Maintenance, Reliability and Condition Monitoring
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Unveiling the future of cardiac care: advances in mechanical circulatory support
Get PDFCongestive heart failure (CHF) is a multifaceted clinical syndrome characterized by the inability of the heart to pump blood effectively, leading to inadequate oxygen and nutrient delivery to the body tissues. Despite advancements in treatment strategies, including guideline-directed medical treatment (GDMT), end-stage CHF remains a significant cause of morbidity and mortality worldwide. Heart transplantation is considered to be the gold standard treatment of end stage CHF but constrained by the lack of organ donors, lengthening waitlists, and the negative side effects of lifelong immunosuppressive medications. Mechanical circulatory support (MCS) has emerged as a pivotal intervention for patients with end-stage CHF, serving as a bridge to recovery, transplantation, or destination therapy. The aim of this narrative review is to highlight the historical development of MCS, to assess the recent status of MCS device technology and discuss current challenges associated with complications of MCS that need to be solved in the future by device development. The history of MCS dates back to pioneering efforts in the 1960s, with significant progress in device development and utilization over decades. MCS devices, including left ventricular assist devices (LVADs), extracorporeal membrane oxygenation (ECMO), and artificial hearts, play a crucial role in providing circulatory support to patients with end-stage CHF. Recent advancements in MCS technology aim to decrease the device size, enhance blood compatibility, reduce thrombo-embolic complications, and prolong device durability and battery life and improve physiological performance of MCS. Continued research and innovation are essential to address these challenges and improve outcomes in patients with end-stage CHF. Artificial intelligence (AI) has emerged as a valuable tool in cardiovascular medicine to facilitate risk prediction, patient selection, and treatment optimization for MCS and heart transplantation. Despite these advancements, challenges persist in MCS device selection, resource allocation, and integration of AI into clinical practice. Continued research and innovation are essential to address these challenges and improve outcomes in patients with advanced heart failure
Influence of sliding wear on contact characteristics based on 3-D wheel/rail contact model
Get PDFDuring the process of starting, braking and running of the train, sliding contact between wheel and rail occurs. The wear caused by sliding contact exerts a noteworthy influence on the contact characteristics of wheel/rail. To analyze these characteristics, a three-dimensional wheel/rail contact wear model is established, and the contact characteristics at different wear depths are studied. The results indicate that at initial contact, the wheel/rail contact patch is approximately elliptical in shape and its area is 122.5 mm2. The von Mises stress of the wheel and rail is maximum in the subsurface at a distance of 2 mm from the contact interface, with maximum values of 559 MPa and 628 MPa respectively. When the wear depth is less than 0.5 mm, the wear depth, contact area and size increase quickly. As the amount of wheel contact wear increases, the maximum contact stress gradually decreases and the contact stress becomes uniform. In addition, the calculation results indicate that the contact patch shape does not always remain elliptical, the shape can change from elliptical to rectangular as the wear depth increases. As the increasing of wear amount, the contact stress gradient on the inner side of wheel contact surface increases
Adoption of metal additive manufacturing in nnpc limited: current state and challenges
Get PDFMetal additive manufacturing has emerged as a promising technology with vast potential in the oil and gas industry. The Nigerian National Petroleum Company (NNPC) Limited recognizes the significance of this technology and has initiated efforts to adopt metal additive manufacturing within its operations. This paper aims to provide an overview of the current state of metal additive manufacturing in the NNPC and highlight the challenges faced during its adoption process. The study goes on further to suggest strategies and future directions to ensure successful company-wide and industry-wide adoption and acceptance
Numerical modelling of the warping behaviour at the first layer-build plate interface in 3D-printed models produced via the fused deposition modelling process
Get PDFThe material structure of 3D-models printed via the fused deposition modelling (FDM) technique is mainly affected in the z-direction of the 3D-print as a result of the layer-by-layer approach which tend to exhibit a deformation behavior corresponding to a type of transversely orthotropic material. Moreover, uncontrolled parameters such as printing temperature and printing speed have been reported to adversely affect 3D-print quality leading to undesired effects such as distortion and warpage. The additive manufacturing process is a relatively new field in advanced manufacturing where further research and innovation are required to overcome the limited strength and structural performance observed in presently 3D-printed components. In line with the above, this study proposes the numerical investigation of the warping behavior in PLA (Polylactic acid) - based 3D printed models by considering the finite element method (FEM) software of LS-DYNA. The warping investigation was specifically centered on the cooling cycle prevailing between the layer-by-layer structures. The findings of this study showed that warpage would most likely occur in the thermal process model corresponding to abrupt change in temperature due to a buildup of strain between the bottom most layers of the 3D model and the build plate. The findings of this study, which shed light on the warping behaviour in 3D-models, has direct implications on the final quality of 3D-printed components
Modal analysis of key components of crusher based on digital simulation technology
