Method for determining a delay law, and associated inspecting method, device and computer program product

Abstract

The invention relates to a method for determining a delay law for ultrasonic inspection of a weld (10), comprising the following steps: - providing information on the weld (10) comprising the arrangement of grains of the weld and a respective orientation of said grains, - modeling the weld (10) with a digital model based on the provided information, - positioning a defect in the digital model in a desired place, - simulating in the digital model propagation of an ultrasonic wave from a location through the weld (10) to the defect and of a resulting reflected wave, - determining the times of flight of the resulting reflected wave, and - applying time reversal to the times of flight to determine a suitable delay law. The invention also relates to an associated inspecting method, device and computer program product.

Description

[0001] TITLE: Method for determining a delay law, inspection method, device and associated computer program product

[0002] The present invention relates to a method for determining a delay law for the ultrasonic inspection of a weld.

[0003] It is known to use a multi-element ultrasonic probe for the inspection of a weld.

[0004] It is common to apply a delay law for the emission of the ultrasonic beam by the probe to focus the beam at a detection location and to compensate for the loss of acoustic energy due to the diffusion phenomenon.

[0005] However, the calculation of these delay laws is based on an isotropic material.

[0006] However, a weld is not an isotropic structure.

[0007] Using such a delay law results in less good focusing of the beam at the desired location and a lower signal-to-noise ratio, which complicates the possible detection of defects in the weld at that location.

[0008] An alternative is to use another non-destructive testing technology, for example radiography. However, such a method is more expensive to implement.

[0009] The aim of the invention is then to propose a method for determining a delay law for the ultrasonic inspection of a weld, adapted to the weld.

[0010] To this end, the invention relates to a method for determining a delay law for the ultrasonic inspection of a weld by a multi-element probe, more particularly of the primary circuit of a nuclear power plant, the weld having grains, the method comprising the following steps:

[0011] - providing information about the weld, the information including the arrangement of at least a portion of the grains of the weld and a respective orientation of said grains,

[0012] - modeling of the weld in the form of a digital model, the digital model being based on the information provided,

[0013] - positioning of a defect in the digital model at a desired focusing location,

[0014] - simulation in the numerical model of a propagation of an ultrasonic wave from a location through the weld to the defect at the desired location and of a resulting reflected wave,

[0015] - determination of the flight times of the resulting reflected wave, and - application of a time reversal on the flight times to determine a suitable delay law for focusing an ultrasonic wave from the multi-element probe to the desired location from the localization.

[0016] Modeling the weld from information about it and determining the delay law from this model makes it possible to take into account the microstructure of the weld, and in particular the orientation of the weld grains.

[0017] The invention further relates to a method for determining a delay law for the ultrasonic inspection of a weld by a multi-element probe, more particularly of the primary circuit of a nuclear power plant, the weld having grains, the determination method comprising the following steps:

[0018] - providing information about the weld or other welds, the information including the arrangement of at least some of the grains of the weld or said other welds and a respective orientation of said grains,

[0019] - modeling of the weld in the form of a digital model, the digital model being based on or deduced from the information provided,

[0020] - positioning of a defect in the digital model at a desired focusing location,

[0021] - simulation in the numerical model of a propagation of an ultrasonic wave from a location through the weld to the defect at the desired location and of a resulting reflected wave,

[0022] - determination of the resulting reflected wave flight times, and

[0023] - application of a time reversal on the flight times to determine a suitable delay law to focus an ultrasonic wave from the multi-element probe at the desired location from the localization.

[0024] According to other advantageous aspects of the invention, the method comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0025] - the weld information relates to a section of the weld perpendicular to a direction of extension of the weld, the digital model being a two-dimensional model,

[0026] - the method comprises a step of obtaining information on the weld comprising the application of a chemical attack on a model of the weld, the observation of the respective orientation of at least one part of the grains of the model of the weld and the memorization of the respective orientations,

[0027] - the digital model of the weld comprises a finite number of elements, more particularly such that each grain of the weld is modeled by at least one element, with each element being associated a respective representative orientation, the respective representative orientation of the element(s) modeling a grain being the respective orientation of said grain of the weld,

[0028] - the steps of positioning a defect, simulation, determination and application are repeated by successively considering different desired locations for at least one respective location,

