No abstract

In this paper, a novel temperature compensation method for a dual-mass MEMS gyroscope is proposed based on drive mode vibration characteristic compensation using a temperature variable resistor. Firstly, the drive and sense modes of the gyroscope re analyzed and investigated, and it is found that the scale factor is proportional to the drive mode amplitude controlling reference voltage. Then, the scale factor temperature compensation method is proposed, and a temperature variable resistor is utilized to compensate the drive amplitude working point and make it change with temperature. In addition, the temperature compensation circuit is designed and simulated. After that, the temperature bias drift is compensated in a modular output. The experimental results show that scale factor and bias variation during the temperature range from −40 °C to 60 °C decrease from 3.680% to 1.577% and 3.880% to 1.913%, respectively. In addition, the bias value improves from 103.395 °/s to 22.478 °/s (optimized 78.26%). The bias stability and angular rate walking parameter are also optimized to 45.97% and 16.08%, respectively, which verify the method proposed in this paper.

The effect of the strain rate, experimental temperature, Zn content in the test solution, and prefilming time on the mechanical properties was investigated by a tensile test with a slow strain rate, at a chemical solution of 2.2 ppm Li and 1200 ppm B in a static autoclave with 8.2 MPa. The experimental parameters clearly affected the tensile properties. The surface morphology, fractograph, and cross-sectional microstructure were analyzed by scanning electron microscopy and transmission electron microscopy. The δ (elongation) and UTS (ultimate tensile strength) of the samples tested in chemical solution were obviously lower than those of the samples tested under a nitrogen atmosphere. However, in general, all samples showed a ductile fracture characteristic and an excellent tensile property in all experimental conditions. The δ and UTS were first increased with increasing Zn content, and then decreased at both conditions of 9.26 × 10−7/s and 4.63 × 10−7/s strain rates. The difference values of tensile properties at different strain rates showed fluctuations with increasing Zn content. The δ increased with both increasing experimental temperature and prefilming time. The UTS first decreased with increasing prefilming time and then increased. The Iscc (stress corrosion cracking susceptibility) decreased with an increasing strain rate, experiment temperature, and prefilming time. Many particles with polyhedrons were formed on the sample surfaces, which was attributed to corrosion in a periodical location at the sample surface. The average length of the particles decreased with increasing Zn content, but increased with both increasing experimental temperatures and prefilming time. The corresponding mechanism is also discussed in this work.

This paper is a synthesis of earlier results supplemented by new results to define a comprehensive analysis of the growth rate of stress corrosion cracking (SCC). Two mechanisms, anodic dissolution (AD) and hydrogen embrittlement (HE), have been considered to calculate the SCC growth rate of AA 7050-T6 for a surface-breaking crack with blunt tip in an aqueous environment. The relative contributions of each mechanism and their mutual interactions have been quantitatively assessed. Results show that AD provides critical conditions for HE, which explains in part a stepwise propagation of the crack. Finally, the total crack growth rate due to the combined effects of AD and HE has been determined, and numerical results have been compared with experimental data, and a calculation of the crack growth rate for a practical configuration has been presented.