Method and device for mapping components for detecting elongation direction

Abstract

The invention concerns a method for the non-destructive mapping of a component, in order to determine an elongation direction of the elongate microstructure of the component at at least one point of interest, characterised in that it comprises at least two successive intensity measurement steps comprising the following steps: a sub-step of rotating a linear transducer into a plurality of angular positions, said linear transducer comprising a plurality of transducer elements, a sub-step of emitting a plurality of elementary ultrasonic beams at each angular position, a sub-step of measuring a plurality of backscattered signals resulting from the backscattering of the elementary ultrasonic beams by said elongate microstructure, the intensity measurement steps making it possible to obtain two series of intensities measured according to two axes of rotation, and in that the method comprises a step of combining the measured series of intensities so as to determine the elongation direction of the microstructure at said at least one point of interest.

Claims

1. Method for a non-destructive mapping of a component comprising an elongated microstructure, to determine an elongation direction of the elongated microstructure at at least one point of interest of the component, wherein said method includes at least two successive intensity measurement steps comprising the following steps: a sub-step of rotating a linear transducer in a plurality of angular positions each defining an angle of rotation about an axis of rotation passing through said at least one point of interest, said linear transducer extending along a main plane and comprising a plurality of transducer elements aligned along a main direction of said linear transducer, a sub-step of emitting a plurality of elementary ultrasonic beams at each angular position by each of said plurality of transducer elements in the a direction of said point of interest, a sub-step of measuring by each of said plurality of transducer elements of the intensity at each angular position of a plurality of backscattered signals resulting from the backscattering of the elementary ultrasonic beams by said elongated microstructure, a first intensity measurement step of making it possible to obtain a first series of intensities measured along a first axis of rotation, and a second intensity measurement step making it possible to obtain a second series of intensities measured along a second axis of rotation different from the first axis of rotation, and in that the method comprises a step of combining the first series of measured intensities and the second series of measured intensities so as to determine the elongation direction of the microstructure at said at least one point of interest and a mapping step attributing at each point, the elongation direction determined at said point.

2. Non-destructive mapping method according to claim 1, wherein the emission sub-step comprises focusing of the elementary ultrasonic beams at a focus point corresponding to said at least one point of interest.

3. Non-destructive mapping method according to claim 1, wherein the intensity measurement sub-step further comprises a standardisation of the intensities measured according to a sinusoidal function expressing the intensity measured according to the angle of rotation of the transducer, the sinusoidal function having in particular, as a parameter, an amplitude representing a confidence index (E) of the elongation, and the angle (x0) at which the sinusoidal function reaches its maximum defines a straight line perpendicular to the elongation direction at said at least one point of interest along a plane parallel to the main plane of the linear transducer.

4. Non-destructive mapping method according to claim 1, wherein the elongation direction of the microstructure is determined for a plurality of points of interest distributed on the component and in that it comprises a step of 3D mapping of the component associating with each point of interest its elongation direction in a 3D representation of the component.

5. Non-destructive mapping method according to claim 1, wherein the angle between the first axis of rotation and the second axis of rotation is between 20° and 90°.

6. Non-destructive mapping method according to claim 1, wherein said method includes a step of determining actual dimensions of grains of the elongated microstructure at said point of interest, said step comprising: a step of calculating models of backscattered intensity according to a predetermined mathematical relationship, each model being calculated with said mathematical relationship by taking as parameters different dimensions of the grains of the elongated microstructure, a step of comparing one of the series of intensities measured with said models of intensity, the actual dimensions of the grains of the elongated microstructure corresponding to the dimensions used as a parameter with the backscattered model of intensity closest to the series of intensities measured.

