Monolithic Components Research Articles

Material Characterisation Experiments and Data Preparation for a Finite Element Analysis of the Deep Drawing Process Using AA 1050-O

The use of computer simulation to imitate physical processes has proven to be a time-efficient and cost-effective way of performing scenario testing for process optimisation in different applications. The finite element analysis (FEA) is the dominant numerical simulation method for analysing sheet metal forming processes. It uses mathematical tools and computer-aided engineering software programmes to predict forming processes. To improve the quality of output from the simulation, accurate material characterisation data that correctly model the behaviour of the material when it undergoes deformation must be provided. This paper outlines the stages of conducting material characterisation experiments, such as tensile, hardness, and formability tests, using the aluminium alloy AA1050-O. Sample preparation, the machine setup, and testing procedures for the material characterisation tests are given. Subsequent data preparation methods for input into an FEA software programme are also outlined. Implications of the testing results to a deep drawing process are examined while considering the formation of a rectangular monolithic component measuring 2300 mm by 1400 mm with a drawing depth of approximately 150 mm. The results from the characterisation tests indicate that the forming process for the product can be achieved using cold forming at room temperatures as a 25% strain was recorded before necking against an anticipated uniaxial strain of 5.93%. The aluminium alloy AA1050-O demonstrated a negligible strain rate sensitivity in the forming region, thus eliminating tool velocity from the key process parameters that should be considered during FEA simulations. A 50% increase in hardness was recorded after strain hardening.

Fully Metallic Additively Manufactured Monopulse Horn Array Antenna in Ka-Band

The Laser Powder-Bed Fusion Additive Manufacturing (LPBF AM) technique is evaluated for the manufacturing of fully metallic monolithic microwave components. To validate the manufacturing technique, a difference pattern array of 4 × 4 horn antennas is designed to operate at mm-Wave frequencies. The antenna is based on H-plane power dividers and a complex structure to obtain a difference radiation pattern by rotating twisted sections in two different orientations. The prototype is manufactured with a monolithic piece of aluminum alloy AlSi10Mg, providing a lightweight single structure that includes both radiating elements and a feeding network consisting of twisters and power dividers in a waveguide. The prototype was experimentally evaluated in an anechoic chamber and the near-field planar acquisition range, obtaining good agreement with full-wave simulations within an operational bandwidth from 34 to 36 GHz. The results demonstrate that the LPBF AM technique is a suitable candidate to produce challenging monolithic metal-only microwave components in the Ka-band, such as monopulse antennas.

Multi-facial freeform monolith optics for astronomical and space applications

The utilization of a multi-facial freeform monolithic (MFFM) component in a compact Cassegrain configuration design offers unprecedented capabilities to accommodate various next-generation science instruments. The concept of the MFFM component can be employed for applications in telescopes working at ultra-violet, optical, infrared, terahertz, microwave, and even radio frequencies. MFFM finds its scope in space optical and astronomical systems where the risks are associated with the alignment, manufacturability, and maintaining large-sized apertures, large number of components, cost, and volume of the flight optical terminals and instruments. The current challenges faced at the manufacturing phase of MFFM are the precision positioning of each surface concerning the optical axis and maintaining the required edge thickness. This paper presents the optical design, fabrication, measurement, and in-laboratory characterization of MFFM. The results of a prototyping effort through ultra-precision single-point diamond turning (SPDT) and coating demonstrate the feasibility of producing these elements as per size and weight requirements. The experimental results show excellent surface qualities in terms of nanometric surface roughness and close-to-submicron form accuracy on each surface of the freeform monolith. Focusing performance and imaging performance are carried out to validate the designed and manufactured precision component. The main contribution is highlighted in terms of the optimized fabrication process for producing the precision MFFM for a fast optical system while balancing the alignment errors. The demonstrated research work highlights the intriguing possibilities of the monolith and creates new avenues for research in domains that use huge optical systems, such as astrophysical study, planetary observation, earth monitoring, and geosciences.

