No abstract

The fiber metal laminates (FMLs) of hybrid Ti/APC-2 neat and nanocomposite laminates were fabricated. Geometrically symmetric and anti-symmetric double-edged cracks were cut in FMLs. From tensile tests, we received the load vs. displacement curves, stress intensity factors of mixed mode and mechanical properties. From cyclic tests, the load vs. cycles (P–N) curves, residual life and failure mechanisms were obtained. The mechanical properties of symmetrically cracked specimens were slightly lower than those of anti-symmetrically cracked counterparts. As the crack length increases and inclination angle decreases, the fatigue life decreases. The enhancement of nanopowder improved the ultimate load and fatigue life. The local stress intensity at the crack tip dominates the fatigue responses. The piece of elliptical part was observed from cyclic tests at failure. Although the attraction of two crack tips accelerated the crack growth towards each other, the delay to failure was caused by two crack tips circling around and forming a small piece of ellipse centrally.

In this work, by using a liquid crystal polarization grating, the error is effectively decreased from 34.4% to 0.1% for improving the accuracy in the circular dichroism measurement system. Meanwhile, the role of the residue is presented and discussed.

Microstructural changes of 10CrNi3MoV marine steel before and after hot forming were detected by testing devices such as X-ray diffractometer, the formation causes and law of gradually changing surface microstructure of hot-formed material and those of the interior martensite structure were analyzed. The study shows that the gradually changing surface microstructure formed in 10CrNi3MoV marine steel after hot forming makes the material hardness increases sharply from surface to interior within the 0-0.25mm surface depth scope, and the hardness is maintained at 40-45HRC after reaching the 0.25mm depth; the material malleability decreases evidently from surface to interior within the 0-0.25mm surface depth scope, with the change amplitude being great, and the decrease amplitude is obviously reduced at the 0.25-0.50mm depth scope, and becomes very small after the 0.50mm depth is reached; the role of its gradually changing surface microstructure and the display of large malleability characteristic by the soft outer layer prevent the interior high-strength martensite from premature failure in the impact process, and enable a gentle structural peak value, and the gentle impact level and the gradual failure of the material enable the structure to keep a high energy absorption capacity and impact resistance. This indicates that hot-formed 10CrNi3MoV marine steel combines the excellent properties of single-phase materials, and is suitable for structural members that should withstand impact and absorb energy.