Aluminum Prototype Research Articles

Development of Microwave Components Using Additive Manufacturing: A Review

In modern telecommunication, there is a growing demand for lightweight, low-cost, and compact microwave components with high transmission functionalities, especially for applications requiring multiple high-performance antennas to provide multi-beam capabilities. Additive manufacturing (AM), also known as three-dimensional (3D) printing, has emerged as a promising solution to meet these demands due to its simplicity, fast prototyping capabilities, and enhanced fabrication accuracy. AM technology has found widespread adoption across various industries, including space-borne, satellite, handheld wireless systems, biomedical, mechanical, electrical, optical, and environmental applications. In particular, AM-based microwave components offer significant advantages, including reduced weight compared to traditional aluminum prototypes, with savings of up to two-thirds of the weight. This paper presents a comprehensive review of the AM process, materials used, and microwave components developed using AM technology. The review encompasses various aspects, including fabrication techniques, performance characteristics, and applications of AM-based microwave components, providing insights into the advancements, and potential future directions of this innovative approach.

Improving resonant ice protection systems with substrate optimization

Electro-mechanical de-icing systems are low-energy ice protection solutions based on ice fracture mechanisms. This article focuses on resonant electro-mechanical de-icing systems that actuate modes of flexion, which require low energy compared to extension modes. However, fracture propagation limits are encountered when using such flexural modes, preventing the ice from being completely detached from the substrate. This study demonstrates the feasibility of extending the ice detachment area by optimizing the thickness of the substrate. First, the interest and the limits of flexural resonant modes are discussed. Then the de-icing of a simple metallic beam in free conditions using a flexural mode is improved owing to the parametric optimization of the substrate thickness. The optimization is verified by tests on aluminum prototypes. The optimization results are then extended to a clamped composite plate and then to a NACA profile, showing interest in the approach to fully de-ice structures with modes of flexion, even in the case of complex geometries. With this last example, the study also demonstrates the feasibility of electro-mechanical ice protection systems for carbon fiber reinforced Polymer composite structures.

Conceptual design of a 714-MHz RFQ for compact proton injectors and development of a new tuning algorithm on its aluminium prototype

Conceptual design of a 714-MHz RFQ for compact proton injectors and development of a new tuning algorithm on its aluminium prototype

Monitoring and modelling the deformation of an aluminium prototype mould insert under different injection moulding and clamping conditions

The conventional material of prototype injection moulds is aluminium. Well-established techniques are available on the applicability of such moulds, yet their operational state is not analysed comprehensively. State monitoring has huge benefits because the mould can be protected from excessive loads and deformations and product quality can be monitored in real time. In this paper, we measured the operational strains, cavity pressure and temperature distribution of prototype injection moulds with the traditional state monitoring method, and analysed the combined effect of holding pressure and clamping force on the operational deformations and cavity pressures. Increasing the clamping force and the holding pressure results in higher operational strains and cavity pressures. The precision of core shift analysis was tested if it can predict operational deformations of aluminium injection moulds. Core shift analysis could accurately predict the maximal deformation but it is inaccurate regarding the time when it occurs. A novel modelling method was also introduced where pressure and temperature results of the injection moulding simulation can be imported into finite element (FE) mechanical simulations. This way, mould deformations can be modelled in mechanical FE simulation environment. The measured operational deformations were compared both with core shift analysis results and with the coupled IM-FE simulation results. Core shift simulation can predict maximal deformations with adequate precision but it does not consider thermal expansion effects properly. In order to improve the accuracy of the simulations, a coupled IM-FE method is necessary, where excellent agreement can be found between the measurements and the calculations. The new, combined modelling technique can improve the accuracy of mould deformation modelling because additional mould material models become available in a professional finite element software. It can be especially useful in the modelling of polymeric mould inserts where stiffness is heavily temperature-dependent and the material creeps.

