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 -

355 views
Technical Discussions
Hermann Wuestenberg
R & D
BAM Berlin, Germany, Joined Nov 1998, 26

Hermann Wuestenberg

R & D
BAM Berlin,
Germany,
Joined Nov 1998
26
03:15 Mar-18-1998
Time reversed mirror technique

Responding to a remark of Prof. Fink

Dear Prof. Fink

The last hint in my short contribution about our experiences with the TMR approach ("the target is painted after the arrival of the arrow") is especially related to hopes and expectations in cases, which can not be solved by Autofocussing or TRM. The general value of this technique is not be called into question, but the example described below may clarify our reluctant position.
Strong focussing is regarded as an important tool especially for anisotropic and coarse grained materials like stainless steel castings or weldments. If for such materials the focussing is optimized for one position and one specific reflector (using suitable optimization strategies for the delay time repartition of the probe array), this is in those materials generally only valid for this specific position and could be totally wrong for a neighbouring area where with that focussing parameters a similar defect can be missed.
In order to avoid such an uncertainty for the detection probability, one should try to inspect the whole volume with sweeping focussing parameters. This is not only time consuming but also useless because the most essential contribution of an TMR approach at such materials is the possibility to define individually adaptable complicated delay time repartitions not simply being based on a curvature and a linear slope .
A sweeping focussing can only vary some parameters and not the whole multitude. That means that a TRM technique has severe limitations in case of dynamically changing propagation conditions like those encountered during the mechanical scanning of austenitic coarse grained material. This has nothing to do with the application in more static situations where the probe is not moved or where the propagation parameters (sound velocity etc.) of the material are constant.

With best regards

H. Wuestenberg


    
 
 

Product Spotlight

Exertus Dual 120

The Exertus Dual 120 Projector has the ability to accept Iridium 192 sources or Selenium 75 source
...
s. This projector incorporates design and safety features that make it flexible, compact and lightweight. The Projector is lighter than most of its competitors. It incorporates an improved source channel, based on a new helicoidal design, which makes maintenance easier. The helicoidal design also allows smoother movement of the source assembly inside the device, making it easier for the operator and improving safety. The Projector also has a unique safety feature not found in competitive products. The source assembly locking mechanism is triggered by the source holder capsule at the front of the source assembly, thereby always assuring the operator that the source has returned to the safe position. The Exertus Dual 120 is ISO3999:2004 compliant.
>

X-ray CT aids research into defect formation in AM parts

X-ray CT is used to research how additive manufacturing process parameters influence defect format
...
ion in AM parts.
>

Magnetic X-Ray Pipeline Crawler

Zhong Yi brand pipeline crawler is magnetic/micro-video controlled crawler with DC X ray unit inst
...
alled for checking welding of pipeline. Move steadily inside the pipeline 6''-60''diameter with speed of up to 18m/min, Max. moving diatance 5 kilometers and provide the efficient inspection of the pipeline.
>

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
s