In this study, simplified nozzle geometry was proposed to quantify the effects of adjacent similar metal weld and weld overlay on residual stresses in dissimilar metal weld. Finite element analyses were conducted with various thickness ratios and safe end lengths and corresponding residual stresses were provided. According to the results, residual stresses in dissimilar metal weld were improved after adjacent similar metal welding. The effect of similar metal welding is more evident with shorter length of safe end. Thus, short length of safe end was recommended for new design of nozzle. Appropriate thickness of preemptive weld overlay reduces the conservative thickness recommended by ASME Code.
In this study, fatigue tests were performed for NiCo alloy which is commonly used in probe tips of test machines of semiconductors. The smooth specimens were fabricated by MEMS process including electro-plating process on a single-side polished 6 inches (100) silicon wafer. The NiCo thin film consists of about 66.2 % Ni and 33.8 % Co. The specimen is 2000 lm long, 9 lm thick and 100 lm wide. The tests were performed using a novel test procedure, a structure of the specimen is easy to manipulate, align and grip a thin-film and a test machine proposed by the authors. The closed-loop feedback control of the magnetic-electric actuator allowed load-controlled and high cycle fatigue tests with 5 Hz frequency, in ambient environment and with a stress ratio of R = 0.1. The fatigue strength coefficient and exponent were 1324 MPa and -0.0558, respectively. In a fatigue test of thin film, it is difficult to perform the fatigue test at R = -1. However, the result of the fatigue test at R = -1 should be required when fatigue life prediction is performed under variable loading. Therefore, in this study, the modified Goodman method, Gerber method and Soderberg method were considered to investigate which method is most reasonable when mean stress is considered.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.