公开(公告)号：US06850055B2

公开(公告)日：2005-02-01

申请号：US10245401

申请日：2002-09-18

Applicant: David John Buttle

Inventor： David John Buttle

IPC: G01N3/00 ,  G01N3/02 ,  G01N3/06 ,  G01N3/32 ,  G01N19/08 ,  G01N27/72 ,  G01N27/90 ,  G01R33/12 ,  G01B7/24

CPC classification number: G01R33/12 ,  G01N3/32 ,  G01N19/08 ,  G01N27/72 ,  G01N27/9053 ,  G01N2203/0019 ,  G01N2203/0073 ,  G01N2203/0244 ,  G01N2203/0635

Abstract: The variation in properties of a ferromagnetic material with depth below the surface is assessed in a nondestructive fashion using a probe that incorporates an electromagnet. An alternating magnetic field is generated in the electromagnet and so in the object, and a magnetic sensor is arranged to sense a magnetic field due to the electromagnet. Signals from the magnetic sensor are analysed into an in-phase component and a quadrature component, and these are mapped directly into material property and lift-off components; this analysis enables accurate measurements of material property (such as stress) to be distinguished from changes in lift-off. The measurements are repeated for at least five different frequencies of the alternating magnetic field; and the measurements at different frequencies are deconvolved assuming a functional form for the variation of material property with depth, the function having no more than five unknown constants. The stress at depths for example in the range 0.5 mm to 5.0 mm can hence be measured nondestructively.

Abstract translation: 使用包含电磁体的探头以非破坏性方式评估具有深度低于表面的铁磁材料的性质变化。 在电磁体中产生交变磁场，并且在物体中产生交变磁场，并且磁传感器布置成感测由于电磁体引起的磁场。 来自磁传感器的信号被分析成同相分量和正交分量，并将其直接映射到材料性质和剥离分量中; 该分析使得能够精确地测量材料性质（例如应力）以与剥离的变化区分开来。 在交变磁场的至少五个不同频率上重复测量; 并且对于不同频率的测量，假设具有随深度的材料特性变化的函数形式，该函数具有不超过五个未知常数。 因此，深度的应力例如在0.5mm至5.0mm的范围内可以非破坏性地测量。