Experimental Research Regarding Static Rigidity in Transversal Direction of “Narrow“ Modules from Modular Fixtures Structure

2015 ◽  
Vol 809-810 ◽  
pp. 754-759 ◽  
Author(s):  
Dragoş Florin Chitariu
Keyword(s):  
Angular Displacement ◽  
Base Plate ◽  
Linear Displacement ◽  
Experimental Results ◽  
Modular Structure ◽  
Total Deformation ◽  
Deformation Curves ◽  
Modular Fixtures ◽  
Static Rigidity ◽  
Measurement Base

In the paper a research methodology was developed and used to determine the rigidity in transversal direction of modular fixture structures. The paper presents experimental results regarding the total deformation of modular structure consisting of ”narrow” modules from modular kits. The research conducted showed the different evolution of deformation curves in the case of modular structure, with different shape and different sizes of modules, in the case of similar loads. The experimental results indicate displacements of the entire modular structure alongside the base plate and, also, tilting. The measured deviations of modules from fixture structure may cause "dimensional"/ position deviations (linear displacement of the measurement base) and deviations of shape and orientation-position (angular displacement of the measurement base) of the workpiece during severe machining conditions.

Experimental Research Regarding Static Rigidity in Axial Direction of "Narrow" Modules from Modular Fixtures Structure

2014 ◽  
Vol 657 ◽  
pp. 514-518 ◽  
Author(s):  
Dragoș Florin Chitariu
Keyword(s):  
Experimental Research ◽  
Research Methodology ◽  
Axial Direction ◽  
Experimental Results ◽  
Modular Structure ◽  
Total Deformation ◽  
Deformation Curves ◽  
Modular Fixtures ◽  
Static Rigidity

In the paper a research methodology was developed and used to determine the rigidity in the axial direction.The paper presents a the experimental results regarding the total deformation of narrow modules found in the structure of modular sets. The research conducted showed the different evolution of deformation curves in the case of modular structure composed of modules, with different shape and different sizes, in the case of similar loads

Suspended Four-Dimensional Motor-Driven Adjusting Mount Structure with High Resolution

2014 ◽  
Vol 513-517 ◽  
pp. 3526-3531
Author(s):  
Jin Song Wang ◽  
Xiao Xuan He ◽  
Zhi Yong An
Keyword(s):  
High Resolution ◽  
Static Analysis ◽  
Angular Displacement ◽  
Linear Displacement ◽  
Experimental Results ◽  
Optical Components

Optical components require multi-dimensional adjustment when being accurately detecting its surface shape.The most of existing adjusting mounts are hand regulation that their efficiency and resolution are lower. Against this situation,a motor-driven four-dimensional adjusting mount which is high resolution and stability is designed. An experiment against the whole structure and the static analysis of key component were carried out. Analysis and experimental results show that the the four-dimensional adjustment mounts can realize the translation adjustment in X, Y direction and the angular adjustment indirection. The angular displacement resolution is and linear displacement adjustment resolution is when the load is 37 kg.

Experimental Robot Identification: Advantages of Combining Internal and External Measurements and of Using Periodic Excitation

2001 ◽  
Vol 123 (4) ◽  
pp. 630-636 ◽  
Author(s):  
Walter Verdonck ◽  
Jan Swevers ◽  
Jean-Claude Samin
Keyword(s):  
Signal Processing ◽  
Parameter Estimation ◽  
Effective Means ◽  
Base Plate ◽  
Experimental Results ◽  
Parameter Estimates ◽  
Periodic Excitation ◽  
Identification Method ◽  
Reaction Forces ◽  
Improved Model

This paper discusses the advantages of using periodic excitation and of combining internal and external measurements in experimental robot identification. This discussion is based on the robot identification method developed by Swevers et al., a method that is recognized by industry as an effective means of robot identification that is frequently used, Hirzinger, G., Fischer, M., Brunner, B., Koeppe, R., Otter, M., Grebenstein, M., and Schafer, I, 1999, “Advances is Robotics: The DLR Experiment,” The International Journal of Robotics Research, Vol. 18, No. 11, pp. 1064–1087 [3]. Experimental results on a KUKA IR 361 show that the periodicity of the robot excitation is a key element of this method. Nonperiodic robot excitation complicates the signal processing preceding the parameter estimation, often yielding less accurate parameter estimates. An extension of this identification method combines internal and external measurements, Chenut, X., Samin, J. C., Swevers, J., and Ganseman, C., 2000, “Combining Internal and External robot Models for improved Model Parameter Estimation,” Mechanical Systems and Signal Processing. Vol. 14, No. 5, pp. 691–704 [4], yielding robot models that allow to accurately predict the actuator torques and the reaction forces/torques of the robot on its base plate, which are both important for the path planning. This paper presents and critically discusses the first experimental results obtained with this method.

