Advanced Materials Research Vols. 838-841

Abstract: The dynamic mechanical properties of radial and chordwise bamboo pieces were tested by dynamic mechanical analysis (DMA). The results show that the storage modulus and loss modulus and tangent delta of chordwise direction were all larger than the radial direction of bamboo; the peak of glass transition temperature of chordwise direction is high than the radial direction, and their sizes are very close; dynamic mechanical analysis can provide a reference for the optimization applicable environment temperature of curtain plybamboo.

Abstract: The paper presents a harmonic homotopy technique to investigate the steady state resonance response of a ship rolls model. By means of polynomial homotopy continuation, all the possible solutions corresponding to the second-order superharmonic response are derived analytically, i.e. without numerical integration. The stabilities of the solutions are determined by the Floquet theory. The sharp resonance and influence of dc component of input wave excitation of ship rolls model are observed analytically and examined by numerical solutions. Furthermore, the gains of the bias, first and second harmonic terms of stable solutions are illustrated to show the importance of each harmonic component on resonance response.

Abstract: Elastic stresses and limit close-bending moments of reducing elbows subject to in–plane close-bending moments were validated by limit element analysis (LMA) and testing. Results of LMA show that if the end bend moment M acts on small end while the large end is fixed, the largest movement acts on neutral line near the larger end, and large circumferential stress lies on inside surface near neutral lines but deflect to intrados of large end. For the same model, if the end bend moment M acts on large end while the small end is fixed, the largest movement acts on near the small end and lies on neutral line, and larger stress acts on small end and nearby. Results of testing show that stress character in tension stress and compressive stresses are consistent with the calculation results from formula. The limit bending moment calculation results from formula of reducing elbow is conservative, but is consistent with the formula of the limit bending moment, which is controlled by small end of reducing elbow.

Abstract: Micro-mechanics models of masonry basic cell were established to obtain homogenized Young's module and Poissons ratio, according to the finite element homogenization analysis (FEA) results in x, y, z. Model results demonstrate that relatively small errors (less than 6%) occur compare with exact solution.The paper concentrates on the issue of linear homogenization, therefore, it can be used as effective estimates for homogeneous material stiffness degradation of nonlinear range. Through linear superposition principle, homogenization material yield criterion obtained from mechanics models, which can be used as the lower limit of cell bearing capacity.

Abstract: Mode I crack for an example, this paper conducts the introduction and analysis of the use of finite element software ANSYS to calculate the stress intensity factor approaches. Compared the stress intensity factor values with the analytic solution, it shows that the finite element method to calculate the stress intensity factor has a very high precision, and easy to operate.

Abstract: With the use of complex analysis, and by introducing adequate conformal mapping, the anti-shear problem of the star-shaped crack in One-dimensional Hexagonal Quasicrystals was studied. An analytical solution to the crack tip stress intensity factor is found.

Abstract: The internal impedance and radiation impedance of a variable cross-section diffsorber were calculated, when adding bandage to the nozzles of tubes of diffsorber, or using non-linear sound resistance to provide appropriate additional internal resistance, the diffsorber will become an excellent sound absorber. Without bandage, the absorption coefficient of the testing sample is larger than 0.7 during 100Hz-2000Hz, and exceed 1 during 500Hz-800Hz; with bandage, the absorption coefficient of the testing samples is no less than 0.8 during 250Hz-4000Hz, and is above 1 during 250Hz-2000Hz. The performance of absorption begins to reduce from 5000Hz to higher frequency due to the mismatch of internal impedance and radiation impedance.

Abstract: Geo-stresses distribution of mining areas was analyzed by means of the partial least squares regression method (PLSRM). Based on the data measured in Wushaoling tunnel ridge section, numerical simulation of initial geo-stress field around the area had been done using the commercial software called ANSYS. PLSRM was achieved through actual measurement data and calculation results of geo-stress, then fitting data was ready. Compared with the traditional method of least squares, it is suggested that, due to the advantage of principal component analysis in applying PLSRM, present method can effectively reduce regression error caused by correlation between response variables. It can more effectively reflect the features of discontinuous geo-stress distribution in comparing to the method of traditional least-squares analysis. Therefore, it can provide effective data support for the establish of geo-stress field and it is applicable in back analysis on initial geo-stress field.

Abstract: The Scaled Boundary Finite Element Method (abbr. SBFEM) developed by Wolf and Song is a numerical method which has a half analytical nature. In the paper, the asymptotic fields of central crack tip and single edge crack tip of the plane elastic plates are evaluated based on the SBFEM. Numerical examples are provided to demonstrate its high accuracy and effectiveness, and the numerical results show that SBFEM can calculate the SIFs, T-stress and the coefficients of higher order terms with higher efficiency and accuracy. The singular fields of crack-tip with complex configuration can be evaluated combining the sub-structuring technique (or super-element).

Abstract: This paper uses the yield line theory in plasticity, combined with the static equilibrium method, which derives bending coefficient calculation chart of parallelogram plate that exposes to uniform load in a variety of support conditions for designers .