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21st InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2022

作者： Lall, Pradeep Saha, Mrinmoy Suhling, Jeff Blecker, Ken Auburn University NSF-CAVE3 Electronics Research Center Department of Mechanical Engineering AuburnAL36849 United States Armament Center US Army Combat Capabilities Development Command Picatinny ArsenalNJ United States

ISBN: (纸本)9781665485036

Electronic parts in military, automotive, avionics and space applications may be subjected to sustained operation at high temperature in addition to high strain-rate loads. Parts may be stored in non-climate-controlled enclosures prior to deployment. Earlier studies on undoped SAC alloys have shown that the material properties evolve after prolonged period of storage at even modest temperatures. In order to mitigate the aging effects, a number of alloy formulation have been proposed. Data of the mechanical properties of lead-free solder alloys which is used for interconnection in the electronic packaging at high strain rates and at high storage temperature is very essential for design optimization of electronic package sustainability at extreme temperature environment because the SAC solders have shown to have degradation in mechanical properties at prolonged exposure to storage temperature. Industries have come up with a solution to reduce the degradation using dopants in SAC solder. In this study, a doped SAC solder called SAC-R (Ecolloy) has been subjected to high strain rate testing after keeping them in storage at temperature of 50°C for 1 - 8months. Samples with no aging and aged samples for up to 8-months have been subjected to uniaxial tensile tests to measure the mechanical properties of SAC-R for High and Low operating temperature ranging from -65°C to 200°C. The material data has been used to compute the constants for the Anand Visco-Plasticity model. The ability of the model to represent the material constitutive behavior has been quantified by comparing the model predictions of the uniaxial tensile test with the experimental data © 2022 IEEE.

关键词： Stress-strain curves

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A Combined Experimental and Computational Analysis of the Flow Field of a Coaxial Counter-Rotating Rotor in Hover 78

A Combined Experimental and Computational Analysis of the Fl...

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78th Vertical Flight Society Annual Forum and Technology Display, FORUM 2022

作者： Mortimer, Patrick Sirohi, Jayant Ho, Jimmy Lopez, Mark Padthe, Ashwani Department of Aerospace Engineering and Engineering Mechanics The University of Texas at Austin AustinTX United States U.S. Army Combat Capabilities Development Command Ames Research Center Moffett Field CA United States San Jose State University Research Foundation Ames Research Center Moffett Field CA United States

The flow fields of a 2m-diameter two-bladed single rotor and a 2×2-bladed coaxial counter-rotating rotor were measured using Particle Image Velocimetry, and computed using a coupled RCAS-VVPM analysis. Time-resolved measurements were performed on the single rotor at 44/rev with at least 552 flow realizations per azimuth. Similar measurements were performed for the coaxial, counter-rotating rotor at 64/rev with at least 260 flow realizations per azimuth. The goal of this study was to compare the flow features of these rotor configurations and validate current numerical analyses. Overall, there was good correlation between the measurements and calculations for the single rotor configuration. Numerical computations captured the axial velocity distribution across the blade radius and rotor azimuth. The radial distributions of axial velocity revealed less agreement in the tip region due to differences in the tip vortex trajectories. The tip vortex positions extracted from the measurements revealed a radial displacement of ∆r/R = 0.112 and an axial displacement of ∆z/R = 0.230 over one rotor revolution. The numerical computations captured the radial position for the first blade passage, but over predicted the radial position after blade passage. The axial positions were under-predicted over the entire azimuthal range. Comparison for the coaxial, counter-rotating rotor configuration revealed a consistent over-prediction in both radial and azimuthal velocity profiles for all spatial locations investigated. The axial position of the tip vortex were captured well with slight under-prediction for the upper rotor. The radial tip vortex positions were over-predicted over the entire azimuthal range investigated. Further validation of the numerical model is required before it can be used to extract state-space inflow models for single and coaxial, counter-rotating rotors. Copyright © 2022 by the Vertical Flight Society. All rights reserved

关键词： Wind tunnels

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Ivabs: A New Design Tool for Composite Slender Structures

SSRN

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SSRN 2024年

作者： Tian, Su Du, Haodong Tao, Fei Yu, Wenbin Lim, Joon W. Haehnel, Robert Wenren, Yonghu Allen, Luke Purdue University West LafayetteIN47906 United States U.S. Army Combat Capabilities Development Command Aviation & Missile Center Ames Research Center Moffett FieldCA94035 United States US Army Engineer Research and Development Center Cold Regions Research and Engineering Laboratory HanoverNH03755 United States