A Novel Gripper with Integrated Rotary Unit and Force Control for Pick and Place Applications

Modern electrical grippers have lower life-cycle costs compared to pneumatic ones. Furthermore, they provide force control, making it possible to grasp objects with different fragility using a single device. At the same time, electrical grippers have a higher end-effector weight, installed on the robot’s flange and lower closing speed, preventing them from replacing pneumatic solutions in high dynamic Pick and Place applications. This research faces both issues by synthesizing a novel gripper mechanism based on a Torque Distribution Gearbox, which makes it possible to relocate the electric motors to the static frame of a delta robot. The proposed gripper not only has a lower mass and a higher closing speed than competitive electric solutions, but it also provides unlimited rotation around the vertical axis. The performance of the gripper was tested in experimental studies, which showed that a created aluminum prototype provides a precise force control in the range from 3 N to 48 N with an accuracy not worse than 1.27 N. Moreover, its finger’s speed is 3.1–56 times higher than market available electrical grippers, which makes it comparable by this parameter with pneumatic solutions used in high dynamic Pick and Place applications.

Improving mechanical ice protection systems with substrate shape optimization

Mechanical and electro-mechanical de-icing systems are low-energy ice protection solutions based on fracture mechanisms. It can, however, be difficult to obtain the protection of an entire surface due to the limited propagation of fractures for some mechanisms. This article shows how it is possible to reshape the substrate in order to favor the propagation of adhesive fracture at the ice/substrate interface. The first part of the paper introduces an analytical beam theory approach for running computations quickly, making it possible to achieve parametric optimization of the substrate thickness and maximize the propagation length. The optimization results were validated using FEM software and tests on an aluminum prototype. A second method is also studied in this paper, topology optimization is used on a 2D finite element model to minimize the substrate mass of the proposed solution and adhesive crack propagation is assessed in comparison with the mass impact. For different boundary conditions, propagation ranges can be increased by up to 150% with a mass increase limited to 50%. Using topology optimization, the additional mass could be reduced by >60% while maintaining the same performances.

Synchronous deployed design concept triggered by carbon fibre reinforced shape memory polymer composites

Synchronous deployments for symmetrical structures such as solar arrays and antennas are desired because they are conducive to subsequent attitude stabilization. In this work, we propose a synchronous deployed mechanism triggered by shape memory polymer composites (SMPCs). Firstly, the material design was developed according to the fibre microbuckling behaviour of unidirectional carbon fibre reinforced laminates undergoing flexural deformation to balance high mechanical requirements and large deploy/fold ratio desirements. Then, two resins with different glass transition temperatures (Tgs) from a similar shape memory epoxy system were used for fabrication. These laminates with different fibre volume fractions, thicknesses, matrices and fibre distributions were tested by three-point bending tests to evaluate their mechanical performance. Recovery tests were carried out under different environmental temperatures. In addition, the recovery stimulated by resistor heaters in vacuum endowed the mechanism with good recovery robustness. Finally, functional validation on an aluminium prototype showed good synchronization. This design concept has the advantage of being lightweight, low-impact and highly reliable. It is expected to provide a reasonable and robust solution for synchronous deployments.

Large Metal Mirrors for Atmospheric Telescopes

We are developing technologies in processing and metrology to fabricate a 1.4-meter aperture, aspherical surface Aluminium prototype mirror for Cherenkov Telescope Array. The aim is to fast process these large aperture mirrors at low cost. The technical development will ensure the high specifications on the surface quality. Different metrology methods including Swinging Arm Profilometry (SAP) and phase measuring deflectomtry (PMD) are being developed. Recent results have shown very promising progress on these developments. We have excellent record in transferring our research results into industry. These cutting-edge technologies will be transferred to our industry partner to explore further developments.

Experimental Analysis of Heat Transfer on the Tubular Tube Heater with a Variable of Twisted Tape Inserts and Wire Coil to Prevent the Icing Contaminated Tailplane Stall

An anti-icing system has the purpose of protecting the leading edge of the tailplane from contamination during aircraft flight. An anti-icing system in a turboprop aircraft employs heaters that use electrical energy as their power source or heat generated by the bleed air. Protecting the tailplane from contamination is preventing the aircraft stall from occurring that triggers dangerous flight conditions. The aluminum prototype tailplane is assembled with a variable of twisted tape insert and wire coil. The twisted tape insert comes in three different geometries with twist ratio T3 = 9.3; T4 = 7; and T5 = 5.6, as well as a wire coil with fixed geometry. This study shows the best heat transfer rate occurs in T3 with a value of 33.90 W. The consequence of this condition is an decrease in pressure drop that occurs. Twisted 3 has the greatest pressure drop when compared to other geometry, with an average value of 4.72 Pa.

