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  • 1
    Electronic Resource
    Electronic Resource
    The Study of Numerical Stability in the SPH Method (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 839-844 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, the numerical stability of the SPH method under both tension andcompression conditions are discussed by using one dimensional impact models. The artificialviscosity and the conservation smoothed approach are tried to suppress both tension and compressioninstability. The result clearly shows that the occurrence possibility of tension instability is much largerthan the compression case. The comparison of the controlling techniques of the artificial viscous andconservation smoothed approach shows that the artificial coefficients are independent on thenumerical instability but can reduce some perturbation, while the conservation smoothed approachdoes well for both tension and compression cases. Considering the tension instability directly , asimple method of inserting particles to avoid the numerical instability is introduced
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.839.pdf
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  • 2
    Electronic Resource
    Electronic Resource
    The Numerical Simulation of a Bird-Impact on an Aircraft Windshield by Using the SPH Method (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 851-856 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: This paper is focused on the development of an effective numerical method to simulatebird-impact aircraft windshield events. A new Smooth Particle Hydrodynamics (SPH) which hasbeen incorporated as a solver option into the explicit finite element program PAM-CRASH wasused to model the bird. The deformation between the numerical results and the experimental resultsis in good agreement. Simulation results of a bird-impact process indicated that the SPH bird modelis more suitable to model the break-up of the bird into particles. Failure of the windshield in theexperiment was simulated, and the good agreement between the numerical and experiment indicatesthat the failure model established in the present paper is reasonable. Finally, the energy changes ofthe bird and the windshield were calculated
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.851.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Improvement of Unstructured Quadrilateral Mesh Quality for Multigrid Analysis (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 833-838 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Due to more complex and severe design restrictions, more effective and faster finiteelement analyses are demanded. There are several ways to compute FE analysis efficiently: parallelcomputing, fast iterative or direct solvers, adaptive analysis and so on. One of the most effectiveanalysis ways is the combination of adaptive analysis and multigrid iterative solver, because anadaptive analysis requires several meshes with difference resolutions and multigrid solver utilizessuch meshes to accelerate its computation. However, convergence of multigrid solver is largelyaffected by initial shape of each element. An effective mesh improvement method is proposed here. Itis the combination of mesh coarsening and refinement. A good mesh can be obtained by the method tobe applied to an initial mesh, and better convergence is achieved by the improved initial mesh
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.833.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    An Experimental Method for Micro-Scale Uniaxial Tension Test (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 326-328 (Dec. 2006), p. 233-236 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A micro-scale uniaxial tension test method for measuring material mechanical propertiesof thin film materials is introduced in this paper. A self-developed test device is established basedon the CMT8202 tension test machine. The Interference Strain/Displacement Gauge (ISDG)method is used to measure the strain in the micro-samples. The three dimensional finite elementmethod (FEM) is utilized to optimize specimen geometry configuration and to reduce the stressconcentration in specimen around grip region. The experiments are carried out for thepolycrystalline copper thin film. The results show that stress-strain curves and the Young’s modulusof the thin film material can be obtained by micro-scale tension test. The Young’s modulusdetermined by micro-sample for polycrystalline copper thin film has a good agreement withpublished results
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/52/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.326-328.233.pdf
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  • 5
    Electronic Resource
    Electronic Resource
    Fracture Parameters on Three-Dimensional Sliding Mode Fracture (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 340-341 (June 2007), p. 447-452 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In the recent years three-dimensional (3D) elastic-plastic analyses have been conductedextensively for the opening mode (mode I) fracture and the constraint effects are discussed in detail.However less work is focused on other modes as sliding mode (mode II), tearing mode (mode III)or the mixed mode fracture in three-dimensional. In this paper the thickness effect on pure mode IIcase is discussed by the finite element method (FEM). Modified Boundary Layer (MBL) model isused, which has the ability to take into account the combined effects of the in-plane constraint(T-stress) and the out-of-plane constraint (finite thickness). The result demonstrates the weakthickness dependence on the near tip stress and strain fields under mode II loading. And the size ofthe 3D zone at mode II loading is determined to range from 1.0 to 1.2 times the thickness. Twofracture parameters of J integral and crack tip sliding displacement (CTSD) are discussed, which arealmost same at different thickness planes except those very near the surface. It is interesting to findthat the relations between J and CTSD keep linear at different thickness planes. T-stress issymmetry on stress and strain distributions along the crack plane. However its effects indicate weakthickness dependent on the CTSD and J integral fracture parameter
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.340-341.447.pdf
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  • 6
    Electronic Resource
    Electronic Resource
