Dynamics, Vibrations and Control Lab Equipment Design

2018 ◽  
Author(s):  
Ayse Tekes ◽  
Kevin Van Der Horn ◽  
Zach Marr ◽  
Chong Tian
Keyword(s):  
Compliant Mechanism ◽  
Low Cost ◽  
Equations Of Motion ◽  
Forced Response ◽  
Small Scale ◽  
Time Data ◽  
Free Response ◽  
Element Analysis ◽  
Flexible Beams ◽  
Simulink Model

Take home lab equipment and hands-on learning tools are still in demand for control theory and vibrations courses. The existing equipment are extremely expensive and require wide lab space. The aim of this research is to build vibratory mechanical system that is compact, modular and small scale so that each student can work on their setup and take it home if necessary. For this purpose, in this study, a semi-compliant mechanism is designed to be utilized in systems control and vibrations courses which would enhance the understanding of students by using experimental demonstration of the theoretical systems. The superiorities of the design over commercially available equipment are their low cost and simplicity. A parallel arm mechanism consisting of several flexible links that can be attached at different points on the slider is designed, finite element analysis (FEA) is performed in Solidworks, and the flexible beams are 3D printed using polyactic acid (PLA) and Polyethylene terephthalate glycol-modified (PETG) filaments. Different configurations of the mechanism are explored by changing the number of flexible beams attached to the slider. The mathematical model of the proposed mechanism can be represented by a single mass and multiple springs in parallel. Since mass is a known property, the equivalent stiffness can be experimentally found from the frequency analysis of free response. For this purpose, a PCB model tri-axial accelerometer is attached to the slider and the equations of motion are derived from the analysis of frequency characteristics of the complaint dual arm mechanism for each configuration. System properties including the equivalent friction are obtained from the acceleration vs time data using logarithmic decrement. The forced response is studied by attaching a load to the mass through a pulley system. The load deflection curve is obtained experimentally from LabVIEW. Since the system parameters are obtained from the free response, Matlab Simulink model outputs for the same initial displacement and force input are verified with the experimental data.

3-D Simulation of Iceberg Towing Operations: Cable Modeling and Frictional Contact Formulation Using Finite Element Analysis

2020 ◽  
Author(s):  
Brian J. O’Rourke ◽  
Mark K. Fuglem ◽  
Tony King
Keyword(s):  
Finite Element ◽  
Sliding Friction ◽  
Equations Of Motion ◽  
Current Phase ◽  
Small Scale ◽  
Wave Forces ◽  
Element Analysis ◽  
Single Loop ◽  
Tangent Stiffness Matrix ◽  
Lagrangian Finite Element

Abstract Ice management in regions of offshore development with icebergs present includes re-direction of icebergs by means of towing. The prevention of tow-rope slippage and iceberg rolling due to hydrostatic instability are essential for an effective and safe operation. The ability to simulate any particular towing operation in the field, prior to attempting it, would provide some measure of assurance of its feasibility. In addition, such a model will allow optimization of towing configuration and application by showing optimal tow direction, maximum force and rate of force application; selection of single tow line or net; and optimum net configuration. The objective of the described work is to develop a simulation tool that can be used for such application. A previous project funded by Hibernia Management and Development Company Ltd. (HMDC) gathered 3-dimensional profile data on 29 icebergs off the East coast of Canada; and further data collection has been ongoing. The present project utilizes these profiles as valuable input in the development of the model for simulating single-line and net tows. This paper presents the first phase of development of a 3-D dynamic iceberg towing model that evolved from an earlier 2-D static version. The current iteration applies the ‘Total Lagrangian’ Finite-Element Method (FEM) to model the cable-and-rope structure between the towing vessel and iceberg, and a contact model that includes sticking and sliding friction between the rope/net and iceberg. The iceberg is modeled as a rigid surface mesh and is fully constrained against motion during the current phase of development, while the cables and ropes are modeled as elastic bar elements with translational inertia and velocity-squared fluid drag. The contact elements consist of penalty springs with proportional damping, and appropriate values of these are found to be critical for numerical stability of the solution. As well, due to the large difference in stiffness values between the heavy tow cable and buoyant ropes, special attention is given to obtaining the initial tangent stiffness matrix of the cable-and-rope structure. The FE dynamic equations of motion are solved implicitly in the time domain using a combination of full and modified Newton-Raphson iteration. Simulations of contact initiation between the rope and iceberg for single-loop and net configurations are presented, as well as slipping during particular single-loop tows. Current challenges and opportunities for further development are discussed, including improving computational speed, implementing iceberg motion, adding wind and wave forces, and validating rope-ice friction characteristics through small-scale iceberg towing response in a laboratory.

