Critical Buckling Load for Lattice Column Elements with Variable Dimensions

Purpose The paper aims to evaluate the energy absorption properties of optimised strut cross-section AlSi10Mg lattice structures fabricated by laser powder bed fusion (PBF-LB) additive manufacturing (AM). Quasi-static evaluations indicate a transformation in deformation behaviour of lattices with increasing optimisation which supports strong energy absorption capabilities. Design/methodology/approach The paper applies a novel strut element optimisation method using a hybrid continuum-beam finite element model to improve energy absorption in metal lattice structures. Impact testing occurs on laser powder bed fusion (PBF-LB) fabricated aluminium alloy (AlSi10Mg) lattices specimens to validate the approach. Findings The study provides both a qualitative and quantitative understanding on how PBF-LB AlSi10Mg lattices behave at high strain rates and how strut geometry can be manipulated to produce superior as-manufactured structures. Research limitations/implications The qualification of structures produced by AM is dependent on material, structure and process technology. Further evaluation of geometric and topologic derivatives of the presented structures is required. Practical implications The paper demonstrates the refinement of lattice structures for the use as metamaterials with unique properties unattainable through conventional material science. Social implications The efficient distribution of lattice material reduces unnecessary material expenditure. Structural optimisation provides the means to further reduce expenditure for high value applications such as crash safety and biomedicine. Originality/value This study provides a method to elicit different behaviours and properties in metal lattice structures, which may lead to wide reaching applications as they become more common in engineering industry. It also provides a direct evaluation of mechanical properties of optimised metal lattice structures.

Gas turbines play a critical role in industries such as power generation and aviation. Additive manufacturing has emerged as a game-changing technology for gas turbine components, offering superior design flexibility and performance enhancements. The present work provides an overview of a multistep approach for integrating lattice structures into a specific gas turbine component, the Nozzle Guide Vane (NGV), using additive manufacturing technology. The first step involves a comprehensive assessment of lattice structures’ influence on the mechanical and thermal properties of the exposed part of NGV. Through computational simulations and experiments, an ideal lattice geometry is determined, optimizing structural integrity and heat transfer properties while minimizing volume usage. The second step sets the baseline performances of the current NGV system components, which were investigated and selected for additive manufacturing analysis. The third step focuses on the overall effect of additive manufacturing capabilities in the NGV system. The fourth and final step optimizes the additive manufacturing process for fabricating gas turbine components with lattice structures. Laser Powder Bed Fusion (L-PBF) technology, united with advanced Topological Optimization analyses, and high-temperature alloys were selected to withstand the demanding gas turbine operating conditions. This multistep approach represents a significant step forward in gas turbine technology, capitalizing the advanced mechanical applications as lattice designs and additive manufacturing, aiming in enhanced performance, reduced weight, and improved efficiency. These developments hold the potential to achieve more sustainable and cost-effective energy generation and transportation systems.

Advancements in understanding the microstructure and properties of additive manufacturing Ti-6Al-4V alloy: A comprehensive review

Metal additive manufacturing (AM) offers promising advancements in producing implants with complex geometry for biomedical applications, where accuracy and near-net-shape production are essential. Metal AM by laser powder bed fusion (PBF-LB) is a promising route to produce biodegradable iron implants made of complex lattice structures. However, processing windows for pure iron remain poorly defined. This work focuses on optimizing PBF-LB parameters for pure iron using a design of experiments (DoE) approach on bulk samples of different geometries to evaluate different parameters. Hatch laser power, scanning speed, hatch distance and point distance were varied and their effect on porosity, surface roughness and dimensional accuracy was evaluated. This was followed by the fabrication of rhombitruncated cuboctahedron (RTCO) lattice structures with the best parameters previously defined for the bulk samples. The best parameter set (hatch laser power 180 W, scanning speed 600 mm/s, hatch distance 110 µm and point distance 12 µm, corresponding to a volumetric energy density of 90.9 J/mm3) produced bulk samples with a porosity as low as 0.07% (99.93% density) measured in polished sections. Using these parameters, RTCO lattices with designed relative densities of 10.28%, 35.29% and 65.16% were successfully manufactured with small geometric deviations and good control of strut thickness and relative density. The results of this study define a robust PBF-LB processing window for pure iron and demonstrate the feasibility of producing geometrically controlled, biodegradable iron lattice structures suitable for future load-bearing biomedical applications.

