Physical Prototype Research Articles

On the influence of local deformation on structural dynamic models of bolted lap joints

The acoustic and structural dynamic behavior of technical products—often referred to as Noise, Vibration, and Harshness (NVH)—is an important criterion in customers’ purchasing decisions. Therefore, NVH optimization is a crucial goal of the development process. NVH is influenced by dynamic excitations, caused by time-varying forces e.g. in gears or electric machines, as well as the transfer path of sound from the location of excitation to a receiver such as a driver’s ear and the sound perception. The behavior of the transfer path is determined by amplification or isolation of structure-borne and airborne sound between the location of the excitation and the location of the receiver. As a result, eigenfrequencies and damping in the transfer path form crucial structural dynamic properties.Within jointed structures, friction between the surfaces of lap joints are the most dominant influencing factor on the transfer path’s damping. In order to increase the efficiency of NVH optimization in the development process, methods of virtual product development have become an established tool. Especially finite element method (FEM) and elastic multi-body simulation (eMBS) have allowed to numerically evaluate the structural dynamic behavior of technical products before manufacturing physical prototypes. While numerous methods for modeling jointed structures exist in FEM and eMBS environments, the choice of suitable eMBS models of joints remains challenging today. This is because the frictional behavior between the jointed partners in higher frequencies is largely influenced by the deformation of the joint surface. However, the deformation of the jointed parts is simplified in eMBS models compared to quasi-continuous FEM models. Accordingly, the choice of a suitable spatial discretization of eMBS joint models is a key factor in the model quality of eMBS models. Thus, this work proposes a modeling guideline for eMBS models of jointed structures based on the deformation of the structure using the criterion of rigidness. The method is demonstrated on an eMBS model of the academic Brake Reuß beam, which consists of two beam elements jointed with three screws in an overlap lap joint. Good agreement between eMBS simulation and measurement with an error of 1 dB is achieved using the proposed modeling method.

METHOD OF PROTOTYPING CONTROL UNITS BASED ON THE OPENPLC APPLICATION

The problem of designing control devices based on programmable logic controllers (PLCs) is their high cost and, as a rule, unavailability at the initial design stage. The purpose of the research is to reduce the time and cost of designing the system by creating prototypes of control units with the software implementation of control algorithms in the languages of the MEK 61131-3 standard and the execution of programs in the Arduino board. The research method consists in the decomposition of project models of operating and control automata of the control device and their implementation in the software environment of the OpenPLC application in the form of program organization components (POU) in Ladder Diagram, Function Block Diagram, Sequential Function Chart and Structured Text languages. The result of the study is a method of creating typical POU operating and control automata of the control system, which are executed in the Arduino board. An example of the application of the proposed methodology for the design of a prototype of the facility's temperature control system is given. The developed prototype was tested using a logical PLC and a physical prototype, which confirmed their functional compliance with the original and a reduction in the cost of the equipment by at least an order of magnitude.

Intelligent Tire Prototype in Longitudinal Slip Operating Conditions.

With the recent advances in autonomous vehicles, there is an increasing need for sensors that can help monitor tire-road conditions and the forces that are applied to the tire. The footprint area of a tire that makes direct contact with the road surface, known as the contact patch, is a key parameter for determining a vehicle's effectiveness in accelerating, braking, and steering at various velocities. Road unevenness from features such as potholes and cracks results in large fluctuations in the contact patch surface area. Such conditions can eventually require the driver to perform driving maneuvers unorthodox to normal traffic patterns, such as excessive pedal depressions or large steering inputs, which can escalate to hazards such as the loss of control or impact. The integration of sensors into the inner liner of a tire has proven to be a promising method for extracting real-time tire-to-road contact patch interface data. In this research, a tire model is developed using Abaqus/CAE and analyzed using Abaqus/Explicit to study the nonlinear behavior of a rolling tire. Strain variations are investigated at the contact patch in three major longitudinal slip driving scenarios, including acceleration, braking, and free-rolling. Multiple vertical loading conditions on the tire are applied and studied. An intelligent tire prototype called KU-iTire is developed and tested to validate the strain results obtained from the simulations. Similar operating and loading conditions are applied to the physical prototype and the simulation model such that valid comparisons can be made. The experimental investigation focuses on the effectiveness of providing usable and reliable tire-to-road contact patch strain variation data under several longitudinal slip operating conditions. In this research, a correlation between FEA and experimental testing was observed between strain shape for free-rolling, acceleration, and braking conditions. A relationship between peak longitudinal strain and vertical load in free-rolling driving conditions was also observed and a correlation was observed between FEA and physical testing.

