Intricate Shapes Research Articles

Morphing matter: from mechanical principles to robotic applications

The adaptability of natural organisms in altering body shapes in response to the environment has inspired the development of artificial morphing matter. These materials encode the ability to transform their geometrical configurations in response to specific stimuli and have diverse applications in soft robotics, wearable electronics, and biomedical devices. However, achieving the morphing of intricate three-dimensional shapes from a two-dimensional flat state is challenging, as it requires manipulations of surface curvature in a controlled manner. In this review, we first summarize the mechanical principles extensively explored for realizing morphing matter, both at the material and structural levels. We then highlight its applications in the soft robotics field. Moreover, we offer insights into the open challenges and opportunities that this rapidly growing field faces. This review aims to inspire researchers to uncover innovative working principles and create multifunctional morphing matter for various engineering fields.

Fractal-Based Hybrid Cryptosystem: Enhancing Image Encryption with RSA, Homomorphic Encryption, and Chaotic Maps.

Protecting digital data, especially digital images, from unauthorized access and malicious activities is crucial in today's digital era. This paper introduces a novel approach to enhance image encryption by combining the strengths of the RSA algorithm, homomorphic encryption, and chaotic maps, specifically the sine and logistic map, alongside the self-similar properties of the fractal Sierpinski triangle. The proposed fractal-based hybrid cryptosystem leverages Paillier encryption for maintaining security and privacy, while the chaotic maps introduce randomness, periodicity, and robustness. Simultaneously, the fractal Sierpinski triangle generates intricate shapes at different scales, resulting in a substantially expanded key space and heightened sensitivity through randomly selected initial points. The secret keys derived from the chaotic maps and Sierpinski triangle are employed for image encryption. The proposed scheme offers simplicity, efficiency, and robust security, effectively safeguarding against statistical, differential, and brute-force attacks. Through comprehensive experimental evaluations, we demonstrate the superior performance of the proposed scheme compared to existing methods in terms of both security and efficiency. This paper makes a significant contribution to the field of digital image encryption, paving the way for further exploration and optimization in the future.

Enhancing low-speed WEDM machining capabilities on Nitronic-50 with a constant frequency ultrasonic hybrid method

Nitronic-50 stainless steel is a high-strength and corrosion-resistant austenitic premium steel. It requires improved surface characteristics due to its wide use in various applications like fasteners, marine hardware, hydroelectric-power turbines, pressure vessels, etc. This work focuses on machining hard-to-machine Nitronic-50 steel is unconventionally machined using constant frequency ultrasonic-aided low-speed wire electrical discharge machining (USV-LS-WEDM) to enhance its machined surface integrity. This method achieves effective results when cutting high-strength materials with intricate shapes. Material removal rate (MRR) and surface roughness (Ra) were measured by considering inputs such as servo voltage (SV), pulse off time ( Toff), pulse on time ( Ton) and current (I) with an ultrasonic-vibration range of 20,000 Hz. The appropriate selection and usage of LS-WEDM parameters is a challenging process and is done with parametric analysis. The MRR of Nitronic-50 was enhanced with an increase in Ton and I along with a reduction in Toff and SV. Surface roughness (Ra) decreased with a gradual reduction in Ton, I, and an increase in SV. The USV-WEDM was compared with a stand-alone WEDM indicating that the MRR for USV-WEDM was improved by 12% and the Ra was decreased by 9% due to effective distribution of spark discharges, which increased material erosion and redistribution of molten metal characteristics. Machining quality for hard-to-machine Nitronic-50 steel was certainly enhanced via hybrid ultrasonic vibration with the existing LS-WEDM.