Finite Element Analysis to Improve the Accuracy of ABS Plastic Parts Made by Desktop 3D Printing Method

2015 ◽  
Vol 760 ◽  
pp. 509-514 ◽  
Author(s):  
Răzvan Păcurar ◽  
Ancuţa Păcurar ◽  
Florin Popişter ◽  
Anca Popişter
Keyword(s):  
Finite Element ◽  
Fused Deposition Modeling ◽  
Tool Path ◽  
Low Cost ◽  
Small Scale ◽  
Slice Thickness ◽  
Technological Parameters ◽  
Element Analysis ◽  
Fused Deposition ◽  
3D Printers

The development of low-cost desktop versions of three-dimensional (3D) printers has made these devices widely accessible for rapid prototyping and small-scale manufacturing in home and office settings. Many desktop 3D printers rely fused deposition modeling process, that it is based on heated thermoplastic filiform material that it is extrused through a nozzle and deposited afterwards onto a heated building platform. The extruding accuracy in part fabrication is subject to transmission machinery and filament diameter on one hand and the technological parameters that are used in the manufacturing process (raster angle, tool path, slice thickness, build orientation, deposition speed, building temperature, etc.) on the other hand. The presented work try to investigate by using the finite element method, how the building temperature in close connection with the material characteristics is influencing the accuracy of a test part that has been designed in order to callibrate an Desktop 3D Printer machine that has been originally designed and produced at the Technical University of Cluj-Napoca (TUC-N).

Multi‐dimensional switched reluctance motors for industrial applications

2011 ◽  
Vol 38 (4) ◽  
pp. 419-428
Author(s):  
J.F. Pan ◽  
Norbert Cheung
Keyword(s):  
Performance Prediction ◽  
Low Cost ◽  
Design Procedure ◽  
Experimental Results ◽  
Circuit Board ◽  
Small Scale ◽  
Direct Drive ◽  
Element Analysis ◽  
Content Type ◽  
Switched Reluctance

PurposeThe paper aims to discuss a new direction of design outline of four‐axis machine with multi‐dimensional motors. It proposes an integrated, direct‐drive machine based on switched reluctance (SR) principles. This includes how the machine is constructed and the structure of each axis of motion. The simulation and control results are also provided for performance prediction. The study aims to provide a solution and find applications for high‐performance, low‐cost manufacturing facilities.Design/methodology/approachThe study is based on simulation and experimental results for performance prediction of the multi‐dimensional motors. With the approach of grounded theory on SR machines, design and construction of each axis of motion is verified with finite element analysis. Then, corresponding control strategy is provided for the control of each axis of motion. Some corresponding experimental results are carried out to verify motor performance.FindingsThe paper provides a general design procedure for direct‐drive, integrated, multi‐dimensional SR motors. It suggests a mechanically robust, low‐cost and simple machine structure for potential applications of industrial multi‐axis machines.Research limitations/implicationsConsidering the performance from the prototype, it is expected to find applications in low‐level force and torque output such as automated small‐scale printed circuit board drillings.Practical implicationsOwing to the limitations of the present study, the machine needs further control tests for robust or adaptive applications. Therefore, researchers are encouraged to implement further advanced control strategies on the machine.Originality/valueThe authors attempt to provide a comprehensive solution of multi‐axis machine design based on direct‐drive, low‐cost multi‐dimensional SR motors.

