Ultrasonic flaw detecting apparatus, ultrasonic transducer, and ultrasonic flaw detecting method

A transducer main body has, on a front end side thereof, an oscillating plane having a bent shape in a side view and corresponding to a larger-diameter curved surface formed at a bend of a laminated part. Over the oscillating plane of the transducer main body, a plurality of piezoelectric oscillators is distributed in a matrix in a bent direction and a width direction. In each oscillator group, a controlling unit switches the piezoelectric oscillators to transmission and reception piezoelectric oscillators by turns in the width direction according to a preset transmission/reception pattern and processes a received signal from the reception piezoelectric oscillator according to an aperture synthesis method.

TECHNICAL FIELD

The present invention relates to an ultrasonic flaw detecting apparatus for detecting an internal defective state at a bend of a laminated part made of composite materials, an ultrasonic transducer that is a principal component of the ultrasonic flaw detecting apparatus, and the like.

BACKGROUND ART

When detecting an internal defective state at a bend of a laminated part made of composite materials such as fiber-reinforced plastics (FRP), an ultrasonic transducer that transmits and receives ultrasonic waves is usually used.

The ultrasonic transducer has a transducer main body that has, on a front end side thereof, an oscillating plane having a bent shape in a side view and corresponding to a larger or smaller diameter curved surface formed at the bend of the laminated part. The oscillating plane of the transducer main body has a plurality of oscillators arranged in a bent direction of the oscillating plane of the transducer main body. Each oscillator transmits an ultrasonic wave toward the bend of the laminated part and receives a reflected wave from the bend of the laminated part. The oscillators are electrically connected to a controlling unit.

When detecting an internal defective state at the bend of the laminated part, the ultrasonic transducer is moved relative to the laminated part so that the oscillating plane of the transducer main body faces the larger or smaller diameter curved surface formed at the bend of the laminated part. The plurality of oscillators transmit ultrasonic waves toward the bend of the laminated part and receive reflected waves from the bend of the laminated part. According to received signals from the plurality of oscillators (flaw detecting signals from the ultrasonic transducer), the controlling unit nondestructively detects an internal defective state at the bend of the laminated part.

Related arts concerning the present invention are disclosed in, for example, Japanese Unexamined Patent Application Publications No. 2003-90829 and No. H06-18488.

SUMMARY OF INVENTION

Problems to be Solved by Invention

If the number of layers of the laminated part is increased, the bend of the laminated part becomes thicker. Then, the intensity of reflected ultrasonic waves becomes weaker, so that the ultrasonic transducer may insufficiently detect the reflected waves from an internal defect at the bend of the laminated part. To deal with this, a reflected-wave detecting sensitivity of the oscillators may be increased. This, however, results in increasing noise echoes to deteriorate an S/N ratio (a ratio of defect echoes to noise echoes) of flaw detecting signals from the ultrasonic transducer (received signals from the oscillators).

There is, therefore, a problem that a detecting accuracy of an internal defective state at a bend of a laminated part will not improve if the number of layers of the laminated part is increased to thicken the bend of the laminated part.

The present invention provides an ultrasonic flaw detecting apparatus, an ultrasonic transducer, and the like capable of realizing a high S/N ratio and improving a flaw detecting accuracy.

Means to Solve Problem

According to a first aspect of the present invention, the ultrasonic flaw detecting apparatus for detecting an internal defective state at a bend (curved portion) of a laminated part made of composite materials includes an ultrasonic transducer that transmits and receives ultrasonic waves and a controlling unit that, according to flaw detecting signals (received signals) from the ultrasonic transducer, detects and processes the internal defective state at the bend of the laminated part. In more detail, the ultrasonic transducer includes a transducer main body that has, on a front end side thereof, an oscillating plane having a bent shape in a side view and corresponding to a larger- or smaller-diameter curved surface formed at the bend of the laminated part and a plurality of oscillators distributed over the oscillating plane in a matrix in a bent direction (curved direction) of the oscillating plane of the transducer main body and a width direction of the transducer main body (i.e., a direction orthogonal to a side face of the transducer main body), to transmit ultrasonic waves toward the bend of the laminated part and receive reflected waves from the bend of the laminated part. The controlling unit successively carries out, for each oscillator group formed of a width-direction row of the plurality of oscillators, switching the oscillators in the oscillator group to oscillators for transmission and reception by turns in the width direction according to a preset transmission/reception pattern and processing a received signal from the reception oscillator according to an aperture synthesis method.