Riverbank Following Planner (RBFP) for USVs Based on Point Cloud Data

Autonomous path planning along riverbanks is crucial for unmanned surface vehicles (USVs) to execute specific tasks such as levee safety detection and underwater pipe inspections, which are vital for riverbank safety and water environment protection. Given the intricate shapes of riverbanks, the dynamic nature of tidal influences, and constraints in real-time cartographic updates, there is a heightened susceptibility to inaccuracies during manual waypoint designation. These factors collectively impact the efficiency of USVs in following riverbank paths. We introduce a riverbank following planner (RBFP) for USVs to tackle this challenge. This planner, utilizing 2D LiDAR, autonomously selects the following point to follow riverbank shapes. Additionally, a PID controller is integrated to compensate for position and yaw errors. Our proposed method reduces the deviation between the USV’s planned path and the actual riverbank shape. We simulated straight, convex, and concave riverbanks in the Virtual RobotX (VRX) simulator while considering the impacts of wind, waves, and USV dynamics. The experimental result indicates the following performance of 96.92%, 67.30%, and 61.15% for straight, convex, and concave banks, respectively. The proposed RBFP can support a novel autonomous navigation scenario for autonomous paths following along the riverbank without any preplanned paths or destinations.

The Quadratic Trigonometric Bezier like Curve With two Shape Parameters

The quadratic trigonometric Bezier model serves as a potent and valuable tool in computer-aided geometric design, boasting exceptional geometric properties. In this study, Novel functions are introduced by leveraging a trigonometric Bezier-like curve with adjustable shape parameters. Each curve segment is formed by three consecutive control points, providing precise control over shape by adjusting these parameters while keeping the control polygon unchanged. These curves exhibit superior proximity to the control polygon compared to quadratic Bezier curves across all shape parameter values, gradually approaching the control polygon as the shape parameter increases. Moreover, for practical application, the quadratic trigonometric Bezier-like curve was utilized to artfully design the Arabic word "الله" (Allah) and define flower contours, employing MATHEMATICA software. The results underscore the model's effectiveness in accurately representing intricate shapes, offering a versatile and efficient solution for diverse design challenges. Furthermore, the fusion of the quadratic trigonometric Bezier-like curve with shape parameters significantly augments design flexibility and adaptability, making it a valuable asset in computer graphics, geometric modeling, and artistic design across multiple domains.

Ceramic 3D printing using lithium silicate prepared by sol-gel method for customizing dental prosthesis with optimal translucency

In dentistry, various ceramics have been tested to overcome the opacity of zirconia. Moreover, three-dimensional (3D) printing technology is being used to accurately reproduce intricate shapes and overcome material wastage. This study described the application of a lithium silicate 3D printing material for the fabrication of transparent ceramic dental prostheses and the optimization of the process. After synthesizing approximately 500 nm of lithium silicate powder using the sol-gel method, field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), were performed and rheological properties were evaluated. Then, the sintering conditions were set based on thermogravimetry differential thermal analysis (TG-DTA). A slurry for 3D printing containing 40 vol% powder along with a photocurable resin, an acrylate binder, and a dispersant was prepared. A specimen measuring 15 mm in diameter and 1.8 mm in height, with a layer thickness of 50 μm, was printed with a digital light process (DLP) 3D printer using different holding times (1, 3, 5, and 10 h) and at a final sintering temperature of 1325 °C among the preceding sintering conditions. The shrinkage rate, Vickers hardness, and translucency of the finished specimens were compared and analyzed. Our study terrified the possibility of 3D printing of lithium silicate. Furthermore, our results suggest that a long sintering holding time has a positive effect on the specimen characteristics.

Recent Progress on the 3D Printing of Dynamically Cross‐Linked Polymers

AbstractThe utilization of dynamic cross‐linking represents a highly promising approach in addressing the escalating issues of plastic pollution and fossil resource consumption. Despite being extensively investigated over the past decade, various dynamically cross‐linked polymers (DCPs) predominantly remain confined to the realm of academic research. To serve as a valuable material for practical application, advanced processing is always essential for all kinds of materials. 3D printing (3DP) enables the creation of intricate shapes layer‐by‐layer without relying on molds, thus the integration of 3DP techniques with DCPs holds significant potential to enhance and expand the practical applicability of DCPs. Here, an overview of the fundamental principles underlying DCPs compatible 3DP techniques are provided, namely photocuring 3DP, extrusion‐based 3DP, and laser sintering‐based 3DP. Additionally, a comprehensive summary of representative research works that specifically focus on the application of DCPs in each respective 3DP technique is presented. The performance and dynamic mechanism involved in the corresponding printing process are thoroughly discussed and comprehensively reviewed. Finally, the existing challenges and issues pertaining to further enhancing 3D printability, performance, efficiency, etc., are extensively deliberated upon, while proposing potential directions to address these concerns.

