where expertise comes together - since 1996 -

The Largest Open Access Portal of Nondestructive Testing (NDT)

Conference Proceedings, Articles, News, Exhibition, Forum, Network and more

where expertise comes together
- since 1996 -

684 views
Technical Discussions
wang
wang
07:54 Aug-25-2008
who can tell me this formula's unit?

who can tell me this formula's unit?
N=V/£¨15.16F sin2(¦Ã)), { british standard [BS EN 12668-2:2001]}
N:nearfied length unit=?
V:sound velocity of the circular transducer unit=?
¦Ã:divergence unit=?
F:centre frequency unit=?
15.16: ?



 
 Reply 
 
Navita
Navita
00:32 Aug-25-2008
Re: who can tell me this formula's unit?
All dimensions for calculation are in mm for length/ distance, Hz for frequency and seconds for time.

----------- Start Original Message -----------
: who can tell me this formula's unit?
: N=V/£¨15.16F sin2(¦Ã)), { british standard [BS EN 12668-2:2001]}
: N:nearfied length unit=?
: V:sound velocity of the circular transducer unit=?
: ¦Ã:divergence unit=?
: F:centre frequency unit=?
: 15.16: ?
------------ End Original Message ------------




 
 Reply 
 
Udo Schlengermann
Consultant, -
Standards Consulting, Germany, Joined Nov 1998, 183

Udo Schlengermann

Consultant, -
Standards Consulting,
Germany,
Joined Nov 1998
183
06:27 Aug-25-2008
Re: who can tell me this formula's unit?
The explanations by Navita on equation A.1 of European Standard EN 12668-2 are correct.

If you use mm/s for velocity and cycles/s = Hz for frequency you get mm for the near field length. The factor 15.16 and sin2(gamma) are dimensionless.

Please note, that the velocity of the block is addressed, not the velocity of the transducer.

Udo Schlengermann
Convener CEN/TC138/WG2

----------- Start Original Message -----------
: who can tell me this formula's unit?
: N=V/£¨15.16F sin2(¦Ã)), { british standard [BS EN 12668-2:2001]}
: N:nearfied length unit=?
: V:sound velocity of the circular transducer unit=?
: ¦Ã:divergence unit=?
: F:centre frequency unit=?
: 15.16: ?
------------ End Original Message ------------




 
 Reply 
 

Product Spotlight

Compact NDT inspection-heads for measurements with active thermography

The compact inspection head is suitable for thermographic ndt tasks. The uncooled infrared camera
...
is specially developed for NDI-tasks and offers a thermal sensitivity until now known only from thermal imagers with cooled detector. All required components and functions are integrated into the inspection-head. You will only need an ethernet cable to connect the sensor with the evaluation system.
>

VeeScan AirCraft Wheel Inspection

The VEESCAN offers maximum flexibility, has a proven mechanical design and records of breakdown-fr
...
ee operation of over 365 days. Appealing to companies in the Aerospace industry, the VEESCAN is ideal for all wheel-testing environments. With a wide selection of probes, the VeeScan allows your wheel testing facility the flexibility to select the most compatible configurations with their workload.
>

Varex Imaging Large Field of View (FOV) Digital Detector Arrays (DDAs)

A larger FOV DDA can reduce the space and volume of the X-ray inspection system on the factory floor
...
, enable faster scanning times, better throughput and better resolution images at a lower dose. Customers can also save time and money. With these benefits in mind, Varex Imaging has designed a family of large FOV detectors (4343HE, XRD 1611, 4343DX-I, 4343CT) for our industrial imaging customers.
>

NEW Wheel Type Phased Array Probe

DOPPLER NEW Wheel Type Phased Array Probe, more stable, new tyre makes lesser acoustic attenuation
...
, much lighter makes easier to handle, more slim size, magnetic and mechanical encoder optional etc...more
>

Share...
We use technical and analytics cookies to ensure that we will give you the best experience of our website - More Info
Accept
top
this is debug window