Devices, systems and methods of detecting defects in workpieces

Abstract

Device and method for detecting a defect in a workpiece with a broadband transducer ( 10 ), a driving circuit connected to the transducer to operate the transducer in a actuator mode, a signal output circuit connectable to operate in a sensor mode, a control for selectively connecting the transducer to the driving circuit or signal output circuit wherein the driving circuit includes at least a pair of oscillators for generating signals of at least frequencies F 1 and F 2 and a summer for summing the signals to provide a driving circuit for the transducer.

1 . A device for use in detecting a defect in a workpiece including:
 (a) a broadband transducer for contacting the workpiece;   (b) a driving circuit connectable to the transducer to operate the transducer in an actuator mode;   (c) a signal output circuit connectable to operate the transducer in a sensor mode; and   (d) a control for selectively connecting the transducer to the driving circuit or the signal output circuit, wherein the driving circuit includes at least a pair of oscillators for generating signals of at least frequencies Fi and F 2  respectively and a summer for summing the signals Fi, F 2  to provide a driving signal for the transducer   
     
     
         2 . A device as claimed in  claim 1  further including a data interface. 
     
     
         3 . A device as claimed in  claim 2  wherein a microprocessor forms both the control and the interface. 
     
     
         4 . A device as claimed in  claim 3  wherein the microprocessor is linked to at least one of an analogue-to-digital convertor; a digital-to-analogue convertor; data memory; a wireless connection and communication link. 
     
     
         5 . A device as claimed in  claim 4  wherein the memory is addressable either by the microprocessor or an external clock counter. 
     
     
         6 . A defect detecting system including an array of devices, as claimed in  claim 1 , and a central computer or other electronics linked to the interface of each device by a communication link. 
     
     
         7 . A system as claimed in  claim 6  wherein the computer is arranged for generating control signals to be sent by the communication link to instruct the controls of the respective devices to operate the associated transducer in an actuator or sensor mode. 
     
     
         8 . A system as claimed in  claim 7  wherein the array is in the form of a grid for extending across a workpiece; wherein the computer or other electronics operates the devices in a time reversal mode and the location of the time reversed defect generated signals is determined by determining the location of the sensor nearest the focus of the time reversed defect generated signals. 
     
     
         9 . A system as claimed in  claim 6  wherein the devices are embedded in a workpiece. 
     
     
         10 . A system as claimed in  claim 6  including a dedicated sensor. 
     
     
         11 . A system as claimed in  claim 6  wherein the system includes a monitor for monitoring the signal received by at least one device, in sensor mode, and for protecting harmonics or intermodulation products in the sensor output signal and producing an output in response to that detection. 
     
     
         12 . A system as claimed in  claim 1  further including a comparator for detecting if the amplitude of the output signal exceeds a first predetermined level. 
     
     
         13 . A system as claimed in  claim 12  wherein the comparator detects when the amplitude of the output signal exceeds a second predetermined level. 
     
     
         14 . A system as claimed in  claim 12  wherein the comparator provides and indication when a predetermined level is exceeded. 
     
     
         15 .- 31 . (canceled) 
     
     
         32 . A method of detecting micro-cracking or de-lamination in a workpiece including: inputting a sonic or ultrasonic impulse or signal into the workpiece; detecting the resultant signal in the workpiece; monitoring the signal to detect the appearance of the third harmonic of the impulse frequency and thereby detecting the presence of micro-cracking and
 further monitoring the signal to detect the subsequent reduction in or disappearance of the third harmonic and thereby detecting the imminent transition to structural failure.   
     
     
         33 . A method as claimed in  claim 32  wherein the input impulse is a high power impulse. 
     
     
         34 . A method as claimed in  claim 32  wherein the input signal comprises a sweep between two frequencies. 
     
     
         35 . A method of detecting a defect in a workpiece including inputting into the workpiece at least two signals at respective frequencies Fi and F 2  to create vibrations in the workpiece, detecting a resultant output at another location on the workpiece with wideband receiver and monitoring one or more of the resultant harmonics, overtones or sidebands to determine the presence or absence of a defect wherein the at least two frequencies Fi and F 2  are inputted simultaneously by a single transmitter. 
     
     
         36 . A method as claimed in  claim 35 , wherein the sidebands are monitored by determining the modulation index. 
     
     
         37 .- 43 . (canceled)