A four-node rectangular plate finite element using Airy functions with transverse shear

PurposeAmong different types of engineering structures, plates play a significant role. Their analysis necessitates numerical modeling with finite elements, such as triangular, quadrangular or sector plate elements, owing to the intricate geometrical shapes and applied loads. The scope of this study is the development of a new rectangular finite element for thin plate bending based on the strain approach using Airy's function. It is called a rectangular plate finite element using Airy function (RPFEUAF) and has four nodes. Each node had three degrees of freedom: one transverse displacement (w) and two normal rotations (x, y).Design/methodology/approachEquilibrium conditions are used to generate the interpolation functions for the fields of strain, displacements and stresses. The evolution of the Airy function solutions yielded the selection of these polynomial bi-harmonic functions. The variational principle and the analytical integration approach are used to evaluate the basic stiffness matrix.FindingsThe numerical findings for thin plates quickly approach the Kirchhoff solution. The results obtained are compared to the analytical solution based on Kirchhoff theory.Originality/valueThe efficiency of the strain based approach using Airy's function is confirmed, and the robustness of the presented element RPFEUAF is demonstrated. Because of this, the current element is more reliable, better suited for computations and especially intriguing for modeling this kind of structure.

Investigation on mechanical properties of polyamide 6 and carbon fiber reinforced composite manufactured by fused deposition modeling technique

Fused deposition modeling (FDM) is one of the additive manufacturing (AM) techniques in which intricate shapes are produced effectively with time and cost. Thermoplastics and filler-incorporated thermoplastics composite materials were used in the form of filament. The mechanical properties of the printed sample varies with the parameters involved in FDM printing. In the present investigation, polyamide 6 (PA) with 20 wt.% of short carbon fiber (CF) was used as filament. The filaments were printed with different raster orientations namely 0°, 45°, 90°, and ±45° by keeping other printing parameters constant such as 100% infill density, 0.2 mm layer thickness, 30 mm/min printing speed, 240°C printing temperature, 80°C bed temperature, and XY or 0° body orientation with a clear justification studied. The printed samples were investigated for structure, morphology and mechanical properties using tensile test and impact test respectively. The results shows that bidirectional ±45° raster orientation specimens show the highest tensile strength of 35.2 MPa in comparison with 0°,45°, and 90° raster orientation, and PACF composite material showed improved mechanical properties as compared to pure PA. The highest impact energy was observed for a PACF composite with a raster orientation of 90°. Morphological analysis of composites showed a uniform dispersion of CF in PA matrix and improved interfacial adhesion between matrix and reinforcement.

Uniform and graded bio-inspired gyroid lattice: Effects of post-curing and print orientation on mechanical property

Additive manufacturing is spreading rapidly because it offers great design freedom in creating intricate lightweight shapes using lattice structures that offer numerous possibilities, including applications in aerospace, automotive, and electronics where mechanical properties are paramount. In this paper, inspired by the wing scale of the C. Rubi butterfly, unique uniform and density-graded gyroid lattice structures were proposed. This research designed the uniform gyroid lattice structure with two design configurations of unit cell sizes (4, 6, and 8) and solidity percentages (20, 30, 40, and 50) and density-graded gyroid with a solidity range of 20–80% in a constant volume of 30*30*30 mm. The designs have been modeled in nTopology software and manufactured using the Vat polymerization additive manufacturing technique with two printing orientations (0° and 25°). Two sets of the samples were printed, and one group was given postcuring treatment at 80°C for 2 hours. Quasi-static compression testing was performed to investigate the improvement in mechanical characteristics due to postcuring treatment and print orientation. The results indicate significant relationships between design parameters and mechanical performance. The density-graded gyroid lattice exhibits four times higher compressive strength than higher solidity uniform gyroid samples (UC-8-solidity-40 and 50%) when subjected to the same or less mass. In addition, debonding of connecting surfaces due to higher postcuring temperature, and better performance of horizontally printed samples have been addressed. Moreover, simulation and experimental deformation patterns for uniform and graded gyroid lattice structures have been displayed.