Efficient Nonlinear Vibration Analysis of the Forced Response of Rotating Cracked Blades

2008 ◽  
Vol 4 (1) ◽  
Author(s):  
Akira Saito ◽  
Matthew P. Castanier ◽  
Christophe Pierre ◽  
Olivier Poudou
Keyword(s):  
Finite Element ◽  
Nonlinear Vibration ◽  
Vibration Analysis ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
Vibration Response ◽  
New Method ◽  
Beam Model ◽  
Element Analysis

The efficient nonlinear vibration analysis of a rotating elastic structure with a crack is examined. In particular, the solution of the forced vibration response of a cracked turbine engine blade is investigated. Starting with a finite element model of the cracked system, the Craig–Bampton method of component mode synthesis is used to generate a reduced-order model that retains the nodes of the crack surfaces as physical degrees of freedom. The nonlinearity due to the intermittent contact of the crack surfaces, which is caused by the opening and closing of the crack during each vibration cycle, is modeled with a piecewise linear term in the equations of motion. Then, the efficient solution procedure for solving the resulting nonlinear equations of motion is presented. The approach employed in this study is a multiharmonic hybrid frequency∕time-domain technique, which is an extension of the traditional harmonic balance method. First, a simple beam model is used to perform a numerical validation by comparing the results of the new method to those from transient finite element analysis (FEA) with contact elements. It is found that the new method retains good accuracy relative to FEA while reducing the computational costs by several orders of magnitude. Second, a representative blade model is used to examine the effects of crack length and rotation speed on the resonant frequency response. Several issues related to the rotation are investigated, including geometry changes of the crack, shifts in resonant frequencies, and the existence of multiple solutions. For the cases considered, it is found that the nonlinear vibration response exhibits the jump phenomenon only when rotation is included in the model.

Efficient Nonlinear Vibration Analysis of the Forced Response of Rotating Cracked Blades

2006 ◽  
Author(s):  
Akira Saito ◽  
Matthew P. Castanier ◽  
Christophe Pierre
Keyword(s):  
Finite Element ◽  
Nonlinear Vibration ◽  
Vibration Analysis ◽  
Piecewise Linear ◽  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Forced Response ◽  
New Method ◽  
Beam Model ◽  
Element Analysis

The efficient nonlinear vibration analysis of a rotating elastic structure with a crack is examined. In particular, the solution of the forced vibration response of a cracked turbine engine blade is investigated. Starting with a finite element model of the cracked system, the Craig-Bampton method of component mode synthesis is used to generate a reduced-order model that retains the nodes of the crack surfaces as physical DOF. The nonlinearity due to the intermittent contact of the crack surfaces, which is caused by the opening and closing of the crack during each vibration cycle, is modeled with a piecewise linear term in the equations of motion. Then, the efficient solution procedure for solving the resulting nonlinear equations of motion is presented. The approach employed in this study is a multi-harmonic, hybrid frequency/time-domain (HFT) technique, which is an extension of the traditional harmonic balance method. First, a simple beam model is used to perform a numerical validation by comparing the results of the new method to those from transient finite element analysis (FEA) with contact elements. It is found that the new method retains good accuracy relative to FEA while reducing the computational costs by several orders of magnitude. Second, a representative blade model is used to examine the effects of crack length and rotation speed on the resonant frequency response. Several issues related to the rotation are investigated, including geometry changes of the crack and the existence of multiple solutions.

