Papers by Author: Xiu Gen Jiang

Abstract: To obtain the pressure distribution model on the sole plate of semi-rigid light steel column footing, the deflection formulas of beams with free ends on elastic foundation subjected to arbitrarily concentrated load and arbitrarily trapezoidal load were developed by applying the Winkler model of elastic foundation beam and initiate-parameter expressions of deformation and internal force by presetting boundary condition and calculating with Maple software. The sole plate of semi-rigid square steel tube column footing was converted into elastic foundation beam which is supported by concrete foundation, the mechanical model of the sole plate subjected to eccentric load was obtained, and the theoretical solution of pressure distribution on the sole plate was presented. Then the theoretical solution was compared with the numerical solution via an example. The results show that the two solutions meet well with each other, and there is much great difference between the pressure distribution on sole plate of semi-rigid light steel column footing and the linear pressure distribution model in common use. As a result, the semi-rigid column footing stiffness would be overestimated by using linear pressure distribution model. The fruits presented in this paper are useful and convenient to the design of semi-rigid light steel column footing.

Abstract: The influence of the structure parameters on the anti-impact performances of the reinforced concrete slab is studied in the article. The reinforced concrete model is established by using ANSYS 13.0/LS-DYNA and nonlinear finite element theory and the parameterized modeling is achieved. The results show that the increase of the thickness of the slab and the steel bar diameter result in the enhancement of impact resistant capability of the slab; a appropriate quantity of reinforcement is significant; Increasing the concrete strength has a distinct impact on the slab’s impact resistance when using relatively low strength concrete. However the influence becomes weak after the concrete strength comes to C60 and higher. The fruits are useful to the designing of reinforced concrete slabs.

Abstract: This paper primarily presents the automation computational analysis techniques to determine the dynamic stress intensity factor for the stiffened damaged aircraft fuselage subjected to triangle blast load. 3-dimention panel models can be created using parameterization and the dynamic stress intensity factor can be obtained in the procedure of the blast automatically. A typical stiffened curved panel model which consists of 7 frames and 8 stringers is calculated. The calculation results show that the peak SIF value of the crack in the panel with strips under blast load is always smaller than that without strips for all longitudinal crack lengths; the strips can slow down the crack growth markedly and the effect of the strips on SIF is most obvious when the crack tips are close to the edge of strips; the blast load time has effect on the SIF peak value, and the effect is most significant when the load time is about 25 milliseconds for the panel with strips.

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: The explicit numerical method is used to trace the impact procedure of the tube columns impacted by a rigid body. The bar and rectangle tube models are both used to simulate the tube column. The elastic and elas-plastic impact load with different mass ratio and impact speed are obtained. The calculation results show that: for elastic models, the bigger the mass ratio and the higher the rigid body speed, the bigger the peak value of elastic impact load; at the same time, the more obvious the reduction effect of local buckling of rectangle tube on the peak value of impact load and the longer the contact time of tube model; so the peak value of impact load of the rectangle tube is not proportional to the rigid body speed. The stress wave in the tube causes a little difference between the load curves of tube model and bar model. For elas-plastic models, the higher the rigid body speed and the smaller the mass ratio, the bigger the peak value of impact load and the longer the contact time. The higher the rigid body speed, the bigger the difference between elastic and elas-plastic impact load peak value due to the expanding of plasticity. Because of the effect of local buckling, the peak value of elas-plastic impact load of rectangle tube is always lower than that of bar.

Abstract: Nonlinear finite element model analysis of the casing plug joints of steel tubular has been realized by ANSYS software. The law of load-carrying capability and stiffness of joint are separately gained by changing the ratio of length and diameter (R/L) and the ratio of the casing length and the main tube length (l/L). The influence of the casing thickness on the load-carrying capability and stiffness are also discussed. The results indicated that the load-carrying capability and stiffness of the joints both increase with the ratio(R/L) increment and the ratio of the casing length and main tube length (l/L). When the main tube thickness is equal to casing thickness, the load-carrying capacity of joints achieves the most.

Abstract: This paper primarily describes the development and application of substructure computational analysis techniques to determine stress intensity factors for the damaged panels subjected to fatigue internal pressure. A program based on substructure analysis technique has been developed for the fracture analysis of curved aircraft panels containing cracks. This program may create whole model which consists of substructure superelements and obtain fracture parameter of the crack by expanding results in superelement automatically. For instance, a typical test curved panel model consists of 7 frames and 8 stringers is calculated. This numerical approach has been validated through comparison between the calculation SIF results and available experimental data of a typical test panel with a longitudinal crack. The technique that has been established here is also applied to the other analysis of a test series of cracked panel with 7 frames and 10 stringers. SIFs of four cracks in it with different crack lengths are obtained efficiently.

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.