Characterization of the Dynamical Response of a Micromachined G-Sensor to Mechanical Shock Loading

2007 ◽  
Author(s):  
Daniel E. Jordy ◽  
Mohammad I. Younis
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Squeeze Film ◽  
Dynamical Response ◽  
Mems Devices ◽  
Damping Coefficients ◽  
Squeeze Film Damping ◽  
Out Of Plane ◽  
Gap Width

Squeeze film damping has a significant effect on the dynamic response of MEMS devices that employ perforated microstructures with large planar areas and small gap widths separating them from the substrate. Perforations can alter the effect of squeeze film damping by allowing the gas underneath the device to easily escape, thereby lowering the damping. By decreasing the size of the holes, the damping increases and the squeeze film damping effect increases. This can be used to minimize the out-of-plane motion of the microstructures toward the substrate, thereby minimizing the possibility of contact and stiction. This paper aims to explore the use of the squeeze-film damping phenomenon as a way to mitigate shock and minimize the possibility of stiction and failure in this class of MEMS devices. As a case study, we consider a G-sensor, which is a sort of a threshold accelerometer, employed in an arming and fusing chip. We study the effect of changing the size of the perforation holes and the gap width separating the microstructure from the substrate. We use a multi-physics finite-element model built using the software ANSYS. First, a modal analysis is conducted to calculate the out-of-plane natural frequency of the G-sensor. Then, a squeeze-film damping finite-element model, for both the air underneath the structure and the flow of the air through the perforations, is developed and utilized to estimate the damping coefficients for several hole sizes. Results are shown for various models of squeeze-film damping assuming no holes, large holes, and assuming a finite pressure drop across the holes, which is the most accurate way of modeling. The extracted damping coefficients are then used in a transient structural-shock analysis. Finally, the transient shock analysis is used to determine the shock loads that induce contacts between the G-sensor and the underlying substrate. It is found that the threshold of shock to contact the substrate has increased significantly when decreasing the holes size or the gap width, which is very promising to help mitigate stiction in this class of devices, thereby improving their reliability.

Characterization of the Dynamical Response of a Micromachined G-Sensor to Mechanical Shock Loading

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Daniel Jordy ◽  
Mohammad I. Younis
Keyword(s):  
Element Model ◽  
Plane Motion ◽  
Squeeze Film ◽  
Dynamical Response ◽  
Mechanical Shock ◽  
Mems Devices ◽  
Squeeze Film Damping ◽  
Out Of Plane ◽  
Gap Width

Squeeze film damping has a significant effect on the dynamic response of microelectromechanical system (MEMS) devices that employ perforated microstructures with large planar areas and small gap widths separating them from the substrate. Perforations can alter the effect of squeeze film damping by allowing the gas underneath the device to easily escape, thereby lowering damping. By decreasing the size of the holes, damping increases and the squeeze film damping effect increases. This can be used to minimize the out-of-plane motion of the microstructures toward the substrate, thereby minimizing the possibility of contact and stiction. This paper aims to explore the use of the squeeze film damping phenomenon as a way to mitigate shock and minimize the possibility of stiction and failure in this class of MEMS devices. As a case study, the performance of a G-sensor (threshold accelerometer) employed in an arming and fusing chip is investigated. The effect of changing the size of the perforation holes and the gap width separating the microstructure from the substrate are studied. A multiphysics finite-element model built using the software ANSYS is utilized for the fluidic and transient structural analysis. A squeeze film damping model, for both the air underneath the structure and the flow of the air through the perforations, is developed. Results are shown for various models of squeeze film damping assuming no holes, large holes, and assuming a finite pressure drop across the holes, which is the most accurate way of modeling. It is found that the threshold of shock that causes the G-sensor to contact the substrate has increased significantly when decreasing the holes size or the gap width, which is very promising to help mitigate stiction in this class of devices, thereby improving their reliability.

Dynamic Finite Element Modeling of Electrostatically Actuated Micro Structures Considering Squeeze Film Damping Effect

2006 ◽  
Author(s):  
M. T. Ahmadian ◽  
Hoseinali Borhan ◽  
M. Moghimi Zand
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Dynamic Models ◽  
Dynamic Equilibrium ◽  
Element Model ◽  
Nonlinear Finite Element ◽  
Squeeze Film ◽  
Solution Technique ◽  
Squeeze Film Damping ◽  
Nonlinear Finite Element Model

Developing a transient fully-meshed model of coupled-domain microsystems is of paramount importance not only for accurate simulation and design but also for creating more accurate low-order or macro dynamic models. So in this paper, a complete nonlinear finite element model for coupled-domain MEMS devices considering electrostatic and squeeze film effects is presented. For this purpose, we use the Galerkin weighted-residual technique for developing the finite element model that capture the original microsystem's nonlinear behaviors, such as the structural dynamics, the squeeze-film damping, the electrostatic actuation and the geometric nonlinearity caused by inherent residual stresses. In addition, using the Newmark's nonlinear solution, technique, the extracted dynamic equilibrium equations are discretised and simulated. The system dynamic behavior is successfully modeled by using the developed nonlinear finite element model and finally some simulated results of electrostatic microactuator behaviors are verified with experimental findings and are in very good agreement.