In the descriptions of the specification and claims of this application, the “internal defective state” means the presence or absence of an internal defect, the size and location of the internal defect, and the like. The “bent shape in a side view corresponding to a curved surface” means a shape that extends along a curved surface and is bent when seen from a side thereof, or a shape that extends along an inversion of the curved surface. The “transmission oscillator” is one selected from the oscillators, to transmit an ultrasonic wave and the “reception oscillator” is one selected from the oscillators, to receive a reflected wave.

According to a second aspect of the present invention, the ultrasonic transducer for use in detecting an internal defective state at a bend (curved portion) of a laminated part made of composite materials by transmitting and receiving ultrasonic waves includes a transducer main body that has, on a front end side thereof, an oscillating plane having a bent shape in a side view and corresponding to a larger- or smaller-diameter curved surface formed at the bend of the laminated part and a plurality of oscillators distributed over the oscillating plane in a matrix in a bent direction of the oscillating plane of the transducer main body and a width direction of the transducer main body, i.e., a direction orthogonal to a side face of the transducer main body, to transmit ultrasonic waves toward the bend of the laminated part and receive reflected waves from the bend of the laminated part.

According to a third aspect of the present invention, the ultrasonic flow detecting method of detecting, with the use of the ultrasonic transducer of the second aspect, an internal defective state at a bend (curved portion) of a laminated part made of composite materials includes moving the ultrasonic transducer relative to the laminated part so that the oscillating plane of the transducer main body faces a larger- or smaller-diameter curved surface formed at the bend of the laminated part, interposing an acoustic medium between the bend of the laminated part and the ultrasonic transducer, grouping each row in the width direction of the plurality of oscillators into an oscillator group, switching the oscillators in a given one of the oscillator groups to oscillators for transmission and reception by turns in the width direction according to a preset transmission/reception pattern, transmitting an ultrasonic wave from the transmission oscillator into the bend of the laminated part, receiving a reflected wave from the bend of the laminated part with the reception oscillator, processing a received signal from the reception oscillator according to an aperture synthesis method, successively carrying out, for each of the remaining oscillator groups, switching the transmission and reception oscillators from one to another in the width direction among the oscillators in the oscillator group, and processing a received signal from the reception oscillator according to the aperture synthesis method, thereby detecting the internal defective state at the bend of the laminated part.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the present invention will be explained with reference toFIGS. 1 to 7.

As illustrated inFIG. 7, an ultrasonic flaw detecting apparatus1according to an embodiment of the present invention detects an internal defective state at a bend (curved portion) Wc of a laminated part W made of composite materials and includes an ultrasonic transducer3that transmits and receives ultrasonic waves S (refer toFIG. 2) through an acoustic medium M and a controlling unit that, according to flaw detecting signals from the ultrasonic transducer3, detects and processes the internal defective state at the bend Wc of the laminated part W. The laminated part W of the embodiment of the present invention is an airplane part such as a casing made of fiber-reinforced plastics (FRP), the bend Wc of the laminated part W is a base of a flange of the casing, and the acoustic medium M is a liquid such as water, or a solid.

The details of a configuration of the ultrasonic transducer3according to an embodiment of the present invention will be explained.

As illustrated inFIGS. 1 to 4, the ultrasonic transducer3has a transducer main body7. The transducer main body7has, on a front end side thereof, an oscillating plane9that has a bent shape in a side view to follow a larger-diameter curved surface formed at the bend Wc of the laminated part W. Instead of the oscillating plane9having the bent shape in a side view to follow the larger-diameter curved surface formed at the bend Wc of the laminated part W, the transducer main body7may have an oscillating plane having a shape to follow a smaller-diameter curved surface formed at the bend Wc of the laminated part W.

Over the oscillating plane9of the transducer main body7, a plurality (8×8 pieces according to the embodiment of the present invention) of piezoelectric oscillators11are distributed in a matrix manner in a bent direction AD of the oscillating plane9of the transducer main body7and a width direction of the transducer main body7, i.e., a direction BD orthogonal to a side face of the transducer main body7. Each of the piezoelectric oscillators11transmits an ultrasonic wave S toward the bend Wc of the laminated part W and receives a reflected wave S from the bend Wc of the laminated part W. Each piezoelectric oscillator11is made of composite materials or ceramics and is connected to the controlling unit5. According to the embodiment of the present invention, eight piezoelectric oscillators11arranged in the width direction BD form a piezoelectric oscillator group11G, and therefore, there are eight piezoelectric oscillator groups11G.

Inside the transducer main body7, there is arranged a damper (not illustrated) to absorb excessive oscillations of the piezoelectric oscillators11.