Tools of Transformation: Appropriate Technology in U.S. Countercultural Literature

2012 ◽  
Vol 44 (2) ◽  
pp. 75-93
Author(s):  
Peter Mortensen
Keyword(s):  
Low Cost ◽  
Appropriate Technology ◽  
Small Scale ◽  
Environmental Transformation ◽  
Buckminster Fuller ◽  
1960S And 1970S ◽  
The 1960S ◽  
Environmentally Sound ◽  
User Friendly ◽  
Second Wave

This essay takes its cue from second-wave ecocriticism and from recent scholarly interest in the “appropriate technology” movement that evolved during the 1960s and 1970s in California and elsewhere. “Appropriate technology” (or AT) refers to a loosely-knit group of writers, engineers and designers active in the years around 1970, and more generally to the counterculture’s promotion, development and application of technologies that were small-scale, low-cost, user-friendly, human-empowering and environmentally sound. Focusing on two roughly contemporary but now largely forgotten American texts Sidney Goldfarb’s lyric poem “Solar-Heated-Rhombic-Dodecahedron” (1969) and Gurney Norman’s novel Divine Right’s Trip (1971)—I consider how “hip” literary writers contributed to eco-technological discourse and argue for the 1960s counterculture’s relevance to present-day ecological concerns. Goldfarb’s and Norman’s texts interest me because they conceptualize iconic 1960s technologies—especially the Buckminster Fuller-inspired geodesic dome and the Volkswagen van—not as inherently alienating machines but as tools of profound individual, social and environmental transformation. Synthesizing antimodernist back-to-nature desires with modernist enthusiasm for (certain kinds of) machinery, these texts adumbrate a humanity- and modernity-centered post-wilderness model of environmentalism that resonates with the dilemmas that we face in our increasingly resource-impoverished, rapidly warming and densely populated world.

Design of a Single-Acting Constant-Force Actuator Based on Dielectric Elastomers

2008 ◽  
Author(s):  
Giovanni Berselli ◽  
Rocco Vertechy ◽  
Gabriele Vassura ◽  
Vincenzo Parenti Castelli
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Compliant Mechanism ◽  
Structural Parameters ◽  
Dielectric Elastomer ◽  
Constant Force ◽  
Element Analysis ◽  
Body Model ◽  
Rigid Body Model ◽  
Supporting Frame

The interest in actuators based on dielectric elastomer films as a promising technology in robotic and mechatronic applications is increasing. The overall actuator performances are influenced by the design of both the active film and the film supporting frame. This paper presents a single-acting actuator which is capable of supplying a constant force over a given range of motion. The actuator is obtained by coupling a rectangular film of silicone dielectric elastomer with a monolithic frame designed to suitably modify the force generated by the dielectric elastomer film. The frame is a fully compliant mechanism whose main structural parameters are calculated using a pseudo-rigid-body model and then verified by finite element analysis. Simulations show promising performance of the proposed actuator.

scholarly journals Development of a simplified gas ultracleaning process: experiments in biomass residue-based fixed-bed gasification syngas

2021 ◽  
Author(s):  
Christian Frilund ◽  
Esa Kurkela ◽  
Ilkka Hiltunen
Keyword(s):  
Activated Carbons ◽  
Low Cost ◽  
Fixed Bed ◽  
Carbonyl Sulfide ◽  
Gas Analysis ◽  
Small Scale ◽  
Cleaning Process ◽  
Medium Temperature ◽  
Gas Cleaning ◽  
Adsorption Affinity

AbstractFor the realization of small-scale biomass-to-liquid (BTL) processes, low-cost syngas cleaning remains a major obstacle, and for this reason a simplified gas ultracleaning process is being developed. In this study, a low- to medium-temperature final gas cleaning process based on adsorption and organic solvent-free scrubbing methods was coupled to a pilot-scale staged fixed-bed gasification facility including hot filtration and catalytic reforming steps for extended duration gas cleaning tests for the generation of ultraclean syngas. The final gas cleaning process purified syngas from woody and agricultural biomass origin to a degree suitable for catalytic synthesis. The gas contained up to 3000 ppm of ammonia, 1300 ppm of benzene, 200 ppm of hydrogen sulfide, 10 ppm of carbonyl sulfide, and 5 ppm of hydrogen cyanide. Post-run characterization displayed that the accumulation of impurities on the Cu-based deoxygenation catalyst (TOS 105 h) did not occur, demonstrating that effective main impurity removal was achieved in the first two steps: acidic water scrubbing (AWC) and adsorption by activated carbons (AR). In the final test campaign, a comprehensive multipoint gas analysis confirmed that ammonia was fully removed by the scrubbing step, and benzene and H2S were fully removed by the subsequent activated carbon beds. The activated carbons achieved > 90% removal of up to 100 ppm of COS and 5 ppm of HCN in the syngas. These results provide insights into the adsorption affinity of activated carbons in a complex impurity matrix, which would be arduous to replicate in laboratory conditions.