A Thermal Model for Ultrasonic Welding of Thermoplastics

2007 ◽  
Author(s):  
S.-F. Ling ◽  
X. Li ◽  
Z. Sun
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Equivalent Circuit Model ◽  
Welding Process ◽  
Element Model ◽  
Ultrasonic Welding ◽  
Joint Interface ◽  
Mems Devices ◽  
Transient Heating ◽  
Temperature Distributions

Ultrasonic welding is one of the most popular techniques for joining thermoplastics and plays an important role in MEMS applications such as fabrication and packaging of MEMS devices. In this paper, an attempt was made to further understand the heating mechanism during ultrasonic welding. Firstly, the equation governing heat generation was derived assuming adiabatic heating. A thermal equivalent circuit model was also developed to describe the heat transfer process from the joint interface into the surroundings, and the governing equation of temperature distribution in the welding sample was deduced. Finite element method was then engaged to solve these equations to reveal the transient heating behaviour. Lastly, temperatures of the joint interface and the point adjacent to the joint were measured. The temperatures of the point adjacent to the joint calculated from finite element model are matched well with the experimental results. Based on the correlation, the temperature distributions of welding samples can be derived from the finite element model. Since the new developed model can be used to obtain the dynamic temperature distributions of welding samples during ultrasonic welding, the model provides an effective way for detailed understanding of the thermal behaviours and monitoring of the ultrasonic welding process.

Forming limit diagrams by including the M–K model in finite element simulation considering the effect of bending

2016 ◽  
Vol 232 (8) ◽  
pp. 625-636 ◽  
Author(s):  
Mostafa Habibi ◽  
Ramin Hashemi ◽  
Ahmad Ghazanfari ◽  
Reza Naghdabadi ◽  
Ahmad Assempour
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Metal Forming ◽  
Forming Limit Diagram ◽  
Element Model ◽  
Forming Limit ◽  
Finite Element Models ◽  
Element Simulation ◽  
Simple Tension ◽  
Out Of Plane

Forming limit diagram is often used as a criterion to predict necking initiation in sheet metal forming processes. In this study, the forming limit diagram was obtained through the inclusion of the Marciniak–Kaczynski model in the Nakazima out-of-plane test finite element model and also a flat model. The effect of bending on the forming limit diagram was investigated numerically and experimentally. Data required for this simulation were determined through a simple tension test in three directions. After comparing the results of the flat and Nakazima finite element models with the experimental results, the forming limit diagram computed by the Nakazima finite element model was more convenient with less than 10% at the lower level of the experimental forming limit diagram.

scholarly journals Vibration Control of an Unbalanced Single-Side Cantilevered Rotor System with a Novel Integral Squeeze Film Bearing Damper

2019 ◽  
Vol 9 (20) ◽  
pp. 4371 ◽  
Author(s):  
Yipeng Zhang ◽  
Lidong He ◽  
Jianjiang Yang ◽  
Fangteng Wan ◽  
Jinji Gao
Keyword(s):  
Finite Element ◽  
Energy Distribution ◽  
Finite Element Model ◽  
Vibration Control ◽  
Element Model ◽  
Rotor System ◽  
Squeeze Film ◽  
Single Side ◽  
The Stability ◽  
Stability Energy

In this paper, vibration control of an unbalanced single-side cantilevered rotor system using a novel integral squeeze film bearing damper in terms of stability, energy distribution, and vibration control is analyzed. A finite element model of such a system with an integral squeeze film bearing damper (ISFBD) is developed. The stability, energy distribution, and vibration control of the unbalanced single-side cantilevered rotor system are calculated and analyzed based on the finite element model. The stiffness of the integral squeeze film bearing damper is designed using theoretical calculation and finite element model (FEM) simulation. The influence of installation position and quantity of integral squeeze film bearing dampers on the vibration control of the unbalanced cantilevered rotor system is discussed. An experimental platform is developed to validate the vibration control effect. The results show that the installation position and quantity of the integral squeeze film bearing dampers have different effects on the stability, energy distribution, and vibration control of the unbalanced cantilevered rotor system. When ISFBDs are installed at both bearing housings, the vibration control is best, and the vibration components of the time and frequency domains have good vibration control effects in four working conditions.

Riveted Hull Joint Design in RMS Titanic and Other Pre—World War I Ships

2003 ◽  
Vol 40 (02) ◽  
pp. 82-92
Author(s):  
Richard Woytowich
Keyword(s):  
Finite Element ◽  
World War I ◽  
Finite Element Model ◽  
Plate Thickness ◽  
Element Model ◽  
World War ◽  
Joint Construction ◽  
Riveted Joints ◽  
Riveted Joint ◽  
Out Of Plane

Beginning with an overview of riveted joint construction, this paper shows that the efficiency of riveted joints in pre-World War I ships decreased as plate thickness increased. In the case of the RMS Titanic, some of the joints involved in the iceberg impact were only about 27% as strong as the plates they connected. A finite element model is used to show how such a joint would respond to the sort of out-of-plane load that the iceberg would have applied. For one possible load configuration, the joint failure is recreated. Finally, although Titanic and her sisters were not built to class, the design of the riveted joints is examined in the context of relevant Lloyd's Register of Shipping Rules.

Out-of-Plane Stability Analysis of U-Section Pin-End Steel Arch

2013 ◽  
Vol 351-352 ◽  
pp. 169-173
Author(s):  
Kuan Tang Xi ◽  
Jin Li ◽  
Tie Gang Zhou ◽  
Qing Xing Xu
Keyword(s):  
Finite Element ◽  
Stability Analysis ◽  
Finite Element Model ◽  
Element Model ◽  
Load Models ◽  
Out Of Plane ◽  
Radial Loading ◽  
Better Than

Two kinds of finite element model which can reflect the effects of different loading positions were constructed with Beam 188 and Shell 181. Effects of different restraints, load models and rise-span ratios on out-of-plane buckling were studied by comparing results of fixed arches with that of pin-end arches under three loading models. It is conservative to design by employing results of radial loading. As for out-of-plane stability, pin-end arches are better than fixed arches when rise-span ratio is big. Compared with U-section pin-end circular arches with diaphragm, those with batten plates have batter out-of-plane stability, and they are more economical and easier to construct.

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