Optimization on initial configuration of monolithic component for machining deformation control

Optimization on initial configuration of monolithic component for machining deformation control

Toolpath and Tool Design Innovations in Deformation Machining for Superior AA-7075 T6 Fins

Abstract A hybrid manufacturing process, deformation machining (DM) combines subtractive manufacturing with incremental forming. Monolithic components with complex profiles are created through the hybridization of manufacturing technologies, which also reduces the wastage of raw materials. The properties of geometry and surface quality of the fin made from the aluminum alloy Al-7075 T6 using the DM process’s bending mode was examined in this research, as were the effects of various approaches, toolpath methods, and tool design. To achieve the desired shape for the machined fin, various combinations of arcuate and slanting fin toolpath techniques were explored utilizing both top-down and bottom-up methods. The bottom-up method and the arcuate toolpath strategy were used to investigate various tool profiles. Using the best combination of toolpath strategy and tool profile, named as the T3 tool profile, which has a 0.6 mm nose radius and a circular sector, bottom-to-top (BTT)technique, and arcuate toolpath method, components with better geometrical features and surface roughness (SR) were produced. The analysis of the forming force in the bending approach of the DM progression was further carried out using this optimal combination.

Broadband and widely tunable second harmonic generation in suspended thin-film LiNbO3 rib waveguides

Our study demonstrates second harmonic generation (SHG) in a high confinement LiNbO3 rib waveguide through type-I birefringence phase matching of fundamental modes. The combination of micro-waveguide dispersion and material birefringence reveals unique SHG characteristics that complement the performance of standard LiNbO3 on insulator (LNOI) components. Dual-pump wavelength phase matching in the near-infrared and mid-infrared regions is shown in a given waveguide. These two wavelengths can be positioned in the 1.1–3.5 μm range or converge near 1.5 μm by adjusting the core waveguide size or through temperature tuning. A 25 °C temperature change enables a broad pump tunability band of 300 nm, ranging from 1350 to 1650 nm, with a conversion efficiency exceeding 40 %/W/cm2 within a single waveguide. A temperature tuning range of up to 900 nm is foreseen by tailoring the waveguide core size. In addition, a broadband response of 150 nm within the telecom window is demonstrated experimentally. The nonlinear waveguide, etched in a thin film membrane, is combined with titanium-indiffused waveguides to form a monolithic LiNbO3 component. This configuration provides low coupling losses of 0.8 dB and single-mode operation. It paves the way for a new generation of versatile and cost-effective frequency conversion components with wide-band spectral responses suitable for optical communications, environmental sensing, and quantum information processing.

Computational biomechanical study on hybrid implant materials for the femoral component of total knee replacements

Multifunctional materials have been described to meet the diverse requirements of implant materials for femoral components of uncemented total knee replacements. These materials aim to combine the high wear and corrosion resistance of oxide ceramics at the joint surfaces with the osteogenic potential of titanium alloys at the bone-implant interface. Our objective was to evaluate the biomechanical performance of hybrid material-based femoral components regarding mechanical stress within the implant during cementless implantation and stress shielding (evaluated by strain energy density) of the periprosthetic bone during two-legged squat motion using finite element modeling. The hybrid materials consisted of alumina-toughened zirconia (ATZ) ceramic joined with additively manufactured Ti–6Al–4V or Ti–35Nb–6Ta alloys. The titanium component was modeled with or without an open porous surface structure. Monolithic femoral components of ATZ ceramic or Co–28Cr–6Mo alloy were used as reference. The elasticity of the open porous surface structure was determined within experimental compression tests and was significantly higher for Ti–35Nb–6Ta compared to Ti–6Al–4V (5.2 ± 0.2 GPa vs. 8.8 ± 0.8 GPa, p < 0.001). During implantation, the maximum stress within the ATZ femoral component decreased from 1568.9 MPa (monolithic ATZ) to 367.6 MPa (Ti–6Al–4V/ATZ), 560.9 MPa (Ti–6Al–4V/ATZ with an open porous surface), 474.9 MPa (Ti–35Nb–6Ta/ATZ), and 648.4 MPa (Ti–35Nb–6Ta/ATZ with an open porous surface). The strain energy density increased at higher flexion angles for all models during the squat movement. At ∼90° knee flexion, the strain energy density in the anterior region of the distal femur increased by 25.7 % (Ti–6Al–4V/ATZ), 70.3 % (Ti–6Al–4V/ATZ with an open porous surface), 43.7 % (Ti–35Nb–6Ta/ATZ), and 82.5% (Ti–35Nb–6Ta/ATZ with an open porous surface) compared to monolithic ATZ. Thus, the hybrid material-based femoral component decreases the intraoperative fracture risk of the ATZ part and considerably reduces the risk of stress shielding of the periprosthetic bone.

