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  • Open Access


    Influence and Enhancement of Damping Properties of Wire Rope Isolators for Naval Applications

    Claude Prost, Bruno Abdelnour

    Sound & Vibration, Vol.52, No.2, pp. 7-10, 2018, DOI:10.32604/sv.2018.03641

    Abstract Wire Rope Isolators (WRI) are well known and used for the protection of sensitive equipment against non-contact underwater explosions (UNDEX) on board Naval Ships, amongst others, which are extremely destructive and can comple`tely impair the ship’s combat capability.
    Traditional WRI exhibit a number of definite advantages, such as large deflection capability, modularity and insensitivity to aggressive environment when proper materials are used. However, their inherent nonlinearity does not always provide the best solution in terms of shock attenuation. (Stiffening tension characteristics)
    Fortunately, there are ways to overcome this problem, namely increasing their damping and/ or changing their aspect ratio. It… More >

  • Open Access


    Control Alternatives for Damping-Off in Tomato Seedling Production

    A. C. Michel-Aceves1, J. F. Díaz-Nájera1, R. Ariza-Flores2, M. A. Otero-Sánchez1, R. Escobar-Martínez1 and C. H. Avendaño-Arrazate3,*

    Phyton-International Journal of Experimental Botany, Vol.88, No.3, pp. 325-333, 2019, DOI:10.32604/phyton.2019.06777

    Abstract In two tomato genotypes, we assessed control alternatives for damping-off with combinations of chemical fungicides and native/commercial strains of biological agents. Forty treatments consisting of 19 levels of mixing products, chemical fungicides, native strains and commercial products from biological control agents, and untreated treatment were used onto Ramsés and Toro hybrids. They were distributed on an incomplete block design in divided plots arrangement, where genotypes constitute the larger ones and the 8-repetition mixed products, the smaller ones. Putting 180 mL of fungal complexes, made of spores and mycellium Fusarium-solani (2 × 106 UFC), Rhizoctonia-solani (1 × 106 UFC), Phytophthora-capsici (1… More >

  • Open Access


    Interphase Effect on Damping in Fiber Reinforced Composites

    Pramod Kumar1, Rakesh Chandra1, S.P. Singh2

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.4, No.2, pp. 67-72, 2007, DOI:10.3970/icces.2007.004.067

    Abstract Polymers composite are modeled as fiber, interphase and matrix. Interphase properties are very crucial for bonding between fiber and matrix. Interphase can be strong and weak depending upon its properties. Damping of composite material depends on interphase properties and required damping can be obtained by varying the properties of interphase. In this paper three phase mathematical model has been proposed for the evaluation of damping incorporating the effect of fiber packing. Effect of interphase has been analysed for the longitudinal loss factor, transverse loss factor, transverse shear loss factor and longitudinal shear loss factor. Results obtained by modeling fiber reinforced… More >

  • Open Access


    Effect of Stacking Sequences on the Mechanical and Damping Properties of Flax Glass Fiber Hybrid

    Khouloud Cheour1,*, Mustapha Assarar1, Daniel Scida1, Rezak Ayad1, Xiaolu Gong2

    Journal of Renewable Materials, Vol.7, No.9, pp. 877-889, 2019, DOI:10.32604/jrm.2019.06826

    Abstract The aim of this study is to show the interest of the mechanical and dynamical properties of glass-flax hybrid composites. Therefore, various staking sequences of glass-flax hybrid composites were manufactured and tested in free vibrations. The damping coefficients were identified by fitting the experimental responses of free-free bending vibrations. The obtained results show that the staking sequences and the position of flax fiber layers in the hybrid composites changed the properties, so a classification of different stacking sequences was established. In fact, the hybrid laminate made of two glass external layers placed on both sides of four flax layers is… More >

  • Open Access


    Effect of Recycling Cycles on the Mechanical and Damping Properties of Short Alfa Fibre Reinforced Polypropylene Composite

    Fatima Ezzahra El Abbassi1,*, Mustapha Assarar2, Rezak Ayad2, Hamid Sabhi2, Stephane Buet2, Nouzha Lamdouar3

    Journal of Renewable Materials, Vol.7, No.3, pp. 253-267, 2019, DOI:10.32604/jrm.2019.01759

    Abstract This paper aims at studying the effect of recycling on the static and dynamic properties of short alfa fibre reinforced polypropylene. For this purpose, alfa fibres reinforced composites were elaborated by an injection moulding process and were subjected to different mechanical recycling cycles. Then, non-recycled and recycled materials were subjected to static tests and Dynamic Mechanical Analysis (DMA) to evaluate the effect of recycling on their behaviour. Besides, the effects of alkali and salt water treatments on the static and dynamic properties of the alfa composite were also investigated. The obtained results show that tensile and flexural properties of alfa… More >