Industrial device for the continuous UV-C treatment of fruit and vegetables: simulation-aided design and model validation

Abstract The irradiation of foods with UV-C light is a non-thermal and non-chemical treatment that allows for achieving several benefits, from surface decontamination to hormetic effects on biological matrices. Nowadays, even if its effects have been extensively proven and discussed, UV-C radiation is not widespread on an industrial level for the treatment of solid and liquid foods, mainly due to technical limitations and the non-uniformity of legislation for different products and among different countries. In this study, numerical simulation was adopted as a tool for the design and optimization of a device for the UV-C treatment of fruits and vegetables. After validating the modelling approach, the radiation treatment was evaluated for different product configurations. The proposed approach aims to facilitate the implementation and the scale-up of the UV-C treatment in the food industry, as it allows for assessing its effects under different operating conditions, prior to the physical prototyping stages.

An open-loop control algorithm for improved tracking in a heliostat

The growing energy demand and its relation to climate change have driven the search for sustainable alternatives, such as concentrated solar energy. In this context, heliostats play a crucial role by reflecting and concentrating solar light onto a receiver. However, traditional control approaches based on geographical data have limitations. This study introduces an autonomous control system for heliostats that eliminates the need for preloaded geographical data. The approach is based on communication between the heliostat and the solar tracker, with two configuration modes: map calibration and automatic. Centralized and autonomous heliostats are distinguished, with the latter being the focus of the study. Autonomous heliostats have their own control system and can make decisions regarding positioning and safety. The methodology involves a mathematical algorithm that calculates the optimal rotation and tilt of the heliostat to redirect light toward a target. Simulation and physical prototype testing validate a remarkable consistency between simulated and experimental data. A key result is the surprising similarity of 97.9% between the obtained data, validating the algorithm's effectiveness. This study provides a robust approach for designing autonomous heliostat control systems, integrating simulation and experimentation. These results support the algorithm's precision and ability to direct solar radiation effectively. Expanding towards autonomous control and complete heliostat system evaluation facilitates the path toward more efficient and sustainable concentrated solar energy.

Reconfigurable Thick-Panel Structures Based on a Stacked Origami Tube

Abstract Variable crease origami that exhibits crease topological morphing allows a given crease pattern to be folded into multiple shapes, greatly extending the reconfigurability of origami structures. However, it is a challenge to enable the thick-panel forms of such crease patterns to bifurcate uniquely and reliably into desired modes. Here, thick-panel theory combined with cuts is applied to a stacked origami tube with multiple bifurcation paths. The thick-panel form corresponding to the stacked origami tube is constructed, which can bifurcate exactly between two desired modes without falling into other bifurcation paths. Then, kinematic analysis is carried out, and the results reveal that the thick-panel origami tube is kinematically equivalent to its zero-thickness form with one degree-of-freedom (DOF). In addition, a reconfigurable physical prototype of the thick-panel origami tube is produced, which achieves reliable bifurcation control through a single actuator. Such thick-panel origami tubes with controllable reconfigurability have great potential engineering applications in the fields of morphing systems such as mechanical metamaterials, morphing wings, and deployable structures.

Optimizing terrestrial locomotion of undulating-fin amphibious robots: Asynchronous control and phase-difference optimization

This paper presents an asynchronous motion-control approach for undulating-fin amphibious robots, with emphasis on optimizing the phase differences of bilateral fin-surface waves to mitigate the pitch-angle instability typically observed in synchronous control. A comprehensive ground dynamics model is used in this study, which facilitates the meticulous analysis of pitch-angle variations. Using simulation software, a virtual prototype is developed to validate the control stability. This approach is further substantiated via experimental tests conducted on a physical prototype in diverse terrestrial environments. Simulation and experimental results indicate that asynchronous motion control methods significantly enhancing postural stability undulating-fin robots during terrestrial locomotion. Experimental findings demonstrate that adopting asynchronous motion control reduces the maximum range of pitch angles by 38.9%–42.3%. This method significantly enhancing postural stability of robot terrestrial locomotion. This study provides new insights for the design of undulating-fin amphibious robots.