Waveguide fabrication with integrated coupling optic

We present the fabrication of a waveguide with integrated injection optics using a laser photoinscription technique in the bulk of a chalcogenide glass. The injection optic is a gradient index lens with a parabolic refractive index profile. Its focusing characteristics depend on the amplitude of the index gradient and the thickness of the lens. These two parameters can be used to optimize light injection when the lens is written in front of a waveguide. We show experimentally that the coupling efficiency can be superior to that obtained by conventional injection with an external lens. Numerical simulations show that this coupling efficiency can be as high as 85%. The simultaneous inscription of a waveguide and its injection lens result in a monolithic component that is compact, lightweight and insensitive to mechanical or thermal perturbations. Performance has been evaluated in the mid-infrared range, but these results can be extended to the visible.

Low‐Volume Cores for Fabrication of Compact, Versatile, and Intelligent Soft Systems

AbstractThis study introduces the low‐volume core (LVC) fabrication method, which enables the monolithic molding of compact, complex, versatile, and intelligent soft robotic systems. This method uses thin and flexible thermoplastic sheets to mold internal chambers in soft fluidic actuators, valves, and circuits. The LVC fabrication method creates low‐volume networks in soft actuators (LV‐net actuators) that can be made with compact and complex geometries, enabling both low actuation volume input and multi‐degree‐of‐freedom actuators. LVC fabrication can also be used for compact, completely soft, and monolithic logic components (valves with low‐volume core, also called as LV valves) to provide directional resistance as well as a switching mechanism that enables fluidic logic in soft systems. The compatibility of the fabrication methods for both soft actuators and valves facilitates the creation of compact, integrated, and versatile soft robotic systems with embodied intelligence. This study introduces two examples of such intelligent soft robotic systems that integrate both LV‐net actuators and LV valves to demonstrate capability for complex system fabrication.

LOD2-Level+ Low-Rise Building Model Extraction Method for Oblique Photography Data Using U-NET and a Multi-Decision RANSAC Segmentation Algorithm

Oblique photography is a regional digital surface model generation technique that can be widely used for building 3D model construction. However, due to the lack of geometric and semantic information about the building, these models make it difficult to differentiate more detailed components in the building, such as roofs and balconies. This paper proposes a deep learning-based method (U-NET) for constructing 3D models of low-rise buildings that address the issues. The method ensures complete geometric and semantic information and conforms to the LOD2 level. First, digital orthophotos are used to perform building extraction based on U-NET, and then a contour optimization method based on the main direction of the building and the center of gravity of the contour is used to obtain the regular building contour. Second, the pure building point cloud model representing a single building is extracted from the whole point cloud scene based on the acquired building contour. Finally, the multi-decision RANSAC algorithm is used to segment the building detail point cloud and construct a triangular mesh of building components, followed by a triangular mesh fusion and splicing method to achieve monolithic building components. The paper presents experimental evidence that the building contour extraction algorithm can achieve a 90.3% success rate and that the resulting single building 3D model contains LOD2 building components, which contain detailed geometric and semantic information.

The Effect of Sintering Temperature on the Densification and Magnetic Performance of NiCuZn-Ferrites (CuO: 0-6 wt.%).