The details of the controlling unit5according to the embodiment of the present invention will be explained.

As illustrated inFIG. 1, the controlling unit5has a signal generating unit13that supplies a drive signal (a transmission signal) to the piezoelectric oscillators11and a receiver15that amplifies received signals from the piezoelectric oscillators11(flaw detection signals from the ultrasonic transducer3). The signal generating unit and piezoelectric oscillators11are connected to a switching circuit17. The switching circuit17is capable of switching a selected one of the piezoelectric oscillators and the signal generating unit13to a connected state and a disconnected state. The receiver15and piezoelectric oscillators11are connected to a signal detecting circuit19. The signal detecting circuit19is capable of switching a selected one of the piezoelectric oscillators11and the receiver15to a connected state and a disconnected state.

More precisely, as illustrated inFIG. 5, the switching circuit17sequentially switches the piezoelectric oscillators11in each piezoelectric oscillator group11G to a transmission piezoelectric oscillator11(T) in eight steps in the width direction BD by use of a preset first transmission/reception pattern. Similarly, the signal detecting circuit19uses the first transmission/reception pattern to sequentially switch between the piezoelectric oscillators11in each piezoelectric oscillator group11G to reception piezoelectric oscillators11(R) in eight steps in the width direction BD.

Instead of the first transmission/reception pattern, a preset second transmission/reception pattern illustrated inFIG. 6may be used to sequentially switch between the piezoelectric oscillators11in each piezoelectric oscillator group11G to transmission and reception piezoelectric oscillators11(transmission piezoelectric oscillator11and reception piezoelectric oscillators11) in four steps in the width direction BD. When the second transmission/reception pattern is used, the transmission piezoelectric oscillator11is located in an intermediate area in the width direction BD on the oscillating plane9of the transducer main body7and the reception piezoelectric oscillators11(R) sandwich the transmission piezoelectric oscillator11(T) from each side in the width direction BD.

The receiver15is connected to a signal processing unit21. The signal processing unit21successively processes received signals, which are received by the reception piezoelectric oscillators11and are amplified, according to an aperture synthesis method (a superposing process). The aperture synthesis method uses system information pieces such as a positional relationship between the ultrasonic transducer3and the bend Wc of the laminated part W, a flaw detecting frequency of the ultrasonic transducer3, acoustic velocities in the laminated part W and acoustic medium M, and the like. The signal processing unit21is connected to a display unit (not illustrated) that combines a process result (such as an aperture synthesis image) of the signal processing unit21with the positional information of the transducer3and displays a combined result.

An ultrasonic flaw detecting method according to an embodiment of the present invention and effect thereof will be explained.

The ultrasonic transducer3is moved relative to the laminated part W so that the oscillating plane9of the transducer main body7faces the large-diameter curved surface formed at the bend Wc of the laminated part W. With the acoustic medium M interposed between the bend Wc of the laminated part W and the ultrasonic transducer3, an ultrasonic wave S is transmitted from a transmission piezoelectric oscillator11and is made incident to the bend Wc of the laminated part W, and a reflected wave S is received by a reception piezoelectric oscillator11. In more detail, the switching circuit17and signal detecting circuit19are used to sequentially switch between the piezoelectric oscillators11in a given piezoelectric oscillator group11G to transmission and reception piezoelectric oscillators11in eight or four steps in the width direction BD according to the first or second transmission/reception pattern (refer toFIGS. 5 and 6). In each step, an ultrasonic wave S transmitted from the transmission piezoelectric oscillator11is made incident to the bend Wc of the laminated part W and a reflected wave S from the bend Wc of the laminated part W is received by the reception piezoelectric oscillator11(refer toFIG. 2). With respect to received signals from the reception piezoelectric oscillators11in the given piezoelectric oscillator group11G, the aperture synthesis method is carried out by the signal processing unit21.

Similarly, in each of the remaining piezoelectric oscillator groups11G, the switching circuit17and signal detecting circuit19are used to sequentially switch between the piezoelectric oscillators11to transmission and reception piezoelectric oscillators11in eight or four steps in the width direction BD according to the first or second transmission/reception pattern. With respect to received signals from the reception piezoelectric oscillators11, the aperture synthesis method is successively carried out by the signal processing unit21. In this way, for a circumferential partial area of the bend Wc of the laminated part W, the controlling unit5conducts a detecting process (a flaw detecting process) of detecting an internal defective state (the presence or absence of an internal defect, the size and location of the internal defect, and the like), thereby testing the internal defective state (finding flaws).

