DepartmentofAppliedMechanics;
NorthwesternPolytechnicalUniversity;
Xi'an710072;
China;
DepartmentofMechanics;
SchoolofCivilEngineeringandMechanics;
ShanghaiJiaotongUniversity;
Shanghai200240;
China;
DepartmentofAppliedMechanics;
NorthwesternPolytechnicalUniversity;
Xi'an710072;
China;