Catálogo de publicaciones - libros

A fracture analysis was carried out to study cracks in fuselage lap joints with a single-countersunk rivet using the finite element and boundary element alternating method. A global–local methodology was developed for crack modelling a complex structure. Stress intensity factor distributions along the crack front at the edge of the rivet hole in the corner of the joint outer sheet were predicted. Parametric studies were performed by varying crack shapes and sizes in the crack analysis. The effects of residual stresses induced by the riveting process on the stress intensity factors were investigated to get a better understanding of the failure mechanism for the lap joints.

A computer packet, which is composed of three-dimensional source–sink distribution approach with boundary element numerical method, is applied to determine the interaction of environmental factories and floating structure in the partly non-linear category and in the frequency domain. Some numerical techniques, such as the form of Green function, the treatment of free surface boundary conditions and the calculation of kernel function of Green function, are discussed and all oconclusion remarks are useful for the engineering practice in this chapter.

The empirical formulas are commonly employed for design of the sockets used in cable structures. By using these formulas, accurate stress distribution in the socket may not be obtained. In response to the demand of the FAST project and the socket-manufacturer, new theoretical design formulas are given in this paper and further revised on basis of the comparison of numerical results by theoretical formulas, FEM and empirical formulas. It is shown that the new formulas are more accurate than existing empirical formulas and more reliable when used in engineering design.

It can decrease significantly the computation time in transient structural analysis to use subcycling algorithms that permit multiple time steps in an explicit integration. In this paper, several subcycling algorithms are tested and it is shown that constant velocity subcycling algorithm possesses the best stability properties. A new subcycling algorithm that introduces damping to velocities is proposed. The numerical examples show that the proposed algorithm is both accurate and computationally efficient.

This chapter presents a new iterative method based on the existence conditions of Hopf bifurcation. By means of proposed method, the problem on how to determine Hopf bifurcation point in an autonomous nonlinear system with bifurcation parameters is converted to how to solve a set of nonlinear algebraic equations. This method can determine both Hopf bifurcation point and the pure imaginary eigen-value pair of Jacobian matrix of a system at the same time. Thus, it can avoid some weakness in some existing methods, such as repeatedly solving the eigen-value whenever the chosen parameters are changed.

This paper investigates the nonlinear dynamic behaviours of a flexible rotor system with elliptical bearing supports. Based on the variational constraint approach, nonlinear oil film forces and their Jacobians are calculated simultaneously. According to the local nonlinearity of the flexible rotor system, a modal reduction technique based on a free-interface component mode synthesis technique is utilized to reduce linear degrees-of-freedom of the system. Nonlinear unbalance periodic responses of the system are obtained by using PNF (Poincaré-Newton-Floquet) method and the bifurcation point of system can be calculated by using the combination of the predictor–corrector mechanism and the PNF method. The local stability and bifurcation behaviours of periodic motions are analysed by the Floquet theory. The numerical examples show that the schemes of this study not only save computing efforts but also have good precision.

This paper deals with stringer stiffened cylinders on local supports. For shell structures, the imperfections of the constructions tend to have a major influence on the structural behaviour. In this contribution, the results of a number of numerical simulations of discretely supported cylinders with different imperfection shapes are presented.

The problem of doubly periodic rigid line inclusions in a rectangular array under a uniform antiplane shear stress at infinity is dealt with. By using the complex potential and the conformal mapping technique, the problem is reduced to a Hilbert one and the exact solution is obtained. The stress singularity factor at the tip of each rigid line is given in closed form and numerical results show the contrary dependence on the ‘column’ and ‘stack’ spacings of the rigid lines. Also, the effective longitudinal shear modulus of the inhomogeneous materials containing a rectangular array of rigid line inclusions is given as a function of the rigid line spacings.

A nonlinear Layered Finite Element Method (LFEM) is applied to investigate the structural behaviour of reinforced concrete walls with openings. Four half-scale concrete walls with openings, tested recently in the laboratory, are analysed. The test variables are the wall slenderness ratio and the size and location of openings. The walls are axially loaded at an eccentricity of one-sixth of the wall thickness. The ultimate loads, the load–deflection responses and the crack patterns predicted by the LFEM are compared with the experimental results. The comparison shows that the LFEM is effective and accurate.

A simple analytical model that can easily be implemented in MATLAB (Matrix Laboratory) is presented for accurately predicting the moment-curvature and load-deflection relations of concrete beams reinforced with internal tensile steel bars and rehabilitated with externally bonded carbon fibre reinforced polymer (CFRP) strips. The model has been verified by comparing model results with those obtained experimentally. The model results and test data show that, with adequate bond strength, application of a CFRP strip to a reinforced concrete beam significantly increases the capacity. Currently, the model does not consider debonding failure of CFRP from the beam.