7. Non-destructive mapping method according to claim 6, wherein the predetermined mathematical relationship is written in the form: $I\left(\theta \right)=\frac{1}{N}\underset{i=1}{\overset{N}{.Math.}}\frac{2{\pi \left(2a\right)}^2{\left(2b\right)}^2}{L_x{L}_y}{f}^{x_1^i,x_2^i}\left(\frac{A_i}{L_x}\cos \left(\theta \right)-\frac{B_i}{L_y}\sin \left(\theta \right)\right)g^{y_1^i,y_2^i}\left(\frac{A_i}{L_x}\sin \left(\theta \right)+\frac{B_i}{L_y}\cos \left(\theta \right)\right)$ with N being a whole number, preferably greater than 100,000, and: $f^{x_1^i,x_2^i}\left(u\right)={\Pi }^a\left(x_1-u\right){\Pi }^a\left(x_2-u\right)g^{y_1^i,y_2^i}\left(v\right)=\exp \left(-\frac{j\pi f}{{\mathrm{Dc}}_1+{\mathrm{Lc}}_2},{\left(y_1-v\right)}^2\right)\sin \text{⁠}C\left(\frac{2\pi }{\lambda z}\left(y_1-v\right)b\right)\exp \left(-\frac{j\pi f}{{\mathrm{Dc}}_1+{\mathrm{Lc}}_2},{\left(y_2-v\right)}^2\right)\sin C\left(\frac{2\pi }{\lambda z}\left(y_2-v\right)b\right)$ with a being the width of a transducer element of the linear transducer, b the height of the transducer element, D the distance between the linear transducer and the component, L the distance between the entry point of the beams and the point of interest, c1 the celerity in the propagation medium of the beams between the linear transducer and the component, c2 the celerity in the component as propagation medium of the beams, f the frequency of the ultrasonic beams, θ the angular position of the probe, sinC the function sin(x)/x, L.sub.x and L.sub.y the dimensions characteristic of the elongated microstructure and Ai and Bi random numbers drawn in a reduced centred normal distribution, x.sub.1.sup.i, x.sub.2.sup.i, y.sub.1.sup.i, y.sub.2.sup.i random numbers drawn in a uniform distribution on the domains [−a, a] for x.sub.1.sup.i and x.sub.2.sup.i, and [−b, b] for y.sub.1.sup.i and y.sub.2.sup.i, and Π.sup.a is a gate function of width a.

8. Non-destructive mapping device for a component comprising an elongated microstructure, to determine an elongation direction of the elongated microstructure at at least one point of interest of the component, wherein it comprises: a linear transducer extending along a main plane and comprising a plurality of transducer elements aligned along a main direction of said linear transducer, means for rotating the linear transducer in a plurality of angular positions each defining an angle of rotation about an axis of rotation passing through said at least one point of interest, means for emitting a plurality of elementary ultrasonic beams at each angular position by each of said plurality of transducer elements in a direction of said point of interest, means for measuring by each of said plurality of transducer elements the intensity at each angular position of a plurality of backscattered signals resulting from the backscattering of the elementary ultrasonic beams by said elongated microstructure, said rotating means, emission means and measuring means being configured to obtain a first series of intensities measured along a first axis of rotation, and a second series of intensities measured along a second axis of rotation different from the first axis of rotation, the mapping device further comprising means for combining the first series of intensities measured and the second series of intensities measured so as to determine the elongation direction of the microstructure at said at least one point of interest.

Description

5. LIST OF FIGURES

(1) Other aims, features and advantages of the invention will appear upon reading the following description given only in a non-limiting manner, and which refers to the appended figures, in which:

(2) FIG. 1 is a schematic view of a mapping device according to an embodiment of the invention,

(3) FIG. 2 is a schematic view of a portion of a mapping device according to an embodiment of the invention,

(4) FIG. 3 is a schematic view of a non-destructive mapping according to a mapping method according to an embodiment of the invention,

(5) FIG. 4 is an intensity curve of backscattered signals according to the angle of the linear transducer during the implementation of a mapping method according to an embodiment of the invention,

(6) FIG. 5 is a schematic view of a first step of a non-destructive mapping according to a mapping method according to an embodiment of the invention,

(7) FIG. 6 is a schematic view of a second step of a non-destructive mapping according to a mapping method according to an embodiment of the invention,

(8) FIG. 7 is a schematic view of an intensity measurement step of a mapping method according to an embodiment of the invention,

(9) FIG. 8 is a schematic view of a mapping method according to an embodiment of the invention.

6. DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

(10) The following embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined to provide other embodiments. In the figures, scales and proportions are not strictly respected for the purposes of illustration and clarity.

(11) FIG. 1 schematically shows a mapping device 10 according to an embodiment of the invention, allowing a mapping and a non-destructive inspection of a component 12, to determine an elongation direction of the elongated microstructure at at least one point of interest of the component 12.

(12) The mapping device 10 comprises a linear transducer 14 comprising a plurality of transducer elements aligned along a main direction of said linear transducer, arranged on means 16 for rotating said linear transducer 14, here a 6-axis robotic arm.

(13) The transducer elements allow the emission of a plurality of elementary ultrasonic beams in the direction of the component. The ultrasonic beams are backscattered on the linear transducer 14 and this makes it possible to measure the intensity of these signals. The intensities measured are transmitted to a computer 18 for saving and processing, optionally after amplification by an amplifier 20. The computer 18 comprises means for rotating the linear transducer 14, means for emitting a plurality of elementary ultrasonic beams, measuring means and combination means making it possible to implement the mapping method described below.

(14) FIG. 2 schematically shows a portion of a mapping device according to an embodiment of the invention. In particular, only the linear transducer 14 and the component 12 are shown.

(15) The linear transducer 14 emits the plurality of elementary ultrasonic beams 22 at each angular position via each of the plurality of transducer elements in the direction of a point 24 of interest of the component. A single point of interest is shown in this figure (and in FIG. 3), but the aim is to reproduce the measurements stated here on a plurality of points of interest so as to define the elongated microstructure of the component. The plurality of ultrasonic beams 22 are focused towards a focus point combined with the point 24 of interest considered during the intensity measurement.

(16) To determine the elongation direction of the elongated microstructure, the linear transducer 14 is arranged perpendicularly to an axis 26 of rotation and along a main plane 28.

(17) The intensity measurement is taken according to an intensity measurement step of a mapping method, an intensity measurement step 100 of a mapping method according to an embodiment of the invention, schematically represented in FIG. 7.

(18) The measurement step comprises a sub-step of determining 102 the point 24 of interest, in particular its coordinates. The linear transducer 14 is positioned so that the axis 26 of rotation passes through the point 24 of interest in a step 104 of positioning the linear transducer.

(19) The measurement step then comprises a sub-step 106 of emitting the plurality of elementary ultrasonic beams 22 by each of said plurality of transducer elements in the direction of said point 24 of interest, wherein the plurality of beams are focused on the point 24 of interest.

(20) Then a sub-step 107 of measuring by each of said plurality of transducer elements of the intensity at each angular position of a plurality of backscattered signals resulting from the backscattering of the elementary ultrasonic beams by said elongated microstructure makes it possible to recover the intensity measurements.

(21) A sub-step 108 of rotating the linear transducer about the axis of rotation (also represented by the arrow 30 in FIG. 2) makes it possible to modify the angular position defining an angle of rotation about the axis 26 of rotation.

(22) The sub-steps of emitting, measuring and rotating occur for all the predefined angular positions at which a measurement is sought to be obtained.

(23) The measurements make it possible to obtain a curve of intensity of backscattered signals according to the angle of the linear transducer during the implementation of a mapping method according to an embodiment of the invention, as shown in FIG. 4.

