Designs, Volume 7, Issue 5 (October 2023) – 17 articles

Mechanical couplings in engineering usually use interference fits to connect the shaft and hub. A railway wheel axle is a press fit that is connected by interference and can be subjected to bending stress. In loaded press fits, a high concentration of contact stresses can be generated in the area of the axle-fillet beam, which in most cases leads to the failure of the axle due to fatigue and fretting fatigues. Therefore, it is crucial to determine the ability of the press-fitted joints to provide sufficient frictional resistance that can withstand the loads and torques by evaluating the safety factor, especially when the mechanical or structural system is loaded. In this paper, the contact pressure and stress distribution along the radius of the wheel axle are studied using the analytical calculation of Lame’s equation, and the numerical method used is by ANSYS software. It was found that interference fits have a great influence on the connection strength of interference fits, which are directly related to the contact pressure. Increasing the interference increases the contact pressure, which allows higher torque and load capacity to be transmitted. The finite element analysis showed good agreement for the highest interference value of 230 µm with a relative error of 1.4%, while this error increased to the maximum relative error of 14.33% for a minimum interference of 100 µm. Full article

The aim of this study was to evaluate and compare the fracture resistance of a temporary three-unit fixed dental prosthesis (FDP) made of a new polymeric material obtained by an additive technique (3DPP) using a computer-aided design and manufacturing (CAD/CAM) system, comparing the prosthesis to the respective outcomes of temporary polymethylmethacrylate (PMMA) FDPs obtained by a subtractive technique (milling). Methods: Three-unit FDPs were 3D printed using a polymeric material (n = 20) or milled using polymethylmethacrylate (n = 20). After thermocycling at 5000 cycles at extreme temperatures of 5 °C and 55 °C in distilled water, each specimen was subjected to a compression test on a universal testing machine at a rate of 0.5 mm/min until failure occurred, recording the value in newtons (N). Results: There were statistically significant differences (p-value < 0.005) between the PMMA material (2104.7 N; SD = 178.97 N) and 3DPP (1000.8 N; SD = 196.4 N). Conclusions: The fracture resistance of the PDFs manufactured from milled PMMA showed higher values for fracture resistance. However, the resistance of the 3DPP showed acceptable values under mechanical load; this notable advance in the resistance of printed materials consolidates them as an important alternative to use in interim indirect restorations. Full article

Globally, most bridges fail due to hydrological causes such as scouring or flooding. Therefore, using a hydrological approach, this study proposes a methodology that contributes to prioritizing the intervention of bridges to prevent their collapse. Through an exhaustive literature review, an evaluation matrix subdivided into four dimensions was developed and a total of 18 evaluation parameters were considered, distributed as follows: four environmental, six technical, four social, and four economic. This matrix was applied to eight bridges with a history of hydrological problems in the same river and validated through semi-structured interviews with specialists. Data were collected through field visits, journalistic information, a review of the gauged basin’s historical hydrological flow rates, and consultations with the population. Modeling was then conducted, which considered the influence of gullies that discharge additional flow using HEC-HMS and HEC-RAS, before being calibrated. The application of the matrix, which is an optimal tool for prioritizing bridge interventions, revealed that five bridges have a high vulnerability with scores between 3 and 3.56, and three bridges have a medium vulnerability with scores between 2.75 and 2.94. The hydrological multidimensional approach, which can be adapted for similar studies, contributes to a better decision-making process for important infrastructure interventions such as riverine bridges. Full article

A variety of bearing profile designs can be used to improve the performance of a rotor–bearing system in severe conditions, such as operating with a shaft misalignment. Misalignments usually occur due to a deformation of the journal, bearing wear, and installation errors. This paper investigates the effects of bearing design parameters under a 3D journal misalignment for a wide range of length-to-diameter ratios to consider short, finite-length, and long journal bearings. Furthermore, the dynamic response of the system to journal perturbation considering linear and parabolic bearing profiles is also investigated. A numerical solution is identified based on the finite difference method, and the equations of motion are derived based on a linear stability analysis in which the fourth-order Runge–Kutta method is used to obtain the journal trajectories. The results show that both profiles help to enhance the rotor–bearing system’s performance regarding the lubricant layer thickness and pressure distribution, in addition to the shaft critical speed over the entire considered range of length-to-diameter ratios. This enhancement reduces the misalignment negative effects on the system performance. The response of the rotor-bearing system to journal perturbation in the case of the parabolic profile are very close to the perfect alignment case in comparison with a linear modification. Full article