Fabrication and cold test of prototype of spatially periodic radio frequency quadrupole focusing linac

A 325 MHz aluminum prototype of a spatially periodic RF quadrupole focusing linac was developed at the Institute of Modern Physics, Chinese Academy of Sciences, as a promising candidate for the front end of a high-current linac. It consists of an alternating series of crossbar H-type drift tubes and RF quadrupole sections. Owing to its special geometry, cavity fabrication is a major hurdle for its engineering development and application. In this paper, we report the detailed mechanical design of this structure and describe its fabrication process, including machining, assembly, and inspection. The field distribution was measured by the bead-pull technique. The results show that the field errors of both the accelerating and focusing fields are within an acceptable range. A tuning scheme for this new structure is proposed and verified. The cold test process and results are presented in detail. The development of this prototype provides valuable guidance for the application of the spatially periodic RF quadrupole structure.

Cold-Test of Transverse Input-Output Microwave Circuit Components for a High-Power W-Band Gyro-TWT

The input/output microwave circuit of a W-band gyrotron traveling-wave tube (gyro-TWT) with a predicted output pulse power of more than 300 kW and a bandwidth of about 8% is under investigation. A distinctive feature of this circuit is the transverse (relative to the axial velocity of the electrons in the gyro-TWT) extraction of the output power and its compatibility for feeding and coupling the microwaves out through one oversized barrier window. The whole circuit consists of components inside and outside the tube vacuum volume. The key elements of the inner circuit are a waveguide mode converter forming the ring-like distribution of the radiation from the incoming TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1,1</sub> mode and a 45° inclined mirror with a hole enabling a lossless transport of the gyro-TWT electron beam to the collector. Aluminum prototypes of these components have been fabricated and cold-tested in the frequency range of 90-102 GHz. The measured 2D mode patterns and level of the cross-polarization are found to be in good agreement with the simulations.

Life cycle assessment of electric vehicles and buses in Brazil: effects of local manufacturing, mass reduction, and energy consumption evolution

Environmental impacts of battery electric vehicles (BEVs) and internal combustion engine vehicles have been broadly studied and compared. However, there is scarce evidence of studies analyzing the potential effect of evolution key factors. The purpose of this study was to evaluate what would be the environmental impact of manufacturing BEVs and battery electric buses (BEBs) in Brazilian southeast, whereas vehicle mass reduction, material switching, energy consumption, battery improving, geographic adaptation of life cycle inventories, and electricity mix evolution effects are considered. The methodology was based on adapting a representative number of global Ecoinvent V.3.2 datasets to better represent local conditions and subsequently to include evolution parameters for a 2030 scenario. Thus, we were able to establish a comparison for BEVs and BEBs in 2015 and 2030 for Brazilian and global conditions. This study compared BEV and BEB production (one vehicle as comparison unit) and also well-to-wheel (WTW) stage (1 km as functional unit). The research envisioned mass reduction configurations for cars and buses in 2030. BEV analysis in 2030 includes two material switching scenarios: plastic and aluminum prototypes. For one BEV as comparison unit, ozone depletion, human toxicity, metal depletion, and ecotoxicities displayed larger impacts for Brazilian cars, mostly due to material switching in the new prototypes, in spite of total mass reduction. In fact, neither the BEBs nor BEVs made in Brazil displayed a consistent environmental advantage over the global reference; and in fact, low production plants might cause larger impacts. Life expectancy increase is suggested to be more effective in reducing impacts than mass or energy consumption reduction. For the 2030 BEV, an unexpected burden shifting result appears. Ozone depletion increases for the Brazilian aluminum prototype since emissions arising from scrap treatment do have a significant impact, even though mass reduction was considered. Bus results portrayed a tendency for Brazilian bus to perform better than its global counterpart except for metal depletion, ecotoxicities, and ozone depletion. A large environmental contribution from treatment of mining residues is common for human toxicity and freshwater eutrophication, the most concerning categories. Large contributions from mining residues led us to conclude that in order to manufacture environmentally competitive BEBs and BEVs, either reduction of impacts on metal extraction, e.g., copper, magnesium, etc., or metal use decrease must be prioritized. Negative consequences of vehicle evolution are especially concerning for human health and bodies of water, and impact decrease will be unlikely, at least until 2030.