    Mesh Generation of Revealable and Non-Revealable Multi-Shaped Sub-Domains (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 737-744 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper, the mathematical model for nonlinear multi-shaped randomly distributeddomains in revealable and non-revealbale fields is established by using waveform mesh generation(WMG) method with damp, and made the application function of finite element pre and posthandling system. The results show, this method can conduct mesh transformation to any givennonlinear function or given shapes in different scale randomly distributed domain in revealable andnon-revealable fields, and obtained some smoothly mesh with matching each boundary andneighboring domains interaction
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.737.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    A Simple Method in Preventing Numerical Fractures of SPH Computations (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 33-37 (Mar. 2008), p. 845-850 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A non-triangulation inserting particle method is presented to prevent numerical fractures ofSPH computations. The particles in those regions in which numerical fractures may occur are chosenat the beginning of SPH computations. And, the chosen particles are arrayed by the two different rulesrespectively according to the particle position relations. When the distance between each two chosenconnected particles exceeds a certain value and neither of the corresponding two particles hasfractured in SPH computations, a new particle is generated between those two ones and the positionrelation of particles is updated. The physical quantities that the new particle carries are obtainedaccording to some given rules. The method and the same type of method in the reference arecompared. The application of the method is analyzed. Conservation of mass and Conservation ofmomentum of the whole system are kept in this method. Several examples are given to validate theefficiency of the method to prevent numerical fractures
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/40/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.33-37.845.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic variation of Cordyceps sinensis, a fruit-body-producing entomopathogenic species from different geographical regions in China (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 230 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Cordyceps sinensis is one of the most valuable medicinal fungi in the Orient. It is naturally distributed in the eastern extension area of the Qinghai–Tibet plateau, at an altitude over 4000 m high. In order to investigate genetic variation and evolutionary relationships of C. sinensis from different geographical regions, 17 isolates of C. sinensis were collected from different provinces and the complete sequences of rDNA ITS were determined. On the basis of 5.8S rDNA and ITS region analysis, it was clearly shown that the ITS sequences within C. sinensis are highly homologous regardless of geographical origin. The distance values between the sequences in this study were lower than 0.03. This implied that C. sinensis from different geographic regions are the same species; they are not different species or a species complex. The results also showed that distance values between C. sinensis and Hirsutella sinensis are of the same order as those within C. sinensis from different geographic regions. This confirmed our previous results that C. sinensis should only have H. sinensis as its asexual stage whatever the geographic region from which the samples were collected. An rDNA ITS clone library was established to obtain further evidence for the interpretation of the fungal community structure from C. sinensis and to confirm the accuracy of the taxonomic identities produced by directly sequencing the rDNA ITS region. The discrimination between intraspecies of C. sinensis might provide additional data for the authentication of medicinal material at the species or intraspecies level.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(03)00889-9
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  • 9
    Electronic Resource
    Electronic Resource
    Dielectric and piezoelectric properties of sol–gel derived lead magnesium niobium titanate films with different textures (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 89 (2001), S. 568-574 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The piezoelectric and dielectric constants for Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN–PT, 70/30) films with different orientations were measured. PMN–PT films were deposited on Pt(111)-passivated silicon substrates using a modified sol–gel process. The room temperature dielectric constants K for the {100}-oriented films were 2500–2600, while K for {111}-oriented films were 1900–2000. In both cases tan δ was less than 0.03. The dependence of the piezoelectric coefficient d31 of the PMN–PT films on the poling fields was investigated. The d31 coefficients of {100}-oriented PMN–PT films were found to range from −28 to −69 pC/N with poling field. The {100}-oriented PMN–PT films showed larger piezoelectric coefficient than {111}-oriented films. The d33 coefficients of the 1.5 μm thick {100} oriented PMN–PT films were ∼170–183 pC/N. The aging rate of −d31 was ∼4%–10%/decade. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1324685
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  • 10
    Electronic Resource
    Electronic Resource
    A Simplified Linear Consistency Kernel Function in SPH Method (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 306-308 (Mar. 2006), p. 595-600 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Smoothed Particle Hydrodynamics (SPH) is a relatively new technique for simulating the dynamic response of solids, especially for high velocity impact and fracture problem. However, closer examination of SPH reveals some severe problems. The major difficulties are: (1) tensile instability; (2) zero-energy mode; (3) boundary deficiency; (4) less accuracy. One solution to thesemajor difficulties with SPH is to improve the consistency of the kernel function. Based on the Reproducing Kernel Particle Method (RKPM), the concept of the proposed simplified linear consistency is introduced. The most attractive feature of the simplified linear consistency is the ease and cheapness of doing 3D calculation. One contribution of this paper is to show clearly the accuracy of solution gradually improved by increasing the order of the consistency. Simple 3D impacting models are established with different geometries and higher accurate results are obtainedby using higher consistency kernel functions. Other features as numerical convergence, computational efficiency, etc. and some considerations of the simplified linear consistency kernel function are also discussed
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/50/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.306-308.595.pdf
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