Recent Patents on Mechanical Engineering - Volume 16, Issue 5, 2023

Background: Crashworthiness studies the safety qualification of a vehicle (both airborne and road transports) to protect its occupants during an impact. Before an aircraft can receive transport certification, it must meet a number of crashworthiness requirements, such as the structure's deformation pattern, absorbed kinetic energy profile, and acceleration responses experienced by the components and human body models. Therefore, in recent times, crashworthiness has emerged as a crucial field of study during the early design stages of aircraft, along with other key parameters like weight reduction, load factor, fatigue life estimation, etc.Objective: The main objective of the present article is to undertake an in-depth analysis of the developments in crashworthiness related to the civil aircraft fuselage section. Furthermore, it aims to identify and address the future challenges that must be overcome to ensure the utmost safety of the occupants.Methods: Based on the research objectives, the available literature is categorized into three major groups: (i) finite element code validation; (ii) improvement of the crashworthiness criteria; and (iii) impact on different surface models. A methodology to solve fuselage section crashworthiness is briefly described. A review of the research articles discussing general purpose energy absorbers for crashworthy design without any implementation to the fuselage structure is out of the scope of this article.Results: Experimental testing of fuselage section crashworthiness is expensive and non-repeatable. Furthermore, the intricate structure of the fuselage, with its numerous components, makes it nearly impossible to devise crashworthy design solutions through classical hand calculations alone. As a result, commercial software codes play a crucial role in the development of fuselage section crashworthiness, offering valuable assistance in overcoming these limitations.Conclusion: Future challenges of crashworthy design involve exploring novel materials and devices to mitigate injury during controlled crash conditions. An intriguing area of study would be the analysis of lattice components, as they have the potential to enhance crashworthiness. Furthermore, as newly designed fuselage sections emerge, it will be crucial to investigate and establish the necessary requirements to ensure compliance with crashworthiness certification standards.

Background: The electro-hydraulic servo system has the advantages of high stiffness, fast response speed, high precision and power-to-weight ratio.Objective: In this patent, an adaptive robust control strategy based on friction compensation is proposed for insufficient control accuracy due to a large number of nonlinearities and uncertainties in the system.Methods: In this patent, the mathematical relationship between the physical quantities of the valvecontrolled cylinder is analyzed. Then the mathematical model of valve controlled cylinder considering the main nonlinearity and uncertainty of the system is established. The fuzzy proportion-integral-derivative, deterministic robust, and adaptive robust single-cylinder trajectory tracking controllers are designed and the tracking performance of different reference trajectories is analyzed by MATLAB/Simulink software.Results: In this patent, all the three controllers can track the reference trajectories smoothly. Adaptive robust control strategy can make the uncertain parameters of system converge and approach truth value.Conclusion: In this patent, the adaptive robust control strategy has the function of online parameter adjustment. When tracking accuracy is taken as the index, its tracking effect is better than fuzzy proportionintegral- derivative and deterministic robust.

Background: At present, due to the widespread use of robotic arms for the automatic loading and unloading of CNC gear milling machines, there has been an increase in patents related to robotic arms. However, these robotic arms have issues of low efficiency and large space occupation. To solve these problems, a CNC gear milling machine with an automatic loading and unloading manipulator device needs to be designed.Methods: This paper first designs the overall scheme of the automatic loading and unloading manipulator, and then uses Solidworks to establish a three-dimensional model. Finite element analysis software is used to analyze and simulate the deformation, stress distribution, and service life of the key components in the overall device. Finally, a prototype of the robotic arm is created based on the simulation optimization results.Results: This paper designs a new type of automatic loading and unloading manipulator device for CNC gear milling machines, which is different from existing patents in that all its components are installed inside the machine tool protective cover. In production experiments, the operation was found to be stable and reliable, and the loading and unloading process was completed at a speed of 11s/time, consistently exceeding the manual maximum speed of 19s/time. The results indicate that the proposed clamp storage system and core rod perforation feeding method are effective.Conclusion: The new design solves the problems of low efficiency and large space occupation in existing robotic arm patents.