(24) The curve 32 has a periodic profile and a maximum intensity for an angle referenced x0. The amplitude of the curve is referenced E and furthermore corresponds to a confidence index of the elongation: it this is close to 0, this means that there is no or hardly any elongation (the curve is flat or almost flat), if it is close to 1, this means that the confidence on the existence of an elongation is very great. The angle x0 for which the intensity of backscattered signals received is at a maximum corresponds to a direction orthogonal to the elongation direction that this step makes it possible to measure. The angle for which the intensity of backscattered signals received is at a maximum itself corresponds to a direction parallel to the elongation direction that this step makes it possible to measure. To facilitate the processing of the curve and to reduce the risk of erroneous measurements, the curve can be standardised in the form of a sinusoidal function being expressed as follows:
ƒ(x)=E cos(w(x−x0))+d

(25) with w and d being adjustment variables to obtain the desired curve that best approximates to the measurements taken.

(26) The elongation direction measured is always in a plane 34 parallel to the main plane 28 of the linear transducer 14. Thus, as represented in FIG. 2, the elongation direction 36 measured is a projection on the plane parallel to the main plane of the real elongation direction 38, which cannot therefore be determined directly. The projected direction is determined in a sub-step 110 of determining the projected direction, carried out by the computer 18, and makes it possible to obtain the direction projected in one point.

(27) FIG. 3 schematically shows a non-destructive mapping according to a mapping method according to an embodiment of the invention, making it possible to determine an elongation direction closest to the real elongation direction.

(28) To do this, the measurement step is carried out along two axes of rotation by the linear transducer 14, a first axis 26a of rotation and a second axis 26b of rotation different from each other, intersecting at the point 24 of interest and making it possible to determine two elongation directions 36a and 36b projected on different planes. The combination of these two projected directions makes it possible to obtain an elongation direction 38 close to the real elongation direction. Additional measurement steps along other axes of rotation can make it possible to also approach the real elongation direction, for example a measurement along a third axis of rotation orthogonal to the plane formed by the first and the second axis of rotation and passing through the point of interest.

(29) The combination of the two projected directions is achieved by the following calculation:

(30) That is: V: being the direction of the real elongation direction described by a vector in a canonical basis (x, y, z). The direction of V is not important and will not be determined subsequently. k1 and k2, the vectors corresponding to the direction towards which the linear transducer 14 points.

(31) The first step consists in determining a first projected vector corresponding to a first elongation direction as can be seen in FIG. 5. The linear transducer is oriented along the vector k1 corresponding to the first axis of rotation and rotates around this axis. The minimum intensity measured according to the angle of the linear transducer corresponds to the vector d1, representing the projected elongation direction of the microstructure (the direction of this vector will also be arbitrary).

(32) The orthonormal reference frame (x, y, z) can be selected such that the vector k1 is colinear with x and that the targeted point corresponds to the centre of the reference frame at the coordinates (0, 0, 0), and that the axis “y” is colinear with d1. The vectors k1 and d1 are thus expressed as follows:

(33) $k1=\left(\begin{array}{c}1\\ 0\\ 0\end{array}\right)\mathrm{and}d1=\left(\begin{array}{c}0\\ E1\\ 0\end{array}\right)$

(34) With E1, the confidence index determined during the adjustment of the standardised intensity/angle curve 32 and corresponding to the amplitude of this curve 32 (as described above).

(35) The plane P1 (defined by the two vectors (k1, d1)) contains the elongation direction. The normal vector to this plane is denoted n1, and is written as:
n1=cross(k1,d1)

(36) (with the cross function corresponding to the vector product between the two vectors k1 and d1).

(37) The equation of the plane P1 is:

(38) $\left(\begin{array}{c}x\\ y\\ z\end{array}\right).Math.n1=0$

(39) The components of n1 are written:

(40) $n1=\left(\begin{array}{c}0\\ 0\\ E1\end{array}\right)$

(41) Thus, the equation of the plane P1 is:
E1 z=0

(42) k1 is colinear with x and d1 is colinear with y, thus n1 is colinear with z and the bases (x, y, z) and (k1, d1, n1) are combined.

