13th International Conference on Fracture June 16–21, 2013, Beijing, China -6- parameters are constant. Take the relative density were 0.11, 0.22, 0.27, 0.3, 0.44, 0.88. When the impact velocity of the rigid ball is 10m/s, the deformation variation curve of structure is shown in figure 6.It is revealed that the homogenization equivalent method of grid structure is reasonable in a certain relative density range. When the relative density ranges from 0.2 to 0.4, the equivalent effect of structure is good, and the error is controlled within 10%. But, when the relative densities are 0.11 and 0.88, the errors are 30% and 104%, respectively. The impact performance of grid cylindrical structure has not been reflected really. Then, this kind of equivalent method is failure. The relative density has a great influence on equivalent properties of structure. Grid cylindrical structure has a tendency to local deformation, and grid topology structure form has greater influence on deformation of structure. But the topology form has no influence on equivalent continuum cylindrical structure, which is the major reason to cause different deformations of structure. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Deformation/mm Relative density grid continuous Figure 6. The relationship of relative density and deformation 4.3 The effect of the relative thickness The relative thickness is defined as T2/T1, which is changed by thickness of the cylinder structureT1. Take the relative density were 0.41、0.61、1.22、2.44 respectively. When the relative density is 0.27, the largest deformation change of structure with the increase of relative thickness is shown in figure 7.When the relative thickness less than 1.2, the maximum deformations of the two structure are almost to be equal. But the relative error has reached 23% at the relative thickness up to 2.44. It can be seen that with invariable thickness of grid cylindrical structure, the thicker the cylindrical structure is, the better the equivalent result is. However, the out-of-plane performance of grid cylindrical structure will gradually highlight with the increase of the thickness of the cylindrical structure, which will result in the failure of the equivalent method.
RkJQdWJsaXNoZXIy MjM0NDE=