[0029] - the method comprises a step of validating the digital model between the modeling step and the positioning step, the validation step comprising the simulation of the propagation of at least one ultrasonic wave in the digital model and the comparison of the deflection of the simulated ultrasonic wave with a deflection obtained experimentally on the weld,

[0030] - the defect is a hole drilled laterally in the digital model, and / or

[0031] - the adapted delay law includes an emission time for each element of the multi-element probe, the emission time being equal to the subtraction at a given time of flight of the reflected wave received at the location of said element of the multi-element probe,

[0032] - the modeling step includes a step of generating a metamodel from the information provided on other welds and a step of applying the metamodel to the weld,

[0033] - the method comprises, before the step of providing information on other welds, an observation or measurement of the arrangement of at least part of the grains of each of the other welds and of the respective orientation of said grains and / or a simulation of said other welds from parameters for producing the corresponding weld, and / or

[0034] - the generation step is implemented by artificial intelligence, more specifically by an artificial neural network.

[0035] The invention also relates to a method for ultrasonic inspection of a weld, using a multi-element ultrasonic probe, the multi-element ultrasonic probe emitting an ultrasonic wave with the adapted delay law determined by the determination method as described previously.

[0036] The inspection method is likely to have the following characteristic: the multi-element ultrasonic probe successively emits an ultrasonic wave with each delay law adapted for each desired location considered.

[0037] The invention also relates to an electronic device for determining a delay law for the ultrasonic inspection of a weld having grains, the electronic device being adapted to: - receive information on the weld, the information comprising the arrangement of at least part of the grains of the weld and a respective orientation of said grains,

[0038] - model the weld in the form of a digital model, the digital model being based on the orientation of the weld grains,

[0039] - position a defect in the digital model at a desired focusing location,

[0040] - simulate in the numerical model a propagation of an ultrasonic wave from a location through the weld to the defect at the desired location and a resulting reflected wave,

[0041] - determine the resulting reflected wave flight times, and

[0042] - apply a time reversal on the flight times to determine a suitable delay law to focus an ultrasonic wave from the multi-element probe to the desired location from the localization.

[0043] The invention further relates to a computer program product comprising instructions for carrying out the steps of a method as described above.

[0044] The invention also relates to a computer program comprising software instructions which, when executed by a computer, implement a method for determining a delay law as defined above.

[0045] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0046] [Fig. 1] Figure 1 is a sectional view of a weld to be inspected according to an example,

[0047] [Fig 2] Figure 2 is a schematic representation of a first example of a determination method according to the invention,

[0048] [Fig 3] Figure 3 is a schematic representation of a second example of a determination method according to the invention,

[0049] [Fig 4] Figure 4 is a schematic view of a mock-up of the weld of Figure 1,

[0050] [Fig 5] Figure 5 is a schematic representation of a digital model of the weld of Figure 1 with a defect and a multi-element probe, according to an embodiment of the invention, and

[0051] [Fig 6] Figure 6 is an example of improving the focusing of the ultrasonic wave by applying the adapted delay laws.

[0052] An example of a weld cross-section 10 to be inspected is shown in Figure 1, for illustration purposes only. The weld 10 is, for example, a weld between two pieces of piping, more particularly of a nuclear power plant.

[0053] Weld 10 is, for example, a weld in the primary circuit of a nuclear power plant.

[0054] Weld 10 has an extension direction.

[0055] The sectional view in Figure 1 is taken perpendicular to the direction of extension.

[0056] The weld 10 has a surface on which a multi-element ultrasonic probe can be arranged.

[0057] Solder 10 has grains, each grain having a respective orientation.

[0058] In Figure 1, respective orientations 12 of the grains are shown at several locations of the weld 10.

[0059] A method for determining a delay law for the ultrasonic inspection of a weld by a multi-element probe, in particular as described previously, will now be described with reference to Figures 2 and 3.

[0060] A simplified embodiment of the determination method is shown in Figure 3. An enhanced embodiment of the determination method is shown in Figure 4.

[0061] The phased array probe is an ultrasonic probe comprising a plurality of elements, each element being adapted to emit and receive an ultrasonic wave.

[0062] The plurality of elements is, for example, in the form of a rectangular matrix distributed on a plane, a linear matrix, or concentric rings.