Accurate models of power electronic converters can greatly enhance the accuracy of hardware-in-the-loop (HIL) simulators. This can result in faster and more cost-effective design cycles in industrial applications. This paper presents a detailed hardware model of the IGBT and power diode at the device level suggested for emulating power electronic converters on a field programmable gate array (FPGA). The static visualization of the IGBT component involves an arrangement of equivalent models for both the MOSFET and bipolar transistor in a cascading configuration. The dynamic aspect is represented by inter-electrode nonlinear capacitances. In an effort to expedite the development process while still producing reliable results, the algorithm for the simulation system was built utilizing FPGA-based rapid prototyping via the HDL Coder in MATLAB software (R2019b). Essentially, the HDL Coder transforms the Simulink blocks of these devices within MATLAB into a hardware description language (HDL) suitable for implementation on an FPGA. To evaluate the suggested IGBT hardware model and the nonlinear circuit simulation technique, a chopper circuit is replicated, and an FPGA-in-the-loop simulation is carried out to compare the efficacy and accuracy of the model with both offline simulation results and real-time simulation results using MATLAB Simulink software and the Altera FPGA Cyclone IV GX development board. Full article

This paper designs two DC-DC converter configurations integrated with solar PV renewable energy resource. Its focuses on comparing two converter topologies: the conventional boost converter and the switched capacitor boost converter. The Perturb and Observe (P&O), Incremental Conductance (INC), Genetic Algorithm (GA), and Particle Swarm Optimization (PSO) algorithms are employed to dynamically enhance the Maximum Power Point Tracking (MPPT) performance for both converters. The simulation results demonstrate that both converter topologies, when integrated with appropriate MPPT algorithms, can effectively harvest maximum power from the solar PV. However, the switched capacitor topology converter exhibits advantages in terms of current capabilities and voltage performance. In addition, combing the switched capacitor boost converter with the GA-MPPT algorithm improved the output voltage profile. The switched capacitor topology demonstrates distinct advantages by exhibiting enhanced current control, enabling improved handling of dynamic load changes and varying irradiance conditions. It shows voltage regulation, resulting in reduced output voltage fluctuations and enhanced stability, thereby optimizing energy extraction. The GA-MPPT simulation demonstrates a substantial increase in maximized output current for the switched capacitor boost configuration (70 A) when compared to the conventional type (10 A). The validation and implementation of the system models are carried out using MATLAB/Simulink. Full article

The present paper investigates the mechanical behavior of a biomimetic Voronoi structure, inspired by the microstructure of the shell of the sea urchin Paracentrotus lividus, with its characteristic topological attributes constituting the technical evaluation stage of a novel biomimetic design strategy. A parametric design algorithm was used as a basis to generate design permutations with gradually increasing rod thickness, node count, and model smoothness, geometric parameters that define a Voronoi structure and increase its relative density as they are enhanced. Physical PLA specimens were manufactured with a fused filament fabrication (FFF) printer and subjected to quasi-static loading. Finite element analysis (FEA) was conducted in order to verify the experimental results. A minor discrepancy between the relative density of the designed and printed models was calculated. The tests revealed that the compressive behavior of the structure consists of an elastic region followed by a smooth plateau region and, finally, by the densification zone. The yield strength, compressive modulus, and plateau stress of the structure are improved as the specific geometric parameters are enhanced. The same trend is observed in the energy absorption capabilities of the structure while a reverse one characterizes the densification strain of the specimens. A second-degree polynomial relation is also identified between the modulus, plateau stress, and energy capacity when plotted against the relative density of the specimens. Distinct Voronoi morphologies can be acquired with similar mechanical characteristics, depending on the design requirements and application. Potential applications include lightweight structural materials and protective gear and accessories. Full article

Because of its numerous advantages, 3D printing is widely employed for a variety of purposes. The mechanical characteristics of 3D-printed items are quite important. 3D-printed polylactic acid (PLA) is a common thermoplastic polymer due to its excellent characteristics and affordable cost. Because of its enhanced characteristics, polyethylene terephthalate glycol (PETG) has recently received a lot of attention. Despite PETG’s potential appeal in the 3D-printing field, little research has been conducted to explore its qualities, such as the impacts of raster angle on elasticity, which could lead to the development of more accurate guidelines for inspection and assessment. In this regard, this study examines the mechanical characteristics of polylactic acid (PLA) and polyethylene terephthalate glycol (PETG) 3D-printing specimens with different raster angles. Test specimens with raster angles of 15° and 30° were printed, and the stress–strain responses were recorded and compared with the simulated profiles generated using ANSYS software. The results showed that the raster angle significantly affected the mechanical properties of both types of materials. The simulated profile matched well with the experimental profile only in the case of PLA printed with a raster angle of 15°. These findings imply that extra effort should be made to ensure that the raster angle is tailored to yield the optimal mechanical properties of 3D-printed products. Full article