Optimization of olive pomace dehydration process through the integration of computational fluid dynamics and deep learning

ABSTRACT This study introduces an innovative approach to optimize the dehydration process of olive pomace by combining computational fluid dynamics (CFD) and deep learning. Through CFD, it identifies the optimal air inlet velocity in a prototype of a passive direct solar dehydrator for olive pomace, which allows for the reduction of its moisture content for subsequent use as biomass. The prototype was simulated in ANSYS software, and this simulation consisted of the following steps: prototype design, meshing, selection of physical models, material assignment, boundary condition simulation, and validation of results with data obtained from the prototype. Following this process, it was concluded that the optimal air inlet velocity to the dehydration chamber is 0.1 m/s. Concurrently, an artificial neural network model was used to analyze data from sensors in the physical prototype, revealing that solar radiation and ambient temperature are the most influential variables on the temperature of the dehydration chamber. This analysis resulted in a predictive model for the optimization of the dehydration process, with a correlation coefficient of 0.9699 for temp_up and 0.9710 for temp_down, and a Willmott coefficient of 0.9999, demonstrating a high concordance between the model’s predictions and the experimental data. The model’s input variables include solar radiation, ambient temperature, and both external and internal air humidity. This integration of CFD and deep learning offers a promising methodology for improving olive pomace dehydration systems and the industry in general.

A simple 90° hybrid branchline coupler with wideband phase balance for 5G applications

Abstract A 90° hybrid coupler operating at a central frequency of 5.40 GHz is introduced, offering high-performance characteristics with compact dimensions of 616.65 mm² (33.3 mm × 18.5 mm). These features are achieved while maintaining a design that makes it easy to produce. The unique aspect of this microstrip FR4 substrate-based design is the consistent S-parameters, which remain steady despite changes in structural dimensions, thereby making it adaptable to fabrication variations. The reported S-parameters measured in 5.4 GHz are as follows: |S11|= –29.46 dB, |S21|= –4.11 dB, |S31|= –3.96 dB, and |S41|= –21.23 dB. This hybrid coupler operates over a bandwidth of 0.8 GHz (16%), demonstrating remarkable performance within this spectrum. In addition to its design, the coupler exhibits robust resilience against changes in substrate parameters and structural dimensions, ensuring reliability during the fabrication process. Following thorough simulation studies, a physical prototype of the coupler was constructed and subjected to laboratory measurements. The experimental results align closely with the simulation data, validating the accuracy and predictability of the design. In comparison with other studies and designs documented in the literature, this compact, high-performance 90° hybrid coupler exhibits clear advantages in terms of size, isolation, phase deviation, and structural complexity. Therefore, the benefits and applicability of this presented structure in the context of microwave circuits and systems are underscored. It’s noteworthy to mention that the central frequency of 5.4 GHz falls within the sub-6 GHz 5G band range.