[0063] The determination method includes the following steps:

[0064] - provision 102, 202 of information on welding,

[0065] - modeling 104; 204 of the weld in the form of a digital model,

[0066] - positioning 106; 206 of a defect in the digital model at a desired focusing location,

[0067] - simulation 108; 208 in the numerical model of a propagation of an ultrasonic wave from a location of a multi-element probe through the weld to the defect at the desired location and of a resulting reflected wave,

[0068] - determination 110; 210 of the flight times of the reflected wave, and

[0069] - application 112; 212 of a time reversal on the flight times to determine a delay law suitable for focusing an ultrasonic wave from the multi-element probe at the desired location from the localization.

[0070] In a particular embodiment, the method further comprises a step 200 of obtaining information on the weld before the supply step 102, 202. The step 200 of obtaining is, for example, carried out by observation and / or measurement on the weld or a model of the weld of the arrangement and the respective orientation of at least part of the grains of the weld.

[0071] The obtaining step 200 comprises, for example, the application of a chemical attack on a model 250 of the weld, an example of which is shown in FIG. 4, more particularly on an observation plane of the model of the weld 10 perpendicular to the direction X of the model corresponding to the direction of extension of the weld, the observation of the respective orientation of grains of the model of the weld 10, in particular of all the grains of the observation plane, and the memorization of the respective orientations.

[0072] The weld model comprises a weld 252 between parts 254, 256 similar to the parts welded by the weld, according to the same welding process.

[0073] Similar parts are, for example, portions of the welded parts, for example a section of the welded parts according to a cut perpendicular to the direction of extension of the weld.

[0074] More particularly in the case of piping parts, the model includes a section of a portion of piping.

[0075] The application of the chemical attack is, for example, carried out on a visible face 258 of the weld 252 of the model 250.

[0076] Alternatively or additionally, the obtaining step 200 comprises at least one step of cutting the model 250 along a plane perpendicular to the direction X of the model corresponding to the direction of extension of the weld 10. The chemical attack is then, for example, applied to at least one of the newly accessible faces of the weld 252.

[0077] Chemical attack makes it possible in particular to improve the visualization of the respective orientation of the grains of the weld 10.

[0078] The observation of the respective orientation of the grains is, for example, carried out by acquiring an image of said plane and analyzing the image to deduce the respective orientation of the grains of the weld.

[0079] Alternatively, the obtaining step 200 comprises the implementation of a characterization by diffraction of backscattered electrons called EBSD characterization for Electron BackScattered Diffraction in English, in a scanning electron microscope.

[0080] Alternatively, the obtaining step 200 comprises observing the respective orientation of at least a portion of the grains of the ultrasonic weld. In an alternative embodiment, the obtaining step 200 comprises a step of simulating the production of the weld, the simulation step deducing the arrangement of at least a portion of the grains of the weld and a respective orientation of said grains from welding parameters.

[0081] More specifically, welding parameters, corresponding to the execution of the weld, are provided beforehand.

[0082] Welding parameters include, for example, the material(s) of the parts to be welded together, the welding technique, and the material used for the weld. Welding parameters additionally include, for example, the geometry of the parts to be welded together in the vicinity of the weld.

[0083] The simulation step comprises the simulation of the production of the weld on the parts welded together by the weld with the welding technique and the material used for the weld, including the simulation of the resulting arrangement of at least a part of the grains of the weld and a respective orientation of said grains from the welding parameters.

[0084] Then, the arrangement of a part of the grains of the weld, in particular of all the grains of the observation plane, and the respective orientation of said grains are memorized.

[0085] During the provision step 102; 202, the information provided includes the arrangement of at least a portion of the grains of the weld, here of all the grains of the observation plane, and a respective orientation of said grains.

[0086] The weld information here relates to at least one, here a, section of the weld perpendicular to the direction of extension X of the weld 10, here to the observation plane.

[0087] The information is, for example, provided to a receiving module.

[0088] The digital model of weld 10 is based on the information provided.

[0089] In particular, the digital model is representative of the arrangement of at least part of the grains of the weld and the respective orientation of said grains.

[0090] The digital model is generated here by a modeling module, connected to the receiving module. The receiving module sends the information to the modeling module.

