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Graph neural network coarse-grain force field for the molecular crystal RDX

npj Computational Materials 2024年第1期10卷 1060-1070页

作者： Brian H.Lee James P.Larentzos John K.Brennan Alejandro Strachan School of Materials Engineering and Birck Nanotechnology Center Purdue UniversityWest LafayetteLafayetteINUSA U.S.Army Combat Capabilities Development Command(DEVCOM)Army Research Laboratory Aberdeen Proving GroundMDUSA

Condense phase molecular systems organize in wide range of distinct molecular configurations,including amorphous melt and glass as well as crystals often exhibiting polymorphism,that originate from their intricate intra-and intermolecular *** accurate coarse-grain(CG)models for these materials are critical to understand phenomena beyond the reach of all-atom simulations,current models cannot capture the diversity of molecular *** introduce a generally applicable approach to develop CG force fields for molecular crystals combining graph neural networks(GNN)and data from an all-atom simulations and apply it to the high-energy density material *** address the challenge of expanding the training data with relevant configurations via an iterative procedure that performs CG molecular dynamics of processes of interest and reconstructs the atomistic configurations using a pre-trained neural network *** multi-site CG model uses a GNN architecture constructed to satisfy translational invariance and rotational covariance for *** resulting model captures both crystalline and amorphous states for a wide range of temperatures and densities.

关键词： grain neural network

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Correlation of Tiltrotor Aeroelastic Stability Wind Tunnel Test 79

Correlation of Tiltrotor Aeroelastic Stability Wind Tunnel T...

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79th Vertical Flight Society Annual Forum and Technology Display, FORUM 2023

作者： Kang, Hao Kreshock, Andrew R. Thornburgh, Robert P. Floros, Matthew Yeo, Hyeonsoo Shen, Jinwei U. S. Army Combat Capabilities Development Command Army Research Laboratory Langley Research Center HamptonVA United States U. S. Army Combat Capabilities Development Command Aviation & Missile Center Ames Research Center Moffett FieldCA United States Department of Aerospace Engineering and Mechanics University of Alabama TuscaloosaAL United States

ISBN: (纸本)9781713874799

This paper presents a correlation study of detailed finite element modeling with component vibration tests and comprehensive analysis modeling with whirl flutter experimental data for the TiltRotor Aeroelastic Stability Testbed (TRAST). TRAST is a semi-span tiltrotor model system that has been developed to investigate tiltrotor whirl flutter phenomena and to provide experimental data for rotorcraft analysis validations. To ensure that real structures are represented accurately by the comprehensive analysis codes, detailed NASTRAN models using 2D/3D shell and solid elements were developed and refined based on vibration tests of the TRAST components. Details of the component vibration tests and correlation with NASTRAN models are described for the rotor blades, hub, and the wing and pylon assembly. The 2D/3D NASTRAN rotor blade model was simplified to a 1-D model consisting solely of beam and other 1-D elements. Using the components and the properties of the 1-D model, structural models for the comprehensive analyses were developed and validated against the vibration test data. Whirl flutter models were developed by adding aerodynamics to the validated structural models. These models were compared to wind-tunnel experimental data. Two comprehensive rotorcraft analysis codes, CAMRAD II and RCAS, were used for the whirl flutter correlation study. Sensitivity of the TRAST whirl flutter prediction to modeling details is discussed. Copyright © 2023 by the Vertical Flight Society. All rights reserved.