Design optimization of composite slender structures such as helicopter rotor blades requires a structural design optimization tool with a fast and accurate evaluation of beam properties. VABS has been widely used by many for decades. However, there lacks a design tool that can make full use of its capabilities. This work proposes a new framework and develops a new toolset named iVABS for this purpose. It is an integration of VABS along with a cross-sectional builder, a versatile parameterization method of composite slender structures, design methods (available via Dakota), and an interface to external analysis tools such as RCAS. Examples are provided to demonstrate the capability of generating proper designs of composite structures that can satisfy the performance requirements. © 2024, The Authors. All rights reserved.

关键词： Structural optimization

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Impact of Bi-Content on the High Strain Rate Properties of SnAgCu Solders Under Sustained High-Temperature Operation

Impact of Bi-Content on the High Strain Rate Properties of S...

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Electronic Components and Technology Conference (ECTC)

作者： Pradeep Lall Vishal Mehta Mrinmoy Saha Jeff Suhling David Locker Department of Mechanical Engineering NSF-CAVE3 Electronics Research Center Auburn University Auburn AL US Army Combat Capabilities Development Command – AvMC Huntsville AL

ISBN: (数字)9798350375985

ISBN: (纸本)9798350375992

In applications such as automotive and aerospace, electronics may require prolonged high-temperature exposure in the range of 150-200°C and random exposure to mechanical shock and vibration. Additionally, electronics may be stored for extended periods in non-climate-controlled enclosures before deployment. To address the negative effects of sustained high-temperature exposure, the industry has experimented with the addition of dopants to SAC solders. There is limited information on new formulations' mechanical performance, reliability, and constitutive models. The research presented in this paper aims to fill a gap in the state of the art by measuring the effect of Bismuth addition on the properties of SAC-Bi alloys at low temperatures, high strain rates, and varying periods of thermal aging of up to 1 year. Various doped alloys have been studied, including SAC-Q, SAC-R, M758, QSAC10, QSAC20, and SAC305 solder, in a strain-rate range of 1-100 per second in the temperature range of -65°C to +200°C after one year of sustained exposure to 50°C and 100°C. The Anand parameters have been computed and used to quantify the accuracy of the Anand model by comparing the experimentally measured data with the predicted data with the computed model constants. The Anand parameters have been integrated into an FE framework to simulate drop events for a ball-grid array package on a printed circuit board assembly, aiming to determine the hysteresis loop and plastic work density. An increase in the bismuth content has been shown to mitigate the UTS degradation and effective modulus at high strain rates under sustained high-temperature operation.

关键词： Temperature measurement Vibrations Temperature distribution Computational modeling Predictive models Bismuth Iron

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Study of High-G Level Shock Damage-Accrual in Doped/Undoped SAC Solders during Prolonged Sustained Operation at 100°C

Study of High-G Level Shock Damage-Accrual in Doped/Undoped ...

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Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM)

作者： Pradeep Lall Vishal Mehta Jeff Suhling David Locker NSF-CAVE3 Electronics Research Center Department of Mechanical Engineering Auburn University Auburn AL US Army Combat Capabilities Development Command – AvMC Huntsville AL

ISBN: (数字)9798350364330

ISBN: (纸本)9798350364347

Electronic components may experience increased strain rate, high-g loads, and wide temperature extremes in the automotive and aerospace applications during transport, storage, and normal operation. Electronics may be routinely subjected to temperatures between -65°C and 200°C for sustained durations at high strain rates, ranging from 1 to 100 per second. A number of doped SnAgCu alloys have emerged to mitigate the damaging effects of sustained high-temperature operation on the properties. The efficacy of doping in mitigating the detrimental effects of high strain rate operation at high strain rates is not understood. In this study, tensile specimens are prepared from various doped SAC solders and tested at working temperatures ranging from -65°C to 200°C at strain rates of up to 75 per second for up to 1 year of isothermal aging at a storage temperature of 100°C. Mechanical properties like UTS and E, at high strain rate testing are reported and compared for the undoped and doped solders containing different Bismuth content. Mechanical properties of doped solders are found to be higher than that of undoped solders. Also, after high temperature storage for prolonged durations, solders containing higher Bismuth content performed better than the undoped solder SAC305. The experimental results and data were fitted to the Anand viscoplasticity model. Anand constants are extracted for various aging durations and employed for studying the solder joint’s visco-plastic behavior in the FE analysis of Drop/Shock events. For the assembly of CABGA208 packages with PCB, FE analysis for drop/shock events at 1500g has also been carried out for various conditions, according to JEDEC standard JESD22-B111A (2016).