scholarly journals Evaluation of a Low-Cost Commercial Actigraph and Its Potential Use in Detecting Cultural Variations in Physical Activity and Sleep

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3774
Author(s):  
Pavlos Topalidis ◽  
Cristina Florea ◽  
Esther-Sevil Eigl ◽  
Anton Kurapov ◽  
Carlos Alberto Beltran Leon ◽  
...  
Keyword(s):  
Physical Activity ◽  
Low Income ◽  
Large Scale ◽  
Low Cost ◽  
Low Income Countries ◽  
Time Data ◽  
Cultural Variations ◽  
Step Counts ◽  
Scale Step ◽  
Potential Use

The purpose of the present study was to evaluate the performance of a low-cost commercial smartwatch, the Xiaomi Mi Band (MB), in extracting physical activity and sleep-related measures and show its potential use in addressing questions that require large-scale real-time data and/or intercultural data including low-income countries. We evaluated physical activity and sleep-related measures and discussed the potential application of such devices for large-scale step and sleep data acquisition. To that end, we conducted two separate studies. In Study 1, we evaluated the performance of MB by comparing it to the GT3X (ActiGraph, wGT3X-BT), a scientific actigraph used in research, as well as subjective sleep reports. In Study 2, we distributed the MB across four countries (Austria, Germany, Cuba, and Ukraine) and investigated physical activity and sleep among these countries. The results of Study 1 indicated that MB step counts correlated highly with the scientific GT3X device, but did display biases. In addition, the MB-derived wake-up and total-sleep-times showed high agreement with subjective reports, but partly deviated from GT3X predictions. Study 2 revealed similar MB step counts across countries, but significant later wake-up and bedtimes for Ukraine than the other countries. We hope that our studies will stimulate future large-scale sensor-based physical activity and sleep research studies, including various cultures.

scholarly journals Understanding Spatial Variability of NO2 in Urban Areas Using Spatial Modelling and Data Fusion Approaches

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 179
Author(s):  
Said Munir ◽  
Martin Mayfield ◽  
Daniel Coca
Keyword(s):  
Data Fusion ◽  
Spatial Variability ◽  
Urban Areas ◽  
Road Traffic ◽  
Dispersion Model ◽  
Low Cost ◽  
Spatial Modelling ◽  
City Centre ◽  
Small Scale ◽  
The City

Small-scale spatial variability in NO2 concentrations is analysed with the help of pollution maps. Maps of NO2 estimated by the Airviro dispersion model and land use regression (LUR) model are fused with measured NO2 concentrations from low-cost sensors (LCS), reference sensors and diffusion tubes. In this study, geostatistical universal kriging was employed for fusing (integrating) model estimations with measured NO2 concentrations. The results showed that the data fusion approach was capable of estimating realistic NO2 concentration maps that inherited spatial patterns of the pollutant from the model estimations and adjusted the modelled values using the measured concentrations. Maps produced by the fusion of NO2-LCS with NO2-LUR produced better results, with r-value 0.96 and RMSE 9.09. Data fusion adds value to both measured and estimated concentrations: the measured data are improved by predicting spatiotemporal gaps, whereas the modelled data are improved by constraining them with observed data. Hotspots of NO2 were shown in the city centre, eastern parts of the city towards the motorway (M1) and on some major roads. Air quality standards were exceeded at several locations in Sheffield, where annual mean NO2 levels were higher than 40 µg/m3. Road traffic was considered to be the dominant emission source of NO2 in Sheffield.

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