Method and system for assessing quality of spot welds

A method of analyzing an A-scan ultrasound image to reduce the angular dependence of matrix transducer elements and improve C-scan image quality, wherein the ultrasound image represents a surface sample of a spot-weld joint, the method of comprising the steps of:

• locating the positions and amplitudes of surface peaks in the ultrasound image;
• measuring a global tilt of the surface sample with respect to the transducer surface, using weighted bilinear regression;
• using an empiric tilt-amplitude calibration curve to compute an amplitude drop compensation factor based on the global tilt;
• and
• multiplying the value of each sample point in each A-scan by the amplitude drop compensation factor, such that the factor is applied for all transducer channels;
• wherein subsequently acquired C-scan images have more stable amplitudes that are less dependent on the transducer tilt than images acquired using un-compensated transducers.

A method of compensating for variations in the velocity of sound in different media in the analysis of ultrasound images, wherein an ultrasound transducer system is used to acquire ultrasound images, the method comprising the steps of:

• acquiring a set of A-scan ultrasound images;
• shifting each A-scan along its time axis so that the position of surface peaks for becomes the same for all ultrasound transducer channels;
• building a C-scan image from the A-scan images, wherein the C-scan image reflects the shifting;
• and
• displaying the C-scan image.