Get PDFThe modal characteristics of the crusher rotor and shell constitute the crucial factors influencing vibration and noise. Based on the principle of simplification, the rotor component model was established. Through mesh optimization, the model accuracy and calculation efficiency can be ensured, and the calculation of natural frequency and modal shapes was completed based on ANSYS. To verify the accuracy of the finite element model, the modal test was carried out by the hammering method. Sensors were set in three different directions to obtain the frequency response function and the modal assurance criterion matrix mode confidence criterion. Using the same research method, the modal characteristics of the shell model were simulated and analyzed. The research results show that the modal parameters identified by the modal test are basically consistent with the simulation model. The natural frequencies of the rotor and the shell are quite different from the excitation frequency of the motor, and resonance problems will not occur when the crusher is proper functioning
Influence of Copper-Iron (CuFe) and Copper-Tin (CuSN) alloys over mechanical strength properties in crimping process
Get PDFThis study investigates the comparative performance of Copper-Iron (CuFe) and Copper-Tin (CuSn) alloys in crimping processes, with a focus on their mechanical, electrical, and corrosion-resistance properties. Crimping is a critical method for creating reliable electrical and mechanical connections, particularly in environments subjected to significant mechanical stress and varying temperatures [1]. CuFe alloys, known for their superior mechanical strength and hardness, present challenges in crimping due to their increased resistivity and reduced ductility. Conversely, CuSn alloys offer a balance between electrical conductivity, ease of crimping, and corrosion resistance, making them a preferred choice in many industrial applications. This research aims to provide a comprehensive analysis of how the distinct properties of CuFe and CuSn alloys influence the crimping process, ultimately guiding material selection for optimized performance in various applications [2]. Experimental data will be drawn from tensile strength tests, electrical resistance measurements, and corrosion tests, providing a holistic understanding of the advantages and limitations of each alloy
Study on vibration isolation design using elastomeric pads and its application
Get PDFThe vibration mechanism of railways and urban rail transit is highly intricate, particularly within the railway environment. This study employs a variety of vertical stiffness damping pads to develop an integrated damping system for a floating slab. Through optimization of damper stiffness and arrangement, the modal characteristics of the floating slab are analyzed, resulting in a reduction of the inherent frequency of the track structure and attenuation of vibration transmission. Subsequently, this damping system is implemented in an actual engineering project to assess its effectiveness. The findings indicate that lower stiffness in the vibration isolation pad corresponds to a smaller inherent frequency for the floating slab, thereby enhancing its damping efficacy. Utilizing elastic supports for vibration isolation pads within the track structure can mitigate upper structure vibrations induced by trains
Prediction of concrete sulfuric acid corrosion evaluation index model based on grey system theory
Get PDFIn order to predict the impact of sulfate corrosion on concrete, based on grey system theory, GM(1,1) and GM(1, N) models were used to predict and analyze the compressive strength and relative dynamic elastic modulus of concrete under sulfuric acid corrosion. The results show that the prediction error of the GM(1,1) model for concrete sulfate corrosion attenuation is within 5 %, and the residual size test of the GM(1, N) model for concrete sulfate corrosion is within 10 %
Method of experimental determination of the effective area of a pneumatic spring of high-speed rolling stock
Get PDFThe object of research is a pneumatic spring of high-speed rolling stock of the railway. The method of experimental static testing of a pneumatic spring of high-speed rolling stock is presented. Based on experimental tests, the “force-strain” dependences of a pneumatic spring are obtained when the pressure gauge in the pneumatic spring changes from 2.5 atm up to 5.0 atm. Using a thermodynamic model, a quadratic equation is found to determine the effective area of a pneumatic spring. It is established that when the pressure gauge in the pneumatic spring changes from 2.5 atm up to 5.0 atm the effective area of the pneumatic spring varies from 0.231 m2 to 0.306 m2. The scientific novelty lies in the fact that for the first time, on the basis of static experiments, the change in the effective area of the pneumatic spring of high-speed rolling stock depending on the value of the gauge pressure in the spring was established. This will make it possible to determine the forces acting on the pneumatic spring in different operating conditions, ensuring the required level of safety of rolling stock
Modal analysis and seismic optimization of multi-storey gymnasium frame
Get PDFIn order to improve the seismic resistance capacity of the multi-storey gymnasium frame, based on the finite element analysis method, the dynamic response characteristics were analyzed, and the natural frequencies and vibration modes were obtained. Based on the results of the modal analysis, different reinforcement methods were proposed for verification. Under the excitation conditions of Borego waves, the vibration responses of different nodes in initial model were obtained. Modal verification was carried out by using two methods of shear strengthening and support rod strengthening respectively. The analysis results show that the bearing capacity of the single-span frame is insufficient, the lateral stiffness is small, and it is prone to cause severe torsional vibration damage. It can also be known that the seismic resistance capacity of the support rods reinforcement is more balanced in different directions. It can not only effectively improve the lateral stiffness and bearing capacity of the structure, but also improve the seismic performance of the main structure through the energy dissipation of component yield, which is more suitable for multi-story buildings