Lifetime Distribution Estimation of Boot Seals in Automotive Applications by Bayesian Method

2006 ◽  
Vol 129 (3) ◽  
pp. 275-282 ◽  
Author(s):  
Fabrice Guerin ◽  
Ridha Hambli
Keyword(s):  
Finite Element ◽  
Bayesian Method ◽  
Life Time ◽  
Automotive Applications ◽  
Fatigue Lifetime ◽  
Time Prediction ◽  
Steering Mechanism ◽  
Market Requirements ◽  
Distribution Parameters ◽  
Lifetime Testing

The constantly increasing market requirements of high quality vehicles ask for the automotive manufacturers to perform lifetime testing to verify the reliability levels of new products. A common problem is that only a small number of examples of a component of system can be tested. In the automotive applications, mechanical components subjected to cyclic loading have to be designed against fatigue. Boot seals are used to protect velocity joint and steering mechanisms in automobiles. These flexible components must accommodate the motions associated with angulation of the steering mechanism. Some regions of the boot seal are always in contact with an internal metal shaft, while other areas come into contact with the metal shaft during angulation. In addition, the boot seal may also come into contact with itself, both internally and externally. The contacting regions affect the performance and longevity of the boot seal. In this paper, the Bayesian estimation of lognormal distribution parameters (usually used to define the fatigue lifetime of rubber components) is studied to improve the accuracy of estimation in incorporating the available knowledge on the product. In particular, the finite element results and expert belief are considered as prior knowledge. For life time prediction by finite element method, a model based on Brown–Miller law was developed for the boot seal rubber-like material.

Experimental Characterization and Finite Element Modeling of Film Capacitors for Automotive Applications

2016 ◽  
Author(s):  
D. Croccolo ◽  
T. M. Brugo ◽  
M. De Agostinis ◽  
S. Fini ◽  
G. Olmi
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
High Reliability ◽  
Three Dimensional ◽  
Strain Analysis ◽  
Life Time ◽  
Element Model ◽  
Image Correlation ◽  
Thermal Loads ◽  
Mechanical Shock

As electronics keeps on its trend towards miniaturization, increased functionality and connectivity, the need for improved reliability capacitors is growing rapidly in several industrial compartments, such as automotive, medical, aerospace and military. Particularly, recent developments of the automotive compartment, mostly due to changes in standards and regulations, are challenging the capabilities of capacitors in general, and especially film capacitors. Among the required features for a modern capacitor are the following: (i) high reliability under mechanical shock, (ii) wide working temperature range, (iii) high insulation resistance, (iv) small dimensions, (v) long expected life time and (vi) high peak withstanding voltage. This work aims at analyzing the key features that characterize the mechanical response of the capacitor towards temperature changes. Firstly, all the key components of the capacitor have been characterized, in terms of strength and stiffness, as a function of temperature. These objectives have been accomplished by means of several strain analysis methods, such as strain gauges, digital image correlation (DIC) or dynamic mechanical analysis (DMA). All the materials used to manufacture the capacitor, have been characterized, at least, with respect to their Young’s modulus and Poisson’s ratio. Then, a three-dimensional finite element model of the whole capacitor has been set up using the ANSYS code. Based on all the previously collected rehological data, the numerical model allowed to simulate the response in terms of stress and strain of each of the capacitor components when a steady state thermal load is applied. Due to noticeable differences between the thermal expansion coefficients of the capacitor components, stresses and strains build up, especially at the interface between different components, when thermal loads are applied to the assembly. Therefore, the final aim of these numerical analyses is to allow the design engineer to define structural optimization strategies, aimed at reducing the mechanical stresses on the capacitor components when thermal loads are applied.

Life-time prediction for rocks under static compressive and tensile loads: a new simulation approach

2009 ◽  
Vol 4 (1) ◽  
pp. 73-78 ◽  
Author(s):  
H. Konietzky ◽  
A. Heftenberger ◽  
M. Feige
Keyword(s):  
Life Time ◽  
Simulation Approach ◽  
Time Prediction

Fatigue Crack Initiation in Solder Joints

1996 ◽  
Vol 118 (2) ◽  
pp. 41-44 ◽  
Author(s):  
Z. Zhang ◽  
Daping Yao ◽  
J. K. Shang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Lap Joints ◽  
Stress Cycle ◽  
Fatigue Lifetime ◽  
Peak Value

A backface strain technique is introduced to examine fatigue crack initiation in solder lap joints. The technique detects the fatigue crack initiation by monitoring the backface strain at the end of the overlap. Variation of the backface strain with the development of a crack was simulated by finite element method. The simulation indicated that the backface strain at the end of the overlap reached a peak value when a fatigue crack initiated. Experimental verification was carried out in 63Sn-37Pb solder joints. The backface strain was recorded as a function of stress cycle to demonstrate the applicability of this technique. Experimental results showed that fatigue crack initiation took about half of the fatigue lifetime of the solder joints.

Consideration of Parameter Scattering in Thermo-Mechanical Characterization of Advanced Packages

1999 ◽  
Vol 121 (4) ◽  
pp. 282-285 ◽  
Author(s):  
T. Winkler ◽  
A. Schubert ◽  
E. Kaulfersch ◽  
B. Michel
Keyword(s):  
Finite Element ◽  
Life Time ◽  
Electronic Packages ◽  
Element Determination ◽  
Local Material ◽  
Element Simulation ◽  
Geometrical Imperfections ◽  
Element Approach ◽  
Partial Randomness ◽  
Local Material Properties

Much progress has been made in the simulation and verification of the thermo-mechanical behavior of plastic packages. On the other hand, until now there is a lack in the consideration of the scatter or uncertainty, respectively, of certain characteristics. A comparatively large scatter of local material properties or random geometrical imperfections can often be observed within the material compounds of electronic packages. The partial randomness of certain input parameters creates uncertainties in the finite element determination of mechanical quantities which are provided for thermo-mechanical reliability optimization and life time prediction. In the following the STOFEM stochastic finite element approach based on perturbation theory is applied as a part of the finite element simulation. It is used to find out some additional effects arising from uncertainties in the modeling, slightly varying parameters or probabilistic influences, respectively. In a second part of the paper, another approach to the consideration of random variations is discussed. It is based on the randomization of initially deterministic relations.

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