Surface reconstruction, modification and functionalization of natural diatomites for miniaturization of shaped heterogeneous catalysts

Since the discovery of mesoporous silica in 1990s, there have been numerous mesoporous silica-based nanomaterials developed for catalytic applications, aiming at enhanced catalytic activity and stability. Recently, there have also been considerable interests in endowing them with hierarchical porosities to overcome the diffusional limitation for those with long unimodal channels. Present processes of making mesoporous silica largely rely on chemical sources which are relatively expensive and impose environmental concerns on their processes. In this regard, it is desirable to develop hierarchical silica supports from natural minerals. Herein, we present a series of work on surface reconstruction, modification, and functionalization to produce diatomite-based catalysts with original morphology and macro-meso-micro porosities and to test their suitability as catalyst supports for both liquid- and gas-phase reactions. Two wet-chemical routes were developed to introduce mesoporosity to both amorphous and crystalline diatomites. Importantly, we have used computational modeling to affirm that the diatomite morphology can improve catalytic performance based on fluid dynamics simulations. Thus, one could obtain this type of catalysts from numerous natural diatoms that have inherently intricate morphologies and shapes in micrometer scale. In principle, such catalytic nanocomposites acting as miniaturized industrial catalysts could be employed in microfluidic reactors for process intensification.

Additive Manufacturing of a Steel Splice Joint for Tubular Elements in a Modular Wind Tower

AbstractWind turbines of large size pose a challenge to structural engineers in providing suitable supporting structures. Nevertheless, these structures frequently result in complex logistical requirements, raising the expenses of new projects. Hence, the design philosophy is shifting towards lighter and modular towers, which often use tubular components. However, due to the intricate shape of the joints, connecting these tubular components is costly and laborious. Therefore, considering the advantages of new fabrication techniques, such as additive manufacturing, a ‘plug and play’ (PnP) device is in development to satisfy the requirements of a splice joint part of an onshore modular tower supporting a wind energy converter. An optimisation methodology was developed to determine the geometry of the device by structural topology optimisation and validate using finite element method software. As result from this methodology, three optimised geometries able to meet the desired requirements were found. Finally, the PnP device delivered a bespoke solution that allows for the simple joining of modular tubular components and reduces the raw material consumption without compromising the performance of the joint.

USING SOLIDWORKS FOR PROTOTYPING AERODYNAMIC STEERING DRIVES

The work discusses the effective use of the Solidworks software for modeling complex mechanisms with moving elements of intricate shapes. The application of the program by designers in enterprises significantly increases the efficiency of the work of design bureaus and research and experimental departments. Development time is greatly reduced, and many analysis tools allow for the avoidance of errors. The use of Solidworks for creating 3D models, along with additive technologies for manufacturing these models, takes the creation of prototypes of complex steering drives to a qualitatively different level. To model such complex-shaped parts as ailerons, the Solidworks tool, “Section hood” was used, such a tool greatly simplifies modeling and allows you to achieve the desired shape of the model. The engine models were used in the Solidworks assembly and combined with the mating conditions with other components, this allowed to adjust the design “in the context of the assembly” to the actual dimensions of the engines. To analyze the correct movements of the drive elements, “mechanical couplings” with real gear ratios were installed on all gears. In this way, it was possible to fully analyze the movement of all drive elements, to determine their position during movement After the modeling and analysis process was completed, the prototype manufacturing process began, for which the FDM printing technology was chosen as the fastest, cheapest, but capable of reproducing complex shape details. CoPET plastic is chosen as the main material for printing, bearings are used for smooth rotation of drive elements, all axes of mechanisms are made of metal with the help of mechanical processing.The manufactured prototype turned out to be working, all movements are performed as intended in the modeling process, you can perform experiments and research with the obtained product to obtain the necessary results. The Solidworks software product allowed not only to fully simulate the steering drive, but also to avoid many errors thanks to the available analysis tools. The FDM printing technology made it possible to quickly create a prototype, provide all the intended functionality, the quality of the parts allows the drive to work correctly.

