Vibration Analysis and Optimization of Sandwiched Beam Structure Using Higher Order Variation of Core Layer Displacement

2012 ◽  
Author(s):  
Jasrobin Singh Grewal ◽  
Ramin Sedaghati ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Linear Model ◽  
Linear Models ◽  
Core Layer ◽  
Higher Order ◽  
Order Model ◽  
Various Boundary Conditions ◽  
The Core ◽  
Parametric Studies ◽  
Beam Type ◽  
Core Thickness

Vibration characteristic of a sandwiched beam type structure is analyzed using the finite element method based on a higher order model for displacement field in the core layer of the structure. Results of the higher order and linear models were compared with those of experimental ones reported in literature and shown that higher order model provides more accurate results than the linear model. The parametric studies for the developed model are presented to indicate the effect of the core thickness on the loss factor and the natural frequencies, and the results are compared with those obtained for the linear model. Finally, using the higher order model, an optimization problem is formulated to find the optimal distribution and the number of partial treatments in order to achieve highest damping value in the sandwiched beam with various boundary conditions.

A Theoretical Examination of Mems Microactuator Responses with an Emphasis on Materials and Fabrication

1994 ◽  
Vol 360 ◽  
Author(s):  
D.E. Glumac ◽  
T.G. Cooney ◽  
L.F. Francis ◽  
W.P. Robbins
Keyword(s):  
Material Properties ◽  
Elastic Moduli ◽  
Beam Theory ◽  
Core Layer ◽  
Metal Electrode ◽  
Force Output ◽  
Free Standing ◽  
Element Analysis ◽  
The Core ◽  
Core Thickness

AbstractA free standing cantilever beam consisting of a support structural material (polysilicon/silicon nitride), a piezoelectric PZT ceramic layer, and metal electrode layers has been analyzed. Beam theory and finite element analysis were used to model the electric field induced deflections of this structure, and provided information as to how material choices influenced actuator function. Both support material and PZT thicknesses varied from 0-1.0 gim, and bulk piezoelectric coefficients and elastic moduli were assumed. The beam theory uses known (or assumed) material properties to predict actuator responses. Conversely, if device responses can be measured, material properties may be inferred from the theory. For a PZT thickness of 0.3 μm, a core layer thickness of 0.13 μm was found to maximize displacement. Also, the force output was found to be more dependent on the core thickness than that of the PZT. This information can then be used to predict the response of a more complex microactuator.

Optimal Structural Design of Multi Chip Package to Reduce the Failure in Substrate

2005 ◽  
Vol 297-300 ◽  
pp. 912-917 ◽  
Author(s):  
Dong Kil Shin ◽  
Seung Woo Kim ◽  
Shin Kim ◽  
Seok Won Lee ◽  
Hee Kook Choi
Keyword(s):  
Numerical Analysis ◽  
Structural Design ◽  
Thermal Loading ◽  
Three Dimensional ◽  
Chip Thickness ◽  
Core Layer ◽  
Component Level ◽  
The Core ◽  
Out Of Plane ◽  
Core Thickness

In this study, epoxy molded multi chip package was investigated and a highly reliable structure against failure of copper trace on PCB substrate was proposed. Function failure caused by the pattern crack during component level thermal cycle test was considered. In-plane and out-of-plane movements of package during thermal loading were measured by moiré interferometry and shadow moiré. Measured data were compared with numerical analysis results. Two dimensional and three dimensional numerical analysis were performed considering visco-elastic material properties. Tensile stress in the core layer was analyzed quantitatively and qualitatively. Analysis showed that the reliability of pattern crack could be improved by decreasing the chip thickness and increasing the core thickness, and that the material property of die adhesive was important.

scholarly journals Numerical Analysis of Sandwich Composite Deep Submarine Pressure Hull Considering Failure Criteria

2019 ◽  
Vol 7 (10) ◽  
pp. 377 ◽  
Author(s):  
Mahmoud Helal ◽  
Huinan Huang ◽  
Defu Wang ◽  
Elsayed Fathallah
Keyword(s):  
Numerical Analysis ◽  
Core Layer ◽  
Failure Criteria ◽  
Control Surface ◽  
Sandwich Composite ◽  
Minor Role ◽  
Analysis And Design ◽  
The Core ◽  
Hull Design ◽  
Core Thickness

The pressure hull is the primary element of submarine, which withstands diving pressure and provides essential capacity for electronic systems and buoyancy. This study presents a numerical analysis and design optimization of sandwich composite deep submarine pressure hull using finite element modeling technique. This study aims to minimize buoyancy factor and maximize deck area and buckling strength factors. The collapse depth is taken as a base in the pressure hull design. The pressure hull has been analyzed using two composite materials, T700/Epoxy and B(4)5505/Epoxy, to form the upper and lower faces of the sandwich composite deep submarine pressure hull. The laminated control surface is optimized for the first ply failure index (FI) considering both Tsai–Wu and maximum stress failure criteria. The results obtained emphasize an important fact that the presence of core layer in sandwich composite pressure hull is not always more efficient. The use of sandwich in the design of composite deep submarine pressure hull at extreme depths is not a safe option. Additionally, the core thickness plays a minor role in the design of composite deep submarine pressure hull. The outcome of an optimization at extreme depths illustrates that the upper and lower faces become thicker and the core thickness becomes thinner. However, at shallow-to-moderate depths, it is recommended to use sandwich composite with a thick core to resist the shell buckling of composite submarine pressure hull.

Testing a Higher-Order Model of Psychological Resilience in Recruits

2010 ◽  
Author(s):  
Donald R. McCreary ◽  
Jennifer E. C. Lee ◽  
Kerry A. Sudom
Keyword(s):  
Higher Order ◽  
Psychological Resilience ◽  
Order Model

scholarly journals Analysis of a Linear Model for Non-Synchronous Vibrations Near Stall

2021 ◽  
Vol 6 (3) ◽  
pp. 26
Author(s):  
Christoph Brandstetter ◽  
Sina Stapelfeldt
Keyword(s):  
Linear Model ◽  
Linear Models ◽  
Structural Vibration ◽  
Experimental Investigations ◽  
Vibration Modes ◽  
Critical Problem ◽  
Safety Critical ◽  
Unstable Vibration ◽  
Aero Engines ◽  
Lock In

Non-synchronous vibrations arising near the stall boundary of compressors are a recurring and potentially safety-critical problem in modern aero-engines. Recent numerical and experimental investigations have shown that these vibrations are caused by the lock-in of circumferentially convected aerodynamic disturbances and structural vibration modes, and that it is possible to predict unstable vibration modes using coupled linear models. This paper aims to further investigate non-synchronous vibrations by casting a reduced model for NSV in the frequency domain and analysing stability for a range of parameters. It is shown how, and why, under certain conditions linear models are able to capture a phenomenon, which has traditionally been associated with aerodynamic non-linearities. The formulation clearly highlights the differences between convective non-synchronous vibrations and flutter and identifies the modifications necessary to make quantitative predictions.

Development of a higher-order model for a roll simulator

2014 ◽  
Vol 66 (1) ◽  
pp. 69
Author(s):  
Scott B. Zagorski ◽  
Dennis A. Guenther ◽  
Gary J. Heydinger
Keyword(s):  
Higher Order ◽  
Order Model
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