The importance of sustainable design for achieving sustainable development goals (SDG) has become increasingly prevalent. Agility for sustainable design development is a project management approach that aims to provide a flexible and efficient way of developing new products. However, the application of agility for sustainable design development is not well-defined, with unknown processes and benefits. To address this, this study aims to explore the benefits of theoretical research and the application of agility in sustainable design. The study critically examines the application of agility in sustainable design development through a literature review. The results identify eight integration directions of agility that contribute to sustainable design, providing a better understanding of agility and enabling its implementation in the development of new products. This study seeks to create a more coherent and rigorous system of theory and practice for sustainable design. Full article

This paper presents an approach to implem enting centralized multirobot simultaneous localization and mapping (MR-SLAM) in an unknown environment based on LiDAR sensors. The suggested implementation addresses two main challenges faced in MR-SLAM, particularly in real-time applications: computing complexity (solving the problem with minimum time and resources) and map merging (finding the alignment between the maps and merging maps by integrating information from the aligned maps into one map). The proposed approach integrates Fast LiDAR and Odometry Mapping (FLOAM), which reduces the computational complexity of localization and mapping for individual robots by adopting a non-iterative two-stage distortion compensation method. This, in turn, accelerates inputs for the map merging algorithm and expedites the creation of a comprehensive map. The map merging algorithm utilizes feature matching techniques, Singular Value Decomposition (SVD), and the Iterative Closest Point (ICP) algorithm to estimate the transformation between the maps. Subsequently, the algorithm employs a map-merging graph to estimate the global transformation. Our system has been designed to utilize two robots and has been evaluated on datasets and in a simulated environment using ROS and Gazebo. The system required less computing time to build the global map and achieved good estimation accuracy. Full article

In the context of current societal challenges, such as climate neutrality, industry digitization, and circular economy, this paper addresses the importance of improving recycling practices for electric vehicle (EV) battery packs, with a specific focus on lithium–ion batteries (LIBs). To achieve this, the paper conducts a systematic review (using Google Scholar, Scopus, and Web of Science as search engines), considering the last 10 years, to examine existing recycling methods, robotic/collaborative disassembly cells, and associated control techniques. The aim is to provide a comprehensive and detailed review that can serve as a valuable resource for future research in the industrial domain. By analyzing the current state of the field, this review identifies emerging needs and challenges that need to be addressed for the successful implementation of automatic robotic disassembly cells for end-of-life (EOL) electronic products, such as EV LIBs. The findings presented in this paper enhance our understanding of recycling practices and lay the groundwork for more precise research directions in this important area. Full article

The effect of printing parameters (nozzle diameter, layer height, nozzle temperature, and printing speed), dimensions (wall thickness), and filament material on the crashworthiness performance of 3D-printed thin-walled multi-cell structures (TWMCS) undergoing quasi-static compression is presented. The ideal combination of parameters was determined by employing the Signal-to-Noise ratio (S/N), while Analysis of Variance (ANOVA) was utilized to identify the significant parameters and assess their impact on crashworthiness performance. The findings indicated that the ideal parameters for the specific energy absorption (SEA) consisted of a nozzle diameter of 0.6 mm, layer height of 0.3 mm, nozzle temperature of 220 °C, printing speed of 90 mm/s, wall thickness of 1.6 mm, and PLA(+) filament material. Afterward, the optimal parameters for crushing force efficiency (CFE) included a nozzle diameter of 0.8 mm, layer height of 0.3 mm, nozzle temperature of 230 °C, print speed of 90 mm/s, wall thickness of 1.6 mm, and PLA(ST) filament material. The optimum parameter to minimize manufacturing time is 0.3 mm for layer height and 90 mm/s for printing speed. This research presents novel opportunities for optimizing lightweight structures with enhanced energy absorption capacities. These advancements hold the potential to elevate passenger safety and fortify transportation systems. By elucidating the fundamental factors governing the crashworthiness of thin-walled multi-cell PLA 3D-printed tubes, this study contributes to a deeper understanding of the field. Full article