This article reported on the effect of Cu-content and sintering temperature on the magnetic permeability and power losses of monolithic iron-deficient NiCuZn-ferrite components with low Cu-contents aimed to be used for power applications at frequencies up to 1 MHz. In particular NiαZnb1-xCuxFe1.9O4 ferrite compositions are investigated with a constant Ni/Zn atomic ratio a/b = 0.9 and 0 < x < 0.017. As found, the addition of Cu enables the achievement of good magnetic performance at lower sintering temperatures and, therefore, lower production cost. At all Cu-contents, the initial permeability as a function of the sintering temperature passes through a maximum above which structural deterioration due to asymmetric grain growth occurs. The temperature at which this maximum permeability occurs depends on the Cu content and coincides with the achievement of the maximum density of 5.1-5.2 g cm-3 (relative density ~97%). At Cu-contents x = 0.006-0.012 and sintering temperatures 1200-1100 °C power losses (tan(δ)/μ at 1 MHz, 25 °C) οf 50 × 10-6 could be achieved and initial permeabilities (10 kHz, 0.1 mT, 25 °C) of around 400 with very good frequency and temperature stability. At CuO content higher than 4 wt.% (i.e., x > 0.012) and sintering temperatures higher than 1150 °C, pronounced microstructural disturbances due to asymmetric grain growth result in low permeabilities and high losses. It is suggested that at low CuO contents and low sintering temperatures, the densification enhancement may not proceed through Cu-rich phase segregation but through the creation of oxygen vacancies.

In-situ failure behavior and interfacial bonding of an interpenetrating metal matrix composite reinforced with lattice-like metallic glass (Ni60Nb20Ta20) preform

Metallic glasses (MG) have an amorphous atomic structure and exhibit several exceptional properties such as high strength, hardness associated with high elastic strain limit and elastic energy storage. But MGs are also prone to brittle fracture, making them difficult to use as monolithic structural components and might better be used as a reinforcement phase in hybrid composites such as metal matrix composites (MMC). The failure behavior of composites depends on the structure of the reinforcement phase. In this work, the failure behavior of an interpenetrating MMC reinforced with a MG (Ni60Nb20Ta20) lattice-like preform and AlSi12-matrix was investigated by in-situ compression tests under scanning electron microscopy to get a better understanding of the influence of the lattice-like preform and mechanical interference between both phases. Additionally, microstructure analysis by scanning transmission electron microscopy and energy dispersive X-ray measurements were carried out to gain insight into the chemical composition of the interfaces. The failure behavior in manufacturing direction of the MMC is dominated by shear stress whereas transversely to manufacturing direction by normal stress and exhibits therefore an anisotropic failure behavior. Investigations of the interfaces show more of a mechanical than chemical bonding but in general a good interfacial bonding was confirmed.

In-Process Machining Distortion Prediction Method Based on Bulk Residual Stresses Estimation from Reduced Layer Removal

Manufacturing structural monolithic components for the aerospace market often involves machining distortion, which entails high costs and material and energy waste in industry. Despite the development of distortion calculation and avoidance tools, this issue remains unsolved due to the difficulties in accurately and economically measuring the residual stresses of the machining blanks. In the last years, the on-machine layer removal method has shown its potential for industrial implementation, offering the possibility to obtain final components from blanks with measured residual stresses. However, this measuring method requires too long an implementation time to be used in-process as part of the manufacturing chains. In this sense, the objective of this paper is to provide a machining distortion prediction method based on bulk residual stress estimation and hybrid modelling. The bulk residual stresses estimation is performed using reduced layer removal measurements. Considering bulk residual stress data and machining-induced residual stress data, as well as geometry and material data, real-part distortion calculations can be performed. For this, a hybrid model based on the combination of an analytical formulation and finite element modelling is employed, which enables us to perform fast and accurate calculations. With the developments here presented, the machining distortion can be predicted, and its uncertainty range can be calculated, in a simple and fast way. The accuracy and practicality of these developments are evaluated by comparison with the experimental results, showing the capability of the proposed solution in providing distortion predictions with errors lower than 10% in comparison with the experimental results.

