Papers by Author: Xiang Rong Fu

Abstract: The sliding cable structures have found its application in many practical structures, such as ski lifts, electrical transmission lines, and cable systems in the erection procedures of long-span bridges. This paper presents a method for modeling the cable sliding on a pulley or sheaves. “Sliding cable element” is developed to solve the general problem. Based on the foundational principles of finite element analysis, the relation of the forces in the element on equilibrium state is used. The computation is simplified by automatically adjusting the cable length on each side of a pulley or sheave in order to maintain equilibrium. The element models are implemented in a geometrically nonlinear, transient implicit finite element program. Several numerical examples are developed to validate the effective of the sliding cable element.

Abstract: The micro-cracks would occurr with the deformation in the composite materials. It would be expanded to the macro-crack in bonding surface and eventually leads to the overall damage of the structure. The initial defects will be inevitably involved in the production of the laminated composite structures. They also lead to delamination crack propagation and structural damage. This paper focuses on the application of the J-integral in the delamination of the composite laminated structure. The J-integral formula of the planar delamination problem of composite laminated structure was derived and verified in the numerical examples.

Abstract: A new strategy of finite differences method is proposed for analysis of notched cross-section bars under elastic-plastic torsion. Relation curves of the elastic-plastic torque responding with different positions, angles and lengths of the notches in one section are obtained by numerical tests. It can be seen that these relation curves exhibit obvious nonlinearity. Meanwhile, the stress intensity factors can also be easily calculated by utilizing the results of above finite differences method. It provides an effective way for solving such elastic-plastic fracture mechanics problem.

Abstract: This paper primarily describes the development and application of substructure computational analysis techniques in two-step hirarchical strategy to determine stress intensity factors for the stiffened damaged panels subjected to fatigue internal pressure. A program based on substructure analysis technique and global-local hierarchical strategy has been developed for the fracture analysis of curved aircraft panels containing cracks. This program may create superelements in global and local models, and obtain fracture parameter of the crack in local model by expanding results in superelements automatically. The technique is applied to the analysis of a cracked panel with 7 frames and 10 stringers. SIFs of four cracks in it with different crack lengths are obtained efficiently.

Abstract: A new technique, Analytical Trial Function Method (ATFM), is proposed to formulate new finite element models for analysis of plane crack/notch problems. A new analytical finite element, named ATFM-CN, is successfully constructed. Furthermore, in order to determine the eigenvalues of the crack/notch problems, which utilized in above analytical trial functions, a modified sub-region accelerated Müller method is also suggested. Numerical examples show the present approach exhibits excellent performance in the analysis of stress-singularity problems.

Abstract: This paper primarily presents the development and application of automation computational analysis techniques to determine the dynamic stress intensity factor for the damaged aircraft fuselage subjected to triangle blast load. A program based on automated procedure to simulate cracked fuselage is developed. It may create 3-dimention panel model using parameterization. The stress around the crack tips will be captured and the dynamic stress intensity factor can be obtained at every moment of the blast automatically. A typical curved panel model which consists of 7 frames and 8 stringers is calculated. The calculation results shown that the form of the dynamic SIF curve is similar to that of the triangle load curve while the peak point of dynamic SIF curve occurs a little later than that of the load curve due to the inertia effect. The longer the crack is, the more obvious the effect is. The peak SIF value of the crack under blast load is bigger than that under the static load for certain crack length. The longer the crack is, the bigger the difference between the dynamic peak SIF value and static SIF is. At the same time, the load time has effect on the dynamic SIF curve and its peak value. These results show good agreements with theoretical principles.

Abstract: In order to calculate the fracture parameters (Stress intensity factor) in a complicated 3- dimention aircraft model with damage in the aircraft panel, a new two steps global-local hierarchical analysis strategy is used. This paper primarily describes the development and application of advanced computational analysis techniques to determine stress intensity factors for the damaged panels based on the two steps hierarchical analysis strategy from global to 3-D local model, the bulging deformation of crack can be considered in the local model. A fracture parameter calculation programme based on automated global-local procedure to simulate cracked aircraft panel tests is developed for the hierarchical strategy. This programme may create models of two stages, transfer boundary conditions, calculate and obtain fracture parameter automatically. Finally, this paper presents some of the experimental data and the calculated fracture parameters are compared with the experimental results.