Journal of Mechatronics and Artificial Intelligence in Engineering
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Vibration characteristics of axial compressor blade under complex loads
Get PDFIn this study, 3D models of a compressor blade for an aero engine with three different levels of surface accuracy (with 4, 6 and 10 section profiles) were obtained via reverse engineering by fitting point-cloud data. Then, finite element and flow-field models of the blade were established and validated. The vibration characteristics of the blade under typical operating conditions were analyzed by considering the interaction between the aerodynamic load by airflow and the centrifugal load by blade rotating. The results showed that, under complex centrifugal and aerodynamic loads, the three blade models differed significantly in their high-order dynamic frequencies, and the modal frequencies that were dominated by a torsional mode of vibration were sensitive to the aerodynamic load. Hence, considering both the aerodynamic excitation and the centrifugal load increased the accuracy of the numerical computation of the blade vibration characteristics. Moreover, a comparison of the computational results from the three blade models showed that models B6 and B10 differed only insignificantly, and B6 decreased the complexity of the modeling process while satisfying the required computational accuracy. Thus, model B6 is the best option for engineering analysis and computation
Optimization on the jet characteristics of the main nozzle of hot-blowing snow removal device
Get PDFThe exhaust devices used by snow removal vehicles are mainly based on hot-blowing snow removal. Due to the inherent characteristics of the turbojet engine such as low flow rate and high exhaust temperature, the modified hot-blowing snow removal device has problems of low snow removal efficiency and the possibility of ablation and damage to the road surface. In order to solve the problem, transforming the turbofan engine with a high flow rate and a low exhaust temperature into a hot-blowing snow removal device is an important improvement to achieve efficient and safe snow removal operations. In order to convert a medium bypass ratio turbofan engine into a hot-blowing snow removal device, the computational fluid dynamics (CFD) software CFX was used to analyze the internal and external flow field characteristics of the main nozzle of an exhaust device under the 60 % rated condition of the engine. The effective area sizes of the jet velocity and temperature predicted by the external flow field were used to optimize the layout of the main nozzle
Höegh LNG and Altera Infrastructure is scaling up large scale CCS infrastructure
Get PDFIn a joint initiative, called “Stella Maris CCS” Altera Infrastructure and Höegh LNG are working together to provide cost efficient floating Carbon Capture and Storage infrastructure solutions for a global market, not limited to size or geographical location. Valuable infrastructure experience is brought together; with FPSO (Floating Production, Storage and Offloading) and Dynamically Positioned Shuttle Tankers from Altera and FSRU’s (Floating Storage Regasification Unit) from Höegh. We intend to continue to build on our heritage and experience, using our combined skills to contribute to carbon emission reduction around globe. With the “Stella Maris CCS” project, we will essentially be doing what we are doing today, only in reverse. Our solution, initiated in 2019 as the first of its kind, will offer a large-scale floating infrastructure for collection, transport, and injection of CO2 into subsea reservoirs/aquifers. Our infrastructure concept consists of 2-3 Carbon Collection Storage Units (CCSU) to aggregate volumes at different key locations, 3-4 CO2 Shuttle Carriers and one Floating Storage and Injection Unit, the total amount of CO2 injected with these assets can reach up to 10 million tons per year. In order to realize large scale CCS, the unit costs must come down, and the barriers for emitting industries to invest in capture plants must be lowered. With Stella Maris we are addressing these hurdles. The larger ship design enables carrying volumes of CO2 at low pressure and will allow for greater economies of scale in the absence of a pipeline which places less limitations on distance to reservoir and ultimate flow capacity. Having a centralized conditioning of CO2 in a CCSO hub allows more flexibility for on-site capture design from multiple onshore industrial emission sources with shared port access. To defray high logistics cost in e.g. the Baltic region, a hub and spoke transportation approach enables collection in smaller parcels, milk-run gathering and conditioning for large scale transfer for storage in an offshore subsea reservoir on the Norwegian Continental shelf
Squeak and Rattle recognition based on speaker recognition
Get PDFSqueak and Rattle problems seriously affect the quality of the vehicles. In the adjustment stage of the automobile development process, engineers mainly rely on subjective evaluation to diagnose squeak and rattle noises, which is prone to misjudgment, missed judgment and time-consuming problems. There are gaps in relevant objective evaluation methods. This article proposed that speaker identification is used to identify squeak and rattle noises from the audio recorded in the test, to achieve objective and accurate results. In this paper, four kinds of squeak and rattle noise audios are used as samples, Mel Frequency Cepstrum Coefficient is extracted as feature vector to construct target Gaussian mixture models (GMM). The expectation, variance and correlation coefficient of the Gaussian mixture model can be calculated to describe the difference of multiple squeak and rattle noises. Using samples to judge accuracy rate, the results indicated that the acceptance accuracy rate reaches 100 %, and the rejection accuracy rate reaches more than 95 %
Kinematic and dynamic analysis of three-mass oscillatory system of vibro-impact plate compactor with crank excitation mechanism
Get PDFThe paper is aimed at studying the motion conditions of the vibratory compacting machine equipped with the crank excitation mechanism characterized by the changeable geometrical parameters. Unlike numerous scientific publications devoted to similar subject, the novelty of the present research consists in the improved design of the vibro-impact plate compactor and the developed mathematical model describing the motion conditions of the compactor’s oscillatory system. It is proposed to use the crank mechanism to excite the oscillations of the impact body acting upon the frame of the compacting plate at a certain angle to the surface being compacted. The main idea of this improvement is to provide the self-propelling locomotion conditions of the compactor and to reduce the pushing force that must be applied by the operator. The research results obtained by means of the numerical modeling in Mathematica software describe the dynamic behavior of the compactor’s oscillatory system under different geometrical parameters of the crank excitation mechanism (crank eccentricity, impact gap, etc.). The material of the paper can be of significant practical interest for the designers and engineers dealing with the development of new vibratory compactors and the improvement of compacting technologies
