Designed for speed, portability, and performance, RapidScan2 has been developed as a versatile and user-friendly A, B and C-scan inspection
instrument.

Using novel, proprietary, rubber-coupled array sensors, immersion quality A-scan data is recorded very quickly. Powerful gating and evaluation tools ensure that the ultrasonic signals can be analysed and interpreted to the fullest extent. RapidScan2 operates in pulse-echo mode suitable for inspecting medium to large areas. The high resolution C-scans show time of flight and amplitude data, simultaneously displaying both A and B-scans live.

The system includes a 128-channel multiplexing pulser/receiver module; state of-the-art data capture electronics and a standard PC laptop, housed in a low-profile rugged plastic enclosure. The instrument operates through a user-friendly Windows based interface.

RapidScan2 has been successfully employed for inspecting a range of materials and structures. A simple parallel may be drawn to conventional A-scan inspections; if a part can be inspected with a ¼”, single element transducer then it can often be inspected using RapidScan2. Exceptions to this rule are compound curves, complex geometry and parts with restricted access. Common application areas are: the inspection of metal and carbon fibre composite structures, detecting defects such as delaminations, cracks, flaws, corrosion, porosity, foreign material and bond integrity.

Thickness Mapping

A number of applications simply require the thickness of a part to be measured. Such applications include the detection and measurement of corrosion, erosion and the verification of manufacturing dimensions. Often performed on metal components, the gating options available provide the necessary tools for the inspection. Several RapidScan2 features are useful to optimise and simplify the inspection, including interface synchronisation, echo-to-echo time of flight (depth) measurement, Bscan display and multiple C-scan representations that may be viewed simultaneously. All of these and more enable comprehensive evaluation of a part for the accurate assessment and measurement of loss of material.

Bond Inspection

There are a vast range of bonded structures that require inspection, and as such it is not possible to produce a generic method suitable for all. Thin metallic parts can mask the A-scan data with multiple reflections whereas, at the opposite end of the spectrum, composite materials and adhesives may exhibit very high attenuation making the back wall echo difficult to identify. In several cases though, bond inspection is both feasible and simple, when the echoes from the bond-line and the back wall are easily identified and distinguished. For bonded material (good bond), there is a strong echo from the back wall of the material and only a small echo from the bond-line. As the percentage area that is bonded beneath the transducer reduces (partial bond) so the amplitude of the echo from the bond-line increases and the amplitude of the back wall echo reduces. If there is no bond beneath the transducer (disbond) then only an echo from the bond-line is received and the amplitude of the back wall echo reduces. If there is no bond beneath the transducer (disbond) then only an echo from the bond-line is received.

Delamination Detection

A common application for RapidScan2 is the inspection of carbon fibre composite components to detect delaminations and large voids. BVID (barely visible impact damage) is easily visualised, showing the full extent of the sub-surface defects. Detection and interpretation is simplest with time of flight C-scan data, recording the depth of the largest echo beneath the front face, measured relative to the interface gate.

The inspection of composite material usually requires implementation of TCG (time corrected gain). TCG sets variable receiver gain over the time base of the A-scan, compensating for signal attenuation. When a TCG curve is correctly implemented, the amplitudes of echoes from reflectors of the same size at different depths in the same material are equal. The use of TCG optimises the near surface resolution of the inspection such that defects as near as 0.5mm from the top surface can be detected. Once several C-scans have been recorded they may be assembled into

a single compound scan, referred to as a T-scan (tiled scan). Within a T-scan, individual C-scans can be easily added, moved and rotated in order to assemble a single, complete scan. Overlapping areas can be blended using the highest amplitude data for each point or set to overlay one another. C-scans are imported either with or without A-scan data. Importing with the full A-scan data, the T-scan may be re-gated to optimise the set up. Similar to the C-scan, the T-scan data (such as absolute amplitude, time of flight data, etc.) may be toggled to obtain multiple scan types as well as adjustment of the colour maps. The origin for all the coordinates may be reset to anywhere on the scan, which is useful for measuring the location of defects relative to a known features on the scan.

Multiple tools are available for complete analysis, evaluation and reporting. Defects are marked on the scans as circles, rectangles, ellipses or even
arbitrary shaped polygons. Size, shape and statistical data for marked defects are available. Individual defects are automatically named for reference. Scans may be saved, exported or printed either as a scaled image or at actual size over multiple pages to lay the print over the part and accurately locate defects.

Flaw Detection

Small internal flaws typically occur in both composite materials and metals. Examples include foreign bodies (release film), small voids and porosity. Inspection methods monitor the amplitude of the back wall echo and/or the amplitude of internal echoes. For parts of non-constant thickness, conventional gates are difficult to set up and interpret, to guarantee the full internal thickness range is inspected. It is often only possible to inspect the thinnest region. Within RapidScan2 it is possible to reference the width of a gate to another (such as the back wall echo). This feature enables a gate to maintain its position from just below the front face to just above the back wall ensuring the full internal thickness is always monitored. Variable width gates are ideal for detecting low amplitude, internal defects.

Acceptance criteria for amplitude based inspections are commonly specified in decibels. Such methods can be implemented through the use of a logarithmic colour map, easily generated using the colour map editor. For the example shown, colour blocks are set to 0dB to -6dB = light green, -6dB to -12dB = yellow, -12dB to -18dB = orange, < -18dB = red. With this colour map, the upper limit can be easily scaled by adjusting the
high value whilst preserving the relative decibel measurements.