[0091] An example of a digital model 300 is, for example, shown in Figure 4.

[0092] The digital model 300 here includes an envelope 302, representing the contour of the weld, here in the observation plane.

[0093] The digital model 300 comprises a finite number n of elements 304.

[0094] The elements 304 are arranged in the casing 302. More particularly, the weld is divided into the finite number n of elements 304, for example by gridding the casing 302.

[0095] The modeling is, for example, such that each grain of the weld is modeled by at least one element 304, here for example by at least four, here four, elements 304.

[0096] The number of elements representing a grain depends in particular on a plurality of parameters, including, for example, the frequency of the ultrasonic wave intended for the ultrasonic inspection described, the size of the defect sought, and the dimension of the grain.

[0097] Each element 304 is associated with a respective representative orientation.

[0098] The respective representative orientation is representative of the respective orientation of the grain(s) modeled at the level of said element.

[0099] Here, the respective representative orientation of the elements modeling a grain is, for example, the respective orientation of the weld grain.

[0100] Alternatively, the modeling is such that each element 304 models a plurality of grains of the weld.

[0101] The respective representative orientation of the element is, for example, equal to the average orientation of the plurality of grains modeled by the element.

[0102] The digital model 300 is here a two-dimensional model, more particularly of the observation plane of the weld 10.

[0103] More particularly, it is considered here that the volume of the weld is a succession of identical planes, corresponding here to the information observed on the observation plane, so that the digital model 300 is representative of the entire volume of the weld.

[0104] Alternatively, the obtaining step comprises a step of obtaining information on a plurality of observation planes perpendicular to the direction of extension of the weld, for example as described previously on a model.

[0105] The digital model 300 is then, for example, a three-dimensional model integrating the different observation planes.

[0106] In one embodiment, the method further comprises a validation step 205 of the digital model 300 between the modeling step 104, 204 and the positioning step 106, 206.

[0107] The validation step 205 comprises the simulation of the propagation of at least one ultrasonic wave in the digital model 300 and the comparison of the deviation of the simulated ultrasonic wave, corresponding to the curvature of the wave, with a deviation obtained experimentally on the weld 10 with a similar wave and / or the acoustic energy of the simulated wave with the acoustic energy obtained experimentally on the weld 10 with a similar wave in each direction.

[0108] For example, if the simulated deviation differs from the experimentally obtained deviation by only a value below a threshold, then the numerical model is validated.

[0109] Otherwise, the digital model is not validated.

[0110] Then, a new digital model is generated, in particular by the modeling module.

[0111] The new digital model has, for example, a number of elements strictly greater than the number of elements of the digital model, and / or the new digital model is, for example, based on new information provided.

[0112] The validation step is, for example, implemented by a validation module.

[0113] The validation module is connected to the modeling module.

[0114] The modeling module sends the digital model to the validation module.

[0115] The validation module also receives the deviation obtained experimentally.

[0116] The validation module sends, for example to the modeling module, a validation signal if the digital model is validated or a rejection signal if the digital model is not validated.

[0117] Upon positioning 106, 206, the defect 306 is positioned at a desired focus location on the digital model 300.

[0118] The defect 306 extends, for example, over at least one element 304, for example here over a plurality of elements 304.

[0119] The defect 306 is, for example, a hole drilled laterally, that is to say here directly at the desired focusing location, as if the drilling were carried out from one side of the digital model 300, more particularly perpendicular to the two-dimensional digital model 300.

[0120] Alternatively, defect 306 is another type of reflector(s).

[0121] The positioning step is, for example, implemented by a positioning module connected to the modeling module.

[0122] During the simulation step, the emission of an ultrasonic wave is simulated from a location, more particularly present in the digital model on the surface of the weld 10, to the desired location.

[0123] The location here corresponds, in the digital model 300, to the intended location of the multi-element probe 308 on the surface of the weld. The simulated ultrasonic wave has characteristics, for example including frequency, waveform or gain, i.e. amplitude, corresponding to the ultrasonic wave intended for the ultrasonic inspection.

[0124] The propagation of said ultrasonic wave from the location to the defect 306 is further simulated, more particularly by propagation in the elements 304.

[0125] Defect 306 then reflects the wave.