Integration of an &lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$H$ &lt;/tex-math&gt; &lt;/inline-formula&gt;-Plane Bend, a Twist, and a Filter in Ku/K-Band Through Additive Manufacturing

Additive manufacturing technologies have been increasingly applied to the development of radio frequency components in the past few years. Indeed, the free-form capability of these processes allows for the design of novel components, whose actual implementation through conventional machining is rather complex or even not possible. This paper describes a monolithic WR51 component integrating three radio frequency functionalities, namely, bending, twisting, and filtering. Three aluminum prototypes with different bending/twisting radii have been manufactured through the selective laser melting process. They exhibit a measured rejection higher than 60 dB in 17.5 and 21.2 GHz, and a measured return loss better than 20 dB in 12.5 and 15 GHz. Significant mass and envelope reductions (higher than 60% depending on the bending/twisting radius) with respect to the reference subsystem with distinct waveguide components are achieved. These results assess the effectiveness of 3-D metal printing in the miniaturization and integration of waveguide systems.

Electrodynamic characterisitcs measurements of higher order modes in S-band cavity

The 800 MHz superconducting cavities with grooved beam pipes were suggested as one of the harmonic cavities design options for High Luminosity LHC project. Cavity simulations were carried out and scaled aluminium prototype having operational mode frequency of 2400 MHz was manufactured for testing the results of simulations. The experimental measurements of transverse shunt impedance with error estimation for higher order modes TM110 and TE111 for S-band elliptical cavity were done. The experiments using dielectric and metallic spherical beads and with ring probe were carried out. The Q-factor measurements for two-cell structure and array of two cells were carried out.

Design and development of a multimode waveguide corrugated horn antenna using 3D printing technology and its comparison with aluminium‐based prototype

Three-dimensional (3D) printing technology based antenna structures have many promising applications. In this study, a triple mode circular waveguide horn antenna with corrugated chokes is presented. In this antenna configuration, three individual modes consisting of TE 11 , TM 01 , and TE 21 are generated in a single structure. The horn antenna prototypes used precision milling and 3D printing process for the aluminium and 3D printed horn antenna prototypes, respectively. The aluminium prototype is used as a reference antenna for comparing the 3D printed horn prototype. For the 3D printed antenna, Polycarbonate - Acrylonitrile Butadiene Styrene (PC-ABS) material is used and later coated with conductive silver ink. Simulation and aluminium based prototype antennas achieve a common bandwidth of 7.45-8.00GHz for all the three modes. However for the 3D printed antenna prototype, the achieved bandwidth is from 7.40 to 7.89GHz. The aluminium and 3D printed horn prototypes were also tested for radiation pattern quality. While aluminium-based prototype agrees closely with the simulation results, the 3D printed horn shows a reduced gain, higher cross-polarisation levels while keeping the pattern beamwidths similar to the simulated and aluminium-based horn prototypes.

The heat transfer characteristics of liquid cooling heat sink with micro pin fins

This paper numerically and experimentally investigated the liquid cooling efficiency of heat sinks containing micro pin fins. Aluminum prototypes of heat sink with micro pin fin were fabricated to explore the flow and thermal performance. The main geometry parameters included the diameter of micro pin fin and porosity of fin array. The effects of the geometrical parameters and pressure drop on the heat transfer performance of the heat sink were studied. In the experiments, the heat flux from base of heat sink was set as 300kW/m2. The pressure drop between the inlet and the outlet of heat sink was set <3000Pa. Numerical simulations with similar flow and thermal conditions were conducted to estimate the flow patterns, the effective thermal resistance. It was found that the effective thermal resistance would reach an optimum value for various pressure drops. It was also noted that the effective thermal resistance was not sensitive to porosity for sparsely packed pin fins.

