Modal testing circuit board assembly of an electronic apparatus by laser vibrometry

The operating capacity and service life of printed circuit boards in various electronic equipment and devices depends on their ability to resist vibroacoustic loads, including vibration and acoustic noises. In this paper, non-contact laser vibrometry has been applied to perform the modal analysis of a circuit board assembly in order to identify its vulnerable spots and to find solutions to protect the assembly from external vibroacoustic loads. A broadband periodic chirp signal was used to excite vibration, which enabled a rapid generation of results. The paper provides data on eigenfrequencies, vibration velocity fields, and vibration displacement profiles. Frequency ranges have been determined in which eigenfrequencies with the highest vibration amplification lie. The obtained data can be used to develop a quality control technique for printed circuit boards and to optimize their construction as early as the design stage

Relationship between acoustic emission and microcrack formation in single crystals of Hadfield steel

Abrasive wear is not favorable for Hadfield steel. The connection between the acoustic emission signal and th

Theoretical investigation of the dynamics of friction stir welding process by movable cellular automaton method

The paper is devoted to development of a new approach to study of friction stir welding (FSW) process on the mesoscopic scale. This approach is based on computer-aided simulation by movable cellular automaton (MCA) method. In the framework of developed formalism of MCA method the dynamics of the friction stir welding process of duralumin plates was investigated. It was shown that ratio of rotation velocity to velocity of translation motion of rotating tool greatly influences the quality of welded joint. Optimal choice of the ratio of these parameters could significantly decrease volume content of pores and microcracks in the welded joint