[0126] During the simulation step, the propagation of the reflected wave resulting from the reflection on the defect 306 is simulated, more particularly by propagation in the elements 304.

[0127] The simulation step is, for example, implemented by a simulation module connected to the positioning module.

[0128] In the determination step, the resulting reflected wave flight time is determined for each of the locations corresponding to the weld surface opposite which the elements of the multi-element probe are arranged.

[0129] More specifically, for each location, the time of flight corresponds to the time taken by the simulated ultrasonic wave from its emission to the reception of the resulting reflected wave at the surface.

[0130] The said flight times are calculated from the simulation of the propagation of the simulated ultrasonic wave.

[0131] The simulation step is, for example, implemented by a determination module, for example by a Python script.

[0132] The determination module is connected to the simulation module.

[0133] The simulation module sends the simulation of the propagation to the determination module.

[0134] Then, in the application step, the determined flight times are returned temporally.

[0135] More specifically, the adapted delay law includes an emission instant for each element of the probe.

[0136] The emission signal then corresponds to the signal of the reflected wave returned in time.

[0137] The delay law is such that the element of the multi-element probe for which the determined flight time is the highest transmits first, then the element of the multi-element probe for which the determined flight time is the second highest transmits second, and so on up to the element of the multi-element probe having the lowest determined flight time. For each element of the multi-element probe, the transmission time ti is, for example, equal to the subtraction at a given time tO of the flight time tv of the reflected wave received at the expected location of said element, i.e. ti = tO - tv.

[0138] The given moment tO is identical for all elements of the multi-element probe.

[0139] In fact, in a solid, an ultrasonic wave moves according to the following equation: with u the wave displacement, À and p the Lamé coefficients and p s the density of the solid.

[0140] Now, if u(t1) is a solution to the above equation, so is u(-t1), since the equation contains only second-order differentiation operators.

[0141] By inverting the simulated flight times, this allows them to be compensated with the information included in the numerical model, including the arrangement and respective orientation of the grains.

[0142] This allows the determination of a delay law for the desired focusing location, adapted to the weld, and in particular to the anisotropy of the weld.

[0143] The application step is, for example, implemented by an application module.

[0144] The application module is connected to the determination module.

[0145] The determination module sends the determined flight times to the application module.

[0146] In a particular embodiment, the steps of positioning a fault, simulating, determining and applying are repeated by successively considering different desired locations for at least one location, as shown in Figure 3.

[0147] During each iteration of the positioning step, the defect is positioned at the desired location, and the simulation, determination, and application steps are then implemented with said defect.

[0148] The location is, for example, identical for each of the iterations.

[0149] Additionally or alternatively, the steps of positioning a fault, simulating, determining and applying are repeated by successively considering different locations, more particularly different locations provided for the multi-element probe 308.

[0150] In the present embodiment, the steps of positioning a fault, simulating, determining and applying are repeated by considering all the combinations of the different desired locations and the different locations. The steps of positioning a fault, simulating, determining and applying are, for example, repeated successively by successively considering each of the different locations, by successively considering for each different location the different desired locations.

[0151] This means that for a first location, we consider all the desired locations, then for a second location we consider all the desired locations, and so on until the last location.

[0152] This allows in particular to cover the entire area formed by the weld.

[0153] Iteration is, for example, implemented by an iteration module, e.g., a Python script.

[0154] The iteration module is connected to the positioning module.

[0155] This makes it possible to determine a suitable delay law for each of the weld locations, and thus to be able to implement a complete inspection of the weld by successively implementing the different delay laws determined.

[0156] Although in Figure 3 the method with successive iterations is shown with the validation 205 and obtaining 200 steps, in particular embodiments the method includes the successive iterations, but not the validation 205 and obtaining 200 steps, or only the validation 205 step, or only the obtaining 200 step.

[0157] Alternatively, in particular embodiments, the method comprises the validation 205 and obtaining 200 steps, and not the successive iterations, or the validation 205 step only, or the obtaining 200 step only.

[0158] In an alternative embodiment, the determining method includes a step of providing information about welds other than the weld to be inspected, and not the weld to be inspected.

[0159] The information provided includes the arrangement of at least a portion of the grains for each of said other welds and a respective orientation of said grains.

