Delamination detection presents a pertinent problem for SHM be no visible signs of the damage on the surface of the structure. （structural health monitoring）, as in most cases, there may This study investigates the ...Delamination detection presents a pertinent problem for SHM be no visible signs of the damage on the surface of the structure. （structural health monitoring）, as in most cases, there may This study investigates the scattering of a zeroth-order anti-symmetric （A0） Lamb wave mode by an edge delamination using the commercial FE （finite element） package ABAQUS. The Ao Lamb mode is chosen because the corresponding stress distribution is more sensitive to delamination than is the case for symmetric modes. The paper presents results for the scatter field for various angles of incidence, and for varying defect sizes. The regime of small defect size relative to the incident wavelength is of particular interest for SHM as it corresponds to early damage detection. It is shown that, in this regime the scattered field appears to originate from a point source at the origin of the delamination, and the corresponding amplitude is linearly proportional to area of the delamination. These results can be used to guide the use of Lamb waves to detect and quantify edge delamination in plate-like structures.展开更多
Optical fiber sensors have attracted considerable attention in health monitoring of aerospace composite structures. This paper briefly reviews our recent advancement mainly in Brillouin-based distributed sensing. Dama...Optical fiber sensors have attracted considerable attention in health monitoring of aerospace composite structures. This paper briefly reviews our recent advancement mainly in Brillouin-based distributed sensing. Damage detection, life cycle monitoring and shape reconstruction systems applicable to large-scale composite structures are presented, and new technical concepts, ＂smart crack arrester＂ and ＂hierarchical sensing system＂, are described as well, highlighting the great potential of optical fiber sensors for the structural health monitoring （SHM） field.展开更多
An ultrasonic-guided wave(UGW) is a very promising tool in the field of structural health monitoring and non-destructive test.Numerical analysis was used to simulate the propagation in the rebar and explore the charac...An ultrasonic-guided wave(UGW) is a very promising tool in the field of structural health monitoring and non-destructive test.Numerical analysis was used to simulate the propagation in the rebar and explore the characteristics of UGW in the steel rebar waveguide.Two-dimensional fast Fourier transform was used to process the numerical results and to evaluate the damage.Subsequently,different UGW test influence factors were investigated.The results clearly showed that both the group velocity and the amplitude of longitudinal modes were not very sensitive to stress and temperature variations.However,the received UGW signal energy decreased with the increasing concrete strength.Finally,the interface condition between the concrete and the rebar was investigated.Time-domain and frequency-domain analyses were used to process the received signals.Different interface delamination lengths of the UGW energy attenuation were analyzed and a relationship was obtained.This study successfully proved that UGW is an effective tool in the non-destructive test of reinforced concrete interface delamination.展开更多
文摘Delamination detection presents a pertinent problem for SHM be no visible signs of the damage on the surface of the structure. （structural health monitoring）, as in most cases, there may This study investigates the scattering of a zeroth-order anti-symmetric （A0） Lamb wave mode by an edge delamination using the commercial FE （finite element） package ABAQUS. The Ao Lamb mode is chosen because the corresponding stress distribution is more sensitive to delamination than is the case for symmetric modes. The paper presents results for the scatter field for various angles of incidence, and for varying defect sizes. The regime of small defect size relative to the incident wavelength is of particular interest for SHM as it corresponds to early damage detection. It is shown that, in this regime the scattered field appears to originate from a point source at the origin of the delamination, and the corresponding amplitude is linearly proportional to area of the delamination. These results can be used to guide the use of Lamb waves to detect and quantify edge delamination in plate-like structures.
文摘Optical fiber sensors have attracted considerable attention in health monitoring of aerospace composite structures. This paper briefly reviews our recent advancement mainly in Brillouin-based distributed sensing. Damage detection, life cycle monitoring and shape reconstruction systems applicable to large-scale composite structures are presented, and new technical concepts, ＂smart crack arrester＂ and ＂hierarchical sensing system＂, are described as well, highlighting the great potential of optical fiber sensors for the structural health monitoring （SHM） field.
基金supported by the National Natural Science Foundation of China (Grant No. 50808030)the Doctoral Fund of Ministry of Education of China (Grant No. 200801411102)+1 种基金Science and Technology Support Program of China (Grant No. 2011BAK02B04)the Fundamental Research Funds for the Central Universities (Grant No. DUT12LK12)
文摘An ultrasonic-guided wave(UGW) is a very promising tool in the field of structural health monitoring and non-destructive test.Numerical analysis was used to simulate the propagation in the rebar and explore the characteristics of UGW in the steel rebar waveguide.Two-dimensional fast Fourier transform was used to process the numerical results and to evaluate the damage.Subsequently,different UGW test influence factors were investigated.The results clearly showed that both the group velocity and the amplitude of longitudinal modes were not very sensitive to stress and temperature variations.However,the received UGW signal energy decreased with the increasing concrete strength.Finally,the interface condition between the concrete and the rebar was investigated.Time-domain and frequency-domain analyses were used to process the received signals.Different interface delamination lengths of the UGW energy attenuation were analyzed and a relationship was obtained.This study successfully proved that UGW is an effective tool in the non-destructive test of reinforced concrete interface delamination.