关键词： Temperature distribution Thermomechanical processes Bismuth Aging Iron Distance measurement Soldering Standards Strain Testing

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Investigation of the Effects of Sustained High-Temperature on the Reliability of Lead-Free Solder Joint Assemblies in Vibration

Investigation of the Effects of Sustained High-Temperature o...

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Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems (ITHERM)

作者： Pradeep Lall Vishal Mehta Jeff Suhling David Locker Department of Mechanical Engineering Auburn University NSF-CAVE3 Electronics Research Center Auburn AL US Army Combat Capabilities Development Command – AvMC Huntsville AL

ISBN: (数字)9798350364330

ISBN: (纸本)9798350364347

Solder joints are one of the critical package elements in electronic assemblies. Electronics in automotive applications may be installed on-engine, on-transmission in the wheel well in front of the firewall. Electronics in automotive applications may be exposed to high temperatures in the vicinity of +150°C in addition to high strain rates from road vibration. Strain rates may range from 1 to 100 per sec. Prior work on vibration reliability in harsh environments has focused on the use of linear elastic models for solder interconnects. Models for the assessment of damage accrual for solder interconnects at high strain rates are scarce. In this paper, specifically, doped solder alloys have been examined in package format by balling packages with SAC-Q solder for the study of vibration reliability models at high operation temperatures. CABGA208 Package-PCB assemblies were prepared with SAC-Q solder in JEDEC JESD22-B111A format. PCB-Package assemblies were tested to failure under vibration loads of 5g and 10g, and at different ambient test temperatures up to 150°C. FE analysis is carried out for harmonic vibration loading on PCB-Package assemblies under different conditions. Energy based life prediction model is established using characteristic lives and accumulated plastic work densities.

关键词： Vibrations Temperature Roads Semiconductor device reliability Automotive applications Thermomechanical processes Wheels Soldering Strain Load modeling

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development of a BPNN-based portable motor status diagnosis device

Development of a BPNN-based portable motor status diagnosis ...

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IET International Conference on engineering Technologies and Applications (ICETA 2024)

作者： Sheng-Tao Chen Chien-Hung Chen Hui-Juan Zheng Chiung-Lin Tsai Department of Avionics Engineering R.O.C. Air Force Academy Taiwan Design and Research Section Aerospace Technology Research and Development Center Taiwan Student Command R.O.C. Air Force Academy Taiwan

ISBN: (数字)9781837242252

Motors are frequently used in both everyday and industrial settings. Besides manual assessment, monitoring devices are commonly employed to evaluate motor status. Typically, these monitoring devices are fixed to the motor bearings or housing, which can pose challenges for motors that need to be frequently moved. Therefore, this study develops a portable motor status diagnosis device based on Backpropagation Neural Network (BPNN) to enhance the flexibility of data measurement and accommodate a wider range of applications. The training and experimental results of the network model demonstrated a reduction in the loss rate from 68% to 25.6%, and an improvement in prediction accuracy from 8% to 74.31%.

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Data Fusion of Deep Learned Molecular Embeddings for Property Prediction

arXiv

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arXiv 2025年

作者： Appleton, Robert J. Barnes, Brian C. Strachan, Alejandro School of Materials Engineering Birck Nanotechnology Center Purdue University West LafayetteIN47907 United States U.S. Army Combat Capabilities Development Command Army Research Laboratory Aberdeen Proving Ground MD21005 United States

Data-driven approaches such as deep learning can result in predictive models for material properties with exceptional accuracy and efficiency. However, in many problems data is sparse, severely limiting their accuracy and applicability. To improve predictions, techniques such as transfer learning and multi-task learning have been used. The performance of multi-task learning models depends on the strength of the underlying correlations between tasks and the completeness of the dataset. We find that standard multi-task models tend to underperform when trained on sparse datasets with weakly correlated properties. To address this gap, we use data fusion techniques to combine the learned molecular embeddings of various single-task models and trained a multi-task model on this combined embedding. We apply this technique to a widely used benchmark dataset of quantum chemistry data for small molecules as well as a newly compiled sparse dataset of experimental data collected from literature and our own quantum chemistry and thermochemical calculations. The results show that the fused, multi-task models outperform standard multi-task models for sparse datasets and can provide enhanced prediction on data-limited properties compared to single-task models. © 2025, CC BY.