PRINCIPLES OF MATHEMATICAL SIMULATION OF MINING VEHICLES USING APPLIED MATHEMATICAL SOFTWARE

The transportation of rock mass and coal in mining operations relies heavily on the efficiency and reliability of mining transport systems. This study delves into the intricate dynamics of chassis functions during transportation, emphasizing the critical role of transmitting dynamic stresses and mass to the road or rail structures. With a focus on increasing productivity, modern mining locomotives and heavy dump trucks now carry substantial adhesion adhesive weights, allowing for the hauling of heavier loads even on steep slopes. The integration of scientific simulations and research-based design methods aids in identifying and managing dynamic loading effects within mining vehicle chassis. This approach minimizes the transfer of dynamic loads onto the bolster structure, enhancing system reliability and operational efficiency. Computer-aided software plays a vital role in stream-lining the development process, reducing the need for costly physical prototypes and extensive testing in challenging mining environments. The study outlines simplified calculation schemes for mining transport utilities, balancing the need for accuracy with computational efficiency. By utilizing mathematical models and simulation techniques, the dynamics of mine locomotives and dump trucks can be accurately evaluated, guiding design decisions and operational strategies. The application of Lagrange equations and software tools like “Wolfram Mathematica” facilitates the generation of differential equations for dynamic analysis, providing insights into vehicle dynamics and road interactions. Overall, this research underscores the importance of advanced modeling and simulation techniques in optimizing mining transport systems, enhancing safety, productivity, and reliability in demanding mining environments. Purpose. To highlight the application of mathematical software as an instrument for mechanical system dynamics study, that allows scientifically substantiate the usage of new technical solutions during their development. Method. Development a system of differential equations using Lagrange equations of the 2nd order, which are solved in Wolfram Mathematica. Preparation of initial conditions and mass-inertia data can be done by any known software. The generalized mathematical model can be used for any vehicle suspending unnecessary coordinates. Results. Implementation of new technical solutions without scientific ground could be resulted in difficulties while exploitation. For its removal necessary to receive dynamical characteristics. Existing engineering calculation methods are not suitable, especially because of tight time and limited financing. The customized mathematical models can be developed and solved on demand using available software. A scientific novelty. Enhancement of theoretical and experimental research become possible owing to the usage of mod- ern approaches of dynamic systems simulation using applied mathematical software Wolfram Mathematica. Obtained model can be modified in few operation from one mass task into multibody system with maximum 69 free displacements (coordinates). Practical value. The possibility to receive customized simulation model fast, verified with increased quality for scientific purposes.

Modelling, optimization and application on C-shaped focusing magnetic field excitation device of electromagnetic torque sensor

To enhance accuracy and sensitivity of electromagnetic torque sensor, a highly focusing magnetic field is essential. This paper proposes a C-shaped excitation device designed to focus the magnetic field. The device is enclosed by dual layers of ferromagnetic metal shields. The C-shaped structure directs most of the magnetic field lines through its magnetic core, enhancing the focusing performance. Theoretical analysis of the device’s focusing magnetic field distribution was conducted under three conditions: unshielded, with a single-layer shield, and with a dual-layer shield, using magnetic path analysis techniques. Using COMSOL 6.1 to examine various configurations, we identified the optimal structure for the device. Subsequently, a physical prototype was fabricated, and the magnetic field distribution was measured. Furthermore, an analysis was conducted on the phase differences of the induced voltage generated under its influence. The nonlinearity of the measured phase differences was4.37%.

Integrated Wheel–Foot–Arm Design of a Mobile Platform With Linkage Mechanisms

Abstract Inspired by lizards, a novel mobile platform with revolving linkage legs is proposed. The platform consists of four six-bar bipedal modules, and it is designed for heavy transportation on unstructured terrain. The platform possesses smooth-wheeled locomotion and obstacle-adaptive legged locomotion to enhance maneuverability. The kinematics of the six-bar bipedal modules is analyzed using the vector loop method, subsequently ascertaining the drive scheme. The foot trajectory compensation curve is generated using the fixed-axis rotation contour algorithm, which effectively reduces the centroid fluctuation and enables seamless switching between wheels and legs. When encountering obstacles, the revolving linkage legs act as climbing arms, facilitating seamless integration of wheel, foot, and arm. A physical prototype is developed to test the platform on three typical terrains: flat terrain, slope, and vertical obstacle. The experimental results demonstrated the feasibility of the platform structure. The platform can climb obstacles higher than its own height without adding extra actuation.

Independently controlled multifrequency rejection bands in a broadband filter design using shorted T-shaped stub loaded resonator with central square ring

This article discusses the development and analysis of a broadband filter capable of suppressing specific frequencies of wireless applications at 4.7 GHz for WLAN, 8.3 GHz, and 11.5 GHz (for satellite communication) by combining a T-shaped stub loaded resonator with a central square ring to achieves high performance and compact size within the bandwidth of interest. The filter achieves low signal loss of 0.4 dB across the entire passband of 14.9 GHz bandwidth, good reflection suppression exceeding 10 dB, and independently adjustable multi stopbands. It utilizes a simple planar topology for a small footprint of 0.52 λg × 0.32 λg, where λg represents the wavelength at 4.7 GHz. The proposed filter evaluated using classical method an even-odd-mode analysis, and a 3D software tool HFSS-15 is used for simulations. The physical prototype is built on a Rogers RO-4350 substrate using LPKF S63 ProtoLaser machine. To confirm the accuracy and performance of the prototype, measurements were conducted using a ZNB20 vector network analyser. The simulations and measurement results confirm its effectiveness, paving the way for applications in various fields such as radar systems, medical imaging, and wireless communication.

