Inspection of Composite Rocket Nozzle

Product Applications

Rocket nozzles are manufactured with composite material having good structural and heat resistance capabilities.

Because of the severe working environment of those parts, structural integrity has to be assured. Delaminations and inclusions have to be detected. Conventional ultrasound techniques are limited because of very bad ultrasonic penetration.

The use of low-frequency transducers in pulse-echo and transmit/receive configurations combined with the use of phased-array probes ensures good inspection.

A state-of-the-art mechanics with a double oblique arm and a turntable ensure reliable inspection of parts.

Rocket nozzle inspection system.

Performance and Objectives of the Inspection

Full volume ultrasonic inspection of parts for delamination
Detection of delamination and inclusion
Part size:
Height: 300 mm to 1400 mm
Inner diameter: 100 mm to 1500 mm
Thickness: 10 mm to 95 mm
Material: composite
Shape: conic
Rotation speed: 7 r/min
Two conventional 1-MHz probes
One 64-element phased-array probe
Electronics: Tomoscan FOCUS 16:64
Wedge with membrane
Water recirculation system

Description of the Inspection System
The nozzle is mounted on a turntable composed of mandrels adjustable to the diameter of the nozzle.

The ultrasonic probes are mounted on the oblique vertical axis. The angle of the arm can be adjusted.

The water is recirculated through the irrigation system. The loss of water is minimal.

Parts to Inspect
Composite parts (very noisy material)

Part size
Height: 300 mm to 1400 mm
Inner diameter: 100 mm to 1500 mm
Thickness: 10 mm to 95 mm

Defects to Be Detected

Delamination
Inclusion
SDH of 1 mm to 5 mm of diameter for calibration purpose

Close-up of the probe assembly (conventional probes).

Mechanical specifications:

Axis	Stroke	Max. speed	Resolution/repeatability
Z	1000 mm	100 mm/s	0.025 mm/0.25 mm
W	360°	7 r/min	0.01°/0.1°

Material Requirements
Tomoscan FOCUS 16:64 ultrasonic phased-array system
MCDU-02 motor drive with a joystick
TomoView software
Computer
Two 1-MHz conventional probe
One 64-element phased-array probe
Local immersion wedges with membranes
Air compressor

Close-up of the turntable.

Analysis and Reporting Using TomoView Software
All of R/D Tech ultrasound products, whether using phased-array, ultrasound, or EMAT technology, share the same data acquisition and analysis software. The software is PC-based and can be used on standard PCs ranging from simple laptop to powerful multiprocessor workstation.

Data Acquisition and Analysis

Software setup and control of the acquisition system
Easy programming of focal laws for sector, linear, and depth scans, as well as dynamic depth focusing
Automatic volumetric settings
Real-time display of A-scans, B-scans, C-scans, and D-scans
Real-time display of phased-array sector scans
Real-time display of angle-corrected top, side, and end views from either A-scan, C-scan, or peak data
Real-time imaging with part drawing overlay
Capability to proceed to data analysis simultaneously with data acquisition.
Measurement cursors and time-of---flight diffraction measurement tools
Scanner control for automated inspections
Synthetic aperture focusing technique (SAFT)

GRAPHIC: Tuyère_01.eps
CAPTION: Typical display of TomoView.

Phased-array probe asembly with water wedge and membrane.

Cross-section of the part.

Other Aerospace Applications

Inspection of Titanium Billets
R/D Tech has developed a phased array technique with the use of complex Fermat-shaped array probes to inspect billet size ranging from 3 to 14 inches in diameter. The use of outstanding technology as Dynamic Depth Focusing, which keeps the beam focused over a large range, sets the path for minimum beam quantity to inspect the whole billet.
The detection of FBH no 2 (0.8 mm) is done according to industry requirements and detection of small holes as FBH no 1 (0.4 mm) is successful.
Customized software was especially designed for this application.

Thin Welds and Friction Stir Welds
The FSW technique was developed as a method to join materials that are difficult to fusion weld, such as aluminum alloys. The quality of the weld is very high; however, the process may generate small, tight defects that are hard to detect.

The best method to inspect FSW is to use the ultrasonic phased array technique. Because of the weld shape, raster scanning is impossible; but with phased arrays, inspection of the entire weld volume is done in a single-pass scan. Phased arrays also permit lateral scanning to detect transverse defects. Inspection angle optimization maximizes the probability of detection. The increased number of zones covered by phased arrays provides accurate flaw sizing and location. High speed, accuracy, and versatility make phased arrays the choice technique for FSW inspection.