The liberalization of the German energy market has created opportunities for end-consumers, including industrial companies, to actively participate in the electricity market. By making their energy loads more flexible, consumers can generate additional income and thus save money. Energy storage systems can be utilized to achieve the required flexibility by temporarily storing excess electrical energy in the form of heat, cold, or electricity for later use. This publication focuses on how the dimensionality of energy storage is influenced by load forecasting. The results show that inaccuracies in load forecasting lead to a direct over-dimensioning and thus, a deterioration of the economics of energy storage technologies. Using two scenario cases, it shows on the one hand how important good forecasts are and on the other hand that buffers must be included in the conceptual design in order to be able to compensate for forecast errors. Full article

Microelectromechanical system (MEMS) vibrating gyroscope design considerations are always intriguing due to their microscale mechanical, electrical, and material behavior. MEMS vibrating ring gyroscopes have become important inertial sensors in inertial measurement units (IMU) for navigation and sensing applications. The design of a MEMS vibrating ring gyroscope incorporates an oscillating ring structure as a proof mass, reflecting unique design challenges and possibilities. This paper presents a comprehensive design analysis of the MEMS vibrating ring gyroscope from the mechanical, electrical, and damping perspectives. The mechanical design of the MEMS vibrating ring gyroscope investigates the various frame designs of the vibrating ring structure, as well as the various beam structures, including rectangular and semicircular beam structures, which are analyzed using mathematical models and finite element analysis (FEA) simulations that provide an in-depth analysis of the stiffness and deflection of the vibrating structures. The electrical designs of the MEMS vibrating ring gyroscope are analyzed using various electrode configurations, electrostatic actuation, and capacitive detection mechanisms. The design analysis of various forms of damping, including viscous, structural, thermoelastic, and anchor damping, is discussed. The variety of design structures is investigated for MEMS vibrating ring gyroscopes’ mechanical, electrical, and damping performance. Full article

Virtual reality (VR) technology has recently been adopted by educators for use in the classroom. Currently, this educational model includes not only lectures with teachers in the online classroom but also practical sessions using online platforms. Few studies have explored the potential of pedagogical approaches to implementing VR in the classroom for the purpose of design education. The focus of this paper was to study the learning experiences of the 3D visualisation of products among industrial design students through the strategic implementation of virtual reality technology. A within-subjects comparative study was conducted to measure cognitive workload and engagement and enjoyment, while a 3D modelling task was given using two different set-ups (conventional 3D software versus VR-based software). The statistical results show that the NASA-TLX score was lower in the case of the VR-based 3D modelling exercise compared to the conventional 3D software-based exercise. On the other hand, the mean values were higher for the engagement and enjoyment and usability scores, which means that the VR-based experience for 3D modelling was better than the traditional modelling experience using conventional software. Hence, there are possibilities to implement VR-based 3D modelling tools for online industrial design education for 3D visualisation in the near future. Full article

In recent years, people have been buying custom-built PCs based on the performance they want and what they will use them for. However, there are many challenges for non-technical users when purchasing a custom-built PC. Not only is the terminology of computer devices unfamiliar to non-experts, but there are many specifications for different computer devices that need to be considered. Therefore, this paper proposes a method for recommending appropriate device models when purchasing custom-built PCs using a skyline. Because different computer devices have different specifications, we need a method that takes into account multiple attributes. Skyline querying is a technique that considers multiple attributes of an object and indexes them in order of user satisfaction. A grid skyline is a technique that uses a grid-based partitioning technique to reduce the number of calculations of the dominance relationship between objects in the existing skyline technique, thus reducing the index construction time. We measured the similarity between the results of the grid skyline and the leaderboard for each model of computer device. As a result of this experiment, compared to the leaderboard categorized by model of computer device, the average score was 88 out of 100, which was similar to the actual leaderboard. Full article

Fused deposition modeling (FDM) technology is an emerging technology with promising applications, with the nozzle playing a crucial role in extrusion, heating, and material ejection. However, most current extrusion-based 3D printers handle only single-material printing, making the integration of multiple materials through a single nozzle challenging due to compromised quality and clogging risks. This paper introduces a method to design multi-material 3D printing nozzles using the Theory of Inventive Problem Solving (TRIZ) and knowledge graph (KG). By optimizing design and leveraging TRIZ’s contradiction resolution principle, this study addressed bottlenecks and complexities in multi-material nozzle design, providing insightful recommendations. A patent knowledge graph focused on spray nozzles was created, storing material properties, design elements, and constraints for enhanced knowledge sharing. Building on identified challenges and recommendations, the study utilized keyword searches and associative paths in the knowledge graph to guide designers in generating innovative solutions. Validation was achieved through two distinct nozzle design models resulting from guided innovations. The TRIZ-KG methodology presented in this paper provides designers with a systematic cognitive framework to empower designers in overcoming technical obstacles and proposing precise solutions. Full article