Study Of The Sheet Metal Damage Detection

After damage, the structure will lead to the reduction of stiffness, thus affectsthe change of the structural modal parameters. Although using the method of modalanalysis on the method of damage detection of structure has been proposed formany years, in experimental aspect, especially in the aspect of the modal analysisexperiments of the sheet metal structure there is little work has done. This paper isbased on the method of the modal analysis carries on the damage identification tothe square sheet metal structure of four sides clamped.Firstly, using the finite element analysis software, the Patran&Nastran, to dothe simulation on the structure of a square sheet, simulate plate structure withdifferent length of crack damage in center position by setting different number ofcontinuous damage elements, simulate fracture cracks with different depth bysetting damage elements with different rigidity. Analyze the changes of the modalparameters of the structure when it exists the crackle of different lengths, differentdepths and two damage.Then, design experiments, do the modal analysis experiments on the squarealuminum alloy sheet structure, analyze the changes of the modal parameters whenthe structure exists the crackle of different lengths, different depths and two damage,and validate the analyzing result by using software so that propose the method ofdamage identification.Finally, using the modal shape of the structure, extract nodal displacementvector, construct mark of damage identification-curvature mode, and identify thedamage of the structure.Compare pros and cons of natural frequencies, modal shapes and curvaturemode on structural damage identification, and propose damage detection method.