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  • Open Access

    ARTICLE

    A New Method of Camera Calibration for Large Field Videometrics

    Shang Yang1, Sun Xiangyi, Yang Xia, Wang Xi, Yu Qifeng
    Structural Longevity, Vol.5, No.1, pp. 1-15, 2011, DOI:10.3970/sl.2011.005.001
    Abstract A new method of camera calibration is proposed for high-precise videometrics in large field. The camera to be calibrated and the control points used in the new method are both close to the ground. In the condition that the control points and the optical center of the camera are approximately coplanar, the principle point position, focal length, lens distortion coefficients and the camera’s position and attitude parameters are calibrated precisely by the method. Two calibration images are taken by the camera to be calibrated in measurement state and vertical rotation state respectively. If the vertical tangent lens distortion can be… More >

  • Open Access

    ARTICLE

    Size-Dependent Elastic Properties of Micro- and Nano-Open-Celled Foams

    H. X. Zhu1
    Structural Longevity, Vol.5, No.1, pp. 17-24, 2011, DOI:10.3970/sl.2011.005.017
    Abstract Simple analytical results for the size-dependent elastic properties of micro- and nano-sized regular open-celled foams are presented in this paper. The results indicate that at micrometer scale, strain gradient has a dominant effect and at nanometer scale, surface elasticity dominates the effect on the honeycomb elastic properties. In addition, very small micro- or nano- open-celled foams could have a negative Poisson ratio, the elastic properties of nano-sized open-cell foams can be controlled to vary over a range up to around 66% by the application of an electric potential. More >

  • Open Access

    ARTICLE

    An Optimal Pre-stress Die Design of Cold Backward Extrusion by RSM Method

    C.T. Kwan, C.C. Wang1
    Structural Longevity, Vol.5, No.1, pp. 25-32, 2011, DOI:10.3970/sl.2011.005.025
    Abstract In this paper, a pre-stress die design method for cold backward extrusion with a non simple hollow cylinder die by using response surface method is proposed. The radius of the interface and the absolute interference in the interface of a prestress die are chosen as the design variables. Both the two design variables are set at four levels, and then 16 combinations of design parameters are constituted totally. A finite element based code is utilized to investigate the elastic deformation characteristic under different design parameters, and the response surface method is then employed to synthesize the data sets obtained from… More >

  • Open Access

    ARTICLE

    Analysis of Nonlinear Curved Spring When Applying Nonlinear Load

    Dein Shaw1, Chih Ren Huang1, Yi Chi Pan1
    Structural Longevity, Vol.5, No.1, pp. 33-38, 2011, DOI:10.3970/sl.2011.005.033
    Abstract A nonlinear curved spring has a free form shape. In this study, the curved beam is applied a nonlinear load, the load on the spring is pointed to a certain point of the space. This curved spring can be used in an orthosis. A certain load-deformation relation of curved spring which used in orthosis can assist the subject wearing the orthosis to climb the stairs. The analysis of the curved spring should be non-linear due to the applied load is a constant but its direction is point to a certain point. The deformation is hard predicted correctly for this spring.… More >

  • Open Access

    ARTICLE

    Phase-shifting Deflectometric Moiré Topography

    Hongwei Guo1
    Structural Longevity, Vol.5, No.1, pp. 39-47, 2011, DOI:10.3970/sl.2011.005.039
    Abstract This paper presents a moiré-based technique for measuring the threedimensional shapes of specular surfaces. In it, a Ronchi grating is closely located before the measured object and illuminated by diffusive light sources. When we observe the measured object through this grating, moiré fringes are generated by the superposition of this grating and its virtual image produced by the measured specular surface. With this scheme, the movements of the grating along the vertical direction introduce phase shifts in these moiré fringes so that their phases can be recovered by use of a self-calibrating phase-shifting algorithm. From the phases and phase shifts,… More >

  • Open Access

    ARTICLE

    Study of Poisson’s Ratios of Graphene and Single-Walled Carbon Nanotubes Based on an Improved Molecular Structural Mechanics Model

    P. Zhao1, G. Shi2
    Structural Longevity, Vol.5, No.1, pp. 49-58, 2011, DOI:10.3970/sl.2011.005.049
    Abstract The Poisson’s ratios of a single layered graphene sheet and singlewalled carbon nanotubes (SWCNTs) are computed using an improved equivalent structural mechanics model where the bond angle variations are modeled by the flexible connections of framed structures. The accuracy of the results given by the present model is evaluated by comparing the predicted results with the experimental data and the theoretical and computational results reported in the literature. It is shown that the Poisson’s ratios given by the present computational model agree with the experimental data. The present result shows that the Poisson’s ratios of both graphene and SWCNTs are… More >

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