Contactless 3D surface characterization of additive manufactured metallic components using terahertz time-domain spectroscopy

Terahertz time-domain spectroscopy has experienced significant progress in imaging, spectroscopy, and quality inspection, e.g., for semiconductor packaging or the automotive industry. Additive manufacturing alloys (also known as alloys for use in 3D printing) have risen in popularity in aerospace and biomedical industries due to the ability to fabricate intricate designs and shapes with high precision using materials with customized mechanical properties. However, these 3D-printed elements need to be polished thereafter, where the surface roughness is inspected using techniques such as the laser scanning microscope. In this study, we demonstrate the use of terahertz time-domain spectroscopy to assess the average roughness profile and height leveling of stainless steel for comparisons against the same parameters acquired using laser scanning microscopy. Our results highlight the potential of the proposed technique to rapidly inspect 3D-printed alloys over large areas, thus providing an attractive modality for assessing surface profiles of AM-manufactured terahertz components in the future.

Finite element simulations and experimental investigations on formability of magnesium alloys in superplastic forming

The paper presents the formability aspects of magnesium alloy (AZ31B) sheets into regular and intricate shapes during Super Plastic Forming (SPF). Finite Element (FE) simulations are performed at specific strain rates within the superplastic temperature range. The formability of 1 mm sheet into conical, cylindrical, box and groove shaped dies are simulated. The simulated Pressure-Time (P-T) curve is given as pressure control algorithm to form the shapes experimentally. Thickness strains of the experimentally formed components validated with simulation results are found to be in close agreement with each other. It is demonstrated by the analysis that regular shapes posses uniform thickness distribution throughout the profile. The components with complex intricate shapes recorded unevenness in thinning behavior. The unevenness in thinning is influenced by the Grain Boundary Sliding (GBS) and diffusion kinetics. GBS is well controlled by optimum P-T algorithm to produce sharp intricate shapes with uniform thickness.

Influence of the interlayer temperature on structure and properties of CMT wire arc additive manufactured NiTi structures

A potential method for producing intricate Shape Memory Alloy (SMA) structures for uses like actuators and vibration dampers is wire arc additive manufacturing (WAAM). However, excessive heat build-up during the multi-layer deposition procedure in WAAM can result in process instability and departures from the intended mechanical qualities and dimensions. To address these problems, the interlayer temperature was optimized for printing on NiTi walls in this work. Without interlayer temperature control (WITC), 200 °C, and 400 °C were used to create three samples in order to study the impacts on the porosity level, morphology, and mechanical characteristics of the NiTi walls generated by WAAM. The Shape memory behavior of the manufactured NiTi walls was further examined through shape recovery investigations utilizing hot plate actuation. The findings demonstrated that regulating the interlayer temperature below 300 °C, preferably at 200 °C, enhanced the mechanical characteristics, decreased the porosity content, and enhanced the microstructure of the NiTi walls. The development and improvement of WAAM techniques for the manufacture of premium NiTi SMA components can benefit greatly from these findings.

Advanced Optimization of Surface Characteristics and Material Removal Rate for Biocompatible Ti6Al4V Using WEDM Process with BBD and NSGA II.

Machining titanium alloy (Ti6Al4V) used in orthopedic implants via conventional metal cutting processes is challenging due to excessive cutting forces, low surface integrity, and tool wear. To overcome these difficulties and ensure high-quality products, various industries employ wire electrical discharge machining (WEDM) for precise machining of intricate shapes in titanium alloy. The objective is to make WEDM machining parameters as efficient as possible for machining the biocompatible alloy Ti6Al4Vusing Box-Behnken design (BBD) and nondominated sorting genetic algorithm II (NSGA II). A quadratic mathematical model is created to represent the productivity and the quality factor (MRR and surface roughness) in terms of varying input parameters, such as pulse active (Ton) time, pulse inactive (Toff) time, peak amplitude (A) current, and applied servo (V) voltage. The established regression models and related prediction plots provide a reliable approach for predicting how the process variables affect the two responses, namely, MRR and SR. The effects of four process variables on both the responses were examined, and the findings revealed that the pulse duration and voltage have a major influence on the rate at which material is removed (MRR), whereas the pulse duration influences quality (SR). The tradeoff between MRR and SR, when significant process factors are included, emphasizes the need for a reliable multi-objective optimization method. The intelligent metaheuristic optimization method named nondominated sorting genetic algorithm II (NSGA II) was utilized to provide pareto optimum solutions in order to achieve high material removal rate (MRR) and low surface roughness (SR).

