发明授权
- 专利标题: Method and apparatus for evaluating multilayer objects for imperfections
- 专利标题(中): 用于评估缺陷多层物体的方法和装置
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申请号: US571687申请日: 1995-12-13
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公开(公告)号: US5637799A公开(公告)日: 1997-06-10
- 发明人: Joseph S. Heyman , Nurul Abedin , Kuen J. Sun
- 申请人: Joseph S. Heyman , Nurul Abedin , Kuen J. Sun
- 申请人地址: DC Washington
- 专利权人: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
- 当前专利权人: The United States of America as represented by the Administrator of the National Aeronautics and Space Administration
- 当前专利权人地址: DC Washington
- 主分类号: G01N29/07
- IPC分类号: G01N29/07 ; G01N29/11 ; G01N29/28 ; G01N29/50 ; G01N29/04
摘要:
A multilayer object having multiple layers arranged in a stacking direction is evaluated for imperfections such as voids, delaminations and microcracks. First, an acoustic wave is transmitted into the object in the stacking direction via an appropriate transducer/waveguide combination. The wave propagates through the multilayer object and is received by another transducer/waveguide combination preferably located on the same surface as the transmitting combination. The received acoustic wave is correlated with the presence or absence of imperfections by, e.g., generating pulse echo signals indicative of the received acoustic wave, wherein the successive signals form distinct groups over time. The respective peak amplitudes of each group are sampled and curve fit to an exponential curve, wherein a substantial fit of approximately 80-90% indicates an absence of imperfections and a significant deviation indicates the presence of imperfections. Alternatively, the time interval between distinct groups can be measured, wherein equal intervals indicate the absence of imperfections and unequal intervals indicate the presence of imperfections.
公开/授权文献
- US4032953A Sensing circuits 公开/授权日:1977-06-28
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