Browsing by Subject "Inspection"
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Item Evaluation of Superpave Fine Aggregate Angularity Specification(2001-05) Chowdhury, Arif; Button, Joe W.; Kohale, Vipin; Jahn, David W.The validity of the Superpave fine aggregate angularity (FAA) requirement is questioned by both the owner agencies and the paving and aggregate industries. The FAA test is based on the assumption that more fractured faces will result in higher void content in the loosely compacted sample; however, this assumption is not always true. Some agencies have found that cubical shaped particles, even with 100 percent fractured faces, may not meet the FAA requirement for high-volume traffic. State agencies are concerned that local materials, previously considered acceptable and which have provided good field performance, cannot meet the Superpave requirements. Researchers evaluated angularity of 23 fine aggregates representing most types of paving aggregates used in the USA using seven different procedures: FAA test, direct shear test, compacted aggregate resistance (CAR) test, three different image analyses, and visual inspection. The three image analyses techniques included Hough Transform at University of Arkansas at Little Rock (UALR), unified image analysis at Washington State University (WSU), and VDG-40 videograder at Virginia Transportation Research Council (VTRC). A small study was performed to evaluate relative rutting resistance of HMA containing fines with different particle shape parameters using the Asphalt Pavement Analyzer (APA). The FAA test method does not consistently identify angular, cubical aggregates as high quality materials. There is a fair correlation between the CAR stability value and angle of internal friction (AIF) from the direct shear test. No correlation was found between FAA and CAR stability or between FAA and AIF. Fairly good correlations were found between FAA and all three image analysis methods. Some cubical crushed aggregates with FAA values less than 45 gave very high values of CAR stability, AIF, and ‘angularity’ from imaging techniques. Moreover, the three image analysis methods exhibited good correlation among themselves. A statistical analysis of the SHRP-LTPP (Strategic Highway Research Program-Long-Term Pavement Performance) database revealed no significant evidence relationship between FAA and rutting. This lack of relationship is not surprising since many uncontrolled factors contribute to pavement rutting. The APA study revealed that FAA is not sensitive to rut resistance of HMA mixtures. Image analysis methods appear promising for measuring fine aggregate angularity. Until a suitable replacement method(s) for FAA can be identified, the authors recommend that the FAA criteria be lowered from 45 to 43 for 100 percent crushed aggregate. Analysis of the FAA versus rutting data should be examined later as the amount of data in the SHRP-LTTP database is expanded.Item High-throughput, tip-based in-line nanometrology in semiconductor and nano-featured manufacturing(2018-08) Yao, Tsung-Fu; Cullinan, Michael; Djurdjanovic, Dragan; Sreenivasan, S.V.; Sarkar , NeilA high-throughput, tip-based, in-line nanometrology system that can be helpful for developing closed-loop process control in nanomanufacturing of semiconductor industries. One of the most significant barriers stands in the path to in-line inspection in nanomanufacturing is sample-preparation. After the beforehand inspection process detecting regions that have higher chance to be failed, known as “hotspots,” the operator may need to spend much time to position a high-resolution probe to there because small field-of-view (FOV) makes it hard to recognize its position from target. The other barrier to developing in-line inspection is the resolution limitation of conventional metrology technique, a.k.a. optical and e-beam inspections. Especially for technology nodes beyond 10-nm, the critical dimension is going close to resolving capability. As a result, the in-line inspection requires a higher resolution imaging technique with fast and precision method to position the probe. The methodology developed in this study overcomes those barriers by passive alignment methods and a state-of-the-art single-chip atomic force microscopy system. Instead of those prevalent active methods, the passive alignment uses kinematic method providing the wafer adequately constraint to limit degree of freedoms in place. Once the wafer sit into site, a preload applied then a sub-micron precision can be achieved. The passive mechanism almost instantaneously finishes alignment, so no time budget should be counted. Compared with AFM’s FOV, the sub-micron positioning precision guarantees the same location on wafer-by-wafer inspection. To enhance the metrology throughput, the proposed system uses multiple AFM chips distributed over the wafer footprint in order to image on multiple hotspots simultaneously. On