Recently, Additive Manufacturing (AM) technology has been attracting interest because of its process to fabricate directly from CAD data. A laser powder bed fusion (L-PBF), one of the AM technologies, is able to form the metal three dimensional (3D) objects from metal powder by building it layer-by-layer. Generally, intensity distribution of the laser beam employed by L-PBF is Gaussian. Therefore, these beam shape has energy gradient. It is difficult to fabricate with high precision due to metal powder is aggregated at the lower energy area of beam spot. In this study, fabricated with L-PBF for the purpose to clarify the effects of energy gradient of beam spot on surface roughness Ra of 3D objects. As the evaluation method of 3D objects fabricated with L-PBF, it is employed to measuring surface roughness Ra and Vickers hardness.Recently, Additive Manufacturing (AM) technology has been attracting interest because of its process to fabricate directly from CAD data. A laser powder bed fusion (L-PBF), one of the AM technologies, is able to form the metal three dimensional (3D) objects from metal powder by building it layer-by-layer. Generally, intensity distribution of the laser beam employed by L-PBF is Gaussian. Therefore, these beam shape has energy gradient. It is difficult to fabricate with high precision due to metal powder is aggregated at the lower energy area of beam spot. In this study, fabricated with L-PBF for the purpose to clarify the effects of energy gradient of beam spot on surface roughness Ra of 3D objects. As the evaluation method of 3D objects fabricated with L-PBF, it is employed to measuring surface roughness Ra and Vickers hardness.

Additive manufacturing (AM) technology can potentially disrupt offshore and marine industry by effectively reducing manufacturing processes and leadtime, and enabling new product designs. A review of existing literature has revealed limited knowledge in using AM to process shipbuilding materials, which can otherwise enhance existing shipbuilding manufacturing workflow. This has led to the research motivation to establish the technical feasibility of using selective laser melting (SLM) to process ASTM A131 EH36 shipbuilding steel. SLM process is a widely understood AM technology that has been used extensively to process other type of steels, for example stainless steel 316L. EH36 belongs to a class of high tensile low alloy steel which has traditionally been processed through casting. However, knowledge on using lasers to process EH36 is largely unknown, especially in AM applications. Using SLM to process EH36 is novel and will solve the problem of lack of knowledge in this field. The study thus aims to further the understanding of the mechanical properties and microstructure of SLM processed EH36. A preliminary investigation was first carried out to establish the technical feasibility of using SLM to process EH36. The process parameters obtained were then used to further the investigations. Heat treatment process was applied as a possible post processing technique. Mechanical testing was carried out to characterise its mechanical properties. The fracture surfaces and microstructures were then studied to characterise the material. The results showed that EH36 can be processed using SLM without any visible cracks. The mechanical properties of as built SLM processed EH36 exhibit very high tensile strength, but low ductility. The ductility can be improved through tempering heat treatment process, but at the partial sacrifice of tensile strength. Fractography analysis also affirmed the lack of ductility in the SLM processed EH36 samples. Finally, the microstructure showed that fine grain size and martensitic microstructure were the primary drivers behind its high tensile strength. Tempered samples experience grain coarsening and phase transformation to a mainly ferritic structure, which led to recovery in its ductility but a decrease in the tensile strength. A scaled model was fabricated to validate the results from the microstructure studies, and the findings indicate similar microstructures formed. This demonstrates the repeatability of the developed process parameters on fabrication of complex joints. The study contributes to the scientific knowledge with regard to material and mechanical property characterisation of SLM processed EH36. The findings from the fractography and microstructural analysis will contribute towards building the knowledge and facilitate future work on AM of EH36.

