公开(公告)号：US11366082B2

公开(公告)日：2022-06-21

申请号：US17516520

申请日：2021-11-01

Applicant: BEIJING UNIVERSITY OF TECHNOLOGY

Inventor： Jingpin Jiao ,  Li Li ,  Xiang Gao ,  Quan Cheng ,  Cunfu He ,  Bin Wu

IPC: G01N29/04 ,  G01N29/44 ,  G01N29/48 ,  G01N29/12 ,  G01N29/34

Abstract: The invention discloses a non-linear Lamb wave mixing method for measuring stress distribution in thin metal plates. The method is suitable for stress distribution detection and stress concentration area positioning in a plate structure and belongs to the field of nondestructive detection. The steps of the present invention is: first determines the excitation frequencies of two fundamental waves according to the measured object and the nonlinear Lamb wave mixing resonance conditions; the left and right ends of the test piece are oppositely excited two rows of A0 mode waves, and the excitation signal receive the sum-frequency S0 signal at a certain position to detect non-linear mixing stress of the plate structure; by changing the excitation time delay of the excitation signal, perform mixing scan on different positions of the test piece to extract the mixing wave amplitude; finally, according to the variation of amplitude of sum frequency difference signal with mixing position to realize the detection of stress distribution of metal plate and the positioning of the stress concentration area.

公开(公告)号：US20170331474A1

公开(公告)日：2017-11-16

申请号：US15520054

申请日：2016-05-16

Applicant: Beijing University of Technology

Inventor： Jingpin Jiao ,  Liang Li ,  Nan Li ,  Cunfu He ,  Bin Wu

IPC: H03K17/955 ,  G01D5/24 ,  G01B7/02 ,  G01R27/26 ,  B60R19/48

CPC classification number: H03K17/955 ,  B60R19/483 ,  G01B7/023 ,  G01D5/24 ,  G01R27/26 ,  G01R27/2605 ,  H03K2217/960765 ,  H03K2217/960775

Abstract: Embodiments related to a capacitive proximity sensor with a variable spacing electrode structure, which is suited to a non-destructive testing operation, such as the detection of dielectric properties of the polymer materials with a thickness decreases gradually structure. The designed sensor includes a driving electrode, a sensing electrode, a substrate, a guarding electrode and a lead connector. The driving and sensing electrodes include several interdigitated fingers, which are arranged alternately in sequence, based on the characteristic of the thickness decreases gradually structure of the MUT, the width of the electrodes and spacing between two adjacent electrodes in each unit are optimized individually. Namely, under the condition of ensuring penetration depth, the electrode width is made as large as possible to achieve maximum signal strength and detection sensitivity. Compared with the traditional ES-IDE structure capacitive proximity sensor, the newly designed VS-IDE capacitive sensor increases the effective electrode area, which increases the signal strength and measurement sensitivity directly. Besides, the electric field lines of the designed sensor are confined within the thickness gradually changed materials under test mostly as expected simultaneously.

公开(公告)号：US11493479B2

公开(公告)日：2022-11-08

申请号：US17055599

申请日：2020-04-29

Applicant: BEIJING UNIVERSITY OF TECHNOLOGY

Inventor： Jingpin Jiao ,  Wenyuan Liang ,  Cunfu He ,  Bin Wu

IPC: G01N27/82 ,  G01N33/2045

Abstract: The invention discloses a low-frequency electromagnetic detection method for large-scale damage of ferromagnetic materials based on broadband excitation. Detection direction of the magnetic field signal of low-frequency electromagnetic sensor is determined according to the size of ferromagnetic member detection defect; the reference signal and detection signal acquisition position are selected, fix the distance between sensor and tested part, excite a Chirp signal as a broadband excitation signal to perform broadband excitation low-frequency electromagnetic detection; the computer processes collected broadband detection signal; use the difference of Euclidean distance between reference signal and defect detection signal as a defect characterization parameter to obtain the Euclidean distance curve of different depth defects on the upper and lower surfaces of ferromagnetic components with the detection position. Through the analysis and processing of the low-frequency electromagnetic broadband detection signal, the Euclidean response signal and reference signal under broadband excitation are used to characterize the change of material damage degree, which can effectively reduce the influence of magnetic field skin effect, and is beneficial to the effective characterization of the upper and lower material surface defects of at different depths.

公开(公告)号：US10027322B2

公开(公告)日：2018-07-17

申请号：US15520054

申请日：2016-05-16

Applicant: Beijing University of Technology

Inventor： Jingpin Jiao ,  Liang Li ,  Nan Li ,  Cunfu He ,  Bin Wu

IPC: H03K17/955 ,  G01R27/26 ,  G01D5/24 ,  G01B7/02 ,  B60R19/48

Abstract: Embodiments related to a capacitive proximity sensor with a variable spacing electrode structure, which is suited to a non-destructive testing operation, such as the detection of dielectric properties of the polymer materials with a thickness decreases gradually structure. The designed sensor includes a driving electrode, a sensing electrode, a substrate, a guarding electrode and a lead connector. The driving and sensing electrodes include several interdigitated fingers, which are arranged alternately in sequence, based on the characteristic of the thickness decreases gradually structure of the MUT, the width of the electrodes and spacing between two adjacent electrodes in each unit are optimized individually. Namely, under the condition of ensuring penetration depth, the electrode width is made as large as possible to achieve maximum signal strength and detection sensitivity. Compared with the traditional ES-IDE structure capacitive proximity sensor, the newly designed VS-IDE capacitive sensor increases the effective electrode area, which increases the signal strength and measurement sensitivity directly. Besides, the electric field lines of the designed sensor are confined within the thickness gradually changed materials under test mostly as expected simultaneously.