Software for Computing Lenticular Compensators (Bellows)

2014 ◽  
Vol 657 ◽  
pp. 775-779 ◽  
Author(s):  
Emilia Marinela Scheibner
Keyword(s):  
Angular Displacement ◽  
Operating Conditions ◽  
Calculation Procedure ◽  
Total Deformation ◽  
Expansion Joints ◽  
Heating Systems ◽  
Mechanical Calculation ◽  
Automatic Calculation ◽  
Geometrical Characteristics

Expansion joints are used in installations where axial or angular significant changes occur due to operating conditions: differences temperature, arching, vibration etc. Expansion compensation will take over the pipe stresses, preventing so their destruction. Lenticular compensators take pipe thermal expansions; metal compensators are use for take axial, lateral or angular displacement. This paper presents information regarding the lenticular compensators and calculation procedure of their geometrical characteristics, mainly the number of elements that composed them. An automatic calculation program ”CCRT - Comp Lent” (computing pipeline heating systems – lenticular compensation) was developed based on fundamental concepts in mechanical calculation of pipes and lenticular compensators. The algorithm of this program is based on determining the pipeline expansion, the total deformation and the number of the compensation required.

How Geometrical Tolerances Affect the Measurement of Reciprocal Alignment of Two Different Assemblies: A Case Study

2010 ◽  
Author(s):  
David Vetturi ◽  
Matteo Lancini ◽  
Ileana Bodini
Keyword(s):  
Numerical Simulations ◽  
Angular Displacement ◽  
European Space Agency ◽  
Coordinate Measuring Machine ◽  
Linear Displacement ◽  
Repeated Measurements ◽  
Uncertainty Sources ◽  
Component Design ◽  
Measuring Machine ◽  
The Right

Often a designer has the problem to apply a suitable system of geometrical and dimensional tolerances to an assembly. The right solution is not unique, in fact it depends on the chosen parameters. If the tolerances have to be optimized, some important parameters have to be taken into account, e.g. the efficiency of each prescription, or if this last is reachable, or it can be verified and how much the realization costs. The authors opinion is that a statistical approach based on the Monte Carlo Method is very useful when the tolerances chains are complex. This paper shows an application of this method in order to verify the functional alignment between two assemblies and a critical analysis of the uncertainty in phase both of the component design and test. This study has been developed thanks to the strict requirements imposed by ESA (European Space Agency) on the components that Thales Alenia Space has to realize within the LISA Pathfinder experiment. The very critical aspect of this work is to reciprocally align two cylindrical elements of two different assemblies. The specifications require 100 μm as maximum linear displacement and 300 μrad as maximum angular displacement. Moreover this prescriptions have to be verified also when the two elements are independently moving. To be able to reach such strict accuracy level the components have been assembled in an ISO 100 class cleanroom and the work space was a 3D Coordinate-Measuring Machine (CMM). The cylindrical elements have a 10 mm diameter, so the value of the measurement uncertainty associated with the alignment check is fundamental. Starting from the different uncertainty sources, the measurability and verifiability of the alignment have been considered and evaluated. The overall uncertainty has been assessed by numerical simulations which have taken into account the dimensional, geometrical and form tolerances as well as the instrumental uncertainty of the 3D CMM. This estimation has been positively validated by a session of repeated measurements. Numerical simulations have also allowed performing a sensitivity analysis, in order to give information about which sources more contribute to the overall uncertainty.

Experimental Investigation of Enhanced Two-Phase Evaporator Using Aluminum Foams

2015 ◽  
Author(s):  
Francesco Agostini ◽  
Waylon Puckett ◽  
Ryan Nelson ◽  
Daniele Torresin ◽  
Bruno Agostini ◽  
...  
Keyword(s):  
Aluminum Foam ◽  
Metal Foam ◽  
Electronics Cooling ◽  
Base Plate ◽  
Heat Fluxes ◽  
Experimental Results ◽  
Working Fluid ◽  
Vapor Flow ◽  
Base Temperature ◽  
Two Phase

A novel two-phase thermosyphon with a metal foam based evaporator is presented as a solution for the cooling of power-electronic semiconductor modules. A horizontal evaporator configuration is investigated: the evaporator consists of an aluminum chamber, with aluminum foam brazed to the base plate in three different configurations. One of the configurations has an open vapor chamber above the foam, another has foam filling the entire evaporator chamber, and the third has bores drilled in the foam parallel to the base plate from inlet to outlet along the direction of the vapor flow. The aluminum foam has a porosity of 95%, and a pore density of 20 PPI (pores per inch). A liquid distribution and a vapor collector chamber are respectively present at the entrance and at the exit of the evaporator. The power modules are attached on the evaporator body that collects the heat generated during the operation of the semiconductor devices. A vapor riser guides the vapor to a finned-tube air-cooled heat exchanger. A liquid downcomer from the condenser constantly feeds the evaporator channels. The system works with gravity-driven circulation only. The described system was designed and tested with an extensive experimental campaign. The evaporators were tested for power losses ranging between 500 and 3000 W, corresponding to applied heat fluxes between 3 and 20 W/cm2. The experimental results will be presented for inlet air at ambient temperature of 20°C with volumetric flow rates between 100 and 680 m3/h. The working fluid was refrigerant R245fa. The fluid filling effect was investigated. For each evaporator the results will be presented in terms of maximum thermal resistance and cooler base temperature. The base temperature distribution between different evaporators will also be presented and discussed being an important design parameter in power electronics cooling. Thermal resistances were measured between 15 and 30 K/kW. The experimental results indicated a promising conclusion favoring the implementation of aluminum foam evaporators for enhancement of heat transfer during pool boiling.

