Papers by Author: Xu Dan Dang

Abstract: In the tensile strength analysis, the failure criterion and materials stiffness degradation rule were proposed and the X-cor sandwich’s failure modes were also clarified. According to the failure criterion we used the elements with stiffness degradation and their distributions in the finite element model to simulate the types and propagation path of the failure and the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates during the tension firstly the interfaces between resin regions and Z-pin tips fail and the failure mode is Z-pin pull-out from the face-sheets. The finite element simulated results are in good agreement with the experimental results, the error range is -11.6%~9.7%. The comparison results show the failure criterion and stiffness degradation rule are reasonable and this method can be used to predict the X-cor sandwich’s tensile strength.

Abstract: The finite element software was used to get the X-cor sandwich’s shear strength. During the shear strength analysis, the failure criterion and materials stiffness degradation rules fitting for the analysis of X-cor sandwich’s failure mechanism were proposed and the X-cor sandwich’s failure process and modes were also clarified. According to the failure criterion we used the elements with stiffness degradation and their distributions in the finite element model to simulate the types and propagation path of the failure and the failure mechanisms of X-cor sandwich under shear were explained. The finite element analysis indicates during the shear firstly the resin regions fail and then the multiple failure modes of Z-pin pull-out from the face-sheet, Z-pin shear off and Z-pin buckling all exist. The propagation paths of the failure elements are dispersive. By contrasting the finite element results and test results the values are consistent well and the error range is -10.4%~7.4%. The comparison results show that the failure criterion and stiffness degradation rules are reasonable and this method can be used to predict the X-cor sandwich’s shear strength.

Abstract: Through the analysis of micro-structures of Z-pin ends the basic hypothesis of elliptic configuration of the resin regions around Z-pin ends were proposed. The finite element model of the tensile modulus of X-cor sandwich was established and the finite element software ANSYS was used in the computation. The effects of Z-pin angle, diameter and density on the tensile modulus of X-cor sandwich were analyzed. Via the analysis of finite element model, the influencing trends of parameters of X-cor sandwich on the tensile modulus are achieved and the error range is ±10%. So the rationality of the proposed finite element model is verified and the finite element model can be used to forecast the tensile modulus of X-cor sandwich.

Abstract: Through the observation of photomicrographs of resin regions around Z-pin ends, the basic hypothesis of the elliptic configuration of resin regions in the X-cor sandwich were proposed. The parametric equations for describing the microscopic structures of resin regions were given. Then the geometric analysis model of X-cor sandwich was established. The finite element software ANSYS was used to establish the finite element model of the shear modulus and the shear modulus was calculated. The error range of finite element analysis is between ±10%. So the rationality of finite element model is verified and the finite element model can be used to forecast the shear modulus.

Abstract: In this article the finite element software was used to analyse the values for compressive strength of X-cor sandwich. During the analysis, the failure criteria and materials stiffness degradation rules of failure mechanisms were proposed. The failure processes and failure modes were also clarified. In the finite element model we used the distributions of failure elements to simulate the failure processes. Meanwhile the failure mechanisms of X-cor sandwich were explained. The finite element analysis indicates that the resin regions of Z-pin tips fail firstly and the Z-pins fail secondly. The dominant failure mode is the Z-pin elastic buckling and the propagation paths of failure elements are dispersive. Through contrast the finite element values and test results are consistent well and the error range is -7.6%~9.5%. Therefore the failure criteria and stiffness degradation rules are reasonable and the model can be used to predict the compressive strength of X-cor sandwich.

Abstract: In this study, by changing Z-pin’s insertion parameters, the X-cor sandwich was prepared with vacuum curing molding process. The effects of Z-pin’s insertion angle, insertion density and diameter on compression, shear and tension properties were studied. The results show that Z-pin’s insertion parameters can significantly affect the mechanical properties of X-cor sandwich. The compression properties of X-cor sandwich are reduced, while shear properties are improved by the increase of Z-pin’s insertion angle. As Z-pin’s insertion angle increases the tension modulus increases while the tension strength firstly increases and secondly decreases. The mechanical properties increase with the increase of Z-pin’s insertion density and diameter. Compared with the foam core sandwich, the mechanical properties of X-cor sandwich are significantly improved in both modulus and strength.

Abstract: By contrasting the two finite models, a practical finite element computational model of X-cor sandwich’s compressive modulus was proposed. Through numerical analysis the X-cor sandwich’s stress field and compressive modulus were achieved and the effects of changing Z-pin’s radius, density, angle and volume fraction to the X-cor sandwich’s compressive modulus were analyzed. The numerical analysis results indicate that as the Z-pin’s angle increases the X-cor sandwich’s compressive modulus decreases, as the Z-pin’s radius, density and volume fraction increase the X-cor sandwich’s compressive modulus increases. Through the computation of finite model the influencing trends of X-cor sandwich’s parameters are achieved and the rationality of the proposed finite model is verified.