Experimental and numerical analysis of compaction of fine powder bed under artificial high gravity for additive manufacturing

Modeling and simulation of compact strength due to particle bonding using a hybrid discrete-continuum approach

Pressure vessels are widely used equipment in several industries, and can operate at high pressure and temperature, which can cause major accidents in the event of a failure. The objective of this work is to analyze the behavior of longitudinal and circumferential stresses at three specific points on the wall of a pressure vessel, two distant points of geometric discontinuity (at the top and side) and one close to geometric discontinuity (at the intersection of the top and the connection) through theoretical, numerical and experimental analyses. The pressure vessel in this work is a piece of equipment used on offshore oil platforms and is part of a natural gas dehydration system. The results showed that the longitudinal and circumferential stresses at the intersection of the top and the connection were higher than the stress values at the top and side for the experimental and numerical analyses, due to the emergence of bending stresses in regions of geometric discontinuity. Another important point was the good correlation of the results between the experimental and numerical analyses using the FEM in the ANSYS software, showing that this methodology is a powerful and reliable tool in the analysis of stresses in pressure vessels.

In this paper, there are two kinds of impact vibration models: rigid impact model and elastic model. The dynamic responses of the two kinds of gear impact models are compared by experimental and numerical analysis. Firstly, establish the motion equations of the two models. Secondly, verify the correctness of the mechanical models through experimental analysis. Comparing the results of the numerical and experimental analysis, we can find that the intensity noise of gear vibration is reduced by the elastic boundary. Finally, the dynamic bifurcation characteristic of dimensionless excitations magnitude and backlash will be analyzed as well.

Mandar is a percussion musical instrument used in the eastern part of India. It is popular among the tribe people and is similar to Mridangam and Dhol. This is widely used in Jharkhand, West Bengal and near boarder region. There is no analytical numerical and experimental analyses documentation available on it. The primary objective of this study is to understand the behavior of vibration of the mandar membrane and to justify whether it is following harmonics? This is justified by experimental and numerical analyses. The numerical analysis is performed in the ‘FEA SOFTWARE (Simulia Abaqus 6.14),’ and the experimental analysis is performed by using Chladni’s experimental setup which helps us to extract the mode shapes of the vibrating mandar membrane. On the basis of both experimental and numerical analyses, we found the mode shape of mandar membrane does not follow harmonics.KeywordsMandar membrane vibrationExperimental analysisNumerical analysisMode shapesChladni’s setupFEA (Abaqus)

In this work, we present the results of an analytical, numerical, and experimental analysis on the performance of a heat sink system designed as a parallel arrangement of microchannels for cooling a high-concentration photovoltaic (HCPV) cell. The analysis considered the worst-case scenario where no electricity is generated, and the solar incidence is maximum on the northwest region of the Sao Paulo State in Brazil. For the experimental, analytical, and numerical analysis, the considered HCPV cell has a geometrical concentration ratio of 500×, a maximum efficiency of 40% at cell’s operating temperature of 41.0 °C, and a cell base area of 100 mm2. The numerical analysis adopts the finite volume method implemented in ANSYS Fluent v15 to solve flow and energy equations with second-order upwind schemes, and the steady-state, incompressible, and laminar flow. In the experimental apparatus, the copper microchannel heat sink consists of 33 parallel rectangular channels of 10 mm in length, 200 μm in width, and 500 μm in height for each microchannel. A cartridge heater was used to simulate the on-sun test, i.e., it simulates the total heat rate supplied to the microchannel heat sink. The microchannel heat sink is capable of keeping the operating temperature of the cell below the maximum cell’s operating temperature (41.0 °C). In addition, the pressure drops are slightly higher than the predicted models, but not exceeding 34%. Moreover, the energy spent in the pumping in the microchannel represents < 1% of the energy generated by the photovoltaic cell.

