Test fixtures · Investigation example
An 18% shift starts with the fixture photographs
The same specimen shows a displacement shift across two checks, and the setup photographs reveal a change in fixed-end coverage.
What changed
Both checks use 900 N, yet the second displacement is 18% higher. No new visible damage appears on the specimen.
The setup photographs show 70 mm clamped in the first run and 90 mm in the second. The analysis model still carries the first fixed boundary.
Decide whether the runs are comparable
Fixture location, tightening torque, load point and displacement gauge are checked before the specimen is blamed. If one cannot be reproduced, the comparison stays open.
The second result is therefore marked for review, not described as structural degradation. The model is updated to the measured clamp region and another check is scheduled.
Lock three items before the retest
The retest sheet fixes clamped length, the distance from load point to fixed end, and the gauge position relative to the specimen. A scale photograph is taken after setup and before loading.
Only if the difference remains does the review move to specimen stiffness, fastening condition, and environment, without mixing those questions back into the fixture boundary.
Fixture configuration is part of the record
The fixture drawing, locator, torque requirement and setup photographs receive a revision reference of their own.
This example ends at the retest plan. It does not supply a convenient replacement displacement.