In the paper, a modular climbing-wall mobile robot with four magnetic wheels is presented. It can move on the vertical steel wall and inspect the weld seam. First, the structure of the mobile robot is analyzed. It is modular, which consists of a light manipulator module, an ultrasonic probes module and a weld testing sensors module. Then, the magnetic wheels are designed and analysed. One magne...

To have a safe and reliable railway system, nondestructive testing (NDT) methods are necessary to be implemented in order to avoid catastrophic failures. NDT methods also provide a powerful tool for proper maintenance of valuable railway system assets. Among various NDT methods, ultrasonic testing (UT) along with magnetic particle testing (MPT) and eddy current testing (ECT) play significant ro...

APRIL 2004 -S 140 ABSTRACT. This article analyzes the mechanics of the metal ultrasonic welding process as a basis for a new solid free-form fabrication technology. Three-dimensional prototypes are constructed by ultrasonic welding of overlaid metal foil laminations, followed by contour cutting of the 2-D layers. This was implemented in the laboratory by a computer-automated ultrasonic welding ...

The development and fabrication of fusion reactor components utilize different grades of stainless steel materials and different welding techniques. Major candidates are TIG welding, Laser welding and Electron beam welding and Narrow Gap TIG welding. The weld joints quality evaluation and their mechanical properties are to be analyzed for performance of these developed components. The welded jo...

This paper describes a threefold method of testing the performance of an array-based ultrasonic tool for nondestructive testing of spot welds. The tool is described in its capabilities, use, and advantages over existing counterparts. Performance testing is not only described, but results from carrying out the testing are documented as well. The three performance testing methods include the use ...

Delayed coke drums are operated under severe conditions of cyclic heating and forced cooling that apply repetitive thermal stresses to the drum walls. It has long been recognized that the ultimate failure mechanism for coke drums is weld cracking due to low cycle fatigue caused by these thermal stresses. It is also known that coke drums distort and bulge in service and that these bulges can be ...

An advanced computerized complex for Ultrasonic Peening (UP) of parts and welded elements based on piezoelectric transducers was developed recently. The complex consists of a compact ultrasonic transducer, generator and a laptop with an Expert System for UP optimum application: maximum possible increase in fatigue life of parts and welded elements with minimum cost, labor and power consumption....

Heating of workpieces plays an influential role in ultrasonic welding. In the present paper, an attempt was made to further understand the heating mechanism during ultrasonic welding. Three equations in this regard were derived. Firstly, based on the viscoelastic properties of the workpieces, the equation governing heat generation was derived. Secondly, a thermal equivalent circuit model was de...

We review recent work on the application of fluctuation analyses of time series for pattern classification in nondestructive materials inspection. These analyses are based on the evaluation of time-series fluctuations across time intervals of increasing size, and were originally introduced in the study of fractals. A number of examples indicate that this approach yields relevant features allowi...