In this paper,the Fourier spectrum-based strain energy damage detection method for beam-like structures is proposed based on the discrete Fourier transform.The classical strain energy damage detection method localizes...In this paper,the Fourier spectrum-based strain energy damage detection method for beam-like structures is proposed based on the discrete Fourier transform.The classical strain energy damage detection method localizes damage by the comparison of the strain energy between the intact and inspected structures.The evaluation of the 2nd-order derivative term in the strain energy plays a crucial part in the comparison.The classical methods are mostly based on a numerical derivative estimation for this term.The numerical derivative,however,introduces additional disturbances into damage indications.To address this problem,a discrete Fourier transform-based strain energy is proposed with the emphasis of enhancing the performance in noisy condition.The validations conducted on the simulated and experimental data show that the developed method is effective enough for composite beam damage detection in noisy environments.展开更多
Rock,concrete and other geo-materials,due to the presence of microstructural inhomogeneity,their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the mate...Rock,concrete and other geo-materials,due to the presence of microstructural inhomogeneity,their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the materials.In this study,by introducing a cohesive zone model based on fracture mechanics into the framework of deformable discrete element method,a continuous-discontinuous coupling analysis approach for simulating the fracture of quasi-brittle materials is proposed.The cohesive interface elements are inserted into certain engineering or research region.It is assumed that damage and fracture occur only in the interface elements,while bulk material is modeled to be elastic.The Mohr-Coulomb criterion with tension cut-off is adopted as the damage initiation criterion,and a scalar damage variable representing damage in the material is used to describe the rate at which the material stiffness is degraded.Cracks are simulated explicitly by the failure of the interface elements.Numerical simulations are performed in order to validate the suggested method.Partial applications are also listed.The results show that this method provides a simple but effective tool for the simulation of crack initiation and propagation,and it can reflect the whole process of quasi-brittle materials from small deformation to large deformation and failure.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.51405369&51421004)the National Key Basic Research Program of China(Grant No.2015CB057400)+1 种基金the National Natural Science Foundation of Shaanxi Province(Grant No.2016JQ5049)the Postdoctoral Science Foundation of Shaanxi Province
文摘In this paper,the Fourier spectrum-based strain energy damage detection method for beam-like structures is proposed based on the discrete Fourier transform.The classical strain energy damage detection method localizes damage by the comparison of the strain energy between the intact and inspected structures.The evaluation of the 2nd-order derivative term in the strain energy plays a crucial part in the comparison.The classical methods are mostly based on a numerical derivative estimation for this term.The numerical derivative,however,introduces additional disturbances into damage indications.To address this problem,a discrete Fourier transform-based strain energy is proposed with the emphasis of enhancing the performance in noisy condition.The validations conducted on the simulated and experimental data show that the developed method is effective enough for composite beam damage detection in noisy environments.
基金supported by the National Basic Research Program of China(973 Program)(Grant No.2013CB035901)the National Natural Science Foundation of China(Grant No.51379161)+2 种基金the Program for New Century Excellent Talents in University(Grant No.NCET-10-0657)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20120141110008)the Fundamental Research Funds for the Central Universities(Grant No.2012206020207)
文摘Rock,concrete and other geo-materials,due to the presence of microstructural inhomogeneity,their fracture processes and damage characteristics are associated with the distribution of micro-cracks contained in the materials.In this study,by introducing a cohesive zone model based on fracture mechanics into the framework of deformable discrete element method,a continuous-discontinuous coupling analysis approach for simulating the fracture of quasi-brittle materials is proposed.The cohesive interface elements are inserted into certain engineering or research region.It is assumed that damage and fracture occur only in the interface elements,while bulk material is modeled to be elastic.The Mohr-Coulomb criterion with tension cut-off is adopted as the damage initiation criterion,and a scalar damage variable representing damage in the material is used to describe the rate at which the material stiffness is degraded.Cracks are simulated explicitly by the failure of the interface elements.Numerical simulations are performed in order to validate the suggested method.Partial applications are also listed.The results show that this method provides a simple but effective tool for the simulation of crack initiation and propagation,and it can reflect the whole process of quasi-brittle materials from small deformation to large deformation and failure.