Machining distortion control of long beam parts based on optimal design of transition structure

Abstract. In the machining of monolithic components, machining distortion is a severe issue. The presence of initial residual stress is a major contributor to machining distortion. This paper proposes an approach to control the machining distortion of long beam parts by optimizing the workpiece structure before the start of the finishing stage, i.e. the transition structure. The first step is to establish a machining distortion analytical model for long beam parts with an identical cross-section, which is based on reasonable assumptions such as material linear elasticity and ignoring the influence of cutting heat. Then, an optimization model for the cross-section of the transition structure is developed, with the objective function defined as the minimum difference between the predicted distortion of the final part and the transition structure. Finally, a U-shaped beam is designed, followed by numerical simulation and machining experiments for verification. The theoretical maximum distortion of the optimized transition structure and the final part are −0.174 and −0.1782 mm, respectively, with a relative error of 2.9 %. The results of machining experiments and finite-element simulation demonstrate the effectiveness of the proposed model.

Selective crack propagation in steel-nickel component printed by wire arc directed energy deposition

Steel-nickel bimetallic structures exhibit attractive site-specific properties, but it is challenging to fabricate large a monolithic component while maintaining the dense regular interface that enable their properties. This study proposed a criss-crossed interface in steel (316L stainless steel) – nickel (IN 718 alloy) bimetallic component, with in-situ microstructure interlocking and improved mechanical response. A difference in physical properties between these two materials creates cracks at their interface where were fully explored using metallographic examination and numerical simulation. It is found cracks easily occur at their interface near nickel side due to alternate thermal cycles that lead to a variation in residual stress and microstructure, including grain orientation, texture strength, dislocation density and Schmid factors. The research outcomes enable better understanding of crack initiation mechanism in bimetallic structures printed by arc-based metal additive manufacturing and may advance the design and fabrication of advanced structures.

Manufacturing and characterization of an interpenetrating metal matrix composite reinforced with a 3D-printed metallic glass lattice structure (Ni60Nb20Ta20)

Metallic glasses (MG) exhibit remarkable properties, like high strength, hardness, and elastic strain limit due their amorphous structure. But they also exhibit low ductility and brittle behavior, making them less suitable for monolithic components. Therefore, MG offer high potential for use as a reinforcing phase in a ductile matrix. Especially interpenetrating metal matrix composites (MMCs) are suitable, since good interfacial adhesion can be achieved due to the metallic character of the MG and mechanical properties can be further enhanced by the interpenetrating structure. Temperature during manufacturing process must be below crystallization temperature of the MG. Until now, interpenetrating MMCs have been manufactured by infiltrating the metal matrix foam with MG, requiring a high melting temperature of the matrix and thus excludes lightweight metals. In this work it was possible to infiltrate an open porous lattice structure of MG (Ni60Nb20Ta20) due to its high crystallization temperature with AlSi12 by gas pressure infiltration resulting in a novel MMC. X-ray diffraction measurements confirm that no crystallization occurred during infiltration. Micrographs show a good infiltration quality and interfacial bonding between both phases. An increase in Young's modulus of 28 % and compressive strength in the MMC can be achieved compared to the AlSi12-matrix.

Comparison of the strength characteristics of a carbon friction pair of a hip joint endoprosthesis, including components from monolithic or non-monolithic pyrolytic carbon

Introduction The problem a large number of revision operations due to aseptic loosening after primary hip arthroplasty necessitates the search for a new material for a friction pair. The pyrocarbon, which has high tribological characteristics, can be used both in a monolithic and in a prefabricated design; however, the manufacture of a monolithic pyrocarbon block complicates production.Aim Compare the strength characteristics of the stem head and liner designs with monolithic and non-monolithic pyrocarbon.Materials and methods To assess the reliability of the designs, a digital mathematical model of the head and liner implants with a monolithic and non-monolithic pyrocarbon component was built. After the manufacture of prototypes friction pairs, an assessment of the static load on bench tests was carried out.Results While analyzing the mathematical model, the construct of non‑monolithic pyrocarbon broke in one of the experiments, while the strength of the construct of monolithic pyrocarbon was 4.5 times higher than the stresses arising under load. While studying the maximum static load, the friction pair from monolithic pyrocarbon exceeded the maximum possible load in the human hip joint by 5 times.Discussion The studies allow us to be confident about the reliability of the design in in vitro studies, which will create conditions for reducing the number of revision surgeries after hip arthroplasty.Conclusion Based on the data obtained, the design of the head and liner of the hip joint endoprosthesis with a friction pair made of carbon material will provide high reliability under conditions of functioning in the hip joint at maximum loads. It serves as a prerequisite for conducting a clinical study of the proposed friction pair.