A Study of Deployable Structures Based on Nature Inspired Curved-Crease Folding.

Fascinating 3D shapes arise when a thin planar sheet is folded without stretching, tearing or cutting. The elegance amplifies when the fold/crease is changed from a straight line to a curve, due to the association of plastic deformation via folding and elastic deformation via bending. This results in the curved crease working as a hinge support providing deployability to the surface which is of significant interest in industrial engineering and architectural design. Consequently, finding a stable form of curved crease becomes pivotal in the development of deployable structures. This work proposes a novel way to evaluate such curves by taking inspiration from biomimicry. For this purpose, growth mechanism in plants was observed and an analogous model was developed to create a discrete curve of fold. A parametric model was developed for digital construction of the folded models. Test cases were formulated to compare the behavior of different folded models under various loading conditions. A simplified way to visualize the obtained results is proposed using visual programming tools. The models were further translated into physical prototypes with the aid of 3D printing, hybrid and cured-composite systems, where different mechanisms were adopted to achieve the folds. The prototypes were further tested under constrained boundary and compressive loading conditions, with results validating the analytical model.

Height-posture and load coupling control methodology of URAPM and its application in active suspension control of multi-axle vehicles

Unidirectional redundant actuated parallel mechanism (URAPM) is the physical prototype of active suspension system, truck crane outrigger system, etc. As the number of adjustment mechanisms (AMs) increases to more than three, the difficulty of height-posture control of the upper component (UC) increases considerably. The AMs load control is also tough but highly underappreciated, which in turn causes height-posture disturbance. In this work, a convenient height-posture and bearing load coupling control methodology and its application in the active suspension system are presented. Firstly, by characterizing the force-deformation coupling relationship of the URAPM, a basic geometry and load coupling control model is proposed. And for the desired bearing load control, different optimal load allocation algorithms are developed and evaluated. Secondly, coupling control models for the flexible load control under stationary height-posture, and the flexible height-posture control under balancing load are constructed respectively. Finally, bench tests based on a six-legged URAPM (equivalent to a three-axle active suspension vehicle) validate the proposed method can achieve high precision, high convergence, and most attractively, the height-posture and load coupling adjustment with few iterations, thus demonstrating its good application prospect in low-speed off-road maneuvering of multi-axle vehicles and other related fields.

Design and obstacle-crossing analysis of a four-link rocker-suspension planetary exploration robot

Abstract. At present, there are still many meteorite craters and boulders on the surface of Mars and the Moon that cannot be accessed by existing planetary exploration robots. To provide a solution to this issue, this paper proposes a four-link rocker-suspension planetary exploration robot that combines both the reliability and low complexity of wheeled rovers with competent terrain adaptability and obstacle-crossing performance. Relying on its special differential pitch device, the robot can adapt to fluctuations in terrain by using both active and passive modes. Moreover, the four-link rocker suspensions on both sides of the robot can increase the instantaneous rotation radius of the rockers when the robot climbs over obstacles. In this paper, using modelling and simulations, we demonstrate that the four-link rocker suspension can improve the robot's obstacle-crossing capability. The geometric and static conditions required for the robot to cross obstacles are derived and discussed, and numerical simulations are conducted to identify the maximum obstacle-crossing heights that satisfy different conditions. Finally, a physical prototype of the robot is developed.

Research on resistance detection robot for UHV tension insulator string

Insulator inspection robots can realize automatic and rapid inspection of insulators of ultra-high voltage transmission lines, which is an important guarantee equipment for the continuous safe operation of the national power grid. Aiming at the needs of ultra-high voltage insulator string inspection, an insulator robot is designed to realize efficient and stable insulator string motion and insulator detection, and the main work includes proposing a new insulator string motion robot configuration and realizing its string motion and inspection functions in the form of a physical prototype. It has been proved that the robot has a large motion load and strong motion performance, and can be adapted to the complex working conditions consisting of a variety of insulators within a certain size range.

