Hi Angler,

The answers to your questions are as follows:

(1) Data type: We understand the data type is ultrasonic. Is it correct?
– Yes, that is correct.

(2) Crack type: The specimens look like beams. We are asked to predict the fatigue crack length of the beams. Do you have any specifications of “crack length”, say the crack direction, crack depth and crack curve shape?
– The specimen is made of two aluminum plates mounted with 3 rows of countersunk rivets. Overall, the crack is close to a straight path, propagating from the edge of one countersunk hole to the adjacent one. Once the crack is seen on the surface, it is believed to be through the whole plate thickness.

(3) Data acquisition system: In our understanding, a lot of ultrasonic sensors are equally distributed on the specimen to pick up the ultrasonic signals. These signals are inputted to the receiver to be collected and further to a PC to be stored. Is it correct?
– Yes, that is correct.

(4) Test condition: When testing the ultrasonic signals at specific cycles, is the load added or not? We want to understand whether the load is applied all the time or not applied when conducting tests.
– When collecting the ultrasonic signals, the testing machine was paused near minimum loading to avoid introducing additional noise to the ultrasonic signal. The fatigue testing was resumed right after the ultrasonic data collection process.