Electrical testing of MicroElectroMechanical Systems(MEMS) can take on many different forms including wafer probing, electrical trimming, final test at temperatures, engineering characterization, and reliability evaluations. MEMS testing has had limited visibility in literature from companies that have successfully industrialized applications such as pressure sensors and accelerometers. This limited visibility is not an indication of the importance of this topic that represents a significant portion of the overall cost, rather it is more likely and indication custom nature of test for MEMS. This paper presents a case study that addresses the issues associated with MEMS testing of accelerometer devices and an effective solution based on a system approach.
This study investigated the validity of various monotonic cracking performance assessment testing standards and indicators to describe the expected cracking performance in the field. A total number of 17 field test sections with known field cracking performance were selected and evaluated. Field cores were extracted from these sections, and a comprehensive laboratory testing program was carried out. The authors conducted four monotonic testing standards and calculated 11 performance indicators. The study findings showed that there was no direct correlation between the laboratory testing results of monotonic tests and indicators and the observed field cracking performance. The variable air void content and thickness of the extracted field cores are believed to influence the laboratory testing results of monotonic tests and indicators. Therefore, this study proposed an alternative approach to develop performance specifications (thresholds) for monotonic tests and indicators. The thresholds were developed indirectly using a correlation between cyclic testing and both monotonic tests and the observed field cracking performance. The results demonstrated the effectiveness and success of the proposed approach in developing performance thresholds. Pass/fail cracking performance assessment thresholds were proposed for various monotonic indicators to distinguish between asphalt mixes with good, fair, and poor cracking resistance. Besides, the study recommends the Weibull cracking resistance index, determined from the indirect tension test, as a simple performance indicator to assess mixes resistance to cracking.
The Uniform Building Code allows plywood sheathed narrow shear panels having a height-to-width ratio of 3.5-to-one (UBC Table 25-I) to be used as lateral force resisting elements. Previous laboratory testing has concentrated on panels having a height-to-width ratio of one-to-one. This paper presents some results from the testing of plywood shear panels with a height-to-width ratio of two-to-one. Three panels were tested; each was configured to model a different construction scenario. The panels were subjected to fully reversed cyclic pseudo-static loads. Comparison of the results from the three panels indicate that the tie-down anchors must be installed with careful attention to bolt tightening sequence and torque in order to better resist lateral displacements in an earthquake. Vertical dead loads were found to reduce uplift of the panel which, in turn, reduces lateral displacements resulting from panel rotation. Decreased shear values for plywood shear walls subjected to cyclic loading and additional decreased shear values for walls with a height-to-width ratio of two-to-one are recommended.
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