Improving the stability of the friction stir channelling technology via a cooled copper backing plate

The development of the friction stir channelling (FSC) technology has a potential to revolutionize the manufacturing industry, providing an innovative way to produce continuous sub-surface channels in monolithic components in a single step. However, the process generates heat that can lead to defects and loss of stationarity, affecting the quality of the channels produced and the process’ efficiency and control. To address these challenges, a ground-breaking study was conducted using a cooled copper backing plate to adjust the process temperatures and investigate the influence of the temperature on FSC stability. The results of the study showed that the cooled copper backing plate has a significantly higher rate of heat conduction, effectively preventing the processed component from overheating and ensuring that the process maintains its stationarity. When using the steel backing plate, only one combination of process parameters (a rotation speed of 450 rev/min and a traverse speed of 71 mm/min) yielded satisfactory results. Moreover, the use of the cooled copper backing plate allowed for a wider range of process parameters to be employed, resulting in sub-surface channels with higher quality and fewer defects. The 710/71 parameters combination resulted in a lower heat input, while the 900/45 parameters set produced channels with a more rectangular geometry. A rotation speed of 900 rev/min and a traverse speed of 45 mm/min have been shown to be the best choice. This innovative approach to FSC technology represents a major step forward in solid-state manufacturing, envisaging new possibilities for producing longer sub-surface channels with superior quality and greater efficiency.Highlights• Conducting the FSC process at low temperature has improved its stability.• The use of a cooled copper backing plate enabled a broader range of FSC process parameters.• Longer and stabler leak-free sub-surface channels have been produced in aluminium alloys.Graphical

An Innovative Metric-based Clustering Approach for Increased Scalability and Dependency Elimination in Monolithic Legacy Systems

Scalability is one of the system’s characteristics highlighted in the recent literature, and it is directly related to issues that are encountered in state-of-the-practice technology. The scalability of a system is challenging because monolithic legacy systems are hard to scale due to the high level of component dependencies. To the best of our knowledge, there is no published work available that can identify the components from a monolithic legacy system in the context of dependent and independent components and scale them accordingly. The main contribution of this paper is the proposal of a novel approach for the exclusive identification of dependent and independent monolithic legacy system components. The proposed approach also helps to remove the dependency among components of monolithic legacy systems. As a result, it establishes a precise method that identifies all the components of an application and removes the dependency among components, helping to increase the scalability of the resulting application. This approach was validated by several experiments, and the key findings were the identification of dependent and independent components, the identification of relationships among components, and the identification of the abstract level architecture of the monolithic legacy system. In future work, the proposed method will be enhanced toward the recovery of the whole system’s architecture.

Characterization of Microchannels Produced by Friction Stir Channeling: An Experimental Study

Friction Stir Channeling (FSC) is a recent and innovative solid state manufacturing technology that allows, in a single pass, the opening of continuous internal channels in monolithic components and can be used in the mold and heat exchanger industries. However, the development of reliable Non-Destructive Testing (NDT) for the characterization of the channels is a major challenge. The focus of this work is the non-destructive characterization of micro channels, and the main goal was to experimentally validate which NDT techniques can be used to identify the presence of microchannels, their regularity along the section, and also their location, size, and path. Five NDT techniques were studied: digital radiology; eddy currents; ultrasounds; thermography; and dye penetrants. These techniques were applied to specimens with linear and curvilinear channels. The specimens were produced using tool pins with 0.5 mm diameter which obtained channels with 0.4 mm width and depths of 0.53 mm. Digital radiology and ultrasounds were effective in detecting channels regardless of its dimensions. Eddy currents did not allow to confirm the exclusive presence of the channels due to microstructural changes caused by the FSC process. Thermography using cold fluid injection was not successful in the channel’s characterization due to the extremely low flow. The dye penetrants confirmed the presence of the channels of all dimensions due to the liquid having traveled along the entire path of the curvilinear channel without reaching the surface.