scholarly journals Experimental Design and Validation of an Accelerated Random Vibration Fatigue Testing Methodology

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Yu Jiang ◽  
Gun Jin Yun ◽  
Li Zhao ◽  
Junyong Tao
Keyword(s):  
Fatigue Life ◽  
Stress Responses ◽  
Life Prediction ◽  
Random Vibration ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Fatigue Life Prediction ◽  
Power Spectral ◽  
Vibration Fatigue ◽  
Non Gaussian

Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a notched specimen structure were measured under different base random excitations. According to the measured stress responses, the structural fatigue lives corresponding to the different vibrational excitations were predicted by using the WAFO simulation technique. Second, a couple of destructive vibration fatigue tests were carried out to validate the accuracy of the WAFO fatigue life prediction method. After applying the proposed experimental and numerical simulation methods, various factors that affect the vibration fatigue life of structures were systematically studied, including root mean squares of acceleration, power spectral density, power spectral bandwidth, and kurtosis. The feasibility of WAFO for non-Gaussian vibration fatigue life prediction and the use of non-Gaussian vibration excitation for accelerated fatigue testing were experimentally verified.

Experimentally Validated Vibration Fatigue Life Prediction Model for Ball Grid Array Solder Joint

2000 ◽  
Author(s):  
T. E. Wong ◽  
F. W. Palmieri ◽  
L. A. Kachatorian
Keyword(s):  
Fatigue Life ◽  
Solder Joint ◽  
Prediction Model ◽  
Life Prediction ◽  
Random Vibration ◽  
Solder Joints ◽  
Fatigue Life Prediction ◽  
Vibration Fatigue ◽  
Joint Vibration ◽  
Life Prediction Model

Abstract A newly developed methodology is used to support test validation of ball grid array (BGA) solder joint vibration fatigue life prediction model. This model is evolved from an empirical formula of universal slopes, which is derived from high-cycle fatigue test data using a curve fitting technique over 29 different materials of metals. To develop the BGA solder joint vibration fatigue life prediction model, a test vehicles (TV), on which various sizes of BGA daisy-chained packages are soldered, is first designed, fabricated and subjected to random vibration tests with continuously monitoring the solder joint integrity. Based on the measurement results, a destructive physical analysis is then conducted to further verify the failure locations and crack paths of the solder joints. Next, a method to determine the stresses/strains of BGA solder joints resulting from exposure of the TV to random vibration environments is developed. In this method, a 3-D modeling technique is used to simulate the vibration responses of the BGA packages. Linear static and dynamic finite element analyses with MSC/NASTRAN™ computer code, combined with a volume-weighted average technique, are conducted to calculate the effective strains of the solder joints. In the calculation process, several in-house developed Fortran programs, in conjunction with the outputs obtained from MSC/NASTRAN™ static and frequency response analyses, are used to perform the required computations. Finally, a vibration fatigue life model is established with two unknown parameters, which can be determined by correlating the derived solder effective strains to the test data. This test-calibrated model is then recommended to serve as an effective tool to determine the integrity of the BGA solder joints during vibration. Selecting more study cases with various package sizes, solder ball configurations, vibration profiles to further calibrate this model is also recommended. An example of a 313-pin plastic and 304-pin ceramic BGAs is illustrated in the present study.

scholarly journals A New Multiparameter Model for Multiaxial Fatigue Life Prediction of Rubber Materials

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1194
Author(s):  
Rafael Tobajas ◽  
Daniel Elduque ◽  
Elena Ibarz ◽  
Carlos Javierre ◽  
Luis Gracia
Keyword(s):  
Fatigue Life ◽  
Life Prediction ◽  
Experimental Testing ◽  
Experimental Tests ◽  
Relevant Information ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Fatigue Life Prediction ◽  
Proposed Model ◽  
Predicted Values

Most of the mechanical components manufactured in rubber materials experience fluctuating loads, which cause material fatigue, significantly reducing their life. Different models have been used to approach this problem. However, most of them just provide life prediction only valid for each of the specific studied material and type of specimen used for the experimental testing. This work focuses on the development of a new generalized model of multiaxial fatigue for rubber materials, introducing a multiparameter variable to improve fatigue life prediction by considering simultaneously relevant information concerning stresses, strains, and strain energies. The model is verified through its correlation with several published fatigue tests for different rubber materials. The proposed model has been compared with more than 20 different parameters used in the specialized literature, calculating the value of the R2 coefficient by comparing the predicted values of every model, with the experimental ones. The obtained results show a significant improvement in the fatigue life prediction. The proposed model does not aim to be a universal and definitive approach for elastomer fatigue, but it provides a reliable general tool that can be used for processing data obtained from experimental tests carried out under different conditions.

Two time domain models for fatigue life prediction under multiaxial random vibrations

2019 ◽  
Vol 233 (13) ◽  
pp. 4707-4718 ◽  
Author(s):  
Zhengbo Luo ◽  
Huaihai Chen ◽  
Xudong He ◽  
Ronghui Zheng
Keyword(s):  
Fatigue Life ◽  
Time Domain ◽  
Life Prediction ◽  
Random Vibration ◽  
Notch Root ◽  
Critical Plane ◽  
Crack Orientation ◽  
Spectral Density Matrix ◽  
Power Spectral ◽  
Domain Models

Two time domain models for fatigue life prediction under multiaxial random vibrations are developed on the basis of the critical plane approach. Firstly, the stress power spectral density matrix of each node at the notch root of the test specimen is obtained by the random vibration analysis with finite element method, and the stress time-histories are generated from the stress power spectral density matrix by the time domain randomization approach. Then, the fatigue life of each node is predicted based on the damage on the critical plane, where the cumulative damage value is the greatest. The minimum fatigue life of all nodes at the notch root is considered as the fatigue life of the test specimen. Finally, the proposed models are validated by the multiaxial random vibration fatigue test with the 6061-T4 aluminum alloy. The results show that the predicted fatigue lives and predicted crack orientation angles are in good agreement with the experimental fatigue lives and experimentally observed crack orientation angles, respectively.

Thermomechanical Fatigue Life Prediction of 63Sn/37Pb Solder

1992 ◽  
Vol 114 (2) ◽  
pp. 145-151 ◽  
Author(s):  
Q. Guo ◽  
E. C. Cutiongco ◽  
L. M. Keer ◽  
M. E. Fine
Keyword(s):  
Fatigue Life ◽  
Plastic Strain ◽  
Life Prediction ◽  
Strain Range ◽  
Thermomechanical Fatigue ◽  
Fatigue Tests ◽  
Experimental Results ◽  
Fatigue Life Prediction ◽  
Total Strain ◽  
Isothermal Fatigue

Isothermal and thermomechanical fatigue of 63Sn/37Pb solder is studied under total strain-controlled tests. A standard definition of failure is proposed to allow inter-laboratory comparison. Based on the suggested failure criterion, load drop per cycle, the Young’s modulus and the ratio of the maximum tensile to maximum compressive stresses remain constant, and the fatigue response of the solder is stable before failure, although cyclic softening was observed from the beginning. Experimental results of isothermal fatigue tests for a total strain range from 0.3 to 3 percent show that the log-log plot of the number of cycles to failure versus the plastic strain range has a kink at the point where the elastic strain is approximately equal to the plastic strain. In this paper, it is shown how the isothermal fatigue life of near-eutectic solder at lower strain ranges can be predicted by using the experimental data of fatigue tests at high strain ranges and early stage information of a fatigue test at the strain range in question. A thermomechanical fatigue life prediction is also given based on a dislocation pile-up model. Comparison with experimental results shows a good agreement.

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