Sources of Fatigue in Random-Vibration Durability of Surface Mount Interconnects

2009 ◽  
Author(s):  
Y. Zhou ◽  
M. Al-Bassyiouni ◽  
A. Dasgupta
Keyword(s):  
Accumulation Rate ◽  
Random Excitation ◽  
Additional Stress ◽  
Dynamic Mode ◽  
Dynamic Prediction ◽  
Element Analysis ◽  
Static Approximation ◽  
Quasi Static Approximation ◽  
Dynamic Movement ◽  
Resonant Modes

The transient response of a PBGA256 assembly to random excitation is explored with quasi-static and transient finite element analysis, as well as with experiments. The quasi-static approximation is based on the first modal contribution to the measured PWB response. The dynamic prediction for solder strain and resulting damage accumulation rate are found to be significantly larger than in the quasi-static approximation. The quasi-static model is clearly missing additional stress drivers such as the dynamic movement of the component relative to the PWB and higher resonant modes of PWB flexure. The dynamic mode of the component is verified in this paper with two accelerometers placed on the component and on the PWB. Investigation of the higher modes of the PWB is deferred to a future study.

Forced Response and Random Vibration Analysis of Printed Circuit Boards

2000 ◽  
Author(s):  
James F. Tarter
Keyword(s):  
Random Vibration ◽  
Printed Circuit Boards ◽  
Random Excitation ◽  
Forced Response ◽  
Circuit Boards ◽  
Element Analysis ◽  
Design Data ◽  
Improve Design ◽  
Printed Circuit ◽  
Contour Plots

Abstract Finite element analysis has been used in conjunction with developed algorithms to analyze forced response and random vibration response of printed circuit boards. Analytical predictions have been compared to random vibration test data for model correlation and validation of the analysis methods. The described methods provide design data for predicting deflections and G levels as a function of frequency or predicting RMS levels for random excitation. These data are utilized for initiating design changes and guiding component placement. Deflection versus frequency contributions for random excitation are analyzed to identify critical design frequencies. Forced response contour plots include effects of modal coupling, modal participation factors, and system damping. These data provide a better description of the expected operating deflection shapes man a simple mode shape. All of these methods are used to improve design integrity and ensure specification compliance prior to hardware fabrication. The analyses utilize aggregate board properties, and do not currently provide data for individual components which are installed on the board.

The role of advection in the quasi-static approximation

1994 ◽  
Vol 432 ◽  
pp. 302 ◽  
Author(s):  
Shlomi Pistinner ◽  
Giora Shaviv
Keyword(s):  
Static Approximation ◽  
Quasi Static Approximation

scholarly journals Cloaking Using the Anisotropic Multilayer Sphere

Photonics ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 52 ◽  
Author(s):  
Sidra Batool ◽  
Mehwish Nisar ◽  
Fabrizio Frezza ◽  
Fabio Mangini
Keyword(s):  
Mathematical Model ◽  
Arbitrary Number ◽  
Static Approximation ◽  
Quasi Static Approximation ◽  
Number Of Layers ◽  
Multilayer Sphere ◽  
Tangential Directions

We studied a Spherically Radially Anisotropic (SRA) multilayer sphere with an arbitrary number of layers. Within each layer permittivity components are different from each other in radial and tangential directions. Under the quasi-static approximation, we developed a more generalized mathematical model that can be used to calculate polarizability of the SRA multilayer sphere with any arbitrary number of layers. Moreover, the functionality of the SRA multilayer sphere as a cloak has been investigated. It has been shown that by choosing a suitable contrast between components of the permittivity, the SRA multilayer sphere can achieve threshold required for invisibility cloaking.

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