After detecting the internal defective state in the circumferential partial detection area at the bend Wc of the laminated part W, the ultrasonic transducer3is moved in a circumferential direction along the laminated part W and the processes mentioned above are repeated, to detect an internal defective state in the whole circumferential area at the bend Wc of the laminated part W.

Since the plurality of piezoelectric oscillators11are distributed over the oscillating plane9of the transducer main body7in a matrix manner in the bend direction AD and width direction BD, the switching circuit17and signal detecting circuit19can switch between the piezoelectric oscillators11in each piezoelectric oscillator group11G to piezoelectric oscillators11for transmission and reception. And the signal processing unit21can carry out the aperture synthesis method on received signals from the piezoelectric oscillators11for reception in each piezoelectric oscillator group11G. Even if the number of layers of the laminated part W is increased to thicken the bend Wc of the laminated part W, the ultrasonic transducer3can sufficiently and surely detect reflected waves S representing an internal defect at the bend W of the laminated part W without increasing a detective sensitivity on reflected waves S received by the piezoelectric oscillators11for reception.

Accordingly, the embodiment of the present invention is capable of reducing noise echoes, heightening an S/N ratio of flaw detecting signals from the ultrasonic transducer3(received signals from reception piezoelectric oscillators11), and improving a detecting accuracy (a flaw detecting accuracy) of an internal defective state at the bend Wc of the laminated part W even if the number of layers of the laminated part W is increased to thicken the bend Wc of the laminated part W.

Particularly when based on the second transmission/reception pattern illustrated inFIG. 6, the embodiment is capable of limiting a detecting area (a flaw detecting area) of the ultrasonic transducer3and carrying out the aperture synthesis method on received signals from reception piezoelectric oscillators11used to receive reflected waves S, thereby improving a detecting accuracy of an internal defective state at the bend Wc of the laminated part W.

As mentioned above, the first and second aspects of the present invention move the ultrasonic transducer relative to a laminated part so that the oscillating plane of the transducer main body faces a larger- or smaller-diameter curved surface at a bend of the laminated part. Thereafter, the controlling unit switches between the oscillators in a given oscillator group to oscillators for transmission and reception in the width direction of the transducer according to a transmission/reception pattern, transmits an ultrasonic wave from the transmission oscillator into the bend of the laminated part, and receives a reflected wave from the bend of the laminated part with the reception oscillator. Thereafter, the controlling unit carries out the aperture synthesis method on a received signal from the reception oscillator. In this way, the controlling unit achieves a detecting process of detecting an internal defective state at the bend of the laminated part, thereby finding the internal defective state at the bend of the laminated part.

In the ultrasonic transducer, the oscillators are distributed over the oscillating plane of the transducer main body in a matrix manner in the bent and width directions, and therefore, the controlling unit can switch between the oscillators in each oscillator group to oscillators for transmission and reception in the width direction according to a transmission/reception pattern and successively process received signals from the reception oscillators according to the aperture synthesis method. Even if the number of layers of the laminated part is increased to thicken the bend of the laminated part, the ultrasonic transducer can sufficiently and surely detect reflected waves representing an internal defect at the bend of the laminated part without increasing a detective sensitivity on the reflected waves received by the reception oscillators.

According to the third aspect of the present invention, the oscillators are distributed over the oscillating plane of the transducer main body of the ultrasonic transducer in a matrix manner in the bent and width directions. Accordingly, as mentioned above, the controlling unit can switch between the oscillators in each oscillator group to transmission and reception oscillators in the width direction according to a transmission/reception pattern and successively process received signals from the reception oscillators according to the aperture synthesis method. Even if the number of layers of the laminated part is increased to thicken the bend of the laminated part, the ultrasonic transducer can sufficiently and surely detect reflected waves representing an internal defect at the bend of the laminated part without increasing a detective sensitivity on the reflected waves received by the reception oscillators.

According to the present invention, even if the number of layers of the laminated part is increased to thicken the bend of the laminated part, the ultrasonic transducer can sufficiently and surely detect reflected waves representing an internal defect at the bend of the laminated part, and therefore, the present invention can reduce noise echoes, heighten an S/N ratio of flaw detecting signals from the ultrasonic transducer, and improve a detecting accuracy of an internal defective state at the bend of the laminated part.

The present invention is not limited to the above-mentioned embodiments but is achievable in various forms. The scope of right covered by the present invention is not limited by these embodiments.

UNITED STATES DESIGNATION

In connection with United States designation, this international patent application claims the benefit of priority under 35 U.S.C. 119(a) to Japanese Patent Application No. 2010-237649 filed on Oct. 22, 2010, the entire content of which is incorporated by reference herein.