关键词： Image fusion

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Meeting report of the seventh annual Tri-Service Microbiome Consortium Symposium

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BMC Proceedings 2024年第SUPPL 20期18卷 1-9页

作者： Liechty, Zachary S. Agans, Richard T. Barbato, Robyn A. Colston, Sophie M. Christian, Monica R. Hammamieh, Rasha Kardish, Melissa R. Karl, J. Philip Leary, Dagmar H. Mauzy, Camilla A. de Goodfellow, Ida Pantoja-Feliciano Racicot, Kenneth Soares, Jason W. Stamps, Blake W. Sweet, Charles R. Tuck, Sara M. Whitman, Jordan A. Goodson, Michael S. 711th Human Performance Wing Air Force Research Laboratory Wright‐Patterson AFB Dayton OH United States United States Army ERDC Cold Regions Research and Engineering Laboratory Hanover NH United States United States Naval Research Laboratory Washington DC United States Medical Readiness Systems Biology Walter Reed Army Institute of Research Silver Spring MD United States Military Nutrition Division United States Army Research Institute of Environmental Medicine Natick MA United States Soldier Effectiveness Directorate United States Army Combat Capabilities Development Command Soldier Center Natick MA United States Unites States Naval Academy Annapolis MD United States

The Tri-Service Microbiome Consortium (TSMC) was founded to enhance collaboration, coordination, and communication of microbiome research among DoD organizations and to facilitate resource, material and information sharing among consortium members, which includes collaborators in academia and industry. The 2023 annual symposium was a hybrid meeting held in Washington DC on 26–27 September 2023 concurrent with the virtual attendance, with oral and poster presentations and discussions centered on microbiome-related topics within five broad thematic areas: 1) Environmental Microbiome Characterization;2) Microbiome Analysis;3) Human Microbiome Characterization;4) Microbiome engineering;and 5) In Vitro and In Vivo Microbiome Models. Collectively, the symposium provided an update on the scope of current DoD and DoD-affiliated microbiome research efforts and fostered collaborative opportunities. This report summarizes the presentations and outcomes of the 7th annual TSMC symposium. © This is a U.S. Government work and not under copyright protection in the US;foreign copyright protection may apply 2024.

关键词： Environmental Microbiome Human Microbiome Microbiome engineering Military Microbiome Model Microbiome Systems

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Implantable photoelectronic charging(I-PEC)for medical implants

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Energy Reviews 2022年第2期1卷 60-69页

作者： Kai Wang Sumanta Kumar Karan Mohan Sanghadasa Congcong Wu Shashank Priya Department of Materials Science and Engineering Pennsylvania State UniversityUniversity ParkPA16802United States Materials Research Institute Pennsylvania State UniversityUniversity ParkPA16802United States U.S.Army Combat Capabilities Development Command Aviation&Missile Center Redstone ArsenalAlabama35898United States Key Laboratory for the Green Preparation and Application of Functional Materials Hubei Key Laboratory of Polymer MaterialsSchool of Materials Science and EngineeringHubei UniversityWuhan430062China

Medical implants with functionalities such as sensing,health monitoring,stimulation,diagnosis,and physiological treatment are rapidly *** the increasing functional sophistication and addition of modules such as data transmission,on-chip processing,and data storage,energy demand of the implantable system is also *** implantable energy harvester either to recharge or ultimately replace hazardous battery is essential to provide a long-term sustainable *** harvesting techniques using piezoelectric,thermoelectric,radio frequency power transmission,biofuel,and photoelectronic(or sometimes termed as“photovoltaic”in terms of solar light harvesting,i.e.,PV)conversion,have been attempted for the implantable,but these methods are currently limited by insufficient power output,large footprint,and low ***,the planar PV with potential of lighter weight,higher energy density,and higher efficiency,provides promising power solution for in-body medical *** this short review,we will discuss the potential opportunities and challenges associated with PV's for medical implants,covering materials,to devices,and to system level requirements.

关键词： photoelectron harvesting charging

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