| 摘要 |
The residual stress is measured in a threaded pre-tensioned metal bar (1) held by its extremities in two supports (2,3). One of the bar extremities (5) is provided with a ultrasound transducer (7) which can generate and detect ultrasound waves. The transducer is connected to a microprocessor (8) which controls the emission and detection of ultrasounds by the transducer. The time taken by the wave for a round trip through the bar is estimated by the microprocessor. A displacement sensor (9) with a probe (10) measures the longitudinal displacement of the bar extremity. The sensor is connected to the same microprocessor. A hydraulic screw (13) coupled to the bar extremity (5) is used to apply a traction effort to the bar. |