Mechanical and Heat Transfer Performance Investigation of High Thermal Conductivity, Commercially Available Polymer Composite Materials for Heat Exchange in Electronic Systems

The thermal, mechanical, and morphological characteristics of three selected commercially available, injection-moldable, high thermal conductivity (20–32 W/m K), polyimide 66 (PA66) polymer composites from two vendors are characterized for possible heat exchange applications in electronic equipment. The fillers are found to consist of 10 μm diameter, 120–350 μm long fibers, made of carbon in two composites, and a hybrid combination of essentially carbon, oxygen, and silicon in the third composite. Fiber weight loading ranges from 63% to 69%. The hybrid, high-length fiber-reinforced material overall displays superior mechanical properties (i.e., ultimate tensile, flexural and impact strengths, and flexural modulus) compared with the other two carbon-filled composites. For the hybrid-filled and one carbon-filled material (both having a thermal conductivity of 20 W/m K), good agreement between mechanical property measurements and corresponding vendor data is obtained. For the material having the highest vendor-specified thermal conductivity (i.e., 32 W/m K) and weight filler fraction (i.e., 69%), mechanical properties are up to 37% lower than corresponding vendor data. The heat transfer rates of parallel plate, cross-flow air–water heat exchanger prototypes made of the three PA66 materials are comparable to that of an aluminum prototype having the same geometry. Based on the combined heat transfer and mechanical property characterization results, the hybrid, long fiber-filled PA66 polymer composite appears to have the best combination of mechanical and heat transfer characteristics, for potential use in electronics heat exchange applications.

3-D Mechanically Tunable Square Slot FSS

We introduce an innovative 3-D mechanically tunable frequency selective surface (FSS), which is inspired by the classical flat square slot FSS. The proposal improves the performance of classical 2-D FSS designs, and it also represents a novel method of achieving mechanical frequency tuning, despite other 3-D designs that consist of a collection of stacked 3-D layers exist. In our proposal, the rotation of an inner element provides tuning capability to the squared cell structure, consisting of metallic grids with a movable inner element. An aluminum prototype was built, which can be tuned from 2.4 to 4 GHz, and also compared its measured performance and numerical simulations. Some characteristics of the proposed structure are the rejection level at main polarization, up to 20 dB, and the maximum frequency sweep of approximately 50% of the fundamental frequency. The prototype showed a stable frequency response for angles of incidence up to 45°. Since results are in good agreement with simulations, we provide parametric equations to design 3-D structures at desired frequencies.

High-precision Photogrammetric Surface Figure Measurements under Cryogenic Environment

Limited by the working temperature of the test equipment, most of high-precision surface figure measurement techniques cannot be put into application under a cryogenic environment. This paper reports the first attempt to measure the surface figure of a high-precision terahertz reflector panel under low temperatures based on photogrammetry. The measurement employs a high-resolution industrial camera sitting on the automatic testing platform which enables photos been taken in an automatic fashion inside a climate chamber. A repeatable accuracy of 2.1μm (rms) is achieved under the cryogenic environment. Furthermore, the surface figure measured by a three-coordinate measuring machine under the room temperature is used to calibrate the thickness differences of the targets. By this technique, the surface figure of an aluminum prototype panel of the 5 meter Dome A Terahertz Telescope (DATE5) is measured from room temperature down to −55°C to obtain the rule of variation of surface deformation of the panel under low temperatures.

A Mode-Matching Technique for Analysis of Scattering by Periodic Comb Surfaces

Numerical techniques for calculating electromagnetic fields within three-dimensional surfaces are computationally intensive. Therefore, this paper presents the application of a mode-matching technique developed for analyzing electromagnetic scattering from periodic comb surfaces illuminated by a plane wave. A set of linear equations has been developed to calculate mode coefficients of the field distribution for both E- and H-polarized incident waves. Analysis is performed for two cases where the comb thickness is either infinitely thin or of a finite thickness. The technique is shown to accurately predict both field intensities within the near-field of the periodic surface and far-field scattering patterns. Results are compared to those obtained using the finite integration techniques (FIT) implemented in CST Microwave Studio. Furthermore, numerical results are compared to measurements of an aluminum prototype. Additional far-field scattering measurements using a bi-static system provide additional confidence in CST simulations and the mode-matching methods presented here.