[0160] The said information provided is, for example, obtained for each weld, as described above with regard to the obtaining step. The information provided is, for example, obtained by different techniques for the different welds.

[0161] Obtaining the information provided includes an observation or measurement of the arrangement of at least a portion of the grains of each of the other welds and the respective orientation of said grains and / or a simulation of said other welds from parameters for producing the corresponding weld, as described above. The information provided here further includes welding parameters of each of said other welds.

[0162] Welding parameters include, for example, the material(s) of the parts to be welded together, the welding technique, and the material used for the weld. Welding parameters additionally include, for example, the geometry of the parts to be welded together in the vicinity of the weld.

[0163] The determination method further comprises a step of providing characteristics of the weld to be inspected.

[0164] The characteristics include, for example, the welding parameters for making the weld to be inspected.

[0165] Welding parameters include, for example, the material(s) of the parts being welded together, the welding technique, and the material used for the weld. Welding parameters additionally include, for example, the geometry of the parts being welded together around the weld.

[0166] In this alternative embodiment, the modeling step comprises a step of generating a metamodel from the information provided on said other welds and a step of applying the metamodel to the weld to be inspected.

[0167] The metamodel comprises a modeling of the arrangement of at least part of the grains of a weld and a respective orientation of said grains, in particular as a function of the characteristics of the weld to be inspected.

[0168] The metamodel generation step is implemented by artificial intelligence, for example by an artificial neural network.

[0169] The neural network consists of an ordered succession of layers of neurons, each of which takes its inputs from the outputs of the previous layer.

[0170] More precisely, each layer consists of neurons taking their inputs from the outputs of the neurons in the previous layer, or from the input variables for the first layer.

[0171] Alternatively, more complex neural network structures can be considered with a layer that can be connected to a layer further away than the immediately preceding layer.

[0172] Each neuron is also associated with an operation, that is, a type of processing, to be carried out by said neuron within the corresponding processing layer.

[0173] Each layer is connected to the other layers by a plurality of synapses. A synaptic weight is associated with each synapse, and each synapse forms a connection between two neurons. It is often a real number, which takes both positive and negative values. In some cases, the synaptic weight is a complex number. Each neuron is capable of performing a weighted sum of the value(s) received from the neurons of the previous layer, each value then being multiplied by the respective synaptic weight of each synapse, or connection, between said neuron and the neurons of the previous layer, then applying an activation function, typically a non-linear function, to said weighted sum, and delivering as output of said neuron, in particular to the neurons of the following layer connected to it, the value resulting from the application of the activation function.The activation function allows non-linearity to be introduced into the processing performed by each neuron. The sigmoid function, the hyperbolic tangent function, and the Heaviside function are examples of activation functions.

[0174] As an optional addition, each neuron is also able to apply, in addition, a multiplicative factor, also called bias, to the output of the activation function, and the value delivered at the output of said neuron is then the product of the bias value and the value from the activation function.

[0175] A convolutional neural network is also sometimes called a convolutional neural network or by the acronym CNN which refers to the English term “Convolutional Neural Networks”.

[0176] In a convolutional neural network, each neuron in a single layer has exactly the same connection pattern as its neighboring neurons, but at different input positions. The connection pattern is called a convolution kernel, or more commonly, a "kernel."

[0177] A fully connected layer of neurons is one in which the neurons in that layer are each connected to all the neurons in the previous layer.

[0178] Such a type of layer is more often referred to as "fully connected" and sometimes referred to as a "dense layer".

[0179] Alternatively, the metamodel generation step is implemented by one or more decision trees, or one or more regression models, or other technique.

[0180] The application step includes applying the metamodel to the weld, more specifically to the provided characteristics of the weld to be inspected.

[0181] The model obtained is, for example, as described previously.

[0182] The determination method in this alternative is, for example, as described previously following modeling step 104; 204.

[0183] The invention further relates to an electronic device for determining a delay law for the ultrasonic inspection of a weld as described above, and capable of implementing the determination method described above. The electronic determination device comprises the receiving module, the modeling module, the positioning module, the simulation module, the determination module and the application module.

[0184] As an optional addition, the electronic determination device includes the validation module and / or the iteration module.