Overview of 3D and 4D Printing Techniques and their Emerging Applications in Medical Sectors

Abstract: Additive manufacturing is a highly effective and versatile technology, especially in the medical sector, due to its customization, material complexity, design flexibility, waste minimization, and ability to fabricate intricate shapes that are cumbersome to manufacture by conventional manufacturing techniques. 4D printing plays a significant role in the medical field, especially in the areas not covered by 3D printing technologies, such as smart implants, devices and tools. Also, 4D printing helps doctors to treat more patients with high accuracy and quality. Hence, this manuscript aims to provide an overview of distinct 3D and 4D printing techniques and their emerging applications in the medical sector. A study of 3D printing technologies is presented by explaining the working principles of distinct 3D printing methods: stereo lithography, fusion deposition modeling, inkjet printing, selective laser sintering, selective laser melting and electron beam melting. In addition, the emerging applications of 3D printing in medical sectors (e.g., bioprinting, surgical guides, pharmaceuticals, prostheses, medical devices, dentistry, physiotherapy, etc.), as well as challenges and the future scope of 3D printing, are also discussed. Further, the concept of 4D printing, the market for both 3D and 4D printing, the benefits of 4D printing, the comparison of 3D and 4D printing, limitations, applications, and the future scope of 4D printing in the medical sector are also covered.

Investigation on Metal Hybrid Fibres Laminate (MHFL) in hybrid machining

Metal hybrid fibre laminates (MHFLs) are gaining extensive attention due to their low weight-high strength and superior durability, which are used for primary constructions in a comprehensive application of aerospace and automobile industries. However, machining intricate shapes in MHFL is a challenge ahead of conventional machining processes. Hence, the present work aims at the machinability study of Titanium metal cored basalt/flax fibre laminate by using ultrasonic frequency vibration coupled wire electrical discharge machining (UFV-WEDM). The process- variables such as pulse on (Ton), pulse off (Toff), current (I), cutting angle (CA), and servo voltage (SV) coupled with ultrasonic frequency vibration (UFV) are varied at experimentation designed by using the Central Composite Design (CCD). The machined surface is characterized by the material removal rate (MRR) and surface roughness (SR). The empirical findings show that the servo voltage significantly influences MRR (73.93 %) and SR (70.02 %). The performance sequence order of significant influencing parameters is SV > Toff>CA > Ton>I. The Desirability analysis generated the optimum setting for minimizing the SR & maximizing MRR is Ton = 16 μs, Toff =14 μs, SV = 70 V, I = 3 A and CA = 30°. Scanning Electron Microscopic, 3D topography and atomic force microscopic (AFM) images were used to perform the micro-analysis on the machined surface of MHFL.

Rapid-Scan Resonant Two-Dimensional Impulsive Stimulated Raman Spectroscopy of Excited States.

Photochemical reactions occur in the electronically excited state, which is effectively represented by a multidimensional potential energy surface (PES) with a vast degree of freedom of nuclear coordinates. The elucidation of the intricate shape of the PES constitutes an important topic in the field of photochemistry and has long been studied both experimentally and theoretically. Recently, fully time-domain resonant two-dimensional Raman spectroscopy has emerged as a potentially powerful tool to provide unique information about the coupling between vibrational manifolds in the excited state. However, the wide application of this technique has been significantly hampered by the technical difficulties associated with experimental implementation and remains challenging. Herein, we demonstrate time-domain resonant two-dimensional impulsive stimulated Raman spectroscopy (2D-ISRS) of excited states using sub-10 fs pulses based on the rapid scan of the time delay, which facilitates the efficient collection of time-domain vibrational signals with high sensitivity. As a proof-of-principle experiment, we performed 2D-ISRS of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) in solution. Through 2D Fourier transformation of the high-quality time-time oscillatory signal, we obtained a 2D frequency-frequency correlation map of excited-state TIPS-pentacene in the broad frequency window of 0-2000 cm-1. The data clearly resolve a number of cross peaks that signify the correlations among excited-state vibrational manifolds. The high capability of the rapid-scan-based 2D-ISRS spectrometer presented in this study enables the systematic investigation of various photochemical reaction systems, thereby further promoting the understanding and applications of this new multidimensional spectroscopy.