Modeling and Characterization of Micromachined Bi-Directional Electro-Thermal Vibromotors

2003 ◽  
Author(s):  
Wen-Pin Shih ◽  
Minfan Pai ◽  
Yu-Yun Lin ◽  
Chung-Yuen Hui ◽  
Norman C. Tien
Keyword(s):  
Periodic Solution ◽  
Thermal Actuator ◽  
Impact Model ◽  
Multiple Impacts ◽  
Preliminary Results ◽  
The Impact ◽  
Theory And Experiments ◽  
Impact Head ◽  
Good Agreement

The motion of a micromachined bi-directional electrothermal vibromotor (BETV) is analyzed using an impact model which takes into account of friction and contact, as well as the compliance of the slider and the impact head. This model is shown to address several important issues on the reliable usage of BETV. These include (a) how to achieve the push or pull mode (b) avoiding multiple impacts in one actuation cycle (c) the existence of periodic solution with the same period as the thermal actuator. To test our theory, we fabricated and conducted experiments on several BETV with different geometries. Preliminary results showed good agreement between theory and experiments.

Two interferometric methods for the mechanical characterization of thin films by bulging tests. Application to single crystal of silicon

1997 ◽  
Vol 12 (9) ◽  
pp. 2234-2248 ◽  
Author(s):  
E. Bonnotte ◽  
P. Delobelle ◽  
L. Bornier ◽  
B. Trolard ◽  
G. Tribillon
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Mechanical Characterization ◽  
Optical Methods ◽  
Fringe Projection ◽  
Phase Measurements ◽  
Experimental Apparatus ◽  
Theory And Experiments ◽  
Good Agreement

Two optical methods are presented for the mechanical characterization of thin films, namely real time holographic interferometry and a fringe projection method called “contouring.” These two methods are coupled to the interferometry by the phase measurements, thus allowing the displacement field to be measured at all points on the membrane. We discuss the solutions retained in terms of their precision and sensitivity. These methods are then applied to membrane bulging tests, a type of test that is widely used in micro-mechanical studies. The measurements are performed on silicon single crystal and the results are compared to the solutions calculated by finite element methods. In both cases, the good agreement between theory and experiments allows the experimental apparatus to be validated.

Characterization of the torsional vibration behavior of circular and rectangular cross-sectional arc springs: Theory and experiments

2021 ◽  
Vol 63 (2) ◽  
pp. 113-118
Author(s):  
Samet Fidanciogullari ◽  
Ahmet Yildiz
Keyword(s):  
Torsional Vibration ◽  
Experimental Tests ◽  
Experimental Results ◽  
Experimental Characterization ◽  
Cross Sectional ◽  
Vibration Behavior ◽  
The Masses ◽  
Theory And Experiments ◽  
Good Agreement

Abstract This paper is about the theoretical and experimental characterizations of the torsional vibration behavior of circular and rectangular cross-sectional arc springs. Firstly, the dynamic behaviors of arc springs with different cross-sectional wire profiles designed for a dual mass flywheel are modeled by mathematical formulations. After that, experimental tests are performed to verify these models and it is observed that the stiffness characterizations are in good agreement with experimental results. Lastly, the masses of two different arc springs are compared by regarding the same vibration stiffness criteria and it is demonstrated that the rectangular wire provides an arc spring with a 9.44 vol.-% lighter structure. Thus, the outcomes of this paper can be good references for the manufacturer about the numerical and experimental characterization of dual mass flywheel springs, especially for rectangular wire arc springs.

Evaluation of damage within sandwich honeycomb panels subjected to impact fatigue loading

2021 ◽  
pp. 002199832110442
Author(s):  
Ahcene Oubouzid ◽  
Boualem Keskes ◽  
Benoit Vieille
Keyword(s):  
Fatigue Loading ◽  
Damage Parameter ◽  
Honeycomb Core ◽  
Multiple Impacts ◽  
Impact Fatigue ◽  
Bending Tests ◽  
The Core ◽  
Repeated Impacts ◽  
The Impact ◽  
Good Agreement

This work was aimed at investigating damage evolution within sandwich panels consisting of aluminum skins and Nomex™ honeycomb core, with three different values of the core densities, subjected to multiple impacts. Repeated impacts at low energy were conducted using an impact fatigue machine. Bending tests were conducted to determine the residual stiffness after impacts in order to analyze the evolution of a damage parameter D. A model was therefore proposed for describing the changes in this parameter as a function of impact cycles N. After repeated impacts, the D(N) curves are characterized by an S-shaped curve. A good agreement is observed between model and experimental results, the maximum standard deviation being less than 7% for different densities. Microscopic observations of the impacted specimens were conducted in order to evaluate the crater growth (associated with permanent indentation). The influence of the number of impacts on the dimensions of the impact zone has also been evaluated. For all the core densities, the permanent indentation gradually increases as a function of impact cycles.

