12:37 Jul-09-2009 sathik basha Teacher Crescent Engineering College, India, Joined Sep 2004 3
Re: reg- Lcr Probe construction -reg.In Reply to bob sudharmin at 13:33 Jul-07-2009 .
Lcr probe is used to find the residual stress in weldment. it consists of Ultrasonic probe of one transmitter and one receiver assembly that create critically refracted waves to analysis the residual stressess in weldment.
please give your siggestion
There is an ASTM Standard Practice for measuring ultrasonic velocity in polyethelene tank walls (E-2479). This too uses the Lcr probe in a transmit-receive setup. The concept of applying this to residual stress measurement would be very similar in that you are associating stress changes with velocity changes. The setup is effectively that used for a TOFD inspection. To reduce thermal effects that could hinder absolute time measurement, you could use 2 receivers in tandem with their separation precisely measured. This would give a relative arrival time difference. A baseline measurement would be requried to rate the unstressed state then you could make measurements during applied and then residual stress states (e.g. before, during and after measurents). This said, the probe angles you require could probably be satisfied by standard TOFD probes.