  • Open Access


    Modeling and Simulation of Dynamic Unloading of Prestressed Rockmass

    Liang Wu1, Xiaorui Xiang1, Yang Chen1, Karrech Ali2,*, Junru Zhou1,*, Ming Chen3

    CMES-Computer Modeling in Engineering & Sciences, Vol.120, No.2, pp. 421-443, 2019, DOI:10.32604/cmes.2019.05218

    Abstract During the excavation of deep rock, a sudden change in boundary conditions will cause the in-situ stress on the excavation surface to release instantaneously. This disturbance propagates in the form of an unloading stress wave, which will enlarge the damage field of surrounding rock. In this paper, the dynamic unloading problem of the in-situ stress in deep rock excavation is studied using theoretical, numerical, and experimental methods. First, the dynamic unloading process of rock is analyzed through adopting the wave equation, and the equivalent viscous damping coefficient of the material is taken into consideration. Calculations show that there is significant… More >

  • Open Access


    Large Deformation Hyper-Elastic Modeling for Nonlinear Dynamic Analysis of Two Dimensional Functionally Graded Domains Using the Meshless Local Petrov-Galerkin (MLPG) Method

    Mohammad Hossein Ghadiri Rad1, Farzad Shahabian1,2, Seyed Mahmoud Hosseini3

    CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.3, pp. 135-157, 2015, DOI:10.3970/cmes.2015.108.135

    Abstract A meshless method based on the local Petrov-Galerkin approach is developed for elasto-dynamic analysis of geometrically nonlinear two dimensional (2D) problems in hyper-elastic functionally graded materials. The radial point interpolation method (RPIM) is utilized to build the shape functions and the Heaviside step function is used as the test function. The mechanical properties of functionally graded material are considered to continuously vary in a certain direction and are simulated using a nonlinear power function in volume fraction form. Considering the large deformations, it is assumed that the domain be made of large deformable neo-Hookean hyperelastic materials. Rayleigh damping is employed… More >

  • Open Access


    A Spring-Damping Regularization and a Novel Lie-Group Integration Method for Nonlinear Inverse Cauchy Problems

    Chein-Shan Liu1, Chung-Lun Kuo2

    CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.1, pp. 57-80, 2011, DOI:10.3970/cmes.2011.077.057

    Abstract In this paper, the solutions of inverse Cauchy problems for quasi-linear elliptic equations are resorted to an unusual mixed group-preserving scheme (MGPS). The bottom of a finite rectangle is imposed by overspecified boundary data, and we seek unknown data on the top side. The spring-damping regularization method (SDRM) is introduced by converting the governing equation into a new one, which includes a spring term and a damping term. The SDRM can further stabilize the inverse Cauchy problems, such that we can apply a direct numerical integration method to solve them by using the MGPS. Several numerical examples are examined to… More >

  • Open Access


    Equivalent One-Dimensional Spring-Dashpot System Representing Impedance Functions of Structural Systems with Non-Classical Damping

    Masato Saitoh1

    CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.3, pp. 211-238, 2010, DOI:10.3970/cmes.2010.067.211

    Abstract This paper describes the transformation of impedance functions in general structural systems with non-classical damping into a one-dimensional spring-dashpot system (1DSD). A transformation procedure based on complex modal analysis is proposed, where the impedance function is transformed into a 1DSD comprising units arranged in series. Each unit is a parallel system composed of a spring, a dashpot, and a unit having a spring and a dashpot arranged in series. Three application examples are presented to verify the applicability of the proposed procedure and the accuracy of the 1DSDs. The results indicate that the 1DSDs accurately simulate the impedance functions for… More >

  • Open Access


    Constitutive Contact Laws in Structural Dynamics

    K.Willner 1

    CMES-Computer Modeling in Engineering & Sciences, Vol.48, No.3, pp. 303-336, 2009, DOI:10.3970/cmes.2009.048.303

    Abstract The dynamic behavior of structures with joints is strongly influenced by the constitutive behavior within the contact areas. In this paper the influence of an elaborate constitutive contact model based on a rough surface model is investigated. The contact model is able to describe several effects like pressure dependent contact stiffness in normal and tangential direction as well as microslip effects. The corresponding constitutive contact laws are implemented in a finite element code. Numerical simulations are compared to experimental results of a clamped double-beam experiment. More >

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