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  • Open Access


    A Frequency Method for Fatigue Life Estimation of Mechanical Components under Bimodal Random Stress Process

    C. Braccesi1, F. Cianetti1, G. Lori1, D. Pioli1

    Structural Durability & Health Monitoring, Vol.1, No.4, pp. 277-290, 2005, DOI:10.3970/sdhm.2005.001.277

    Abstract This paper describes an original frequency method for fatigue life estimation of mechanical components subjected to random inputs. Currently mechanical components life design under random loads is an important task of the research, due to the increasing importance of virtual simulation in opposition to the experimental tests. The frequency domain approach, in this context, seems to be able to supply reliable estimations with small computational effort. The proposed method belongs to the class of corrective coefficient to narrow-band formula methods and it has been thought for bimodal PSDs. The definition of the generalized bimodal processes and the research of the… More >

  • Open Access


    Crack Propagation-Based Fatigue Evaluation of Rib-to-Deck Welded Joints of Orthotropic Steel Bridge Deck by Using Schwartz-Neuman Alternating Method

    Yabin Yang, Guangyu Shi*

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.21, No.2, pp. 35-35, 2019, DOI:10.32604/icces.2019.05623

    Abstract The efficient and high performance orthotropic steel decks have been widely used in long span bridges over the world. The initial defects at welded joints of orthotropic steel bridge decks will undergo fatigue failure under the action of live load of moving vehicles on the bridge decks. And the fatigue cracks at the rib-to-deck welded joints are the most dangerous cracks for the orthotropic steel bridge decks. Therefore, the fatigue life evaluation of the rib-to-deck welded joints is very important for the safety of orthotropic steel bridge decks. This paper presents a crack propagation-based model for the fatigue life prediction… More >

  • Open Access


    An Effective Thermal-mechanical Modeling Methodology for Large-scale Area Array Typed Packages

    H. C. Cheng1, C. Y. Yu2, W. H. Chen3

    CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 1-18, 2005, DOI:10.3970/cmes.2005.007.001

    Abstract In this study, a simple but effective solution methodology that integrates a modified global/local finite element (GLFE) modeling technique and a two-staged constitutive modeling strategy is presented for the thermal-mechanical modeling of solder joints in an area array typed electronic package for characterizing the associated solder joint fatigue life under the JEDEC temperature cycling specification. The effectiveness and applicability of the proposed technique are demonstrated through two case studies, each of which is associated with an area array typed test vehicle. The geometry profile of solder joints in the test vehicle is determined by the Surface Evolver [Brakke (1996)]. For… More >

  • Open Access


    The Role of Bamboo Nanoparticles in Kenaf Fiber Reinforced Unsaturated Polyester Composites

    Enih Rosamah1, Abdul Khalil H.P.S.2*, S.W. Yap2, Chaturbhuj K. Saurabh2, Paridah M. Tahir3, Rudi Dungani4, Abdulwahab F. Owolabi2

    Journal of Renewable Materials, Vol.6, No.1, pp. 75-86, 2018, DOI:10.7569/JRM.2017.634152

    Abstract In this study, bamboo nanoparticles in concentration ranges from 0–5% were incorporated along with woven/nonwoven kenaf fiber mat into unsaturated polyester and the developed composites were further characterized. Bamboo chips were subjected to ball milling process for the synthesis of nanoparticles with a particle size of 52.92 nm. The effect that the incorporation of nanoparticles had on various properties of reinforced composites was further observed. Due to the high surface area of nanoparticles, incorporation of 3% of nanofillers contributed towards strong bonding and better wettability with matrix, thus resulting in excellent mechanical properties and thermal characteristics in reinforced unsaturated polyester… More >

  • Open Access


    Load Test and Fatigue Life Evaluation for Welded Details in Taizhou Yangtze River Bridge

    Meiling Zhuang1,2, Changqing Miao1,2,*, Rongfeng Chen1,2

    Structural Durability & Health Monitoring, Vol.13, No.2, pp. 205-225, 2019, DOI:10.32604/sdhm.2019.04654