the other hand, a flexure-based XY stage which is able to make nm-precision and mm-range is implemented to position AFM probe. The proposed system takes a serial of images neighboring to each other, image-stitching programmatically mosaic all images to generate a large area FOV measurement. This system applies several concepts to thoroughly enhance the throughput of advanced nanometrology and make it compatible with an in-line inspection methodology in the nanomanufacturing process. By the enhanced throughput of metrology, the nanomanufacturing will have a great potential to develop a feedback, process control and improve product’s quality and yield.Item Ultrasonic and vibrational methods to determine changes of state of lithium-ion cells(2023-12) McGee, Tyler Michael; Ezekoye, Ofodike A.; Haberman, Michael R. (Michael Richard), 1977-; Arguelles, Andrea; Khani, HadiLithium-ion batteries (LIBs) are the chosen power source for battery electric vehicles and battery energy storage systems. These high-power, high-capacity applications subject LIBs to challenging operating environments where mechanical, electrical, and thermal abuse is likely. In these applications, thousands to hundreds of thousands of cells are connected in series and parallel, which creates a challenging monitoring problem. The search for improvements to the battery management system (BMS), including new sensing modalities, is a very active and growing field. This work investigates the use of mechanical inspection of lithium-ion batteries using dynamic mechanical loading for state estimation. Ultrasonic inspection is used to monitor cells as they undergo normal charge-discharge cycling and different amounts of thermal loading, sometimes to thermal runaway. By specifically monitoring the ultrasonic signal characteristics of the signal amplitude (SA) and time of flight shift (TOFS), we can monitor changes to the cell's stiffness, density, and attenuation which result from changes in the cell's state of charge (SOC), temperature, or the presence of damage from thermal abuse. We find that ultrasonic signal characteristics warn of impending cell failure up to 25 minutes in advance of traditional monitoring sensors. A transfer matrix model employing a Bloch-Floquet formalism which accounts for the repeating layered scheme of the cell is introduced to explore ultrasonic wave dispersion due to the layered structure and internal losses due to the cell's polymeric components. Experimentally obtained ultrasonic signal characteristics were corroborated with this periodic transfer matrix model (PTMM) which can simulate SA and TOFS by using the appropriate SOC or temperature-dependent material properties of cell components. The PTMM validates experimental measurements, and helps demonstrate which cell components dominate the characteristics of ultrasonic wave propagation in the thickness direction of LIB pouch cells. The results from US inspection demonstrate its applicability to provide advanced warning of cell failure and also to detect the presence of damage from previous thermal abuse. The same chemo-mechanics that drive changes in the cell's ultrasonic response should also affect the cell's modal response. One can imagine implementing modal testing on cell packs as a part of routine maintenance, or making use of ambient vibrations as the excitation for modal testing in applications like BEVs . As such, this work also explores the viability of vibrational inspection for state estimation, focusing primarily on SOC and state of health (SOH) estimation. The surface velocity of lithium-ion pouch cells confined in a fixed-fixed configuration is measured with a scanning laser Doppler vibrometer (SLDV) while the cells are subjected to base excitation using an electrodynamic a shaker. SLDV scans are performed after the cell has been charged or discharged to specific SOC and repeated across numerous cycles. Results from these experiments show that the modal frequency of a cell shifts towards higher frequency with increasing SOC. These results were corroborated with an effective material model of the cell which was created with multiscale homogenization of the cell's components including their microscale heterogeneity. This material model is created using material properties of constituents at full charge and at full discharge, and is input to a finite element simulation of the resonance frequency of the cell. We find good agreement between the resonance frequency predicted by the multiscale model and transmissibility measurements at 0% and 100% SOC. The experimental results for continued cycling showed an increase in modal frequency at the fully charged and fully discharged states with cell aging. While identifying the chemo-mechanical cause of the changing cell modal response with aging remains a challenge, the correlation between SOH and modal response illustrates how the technique can be used for both SOC and SOH estimation.