Background: Hydrocarbons are increasingly being considered as potential fourth-generation refrigerants due to their environmentally-friendly properties. However, accurate prediction and calculation of their thermal properties are essential for their industrial application.Objective: In this study, molecular dynamics simulations were performed to calculate the density, selfdiffusion coefficient, viscosity and thermal conductivity of R290 at various operating temperatures of 200-240 K and pressures of 0.15 and 0.20 MPa, and 270-390 K and pressures of 1.5 and 2.0 MPa to verify the feasibility of the methods.Methods: The equilibrium molecular dynamics simulation (EMD) approach was utilised. The soundness of the model and force field were verified by calculating the density of the system during the relaxation phase. In the output stage, the self-diffusion coefficient was calculated using the Einstein relation, while the viscosity and thermal conductivity were calculated using the Green-Kubo method. The simulation results were compared with the NIST data values, and the errors were analysed.Results: The density simulation results for R290 in the relaxation phase yielded an overall average absolute relative deviation (AARD) value of 3.97%. In the output stage, the simulation results for the transport coefficients of R290 showed AARD values of 7.68%, 6.60% and 11.04% for the self-diffusion coefficient, viscosity, and thermal conductivity, respectively, compared to the NIST data values.Conclusion: These results indicate the feasibility of using molecular dynamics simulations to study the transport properties of hydrocarbon refrigerants. The findings also provide a foundation for future research on hydrocarbon refrigerant mixtures.Patent: The research presented in this work could serve as a valuable reference for future patent applications and technological innovations related to hydrocarbon refrigerants, particularly R290. This includes, but is not limited to, delivery pipelines, connectors, storage containers, control and detection systems, and the preparation and application of R290 and other refrigerant mixtures.

Background: The present work numerically models the incompressible, continuous phase, viscous flow of Newtonian fluid flow in a bounded domain of two-dimensional cavity that is driven by walls and contains grooves in the shape of squares on the lower wall. With the help of the mesoscopic lattice Boltzmann method (LBM) and D2Q9 square lattice model, simulation results are found stable and reliable. The flow physics of the problem by varying Reynolds number, the height and quantity of lower wall grooves, and other fluid flow characteristics within the bounded domain are studied in detail. It is seen that the effects of the groove heights and wavelengths on the fluid flow are structured within the bounded domain. The study is performed from low Re = 100 to high Re = 3200, with minimum two and maximum four-wavelength grooves evaluated on the bottom surface, each having a height of low 0.25 and high 0.75. Additionally, a thorough discussion of complicated vortex dynamics is provided regarding the input parameters and geometry.Objective: The current study aims to use mesoscopic LBM to analyze incompressible viscous fluid flows on complex geometries other than rectangular shapes.Methods: Mesoscopic approach of kinetic theory-based Lattice Boltzmann method (LBM) is implemented in the current work. The popular Single Relaxation Time Lattice Boltzmann method with D2Q9 square lattice model and second-order accurate boundary condition is adopted for the current study.Results: The numerical approach of LBM is used to simulate fluid flows in a 2D bounded domain with grooved bottom surfaces. The influence of different factors, such as the height of bottom-wall surface grooves, flow Reynolds number, and wavelength of these grooves on flow patterns, is then investigated.Conclusion: The numerical study of the bounded domain is considered, and the Reynolds number is varied from 100 to 3200, with two and four-wavelength grooves evaluated on the bottom surface, each having a height of 0.25 and 0.75. The impacts on the flow pattern both within and slightly above the grooves of the computational findings for different Reynolds numbers, groove heights, and groove wavelengths are evaluated. As the Reynolds number rises, the mixing phenomenon of fluid is shown to flow more quickly in the wall-driven enclosures.