Scoring the invisible

This article discusses the computational and material interplays embedded in the making of [re]capture, a research–creation project combining a bio-inspired installation that materialises particulate matter, together with outdoor sensing instruments that collect atmospheric data in at-risk neighbourhoods (Montreal, Canada). With impacts on health and the environment, habitual and slow forms of exposure to atmospheric pollution (Hsu 2016) outline the relationality of air and the porosity of bodies, both human and more-than-human (Nieuwenhuis 2016; Albano 2022). What kind of technical objects, and material-esthetics can “negotiate a rapprochement” (Gissen 2009, 22) with the invisible materiality of air? At the intersection of critical and bio-design, mechanical engineering, and computer science, [re]capture delves into this question through the lens of ‘filtration,’ simultaneously envisioned as a physical process for attending to atmospheric pollution, and as a generative concept for interpolating technology, materiality, and the city. While the artwork iterates a virtual testing model (Blender and ossia score) with physical prototyping, the article examines how to compose with air through digital simulation and scoring to create new alliances between porous meshes, bioindicators, data, particulate matter, light, wind, and electronics. It also asks How to design installations that embody and materialise the affective properties of air? Attending the speculative trajectory of this process, the article draws on feedback from computer-aided simulation techniques and collaborative experiments in residency spaces to investigate the ‘scoring’ of [im]materiality and explore the spatio-temporality of air.

The elastica sling

The nonlinear mechanics of a flexible elastic rod constrained at its edges by a pair of sliding sleeves is analyzed. The planar equilibrium configurations of this variable-length elastica are found to have shape defined only by the inclination of the two constraints, while their distance is responsible only for scaling the size. By extending the theoretical stability criterion available for systems under isoperimetric constraints to the case of variable domains, the existence of no more than one stable equilibrium solution is revealed. The set of sliding sleeves’ inclination pairs for which the stability is lost are identified. Such critical conditions allow the indefinite ejection of the flexible rod from the sliding sleeves, thus realizing an elastica sling. Finally, the theoretical findings are validated by experiments on a physical prototype. The present results lead to a novel actuation principle that may find application as a mechanism in energy harvesting, wave mitigation devices, and soft robotic locomotion.

System modeling of the impact of multiple capacitor coupled substations located at different proximities on a transmission network

Electricity plays a vital role in the economy of any nation, and its availability has transformed from being a luxury to being an essential requirement. However, the implementation of conventional distribution networks in sparsely populated rural areas is often deemed economically impractical. Consequently, the exploration of alternative technologies for rural electrification becomes imperative. One such technology is the Capacitor Coupled Substation (CCS), which taps electrical power from high-voltage lines through coupling capacitors. Given that capacitors can introduce interference in an electrical system, the deployment of a CCS necessitates consideration to minimize these network disturbances. This paper modelled and analyzed the impact of multiple CCSs on the electrical transmission network, with a specific focus on the impact on the transmission line voltage when multiple CCSs are located at different proximity to one another. A typical electrical transmission network with fixed supply voltage represented as 230kVac and downstream parameters with a 230kVac and 100 kW load was selected. A system model comprising three CCSs, located at known proximities from one another, was developed using MATLAB/Simulink to simulate the network's response when one or more CCS units are connected or disconnected from the electrical transmission network. Three prototypes were also constructed to represent real-world electrical systems with different loads. The model simulation was executed while connecting and disconnecting one or more CCS at a time and at different proximities from one another within the electrical transmission network. The same procedure was repeated on the prototypes where they were connected and disconnected from the selected network. The proximity to one another was represented by different resistances which represented the electrical transmission lines between the different locations of each CCS on the electrical network. The obtained test results were subjected to comparison across three platforms: the MATLAB/Simulink model, physical prototype testing using a multimeter, and digital testing using an oscilloscope. The results showed negligible disruptions on the supply side and downstream side of the transmission network. The primary goal of this research was to provide valuable insights into the potential application of CCS technology in rural electrification by examining its impact on the transmission network. Further analysis is recommended to understand the impact of each critical component within a CCS.Capacitor Coupled Substation; Rural Electrification; System Modeling; Multiple CCS