Numerical and experimental analyses were applied to carbon monoxide (CO) concentration dispersion to monitor air quality in an enclosed residential complex parking area in Tehran. Firstly, the parking area was preliminary assessed through verifying the characteristics of the problem including the geometry and boundary conditions. Then, proportion of vehicular exhaust emissions was estimated and eventually experimental and numerical analyses were performed. In order to perform numerical calculation, a three-dimensional model was created to numerically simulate the enclosed residential complex parking area by FLUENT software that solves flow governing equations with finite volume method. In FLUENT, species model was selected to assess the dispersion of CO in flow domain. In experimental analysis, CO concentration was measured using sampling bags with a volume of 10 l in 4 min at 6 different points. The sample air was drawn into sampling bags by electric pumps. The findings show that the maximum amount of CO concentration is above the permissible standard recommended by the World Health Organization. Pollutant accumulation was significant in confined areas. In the place where openings exist, the level of accumulation was lower than other areas. The findings obtained from numerical simulation are in complete accord with experimental results.

The effect of blade frequency mistuning on the forced response of integral radial turbines is studied by means of experimental and numerical analyses. Blade dominated frequencies representing the mistuning are identified based on blade by blade measurements using the example of a MTU ZR140 turbine blisk. Based on these results, numerical simulations of the blade by blade measurements are performed, aiming to update the originally ideal (tuned) finite element model. The damping information to be considered in the update process is taken from results of an experimental modal analysis. The quality of the model is proved by well correlated frequency response functions (FRF) of numerical and experimental analyses. Finally, the models are used to simulate the forced response due to travelling wave excitations. As a result, mode localization phenomena and response amplifications compared to tuned blisks are proved. In order to round off the contribution to a more enhanced understanding of the radial turbine blisk dynamics optically based geometry measurements are performed to assess the influence of geometrical deviations on frequency mistuning. It is shown that geometric imperfections can be the main driver causing a mistuned response characteristic.

A control scheme of artificial gravity based on the spinning tether system is proposed for manned long-term space mission in this paper. Firstly, the mathematical model of space tether system is established by Lagrangrian modeling method. Secondly, a passive deployment method is designed to realize the rapid deployment control of hundreds of meters short tether. Finally, to deal with the overload stability, a global fast terminal sliding mode controller is designed under the spinning of in-plane motion. The proposed artificial gravity scheme is validated by numerical analysis.

Fine powders in the size range of 20-200 ?m are widely used in industries for fluid bed operations and are ideal for gas-solid reactions because of their large external surface areas and favorable heat transfer rates. The fine powders have very poor flow characteristics. Most of the earlier research work in heat transfer in bubbling fluidized beds is focused on coarse grained Geldart B and D particles. Acoustic energy of sufficient intensity and sound pressure level improved the quality of fluidization of fine powders. The objective of this investigation is experimental analysis and CFD simulations for heat transfer in a fluidized bed of fine powders at different acoustic conditions. The Eulerian approach has been identified as an efficient method for the numerical simulation of fluidized beds. The experimental and CFD results are in good agreement with each other.

Water jet ejectors are the silent pumping fluid devices which doesn’t have any rotating parts in functional industrial applications. The dimensionless geometrical parameters effects ejector suction capacity. In this study, it is found that optimum design intervals have been determined by using the Response Surface Method (RSM). Design ranges determined in the dimensionless study have been used in the improvement of the suction capacity of an existing ejector. The suction capacity of the existing ejector is investigated via numerical and experimental analysis. Two new water jet ejector designs (D1 and D2) are built to improve the suction capacity of the initial water jet ejector (D0). The generated design parameters have been analyzed by using SolidWorks flow analysis and optimization software. The suction capacity of the ejector has been determined through the iterative numerical analysis for the selected geometrical parameters under the applied design conditions. The effect of design parameters on the suction capacity of the water jet ejectors is unveiled through numerical and experimental analysis. The established designs were produced as two novel bronze water jet ejectors. The suction capacities of the produced bronze water jet ejectors have been investigated experimentally. The numerical results have been validated using the experimental results. It is achieved that the suction capacity of the manufactured water jet ejector with the improved design (D2) is suddenly increased from 52.05 m3/h to 103.4 m3/h.