Development of an underwater robotic arm using multibody dynamics approach
Get PDFUnderwater robotic arms are important devices that enables workers to carry out tasks remotely from a safe distance reducing or eliminating the risks that are involved with the task. The primary objective of the robotic manipulator is to perform maintenance and cleaning activities of the hull of a ship. However, the control of these devices underwater is quite complicated due to the numerous factors that make these systems unstable and non-linear. The aim of this study is to develop a multibody dynamic robotic manipulator model, integrated with a control strategy to optimize and obtain stable kinematics solutions. The hydrodynamic forces are integrated to the manipulator model considering buoyancy forces and surface drag forces. A basic algorithm is used to generate the joint angles using 7 geometrical parameters. The control of the manipulator was done to simply follow any path that represents the given coordinates. The P, I and D parameters are tuned individually to optimize the kinematic solution of the manipulator. 3-DOF articulated manipulator is the commonly used manipulator configuration. However, a 6-DOF manipulator configuration was selected in this study to allow for change in orientation using wrist motions
Development and application of high-power advanced exploration drilling rig for coal mining TBM
Get PDFWith the continuous popularization and application of TBM equipment and technology in the field of coal mine, aiming at the problems of small torque and small propulsion of existing TBM advanced exploration drilling rigs for coal mine, which is difficult to drill long borehole, and lack of special high-power drilling equipment to match with it, a high-power drilling rig for coal mine TBM is developed. This paper introduces the structure of the drilling rig, analyzes the structure and principle of the luffing mechanism and the rotary table protection device, also the strength of the key parts. Through the application in Guineng Group Heilaga Juxin coal mine shows that this equipment has large torque and propulsion, the hydraulic system and operation mode meet the requirements of long-distance separate layout in TBM. The drilling rig has good stability and high efficiency, and can meet the various needs of long drilling for advanced exploration, which promotes the application of TBM equipment and technology in the field of coal mine
Robotic micromanipulation: b) grippers for biological objects
Get PDFRecent progress in the field of microrobotics tightly linked to an ability to grab an object firmly without the damage to the surface and structure. Process of biological object grabbing by microgrippers faces numerous limitations in the mechanical, electric and thermal domains; these limitations varies from case to case with different objects, therefore, analysis in this area was an aim of this review. This paper covers an area of micrometric size biological object manipulation and performs an analysis of used actuators and kinematic chains of the grippers in the sense of their application. Limitations and restriction of microgrippers applications analysed along available publications in numerous recent references as well as their successful implementation history. Paper provides result of analysis as compact big picture, which will be useful for researchers and designers in the area of microrobotics
Experimental study on influencing factors of anchorage performance of concrete bonded rebars
Get PDFHilti re-100 structural adhesive is used to plant reinforcement in concrete, and the factors affecting the anchorage performance of planted reinforcement are analyzed. The Planting reinforcement of the concrete specimen and the specimen with reinforcement anchored in concrete in advance are compared. A total of 36 groups of tests were carried out, including 27 groups of embedded reinforcement tests and 9 groups of embedded reinforcement tests. The test mainly analyzes the influence of concrete strength, reinforcement diameter and planting depth on the anchorage performance of planting reinforcement. There are three failure modes in the test, which are the separation failure of reinforcement and structural adhesive, the tensile failure of reinforcement and the separation failure of reinforcement and concrete. Through the analysis of the test data, the bond slip data curve is obtained
Design and noise-reduction simulation of an acoustic metamaterial plate incorporating tunable shape memory cantilever absorbers
Get PDFMetamaterials are materials having artificially tailored internal structure and unusual physical and mechanical properties. Due to their unique characteristics, metamaterials possess great potential in engineering applications. This study proposes a tunable metamaterial for the applications in acoustic isolation. Therefore, a stopband in the dispersion curve can be created because of the energy gap. For the conventional metamaterial, the stopband is fixed. Although the metamaterial with tunable characteristics has been proposed in the literature to extend its working stopband, the efficacy is usually compromised. In this study, cantilevers of tunable shape memory materials (SMM) via controlled phase transformation are incorporated into the metamaterial plate. Its theoretical finite element formulation for determining the dynamic characteristics is established. The effect of the configuration of the SMM cantilever absorbers on the metamaterial plate for the desired stopband in wave propagation is simulated by using finite element model and a commercial multi-physics software. The result demonstrates the tunable capability on the stopband of the metamaterial plate under different activation controls of the SMM absorbers, and shows the ability to trap the vibration at the designed frequency and prevent vibration wave from propagating downstream in different absorber arrangements and alloy phases. It should be beneficial to precision machinery and defense industries which have desperate need in vibration and noise isolation