Chapter 25 - State-of-the-art in additive manufacturing of Ti–6Al–4V: recent progress and insights into future developments

Laser additive manufacturing of cellular structure with enhanced compressive performance inspired by Al–Si crystalline microstructure

Additive manufacture (AM) technologies allow innovative structural design, including complex lattice structures. Selective laser melting (SLM) is an AM process that enables the manufacture of space filling lattice structures. Lattice structures are topologically ordered, three-dimensional open-celled structures composed of one or more repeating unit cells. From a mechanical designer viewpoint, a great advantage offered by cellular materials is high strength accompanied by a relatively low mass. Due to their complex structure, fine geometry and the absence of supports structures, the setting of the best parameters to print lattice structures is difficult and could negative influence their mechanical response. This study investigated how different parameters settings influence the compression behaviour of lattice structures in stainless steel 17-4PH (AISI-630) printed by SLM. A comparison between compressive response of structures printed with different parameters is presented and considerations about their behaviour exposed.

Additive manufacturing of WC reinforced maraging steel 300 composites by cold spraying and selective laser melting

Microstructure and fatigue performance of SLM-fabricated Ti6Al4V alloy after different stress-relief heat treatments

This study examined the application of two additive manufacturing (AM) technologies, namely Directed Energy Deposition (DED) and Laser Powder Bed Fusion (L-PBF), within the oil and gas industry with a special focus on the African context. The research highlights the role of these advanced AM technologies in enhancing efficiency and promoting sustainable industrial practices. It further explores the benefits of DED and L-PBF, such as their ability to produce complex, custom metal components, which is crucial for the African oil and gas sector in reducing downtime and operational costs. Various case studies are presented to demonstrate the practical application and benefits of these technologies in the industry. The study also addresses the challenges of implementing DED and L-PBF in Africa from an industry perspective, including skill development and infrastructural needs, and proposes various solutions. Furthermore, the environmental and economic implications of these technologies are discussed, showcasing their potential to support sustainable practices and drive industrial growth in the region. In conclusion, this paper offers a detailed perspective on the role of DED and L-PBF in revolutionising welding practices in the oil and gas industry, providing insights into the benefits, challenges, and strategies for their effective implementation in Africa.

Additively manufactured Ti–6Al–4V thin struts via laser powder bed fusion: Effect of building orientation on geometrical accuracy and mechanical properties

Additive Manufacturing (AM), popularly called 3D Printing, is a scientific term indicating the Rapid Prototyping (RP) technologies developed in 1980s. AM technologies can directly fabricate a complex 3D object from three-dimensional Computer Aided Design (3D CAD) model by adding layer-by-layer of material. Advances in AM technologies are capable of manufacturing highly complicated geometries of product without the need for process planning, the reduction of product development time and cost, the removal of tooling compared to conventional manufacturing technologies. The production of lattice structures is quickly performed by AM technologies in order to attain a product with lightweight and stronger and to provide the high specific mechanical properties such as strength and energy absorption. However, the current product modelling technologies have many difficulties for generation of lattice structure model. Thus, the paper proposes a new approach that allows to create different configuration types of conformal and non-conformal lattice structure model.

Additive manufacturing (AM) of hot-work tool steels such as H13 offers unique opportunities for producing complex, conformally cooled tools with reduced production time and material waste. In this study, five metal AM technologies—Fused Deposition Modeling and Sintering (FDMS, Desktop Metal Studio System and Zetamix), Binder Jetting (BJ), Laser Powder Bed Fusion (LPBF), and Directed Energy Deposition (DED)—were compared in terms of microstructure, porosity, and post-processing heat treatment response. The as-printed microstructures revealed distinct differences among the technologies: FDMS and BJ exhibited high porosity (6–9%), whereas LPBF and DED achieved near-full densification (<0.1%). Samples with sufficiently low porosity (BJ, LPBF, DED) were subjected to tempering and quenching treatments to evaluate hardness evolution and microstructural transformations. The satisfactory post-treatment hardness was observed in both tempered and quenched and tempered BJ samples, associated with secondary carbide precipitation, while LPBF and DED samples retained stable martensitic structures with hardness around 600 HV0.5. Microstructural analyses confirmed the dependence of phase morphology and carbide distribution on the thermal history intrinsic to each AM process. The study demonstrates that while FDMS and BJ are more accessible and cost-effective for low-density prototypes, LPBF and DED offer superior density and mechanical integrity suitable for functional tooling applications.