关键词： Wind tunnels

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Lightweight Low-Cost Multifunctional Composite for Structure

Lightweight Low-Cost Multifunctional Composite for Structure

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Haynes, Robert A. Luzetsky, Harry R. Phifer, Ellen M. U.S. Army Combat Capabilities Development Command Aviation and Missile Center Fort EustisVA23604 United States Research and Analysis Group SURVICE Engineering Company LLC BelcampMD21017 United States

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

The requirement for improved performance in air vehicles necessitates technological advancements in the materials and structures used in those vehicles to achieve weight savings and improved durability and damage tolerance. Simultaneously, vehicle development programs are demanding reductions in cost and fabrication and assembly time. This article presents work to develop a multifunctional composite material technology that saves weight through incorporating electromagnetic shielding into the laminate, improves durability and damage tolerance through use of thermoplastic composite materials, and reduces cost and manufacturing time through continuous compression molding and automated laser in-situ tape placement fabrication techniques. A comparative analysis is conducted with other widely used aircraft designs to quantify the improvements of the multifunctional composite. A representative section of an aircraft tailcone structure is designed, fabricated, and tested to demonstrate the advancements. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Compression molding

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The Geology, Fluid Inclusions, and O-S Isotopes of the Mibei Gold Deposit, Hunan Province, Southern China

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Acta Geologica Sinica(English Edition) 2024年第4期98卷 992-1006页

作者： XUE Wenhao LIANG Yayun LI Xiaofeng LI Mingyi XIE Wenbo PENG Xue XIA Rui HE Hongsheng XIAO Jincheng School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China Geophysical and Geochemical Survey Institute of Hunan Changsha 410116China New Geological Energy Exploration and Development Engineering Technology Research Center of Hunan Changsha 410116China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences(Beijing)Beijing 100083China Comprehensive Survey Command Center for Natural Resources China Geological SurveyBeijing 100055China

The Mibei gold deposit,located in the southwestern part of the Xuefengshan uplift zone,the middle section of the Jiangnan orogenic belt in southern China,has estimated gold resources of approximately seven *** deposit is primarily a quartz vein-type gold deposit,with ore bodies occurring mainly within Neoproterozoic *** main metallic minerals in the ore are pyrite,chalcopyrite,and *** this study,the petrography and microthermometry of ore-forming fluid inclusions,oxygen isotopes of gold-bearing quartz,and sulfur isotopes of goldbearing sulfides and arsenopyrite were *** types of fluid inclusions were identified:type Ⅰa three-phase inclusions comprising vapor and two phases of liquids(V_(CO_(2))+L_(CO_(2))+L_(H2O)),type Ⅰb two-phase liquids(L_(CO_(2))+L_(H2O)),typeⅡ two-phase vapor-rich inclusions(V/V+L> 50%),and type Ⅲ pure liquid *** Ⅰ inclusions were heated uniformly to the liquid phase,type Ⅱ inclusions were heated uniformly to the gas phase,and type Ⅲ inclusions were heated without *** general,the temperature range of homogenization to liquid phase of fluid inclusions in the Mibei gold deposit is 204-227℃.The salinity of the inclusion ranges from 4.6 to 12.2 wt% NaCl *** δ~(18)O_(SMOW) of gold-bearing quartz varies from 16.9‰ to 17.5‰.The δ~(18)O_(H2O) of gold-bearing quartz are varied from 6.5‰ to 7.5‰.The δ~(34)S values of gold-bearing pyrite range from 1.7‰ to 6.8‰.The δ~(34)S values of gold-bearing arsenopy rite range from 5.6%o to 5.9‰.Theδ~(34)S values of pyrite from wall rocks slate range from 6.4‰ to 11.6‰.This evidence implies that the ore-forming fluids of the Mibei gold deposit originated from magmatic-hydrothermal processes,mixing with minor S from the surrounding *** with the evolution of the Jiangnan orogenic belt,due to the magmatic and tectonic activities of the Xuefengshan uplift during the Caledonian period,the fault seal mechanism controlled the ore-forming p

关键词： ore-forming fluid ore genesis Mibei gold deposit Xuefengshan uplift zone Jiangnan orogenic belt

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Study of High-G Level Shock Damage-Accrual in Doped/Undoped SAC Solders during Prolonged Sustained Operation at 100°C 23

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

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23rd IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2024

作者： Lall, Pradeep Mehta, Vishal Suhling, Jeff Locker, David Auburn University NSF-CAVE3 Electronics Research Center Department of Mechanical Engineering AuburnAL36849 United States Us Army Combat Capabilities Development Command - AvMC HuntsvilleAL35898 United States

ISBN: (纸本)9798350364330

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). © 2024 IEEE.