(43) If E1 equals 0, then either the medium has no elongation, or the elongation direction is coincident with k1

(44) Once this first plane has been determined, the linear transducer 14 is moved to point in the direction represented by the vector k2 corresponding to the second axis of rotation, as shown in FIG. 6. By applying a second time the method for measuring intensity according to the angle of the linear transducer 14, the vector d2 corresponding to the minimum intensity is determined.

(45) The vector k2 is expressed in (x, y, z) by using the rotation by the Euler angles ψ, θ and ϕ determined by the user to position the linear transducer according to k2. This set of three rotations makes it possible to define the orthonormal reference frame (X, Y, Z) the vector X of which is colinear with k2 and Y with d2.

(46) The Euler angles are defined both by the orientation of the linear transducer and the projected elongation direction.

(47) In the reference frame (X, Y, Z), the vectors k2 and d2 are expressed as:

(48) $k2=\left(\begin{array}{c}1\\ 0\\ 0\end{array}\right)d2=\left(\begin{array}{c}0\\ E2\\ 0\end{array}\right)$

(49) With E2 the confidence index determined during the adjustment of the standardised intensity/angle curve.

(50) The vectors k2 and d2 can then be expressed in the base (x, y, z) by using the following matrix multiplication:

(51) $k2\left(Ox,y,z\right)=Pk2\left(OX,Y,Z\right)\mathrm{With}:P=\left(\begin{array}{ccc}\cos \left(\psi \right)\cos \left(\phi \right)-\sin \left(\psi \right)\cos \left(\theta \right)\sin \left(\phi \right)& -\cos \left(\psi \right)\sin \left(\phi \right)-\sin \left(\psi \right)\cos \left(\theta \right)\cos \left(\phi \right)& \sin \left(\psi \right)\sin \left(\theta \right)\\ \sin \left(\psi \right)\cos \left(\phi \right)+\cos \left(\psi \right)\cos \left(\theta \right)\sin \left(\phi \right)& -\sin \left(\psi \right)\sin \left(\phi \right)+\cos \left(\psi \right)\cos \left(\theta \right)\cos \left(\phi \right)& -\cos \left(\psi \right)\sin \left(\theta \right)\\ \sin \left(\theta \right)\sin \left(\phi \right)& \sin \left(\theta \right)\cos \left(\phi \right)& \cos \left(\theta \right)\end{array}\right)$

(52) The vector normal to the plane P2 is defined by n2=cross(k2, d2) in the reference frame (x, y, z) and the equation of the plane P2 is defined by:

(53) $\left(\begin{array}{c}x\\ y\\ z\end{array}\right).Math.n2=0$

(54) Accepting that the components of n2 are written:

(55) $n2=\left(\begin{array}{c}e\\ f\\ g\end{array}\right)$

(56) Then the equation of the plane P2 is:
ex+fy+gz=0

(57) The real elongation direction of the microstructure corresponds to the intersection of the planes P1 and P2, which amounts to solving the equation system:

(58) 0$\{\begin{array}{c}{E}_{1}z=0\\ ex+\mathrm{fy}+\mathrm{gz}=0\end{array}$

(59) This system of equations is a straight line in space. The direction of the vector V is combined with this straight line. The direction of the vector V is unnecessary as it is non-existent physically.

(60) FIG. 8 schematically shows a mapping method 120 according to an embodiment of the invention. For each point of interest that is to be studied, the coordinates of this point are taken in a first positioning step 122, and then at least two intensity measurement steps 100a and 100b are carried out along the different axes of rotation as explained above. The result of these two measurements is used in a step 124 of combining the first series of intensities measured and the second series of intensities measured so as to determine the elongation direction of the microstructure at said point of interest. The calculation allowing the combination has been described above.

(61) The positioning, measuring and combining steps are repeated for each point of interest.

(62) When a plurality of points of interest and elongation directions determined for each point of interest are available, the method can implement a step 126 of 3D mapping the component associating with each point of interest its elongation direction in a 3D representation of the component.