[0185] The electronic determination device comprises an information processing unit formed for example of a memory and a processor associated with the memory.

[0186] The reception module, the modeling module, the positioning module, the simulation module, the determination module and the application module, as well as optionally the validation module and / or the iteration module, are each implemented in the form of software, or a software brick, executable by the processor. The memory of the electronic determination device is then capable of storing software for each of the modules. The processor is then capable of executing each of the software.

[0187] In a variant not shown, at least one of the modules among the modeling module, the positioning module, the simulation module, the determination module and the application module, as well as optionally the validation module and / or the iteration module, is produced in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or an integrated circuit, such as an ASIC (Application Specific Integrated Circuit).

[0188] When the electronic determination device is produced in the form of one or more software programs, i.e. in the form of a computer program, also called a computer program product, it is also capable of being recorded on a medium, not shown, that is readable by a computer. The computer-readable medium is, for example, a medium capable of storing electronic instructions and of being coupled to a bus of a computer system. For example, the readable medium is an optical disk, a magneto-optical disk, a ROM memory, a RAM memory, any type of non-volatile memory (for example FLASH or NVRAM) or a magnetic card. A computer program comprising software instructions is then stored on the readable medium.

[0189] The invention further relates to a method for ultrasonic inspection of a weld 10, using a multi-element ultrasonic probe.

[0190] The inspection method comprises the reception by the multi-element ultrasonic probe of the determined adapted delay law(s), with, for each law, the desired location and the localization associated with said law, during a determination method as described previously implemented beforehand. The inspection method comprises the emission by the multi-element ultrasonic probe of an ultrasonic wave with the or one of the adapted delay laws, the multi-element ultrasonic probe being arranged in accordance with the corresponding location, and the reception of the corresponding reflected beam.

[0191] More specifically, each element of the multi-element probe emits an ultrasonic wave at the emission instant of the delay law.

[0192] The ultrasonic beam, formed from all the ultrasonic waves, is then particularly focused at the desired focusing location, including when the weld is particularly anisotropic.

[0193] In the event of a fault, it reflects the ultrasonic beam, which is received by the multi-element probe.

[0194] The received reflected beam has an increased signal-to-noise ratio compared to conventional techniques.

[0195] In a particular embodiment, the multi-element ultrasonic probe successively emits an ultrasonic wave with a delay law adapted for each of the locations of the weld at least in one plane, in particular with each of the adapted delay laws determined during the iterations, with the adapted location of the multi-element probe.

[0196] More particularly here, the multi-element ultrasonic probe successively emits an ultrasonic wave with a delay law adapted for each of the locations of the weld over the entire volume of the weld, considering for each location of the weld the location within the section of the weld perpendicular to the direction of extension.

[0197] This allows for a complete inspection of the weld, with improved quality.

[0198] In the case where the steps of positioning a defect, simulation, determination and application have been implemented for different locations, then the inspection method comprises a plurality of detections, each detection comprising the emission by the multi-element ultrasonic probe of an ultrasonic wave with the or one of the adapted delay laws, the multi-element ultrasonic probe being arranged in accordance with one of the locations, and the reception of the corresponding reflected beam. The detections are implemented with the different locations of the multi-element ultrasonic probe.

[0199] This allows, for example, to improve the coverage of the weld, especially for a complex weld in the case of wave deflection, in particular by its thickness and / or grain structure. It also allows to improve the sensitivity and resolution of the inspection.

[0200] An example of improvement in the focusing of the ultrasonic wave obtained thanks to the invention is shown in Figure 6.

[0201] On the left, the propagation of the ultrasonic wave from the focused probe to an area to be inspected (represented by the circle) is simulated by applying a delay law not adapted to the orientation of the weld grains.

[0202] On the right, the propagation of the ultrasonic wave from the focused probe to the area to be inspected is simulated by applying the delay law adapted to the orientation of the weld grains according to the invention. It can be seen that the focusing of the ultrasonic wave at the area to be inspected is improved thanks to the invention.