关键词： Strain rate

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Investigation of the Effects of Sustained High-Temperature on the Reliability of Lead-Free Solder Joint Assemblies in Vibration 23

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

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23rd IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems, ITherm 2024

ISBN: (纸本)9798350364330

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. © 2024 IEEE.

关键词： Vibration analysis

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Characterization of the Response of a Single Rotor in Hover to Dynamic Collective Pitch 79

Characterization of the Response of a Single Rotor in Hover ...

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79th Vertical Flight Society Annual Forum and Technology Display, FORUM 2023

作者： Mortimer, Patrick Yu, Daniel 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 Aviation & Missile Center Ames Research Center Moffett FieldCA United States San Jose State University Research Foundation Ames Research Center Moffett FieldCA United States

ISBN: (纸本)9781713874799

The flow fields of a 2m-diameter two-bladed single rotor were measured using particle image velocimetry, and computed using a coupled RCAS-VVPM analysis. Dynamic collective pitch inputs were introduced in terms of stepped sines with an amplitude of 1◦, and frequencies of 0.0/rev, 0.2/rev, 0.3/rev, 0.4/rev, 0.6/rev, and 0.7/rev. Phase-resolved particle image velocimetry measurements were performed to capture the flow field response to the dynamic pitch inputs at an azimuthal location of ψb = 90◦. Flow field information was acquired at specific measurement locations in order to capture the dynamic effects at the azimuthal plane of interest. A total of ten measurement locations were captured for each excitation frequency. At each measurement location 200 instantaneous flow realizations were captured. The goal of this study was to develop an experimental and numerical procedure to investigate the wake and loads of a single isolated rotor in hover in response to stepped sine pitch inputs at a nominal collective pitch angle of θ0 = 8◦ and nominal blade loading of CT/σ = 0.08. The change in rotor thrust ranged from ∆CT = 13.5% to 22% over the range of actuation frequencies tested. The corresponding change in rotor power ranged from ∆CP = 2.3% to 6.7%. Frequency analysis performed at multiple radial locations along the rotor blade showed a gradual increase radially in the axial velocity magnitude for all excitation frequencies. The largest axial velocity magnitude corresponded to an actuation frequency of f = 0.2/rev for all radial locations. The numerical results showed a consistent under-prediction at all outboard radial locations, but showed closer agreement to the measured data at inboard radial locations. Copyright © 2023 by the Vertical Flight Society. All rights reserved.

关键词： Flow fields

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Effect of Evolution of High Strain Rate Properties on Plastic-Work of SAC305 Alloy with 100°C Aging for Periods up to 240-days 21

Effect of Evolution of High Strain Rate Properties on Plasti...

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

作者： Lall, Pradeep Mehta, Vishal 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

In the industries related to aerospace applications, medical applications and in oil/gas exploration, the electronic components may have to face very cold to extreme high surrounding temperatures. In addition, these electronic packages and assemblies can be exposed to vibrations, shocks and impacts. In such severe surrounding, electronic components may face strain rates of 1 to 100 per seconds and low surrounding temperature down to-65°C. The records are not existing for lead-free solder alloys tested at extreme surrounding temperature and at high strain rates, with isothermal aging. Previous published results for SAC305 lead-free solder alloys is limited to low strain rates and high operating temperatures. In this paper, lead-free solder alloy SAC305 has been tested and studied at extreme surrounding temperature starting from-65°C up to 200°C, with high strain rates, with isothermal aging at 100°C for up to 240 days. The prepared SAC305 lead-free alloy specimen after reflowing, were stored for thermal aging and then tested at strain rates of 10, 35, 50, and 75 per sec. at multiple operating temperatures ranging from-65°C to 200°C. Stress-strain curves are generated for various operating temperatures and for the range of strain rates. The experimental data has been fit to the Anand Viscoplasticity model for SAC305 and the Anand constants are established by predicting the measured stress-strain behavior for the various surrounding temperatures and high strain rates, for aging durations up to 240 days (i.e. 8 months). Also, FE analysis has been carried out for drop/shock events for BGA package assembly with PCB. Hysteresis stress-strain curves and plastic work density curves are generated for various aging conditions for SAC305 solder ball joints. © 2022 IEEE.