scholarly journals Numerical and experimental characterization of splitter blade impact on pump as turbine performance

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042199324
Author(s):  
Daniel Adu ◽  
Jianguo Du ◽  
Ransford O Darko ◽  
Eric Ofosu Antwi ◽  
Muhammad Aamir Shafique Khan
Keyword(s):  
Rotational Speed ◽  
Simulated Data ◽  
Maximum Deviation ◽  
Cfd Simulations ◽  
Flow Rates ◽  
Turbine Performance ◽  
Hydropower Dams ◽  
The Impact ◽  
Good Agreement

Several rivers and streams are available in Africa and Asian regions with great potentials not applicable for constructing large hydropower dams but feasible for small and mini hydro generation. This study strive for investigating the impact of splitter blade on pump as turbine performance considering different speed and flow rates. Two specific centrifugal pump models one with six blades without splitter and another with four blades and four splitters were used for the study. The inlet diameter and outlet diameters of both impellers were 104 mm/116 mm, and 160 mm respectively at a designed flow rate Q = 12.5 m3/h, head H = 16 m, rotational speed n = 1450 rpm and efficiency of 56%, outlet impeller width of 0.006 m, a blade outlet angle of 30° was used for the study. CFD simulations were conducted with the use of k-ε turbulence model. The influence of splitter blade position on the performance of pump as turbine in the selected specific pumps with and without splitter blades has been investigated both experimentally and numerically at three different flow rates and rotational speed. The simulated data were in good agreement with the experimental results, the maximum deviation error between the CFD and test for each model are 5.6%, 2.6%, for the head and efficiency; 7.5% and 3.6% at different flow conditions.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

The Analyses of Learning Strategies in English as a Second Language: Theoretical Classification and Measurement Test

2020 ◽  
Vol 4 (2) ◽  
pp. 118-129
Author(s):  
Asti Gumartifa ◽  
◽  
Indah Windra Dwie Agustiani
Keyword(s):  
Language Learning ◽  
Learning Outcomes ◽  
Learning Strategies ◽  
Learning Process ◽  
English Learners ◽  
English Language ◽  
Point Of View ◽  
Effective Learning ◽  
The Impact

Gaining English language learning effectively has been discussed all years long. Similarly, Learners have various troubles outcomes in the learning process. Creating a joyful and comfortable situation must be considered by learners. Thus, the implementation of effective learning strategies is certainly necessary for English learners. This descriptive study has two purposes: first, to introduce the classification and characterization of learning strategies such as; memory, cognitive, metacognitive, compensation, social, and affective strategies that are used by learners in the classroom and second, it provides some questionnaires item based on Strategy of Inventory for Language Learning (SILL) version 5.0 that can be used to examine the frequency of students’ learning strategies in the learning process. The summary of this study explains and discusses the researchers’ point of view on the impact of learning outcomes by learning strategies used. Finally, utilizing appropriate learning strategies are certainly beneficial for both teachers and learners to achieve the learning target effectively.

Dynamic model for high-speed rotors based on their experimental characterization

2017 ◽  
Vol 2 (4) ◽  
pp. 25
Author(s):  
L. A. Montoya ◽  
E. E. Rodríguez ◽  
H. J. Zúñiga ◽  
I. Mejía
Keyword(s):  
Dynamic Model ◽  
High Speed ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Experimental Characterization ◽  
Rotating Systems ◽  
Computing Performance ◽  
The Impact ◽  
Stiffness Distribution ◽  
Good Agreement

Rotating systems components such as rotors, have dynamic characteristics that are of great importance to understand because they may cause failure of turbomachinery. Therefore, it is required to study a dynamic model to predict some vibration characteristics, in this case, the natural frequencies and mode shapes (both of free vibration) of a centrifugal compressor shaft. The peculiarity of the dynamic model proposed is that using frequency and displacements values obtained experimentally, it is possible to calculate the mass and stiffness distribution of the shaft, and then use these values to estimate the theoretical modal parameters. The natural frequencies and mode shapes of the shaft were obtained with experimental modal analysis by using the impact test. The results predicted by the model are in good agreement with the experimental test. The model is also flexible with other geometries and has a great time and computing performance, which can be evaluated with respect to other commercial software in the future.

Sign in / Sign up

Export Citation Format

Share Document