In this study, a numerical and experimental analysis of a solar collector with roughness elements in the form of stainless-steel scourers on the absorber surface is presented. According to the location type and number of the stainless steel scourers, the absorber surfaces are referred to as the complex surface (C1), less complex surface (C2), and flat surface (C3). A Computational Fluid Dynamics (CFD) analysis was carried out using ANSYS-CFX-R18.2 commercial software. The results were verified with the experimental study. After the numerical study was confirmation with the experimental study, then the detailed investigation was performed by numerical simulations. The extracted results of the numerical and experimental analysis concerned the air temperature and velocity, and thermal efficiency, which varied with respect to the type of collector. As a result, the C1 type yielded the highest air velocity and air temperature, while the lowest values of air velocity and temperature were recorded for the C3 type, according to both the numerical analysis and experimental tests. This trend was similar for the efficiencies. The efficiency was nearly 80% for collectors with stainless-steel scourers, whilst it was 55% for the flat plate collector. The results showed that the experimental and numerical results agreed well.

Boilers are one of the most used units for both heat generation plants and industry systems. Their operation is subjected to different working loads and maintenance requirements. Exploitation experience points out critical boiler zones where failures and break downs typically occur. This paper analyzes critical zones in hot water fire-tube boiler. Experimental procedure was performed on the model of this type of boilers and its critical element. The tube plate of hot water boiler was identified as the most critical one. Experimental analysis and numerical model verification were performed using Aramis system based on 3-D digital image correlation method. Numerical analysis was done in ANSYS software package and verification of results was done based on measurements obtained by strain gauges and local measurements performed by the Aramis system. Stress-strain analysis indicates the critical zones of boiler tube plate. The character of change parameters such as strain and stress occurring in the critical zones can be verified both by experimental and numerical data. The paper presents a novel approach in experimental and numerical analyses that can be conducted in similar units and used for existing unit optimization, as well as for new product testing on different loads and provide opportunity for further development and improvement for practical industrial application.

Sorption and diffusion of Sr were examined using a typical Japanese bentonite. The experimental results showed that Sr sorption on the bentonite had linear relationship between the equilibrium Sr concentration and Sr sorption amount, i.e., Henry’s type of sorption, in wide initial Sr concentration from 1.1 × 10−9 to 1.1 × 10−4 mol L−1 at pH 10. The Sr sorption also indicated pH dependence in pH range between 2 and 12. Sorption modelling calculation indicated that cation-exchange reactions contributed to Sr sorption in the pH range studied and a surface complexation reaction was predominant above pH 8. Diffusion of Sr in loosely compacted bentonite bed was described by pore and surface diffusion and surface complexation of Sr. Chemical-transport calculations reproduce the diffusion data at pH 5 using the cation-exchange parameters obtained in the analysis of the batch sorption experiment.

This paper presents an experimental and numerical modal analysis of the military vehicle hull. Due to its adaptation to various weapon systems, it is necessary to conduct detailed tests. Computer simulations are a very useful tool. To ensure the reliability of the results, it is necessary to validate the models. The modal analysis was used in this work. It was carried out using the roving hammer method. Both natural frequency and mode shape were compared. The Modal Assurance Criterion was used for the comparison. To determine areas of noncompliance, distributions of relative differences between experimental and finite element (FE) mode shapes were prepared. The presented results indicate a large convergence between the results of numerical and experimental analyses.

With the increasing complexity of the products, engineers face a higher level of uncertainty in both simulation and test. Correlation between numerical and experimental analysis using model updating techniques helps engineers to asses uncertainty. Present research efforts focus to combine finite element analysis and testing in one common framework. Experimental and operational modal analysis and simulation make benefit from common databases. Some applications presented emphasize the advantages of these techniques.