关键词： Drops

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EFFECT of AGING on HIGH STRAIN RATE MECHANICAL PROPERTIES of SAC+BI SOLDERS after EXPOSURE to ISOTHERMAL AGING of 50°C UP to 120 DAYS

EFFECT of AGING on HIGH STRAIN RATE MECHANICAL PROPERTIES of...

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ASME 2022 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems, InterPACK 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 US Army Combat Capabilities Development Command-Armament Center Picatinny ArsenalNJ United States

ISBN: (纸本)9780791886557

In aerospace, military, and automotive applications, various electronic parts may be subjected to sustained operation at high and low surrounding temperatures as well as high strain-rate loads. Previous research studies have shown that material properties of undoped SAC alloys evolve even at moderate temperatures after a prolonged period of storage. A variety of dopants has been introduced into SAC alloy formulations in order to reduce the aging effects. In this study, two doped SAC solder called QSAC10 and QSAC20, have been subjected to high strain rate testing after keeping them in storage at temperature of 50°C for 120 days. Samples with no aging to 120 days aged samples have been subjected to uniaxial tensile tests to measure the mechanical properties of SAC+Bi solders. The High and Low operating temperatures used in this experiment ranged from-65°C to 200°C. Then the experimental material data was used to compute the constants for the Anand Visco-Plasticity model. Using the Anand constitutive model, the material constitutive behavior has been implemented in a finite element framework to simulate the drop events. Copyright © 2022 by ASME.

关键词： Temperature

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High Strain Rate Mechanical Properties of M758 Solder at Extreme Surrounding Temperatures, with 100°C Isothermal Aging for up to 180 Days 21

High Strain Rate Mechanical Properties of M758 Solder at Ext...

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

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

ISBN: (纸本)9781665485036

In the industries related to automotive, oil and gas, aerospace, medical technologies, electronic parts can often be exposed to high strain loads during shocks, vibrations and drop-impact conditions. Such electronic parts can often face the extreme low and high temperatures ranging from-65°C to 200°C. Additionally, these electronic devices can be subjected to strain rates of 1 to 100/sec in the critical environment. Lately, numerous doped solder alloys are being introduced in the electronic component e.g. SAC-Q, SAC-R, Innolot, etc. M758 is a novel general purpose, thermal fatigue resistant doped solder alloy, used for surface mount technology. Mechanical characteristic results and data for lead-free solder alloys are extremely important for optimizing electronic package reliability, at high temperature storage and elevated strain rates. Moreover, the mechanical properties of solder alloys can be transformed considerably due to the thermal aging, which is causing alteration of microstructure. Statistics for the mechanical properties of M758 solder alloy with an extreme low to high operating temperatures, with thermal aging effects are not available. In this work, M758 doped solder material is tested and studied for this study at range of operating temperatures of-65°C to 200°C and at a strain rate up to 75/sec for up to 180 days (i.e. 6 months) of isothermal aging with storage temperature of 100°C. For the extensive range of strain rates and surrounding test temperatures, stress-strain curves are established. Additionally, the measured experimental results and data were fitted to the Anand viscoplasticity model and the Anand constants were calculated by estimating the stress-strain behavior measured for operating temperatures-65°C to 200°C. Also, FE analysis has been carried out for drop/shock events for BGA package assembly with PCB. Hysteresis stress-strain curves and plastic work density curves are generated for various aging conditions for M758 solder ball joint

关键词： Strain rate

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