As the control valve of the propulsion system engine, the electromagnetic valve play an important role in attitude and orbit control for spacecraft. While the leak of the electromagnetic valve has always been the main cause of the failure of the propulsion system. Due to the shell’s complex structure as well as many seam weld on it, the normal NDT is unfit to check out some small cracks and mic...

Significant stress concentrations in welded structures typically arise at crack like defects and at weld toes. The geometry of the weld toe is therefore one of the primary geometrical features that control the fatigue life of welded components. This work is focused on evaluating three non-destructive methods to measure the weld toe radius: Weld Impression Analysis (WIA), Laser Scanning Profilin...

The trend in strong weld metals is towards microstructures dominated by low carbon martensite. The role of oxide particles introduced into the metal during welding then becomes uncertain. The particles do not seem to affect the nucleation or growth of martensite. This is probably because this phase forms at relatively large driving forces and therefore does not rely on heterogeneous nucleation ...

As is well known that sensing and measuring the weld pool surface is very important to design intelligent welding machines which is able to imitate a skilled human welder who can choose suitable welding parameters. Therefore, in this paper, we concentrate the problem of weld pool surface 3D reconstruction, which is a key issue in intelligent welding machines development. Firstly, the framework ...

Characterization of flaws of weld bead is imperative for high-quality welding. Methods of weld bead inspection include radiographic, ultrasonic and vision inspection. However, such methods are costly and time consuming. The proposed sensor is light, low-cost and fast. This paper summarizes our work on weld bead monitoring and defect detection using an electromagnetic sensor. Measurements are ac...

Rotary friction welding (RFW) is used in the production of drill pipes for solid mineral prospecting. The need creation lightened strings high-speed diamond drilling ultradeep wells dictates necessity a greater focus on study weld zone and setting RFW technological parameters. This paper presents results experimental studies welded joint pipe H standard size according to ISO 10097, made 30ХГСА ...

In this Part II, a thorough investigation of the melting of the electrode; the droplet formation, detachment, transfer and impingement onto the workpiece, and the weld-pool formation and dynamics was conducted. The transient melt-flow velocity and temperature distributions in the droplet and in the weld pool were calculated. The resulting crater in the weld pool and the weld-pool oscillation du...

Resistance spot welding process is one of the very useful and widely utilized joining processes in automobile industry due to its high working speed, high productivity, flexibility and economical cost operation. In this paper various optimization techniques like Taguchi method, Artificial neural network (ANN), Genetic algorithm (GA) etc. and their applications are discussed to get the optimum w...

Weld overlay of piping was first used as a method to repair components of simple configurations which were known to contain cracking. An adequate ultrasonic examination of these geometries can be achieved by using a few conventional search units. Currently the application of pre-emptive weld overlays as a mitigation technique and/or to improve the examination surface condition for more complex ...

To satisfy the need of polymer connection in lightweight automobiles, a study on laser transmission spot welding using polymethyl methacrylate (PMMA) is conducted by using an Nd:YAG pulse laser. The influence of three variables, namely peak voltages, defocusing distances and the welding type (type I (pulse frequency and the duration is 25 Hz, 0.6 s) and type II (pulse frequency and the duration...