a great application area for Machine Learning because of the vast volume of data generated and the potential to mine this data to control outcomes. In this paper we present preliminary work on classifying infrared time-series data representing melt-pool temperature in a metal 3D printing process. Our ultimate objecti...

Laser-based surface texturing provides highly controlled interference fit between two parts. In this work, artificial intelligence-based models were used to predict the surface properties of laser processed stainless steel 316 samples. Artificial neural network (ANN) and adaptive neuro-fuzzy inference system (ANFIS) were used to predict the charact...

The manufacture of metal parts requires post processing in most cases. These processes include heat treatment for releasing of the residual stresses resulting on the metal surface due to the excessive mechanical forces applies to cut the metal during machining, i.e. milling, turning and drilling. Another example would be the polishing of parts usin...

The laser surface texturing has been developed for a number of applications including for enhancing the tribological properties of structural components and for improved interference fit joints. In this study, the relationship between the micro-surface textures properties and surface texture dimensions of the material such as diameter increase were...

The roughness of a material’s surface is a significant factor affecting the absorption of energy when scanned with laser beam radiation. It is a robust variable affecting the entire laser process cost and the appropriate levels for the laser processing parameters, such as the power applied. It is thus an important factor for many processes, such as...

اخترت مخطوطة للعالم الكوردي المعروف ابن آدم البالكي الذي ولد في مدينة راوندوز عام (1160ه) لتكون مشروع أطروحة الدكتوراه الموسومة بـ ( مصباح الخافية في شرح نظم الكافية لابن آدم البالكي المتوفى على الراجح عام 1237ه – القسم الأول – الأسماء والممنوع من الصرف/ دراسة وتحقيق). إنّ هذه المخطوطة هي في النحو العربي، شرح مفصل لمنظومة: كفاية الطالب نظم كافية اب...

One of the established limitations of metal additive manufacturing (AM) methods, such as selective laser melting (SLM), is the resulting rough surface finish. Laser polishing is one method that can be used to achieve an improved surface finish on AM printed parts. This study is focused on the laser surface polishing of AM parts using CO2 laser beam...

In this study, the suitability of PTFE-based coating deposited on AA3003 Aluminum alloy by a non-conventional method for corrosion and wear protection was investigated. The coatings were deposited from a mixture of PTFE and alumina powders at room temperature and atmospheric pressure . The coatings were characterised with SEM/EDX, XRD and contact a...

The aim of the project is to implement and demonstrate at large scale the long-term technological and economic feasibility of an innovative, sustainable and efficient solution for the treatment of high salinity wastewater from the F&D industry. Conventional wastewater treatments have proven ineffective for this kind of wastewater, as the bacterial...

This study is investigating the effect of the laser surface melting of 316L stainless steel cylindrical samples on the surface residual stresses and the corrosion resistance. A high speed CO2 laser beam with power range of 300-500 W was used in pulse mode to initiate the surface melting in an argon and argon-nitrogen atmosphere. The produced sample...

Laser surface modification can be used to enhance the mechanical properties of a material, such as hardness, toughness, fatigue strength, and corrosion resistance. Surface nitriding is a widely used thermochemical method of surface modification, in which nitrogen is introduced into a metal or other material at an elevated temperature within a furna...

Laser beams attract the attention of researchers, engineers and manufacturer as they can deliver high energy with finite controlled processing parameters and heat affected zone (HAZ) on almost all kind of materials [1–3]. Laser beams can be generated in the broad range of wavelengths, energies and beam modes in addition to the unique property of pr...

Surface roughness control of polymeric materials is often desirable in various biomedical engineering applications related to biocompatibility control, separation science and surface wettability control. In this study, Polyethylene terephthalate (PET) polymer films were irradiated with Extreme ultraviolet (EUV) photons in nitrogen environment and i...

This study is focused on the development of a novel method for designing high-end interference fit fasteners. In this work, a new surface laser treatment process was utilized to enable enhanced usability and bond strength control of press-fit connections. Cylindrical 10 mm diameter pins of 316L were textured over a 10 mm length using a pulsed CO2 l...

The semi-solid metal (SSM) forming process can be applied to achieve near net shape forming of metal alloys, and provides superior component properties compared to those achievable with conventional casting methods. The technique, also commonly called thixoforming, relies on achieving a spheroidal microstructure within the metal alloy so that its f...