The Ultrasonic Phased Array Inspection Technology Used in Tubular Joint Welds of Offshore Platform Structures
Aimed at the practical requirement of tubular joint wel ds inspection of offshore platform structures, the ultrasonic phased array inspection algorit hm for offshore platform structures is proposed in this paper, and the ultrasonic phased array inspec tion system for offshore platform structures is developed. The experiment of tubula r joint model is performed with the ultrasonic phased array inspection system for offshore platform structures, the flaws characteristic could be exactly estimated and the flaw s size could be measured through ultrasonic phased array inspection software system. Expe riment results show that the ultrasonic phased array inspection algorithm for offshor e platform structures is feasible, the ultrasonic phased array inspection system could detect fl aws in tubular joint model, the whole development trend of flaws is factually imaging by the ul trasonic phased array inspection technology of offshore platform structures.
Groundwork for Rail Flaw Detection Using Ultrasonic Phased Array Inspection
An apparent increase in the detectability of certain flaws results when the ultrasonic inspection beam was oriented off the longitudinal axis of railroad rail. Here, artificial reflectors were used to better define the extent of material “seen” by inspection beams, and determine how surface curvature might affect the inspection. Presumably, such information could be useful for suggesting optimum positioning of linear array probes in testing, and help determine the validity of simulation models of this inspection for various cases.
Active profiling and polishing for efficient control of material removal from large precision surfaces with moderate asphericity
We present the development of an active fabrication technology for controlling material removal on large precision surfaces of moderate departure from a sphere. The underlying philosophy was established as an efficient solution to the challenging problem of fabricating secondary mirrors of up to nominally 2.5 m in diameter for modern 8 m class telescopes and beyond. The facility described comprises a CNC profiler, two contact profilometers, and a full size active polisher. The trial work-piece was a convex surface of 830 mm in diameter on a zero-expansion ceramic (`Cervit') blank – a 1/3 scale hyperbolic mirror for a proposed 2.5 m diameter f/7 secondary mirror for the 8 m Gemini telescope. Using software error-correction from profilometric metrology data, a factor of 2 improvement in generating the convex aspheric profile was achieved. An active loose-abrasive polishing process is also described, in which a full-size tool is configured to deliver variable, edgeless, sub-diameter removal-footprints. Real-time monitoring of process variables is described, and approximately 10% convergence in each polishing pass is reported.