Background: With the rapid development of artificial intelligence, the traditional cloud computing model has serious bandwidth and energy consumption problems when storing and processing massive amounts of raw data. To address this problem, recent patents have investigated methods for intelligent task offloading and allocation in mobile edge computing.Objective: A Directed Acyclic Graph (DAG) task unloading model is established to reduce the problem of task delay and energy consumption in edge networks. At the same time, Modified Tuna Swarm Optimization (MTSO) is used to improve execution efficiency.Methods: Firstly, this paper integrates (i) inter-task dependencies; (ii) heterogeneity of computing resources in the edge network; and (iii) interference of wireless channels in the edge network. A DAG task offloading model is developed to reduce latency and energy consumption. The end users are guided to offload their tasks/sub-tasks to the most appropriate servers in the edge network, thus minimizing the end-to-end latency of all tasks in the edge network. Secondly, the MTSO algorithm is used to coordinate the dependencies and priorities of subtasks to improve execution efficiency.Results: The experimental results show that when the number of users including subtasks is 10, the final edge server utilization rate is as high as 92%. A more fine-grained segmentation scheme can reduce the average delay of tasks and improve the utilization rate of edge servers.Conclusion: The approach proposed in this paper reduces the end-to-end latency and improves resource utilization in complex applications under the premise of ensuring task dependency. It will relieve the pressure on the cloud and has certain engineering application value.

Background: Rickshaws are a popular and inexpensive mode of transportation in Bangladesh for short-distance travel. However, the eye leaf spring in a typical rickshaw suspension system does not provide adequate shock isolation. The coil spring-damper suspension system is more effective, but is costly and not affordable for most manufacturers. Thus, the goal is to modify the eye leaf spring to be inexpensive but a safe and comfortable suspension.Aim: The study aimed to modify the material and structure of the leaf spring to limit the stiffness and the shock energy within a certain range suitable for the rickshaw's suspension. The focus of the study was on modifying the spring structure, which could be cost-effective.Methods: In this study, flexible bolted joints and EVA sheets have been used to change the spring structure. The study compared the performance of the modified spring with the typical eye leaf spring.Results: The modified eye leaf spring provided improved shock isolation and a more comfortable ride compared to the typical eye leaf spring. The changes made to the spring, such as the use of flexible bolted joints and EVA sheets, limited the stiffness and shock energy within a certain range suitable for the rickshaw's suspension. The modified spring was also found to be cost-effective.Conclusion: The study has demonstrated the feasibility of using a modified eye leaf spring for light vehicle suspensions, specifically for rickshaws. The modifications made to the spring structure, such as using flexible bolted joints and EVA sheets, provided improved shock isolation, a more comfortable ride, and cost-effectiveness. The modified spring offers an inexpensive solution for manufacturers to produce rickshaws with a safer and more comfortable suspension system.

Background: Stick-slip actuators are commonly used in Nano/Micro precision positioning systems, but their control is challenging due to factors like nonlinear friction, PEA hysteresis, and uncertainty. Researchers have made efforts to address these challenges and documented their findings in articles and patents.Methods: This study introduces a novel vertical stick-slip actuator and proposes two different methods for overcoming the challenges associated with controlling it. The first method involves training an inverse model of the actuator using a supervised machine-learning algorithm to determine the optimal number of signals and peak voltage required for the saw-tooth signals in an open-loop controller. The second method is a closed-loop controller that utilizes the maximum allowable peak voltage unless the positioning error is smaller than the maximum step size. At this point, the neural network-based controller adjusts the peak voltage to a lower value, ensuring that the actuator reaches the desired position at the end of the final signal.Results: According to the results, both controllers perform effectively. The open-loop and closed-loop controllers exhibit a relative error of 1.59% and 0.4%, respectively, for an arbitrary desired position in the final position.Conclusion: In conclusion, the suggested controllers offer a practical solution to the controlling challenges faced by stick-slip positioners, which are essential in the advancement of Nano/Micro sciences.