scholarly journals Sliding Mode Control of Magnetic Bearings: Comparison of Sensed and Self Sensing Performance

1999 ◽  
Author(s):  
S. Ueno ◽  
J. H. Lee ◽  
P. E. Allaire ◽  
Y. Okada
Keyword(s):  
Sliding Mode Control ◽  
Sliding Mode ◽  
Angular Displacement ◽  
State Space Model ◽  
Experimental Results ◽  
Magnetic Bearings ◽  
Small Scale ◽  
Linear Component ◽  
Mode Control ◽  
Physical Sensors

A sliding mode control algorithm has been designed for control of a balance beam on two symmetric magnetic bearings. A state space model of the system is developed and the controller is separated into a linear and non-linear component. A reaching condition to bring the system to the sliding surface is developed and a continuous function boundary layer approach is evaluated to avoid chattering. Previous works have discussed theoretical and experimental sliding mode control with physical sensors. This paper represents the first use of a simple envelope filter for sliding mode self sensing. The system simulation demonstrates arrival at the hyperplane surface within 0.003 sec and converges to the zero angular displacement value within 0.008 sec. Experimental results produced system convergence to zero angular displacement within approximately 0.35 sec both for the case when an eddy current position sensor was used and the case when system self sensing was employed. Some small scale chatter was observed in the experimental results with a peak to peak magnitude of approximately 3 times larger in the self-sensing case as compared to the case with a physical sensor.

scholarly journals RESEARCH ON THE INFLUENCE OF THE PROPERTIES OF INTERVERTEBRAL DISC STIFFNESS OF THE LUMBAR SPINE ON THE DISPLACEMENT OF VERETBRAE / STUBURO JUOSMENINĖS DALIES TARPSLANKSTELINIO DISKO STANDUMO CHARAKTERISTIKŲ ĮTAKOS SLANKSTELIŲ POSLINKIAMS TYRIMAS

2015 ◽  
Vol 6 (6) ◽  
pp. 595-597
Author(s):  
Artūras Linkel ◽  
Julius Griškevičius ◽  
Gintaras Jonaitis
Keyword(s):  
Lumbar Spine ◽  
Intervertebral Disc ◽  
Degrees Of Freedom ◽  
Angular Displacement ◽  
Fast Response ◽  
Intervertebral Discs ◽  
Linear Displacement ◽  
Basic Task ◽  
Non Linear ◽  
Solid Bodies

The article proposes the method for evaluating angular and linear changes in intervertebral discs of the spine depending on linear and nonlinear intervertebral disc stiffness. A dynamic made of 5 solid bodies connected by damping and stiffness components and applied for 2-D 10 degrees of freedom of the lumbar spine has been used for calculations. The system of the equation has been written in a matrix form. Lumbar intervertebral discs stiffness and damping properties have been selected from scientific articles and make from 200 N/mm to 1200 N/mm and from 229 Ns / mm to 5100 Ns/mm respectively for non-linear calculation and 800 N / mm – 2637 Ns/mm for linear displacement calculation. External loads applied to the model are 1648 N, 2957 N, 3863 N and 4542 N. The basic task of the paper is to calculate the biggest difference in linear and angular displacement considering 2 cases: linear and non-linear stiffness value. The greatest estimated difference, under the highest load, makes 0.6 mm for linear and 0.95 degrees for angular displacement. Because of the fast response of the model to the load, the damping value could not affect displacement. Tyrimo objektas yra stuburo trapslankstelinių diskų poslinkių skirtumai esant tiesiniam ir netiesiniam jų standumo koeficientui. Taikomas 10 laisvės laipsnių 2-D stuburo juosmeninės dalies dinaminis modelis, kuris susideda iš 5 juosmens slankstelių, sujungtų standumo ir slopinimo ryšiais. Modeliui nustatomos juosmens apkrovos, kurios susidaro važiuojant dviračiu. Tarpslankstelinių diskų savybės parenkamos iš mokslinės literatūros. Sudarytas matematinis modelis leido apskaičiuoti stuburo slankstelių linijinius ir kampinius poslinkius įvertinant tarpslankstelinio disko standžio netiesiškumą. Atlikti skaičiavimai parodė, kad didžiausi skirtumai susidaro esant maksimaliai apkrovai. Didžiausi linijinių poslinkių skirtumai yra 0,6 mm, o kampinių – 0,95 laipsnio. Nustatytos slopinimo koeficiento reikšmės dėl greito modelio atsako poslinkių skaičiavimams įtakos neturėjo.

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