    Abstract To study the fatigue performance of welded details in the orthotropic steel decks, the steel box girder for Taizhou Yangtze River Bridge is taken as the research object. Based on the field monitoring data obtained from the load test, the stress response test of the orthotropic steel box girder under wheel loads is performed and the correctness of the vehicle test data obtained from the field monitoring data also have been verified by the numerical results of the finite element model. Based on the Miner linear cumulative damage theory, the S-N curve of the Eurocode3 specification is referenced, and the… More >

  • Open Access


    Dispersion of One Dimensional Stochastic Waves in Continuous Random Media

    C. Du1, H. Bai2, J. Qu3, X. Su1,4

    CMES-Computer Modeling in Engineering & Sciences, Vol.61, No.3, pp. 223-248, 2010, DOI:10.3970/cmes.2010.061.223

    Abstract Second, or higher, order harmonics have great potential in fatigue life prediction. In this study, the dispersion properties of waves propagating in the nonlinear random media are investigated. An one dimensional nonlinear model based on the nonlinear Hikata stress-strain relation is used. We applied perturbation method, the Liouville transformation and the smoothing approximation method to solve the one dimensional nonlinear stochastic wave equation. We show easily that the dispersion equations for all higher order terms will be the same with the corresponding linear random medium by perturbation method. The linear stochastic equation with two random coefficients is greatly simplified to… More >

  • Open Access


    Study of the Underfill Effect on the Thermal Fatigue Life of WLCSP-Experiments and Finite Element Simulations

    Shaw-Jyh Shin1, Chen-Hung Huang2, Y.C. Shiah3

    CMES-Computer Modeling in Engineering & Sciences, Vol.40, No.1, pp. 83-104, 2009, DOI:10.3970/cmes.2009.040.083

    Abstract Owing to the CTE (Coefficient of Thermal Expansion) mismatch among solder joints, IC (Integrated Circuit) chip, and PCB (Printed Circuit Board), electronic packages shall experience fatigue failure after going though a period of thermal cycling. As a major means to enhance the reliability of the solder joints, underfill is often dispensed to fill the gap between the die and the substrate. This study aims at investigating how the underfill may affect the thermal fatigue life of WLCSP (Wafer Level Chip Scale Package) by means of FEA (finite element analysis). In this study, the thermal fatigue life of the WLCSP was… More >

  • Open Access


    Fracture Mechanics Approach to Estimate Fatigue Lives of Welded Lap-Shear Specimens

    1Poh-Sang Lam2, Jwo Pan3

    CMC-Computers, Materials & Continua, Vol.46, No.1, pp. 1-16, 2015, DOI:10.3970/cmc.2015.046.001

    Abstract A full range of stress intensity factor solutions for a kinked crack with finite length is developed as a function of weld width and the sheet thickness. When used with the main crack solutions (global stress intensity factors) in terms of the applied load and the specimen geometric parameters, the fatigue lives of the kinked crack can be estimated for the laser-welded lap-shear specimens. The predicted curve for the load range-fatigue life passes through the cluster of experimental data and is in good agreement. A classical solution associated with an infinitesimal kink is also employed. However, its life prediction tends… More >

  • Open Access


    Thermal-Cyclic Fatigue Life Analysis and Reliability Estimation of a FCCSP based on Probabilistic Design Concept

    Yao Hsu1, Chih-Yen Su2, Wen-Fang Wu3,4

    CMC-Computers, Materials & Continua, Vol.36, No.2, pp. 155-176, 2013, DOI:10.3970/cmc.2013.036.155

    Abstract To study the fatigue reliability of a flip-chip chip scale package (FCCSP) subject to thermal cyclic loading, a Monte Carlo simulation-based parametric study is carried out in the present study. A refined procedure as compared with the recently released Probabilistic Design System (PDS) of ANSYS is proposed and employed in particular. The thermal-cyclic fatigue life of the package is discussed in detail since it is related directly to the reliability of the package. In consideration of the analytical procedure as well as real manufacturing processes, a few geometric dimensions and material properties of the package are assumed random. The empirical… More >

  • Open Access


    Multiscale Fatigue Life Prediction for Composite Panels

    Brett A. Bednarcyk1, Phillip W. Yarrington2, Steven M. Arnold3

    CMC-Computers, Materials & Continua, Vol.35, No.3, pp. 229-254, 2013, DOI:10.3970/cmc.2013.035.229

    Abstract Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer’s coupling with NASA’s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated.… More >

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