Claims

CLAIMS 1. Method for determining a delay law for the ultrasonic inspection of a weld (10) by a multi-element probe, more particularly of the primary circuit of a nuclear power plant, the weld (10) having grains, the determination method comprising the following steps: - providing (102; 202) information on the weld (10) or on other welds, the information comprising the arrangement of at least a part of the grains of the weld or of said other welds and a respective orientation of said grains, - modeling (104; 204) of the weld (10) in the form of a digital model (300), the digital model (300) being based on or deduced from the information provided, - positioning (106; 206) a defect (306) in the digital model (300) at a desired focusing location, - simulation (108; 208) in the digital model (300) of a propagation of an ultrasonic wave from a location through the weld (10) to the defect (306) at the desired location and of a resulting reflected wave, - determination (110; 210) of the flight times of the resulting reflected wave, and - application (112; 212) of a time reversal on the flight times to determine a delay law adapted to focus an ultrasonic wave from the multi-element probe at the desired location from the localization.

2. A determination method according to claim 1, wherein the information on the weld relates to a section of the weld (10) perpendicular to a direction of extension of the weld (10), the digital model (300) being a two-dimensional model.

3. Determination method according to claim 2, comprising a step of obtaining (200) information on the weld comprising the application of a chemical attack on a model of the weld, the observation of the respective orientation of at least one part of the grains of the model of the weld and the storage of the respective orientations.

4. Determination method according to any one of claims 1 to 3, in which the digital model (300) of the weld comprises a finite number of elements (304), more particularly such that each grain of the weld is modeled by at least one element (304), with each element (304) being associated a respective representative orientation, the respective representative orientation of the element(s) modeling a grain being the respective orientation of said grain of the weld.

5. Determination method according to claim 4, wherein the steps of positioning a defect (106; 206), simulating (108; 208), determining (110; 210) and applying (112; 212) are repeated by successively considering different desired locations for at least one respective location.

6. Method of determination according to any one of claims 1 to 6. 5, comprising a validation step (205) of the digital model (300) between the modeling step (204) and the positioning step (206), the validation step (204) comprising the simulation of the propagation of at least one ultrasonic wave in the digital model (300) and the comparison of the deviation of the simulated ultrasonic wave with a deviation obtained experimentally on the weld (10).

7. Method of determination according to any one of claims 1 to 10. 6, wherein the defect (306) is a laterally drilled hole in the digital model (300).

8. Method of determination according to any one of claims 1 to 10. 7, wherein the adapted delay law comprises an emission time for each element of the multi-element probe, the emission time being equal to the subtraction of the time of flight of the reflected wave received at the location of said element of the multi-element probe at a given time.

9. Method of determination according to any one of claims 1 to 10. 8, wherein the modeling step comprises a step of generating a metamodel from the information provided on other welds and a step of applying the metamodel to the weld (10).

10. Determination method according to claim 9, comprising, before the step of providing information on other welds, an observation or measurement of the arrangement of at least part of the grains of each of the other welds and of the respective orientation of said grains and / or a simulation of said other welds from parameters for producing the corresponding weld.

11. Determination method according to claim 9 or 10, in which the generation step is implemented by artificial intelligence, more particularly by an artificial neural network.

12. A method of ultrasonic inspection of a weld (10), using a multi-element ultrasonic probe, the multi-element ultrasonic probe emitting an ultrasonic wave with the adapted delay law determined by the determination method according to any one of claims 1 to 11.

13. An inspection method according to claim 12, when dependent on claim 5, wherein the multi-element ultrasonic probe successively emits an ultrasonic wave with each delay law adapted for each desired location considered.

14. Electronic device for determining a delay law for the ultrasonic inspection of a weld having grains, the electronic device being suitable for: - receiving information about the weld (10) or other welds, the information comprising the arrangement of at least a portion of the grains of the weld or said other welds and a respective orientation of said grains, - modeling the weld (10) in the form of a digital model (300), the digital model (300) being based on the orientation of the grains of the weld (10) or deduced from the information received on the other welds, - positioning a defect (306) in the digital model (300) at a desired focusing location, - simulating in the digital model (300) a propagation of an ultrasonic wave from a location through the weld to the defect at the desired location and of a resulting reflected wave, - determine the resulting reflected wave flight times, and - apply a time reversal on the flight times to determine a suitable delay law to focus an ultrasonic wave from the multi-element probe at the desired location from the localization.

15. Computer program product comprising instructions for carrying out the steps of a method according to any one of claims 1 to 13.

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