Simplification of Finite Element Models for Thermal Fatigue Life Prediction of PBGA Packages

2003 ◽  
Vol 125 (3) ◽  
pp. 347-353 ◽  
Author(s):  
Hasan U. Akay ◽  
Yan Liu ◽  
Mostafa Rassaian
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Correlation Equation ◽  
Fatigue Life Prediction ◽  
Computational Time ◽  
Electronic Packages ◽  
Plastic Ball

The use of PBGA (plastic ball grid array) electronic packages has been greatly increased in the last decade due to high I/O densities offered. The fatigue life prediction for them is a relatively new task in the electronic field. PBGA packages have more complex geometry than conventional SMT (surface mount technology) packages, such as Leaded and Leadless Chip Carriers (LDCC and LLCC), in which the I/O pins are distributed along the perimeters of chip carriers and their geometries are suitable for two-dimensional (2-D) finite element (FE) simulation. This choice is not so clear in PBGAs. In this study, sectional 2-D, sliced three-dimensional (3-D), and 1/8th 3-D FE models for PBGA assemblies are compared to determine the appropriate FE models that are able to save computational time and memory while maintaining reasonable calculation accuracy. The comparisons and merits of each modeling approach are discussed. An energy-based method is used to predict the fatigue life for solder joints in PBGAs. The fatigue coefficients in the correlation equation, which were obtained previously from the analysis of traditional SMT packages, are updated for more accurate prediction. New fatigue coefficients are obtained for different modeling approaches.

TTK Chitra tilting disc heart valve model TC2: An assessment of fatigue life and durability

2017 ◽  
Vol 231 (8) ◽  
pp. 758-765 ◽  
Author(s):  
NN Subhash ◽  
Adathala Rajeev ◽  
Sreedharan Sujesh ◽  
CV Muraleedharan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Heart Valve ◽  
Life Prediction ◽  
Heart Valves ◽  
Failure Modes ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Valve Model

Average age group of heart valve replacement in India and most of the Third World countries is below 30 years. Hence, the valve for such patients need to be designed to have a service life of 50 years or more which corresponds to 2000 million cycles of operation. The purpose of this study was to assess the structural performance of the TTK Chitra tilting disc heart valve model TC2 and thereby address its durability. The TC2 model tilting disc heart valves were assessed to evaluate the risks connected with potential structural failure modes. To be more specific, the studies covered the finite element analysis–based fatigue life prediction and accelerated durability testing of the tilting disc heart valves for nine different valve sizes. First, finite element analysis–based fatigue life prediction showed that all nine valve sizes were in the infinite life region. Second, accelerated durability test showed that all nine valve sizes remained functional for 400 million cycles under experimental conditions. The study ensures the continued function of TC2 model tilting disc heart valves over duration in excess of 50 years. The results imply that the TC2 model valve designs are structurally safe, reliable and durable.

Application of Artificial Neural Network for Fatigue Life Prediction

2005 ◽  
Vol 297-300 ◽  
pp. 96-101
Author(s):  
Ishak Abdul Azid ◽  
Lee Kor Oon ◽  
Ong Kang Eu ◽  
K.N. Seetharamu ◽  
Ghulam Abdul Quadir
Keyword(s):  
Neural Network ◽  
Finite Element ◽  
Fatigue Life ◽  
Solder Joint ◽  
Finite Element Simulation ◽  
Life Prediction ◽  
Fatigue Life Prediction ◽  
Element Simulation ◽  
Parametric Studies ◽  
Solder Joint Fatigue

An extensively published and correlated solder joint fatigue life prediction methodology is incorporated by which finite element simulation results are translated into estimated cycles to failure. This study discusses the analysis methodologies as implemented in the ANSYSTM finite element simulation software tool. Finite element models are used to study the effect of temperature cycles on the solder joints of a flip chip ball grid array package. Through finite element simulation, the plastic work or the strain-energy density of the solder joints are determined. Using an established methodology, the plastic work obtained through simulation is translated into solder joint fatigue life [1]. The corresponding results for the solder joint fatigue life are used for parametric studies. Artificial Neural Network (ANN) has been used to consolidate the parametric studies.

Towards Truly Multiscale Simulation of Fatigue Processes in Metallic Structures

2009 ◽  
Author(s):  
John M. Emery ◽  
Jeffrey E. Bozek ◽  
Anthony R. Ingraffea
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Boundary Conditions ◽  
Finite Element Model ◽  
Life Prediction ◽  
Element Model ◽  
Multiscale Simulation ◽  
Fatigue Life Prediction ◽  
Length Scale ◽  
Metallic Structures

The fatigue resistance of metallic structures is inherently random due to environmental and boundary conditions, and microstructural geometry, including discontinuities, and material properties. A new methodology for fatigue life prediction is under development to account for these sources of randomness. One essential aspect of the methodology is the ability to perform truly multiscale simulations: simulations that directly link the boundary conditions on the structural length scale to the damage mechanisms of the microstructural length scale. This presentation compares and contrasts two multiscale methods suitable for fatigue life prediction. The first is a brute force method employing the widely-used multipoint constraint technique which couples a finite element model of the microstructure within the finite element model of the structural component. The second is a more subtle, modified multi-grid method which alternates analyses between the two finite element models while representing the evolving microstructural damage. Examples and comparisons are made for several geometries and preliminary validation is achieved with comparison to experimental tests conducted by the Northrop Grumman Corporation on a wing-panel structural geometry.

Application of a Multiaxial Fatigue Criterion for the Evaluation of Life of Gears of Complex Geometry

2003 ◽  
Author(s):  
Leonardo Borgianni ◽  
Paola Forte ◽  
Luigi Marchi
Keyword(s):  
Fatigue Life ◽  
Stress State ◽  
Life Prediction ◽  
Complex Geometry ◽  
Biaxial Stress ◽  
Fatigue Life Prediction ◽  
Random Loading ◽  
Complex Load ◽  
Biaxial Stress State ◽  
Principal Axes

Gears can show significant biaxial stress state at tooth root fillet, due to the way they are loaded and their particular geometry. This biaxial stress state can show a significant variability in principal axes during meshing. Moreover loads may have non predictable components that can be evaluated with the aid of recorded data from complex spectra. In these conditions, commonly adopted approaches for fatigue evaluation may be unsuitable for a reliable fatigue life prediction. This work is aimed at discussing a computer implementation of a fatigue life prediction method suitable for multiaxial stress states and constant amplitude or random loading. For random loading a counting procedure to extract cycles from complex load histories is discussed. This method, proposed by Vidal et al., is based on the r.m.s. value of a damage indicator over all the planes through the point where the fatigue life calculation is made. Miner’s rule is used for the evaluation of the overall damage. The whole fatigue life of the component is evaluated in terms of the numbers of repetitions of the loading block. FEM data are used to evaluate stresses under load. The implementation was validated using test data found in the technical literature. Examples of applications to gears are finally discussed.

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