Влияние импульсного лазерного ИК-излучения на динамику и морфологию деформационных полос в алюминий-магниевом сплаве

The dynamics and morphology of deformation bands under the simultaneous effect of mechanical loading and pulsed IR laser radiation on the surface of in aluminum–magnesium alloy AlMg6 were studied by high-speed video recording. The conditions, under which a laser pulse pierces a through hole with a diameter of an order of magnitude smaller than the thickness of a plane specimen, thus inducing the development of a complicated spatiotemporal structure of deformation bands and a macroscopic jump in the tension diagram, were determined. The morphological transitions associated with the transformation of the type, shape, and spatiostatistical distribution of bands with a change in the laser pulse energy density were revealed. The probable mechanism of this phenomenon was discussed.

Research on the Multi-Actuator and Sensor Detecting Technology Based on Piezoelectric Composite Materials

Traditional ultrasonic methods are popular in identifying easily detectable cracks, but are not good enough in minute crack detection. Early damage identification is important in preventing larger crack development and future catastrophes. Highly sensitive and precise actuator/sensor is employed to improve the detection capability of these minute cracks. The Orthotropic Piezoelectric Composite Material (OPCM) has been developed as a functional material that can be conveniently used as a highly sensitive actuator/sensor. Comparing the OPCM with the traditional elements, the former has the ability of exciting and receiving focus power and directional strain waves. They have been used in non-destructive technology in many structural engineering inspections. Using the filtering capabilities of the OPCM sensor and Hilbert-Huang Transform (HHT) method, the experimental results show that by using the multi-actuator and sensor, the simulated cracks inside aluminum plane specimen can be successfully identified.

Influence of Specimen Sampling on Internal Residual Stress Test

Using Finite Element Method, the changing rules of residual stresses in the test specimen cut out from a quenched plate were analyzed, and suitable dimensions of the specimen for crack compliance method test was recommended. The results show that cutting has great influences on residual stresses in the specimen edge areas to a range of about one thickness, while it has little influences on stresses at the center part of the specimen; cutting mainly influences stresses normal to the cutting plane, while it has little effect on stresses parallel to the cutting plane; specimen with length bigger than 2.67 times the thickness and width bigger than 2 times the thickness is suitable for crack compliance method test, under these conditions peak stresses losing in crack compliance method results is less than 5% compared with surface stress X-ray diffraction results.