In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stre...In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method. Through numerical analysis, it has been found that the peak stress concentration factor is located at the saddle position. Thereafter, 80 models have been analyzed, and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated. Based on the experimental values of the numerical stress concentration factor, a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed. The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel, and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.展开更多
With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fa...With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fatigue life at the moments when the pitting appears and reaches failure criterion were obtained at four stressing levels respectively. The distribution rule of fatigue life were distinguished, and the distribution parameters were estimated by statistical analysis. Based on that, the R-S-N curves with confidence 95% of contacting fatigue on gear tooth flank were evaluated. Therefore, the basic data were provided for the reliability design of the gears and prediction of their life.展开更多
Consider the Poisson’s equation Ψ″ (x) = ?e v?Ψ + e Ψ?v ? N(x) with the Dirichlet boundary data, and we mainly investigate the inverse problem of determining the unknown function N(x) from a parameter function fa...Consider the Poisson’s equation Ψ″ (x) = ?e v?Ψ + e Ψ?v ? N(x) with the Dirichlet boundary data, and we mainly investigate the inverse problem of determining the unknown function N(x) from a parameter function family. Some uniqueness and stability results in the inverse problem are obtained.展开更多
基金The research work was financially supported by the National Natural Scientice Foundation of China(Grant No.10142001)by the Shandong Provincial Natural Scientice Foundation(Grant No.Y2006F46)
文摘In engineering practice, tubular X-joints have been widely used in offshore structures. The fatigue failure of tubular X-joints in offshore engineering is mainly caused by axial tensile stress. In this study, the stress concentration factor distribution along the weld toe in the hot spot stress region for tubular X-joints subject to axial loads have been analyzed by use of finite element method. Through numerical analysis, it has been found that the peak stress concentration factor is located at the saddle position. Thereafter, 80 models have been analyzed, and the effect of the geometric parameters of a tubular X-joint on the stress concentration factor has been investigated. Based on the experimental values of the numerical stress concentration factor, a parametric equation to calculate the stress concentration factor of tubular X-joints has been proposed. The accuracy of this equation has been verified against the requirement of the Fatigue Guidance Review Panel, and the proposed equation is found capable of producing reasonably accurate stress concentration factor values for tubular X-joints subject to axial loads.
文摘With the method of group test, fourty pairs of carburization-quenching gears made from 16NCD13 steel for aerocraft were tested to research the contacting fatigue strength on tooth flank. As a result, the samples of fatigue life at the moments when the pitting appears and reaches failure criterion were obtained at four stressing levels respectively. The distribution rule of fatigue life were distinguished, and the distribution parameters were estimated by statistical analysis. Based on that, the R-S-N curves with confidence 95% of contacting fatigue on gear tooth flank were evaluated. Therefore, the basic data were provided for the reliability design of the gears and prediction of their life.
基金This work was partially supported by the National Natural Science Foundation of China(Grant No.10626017)the Science Foundation of the Education Committee of Heilongjiang Province(Grant No.11511276)the Foundation of HeilonKjiang Province(Grant No.LBH-Q05114)
文摘Consider the Poisson’s equation Ψ″ (x) = ?e v?Ψ + e Ψ?v ? N(x) with the Dirichlet boundary data, and we mainly investigate the inverse problem of determining the unknown function N(x) from a parameter function family. Some uniqueness and stability results in the inverse problem are obtained.
