Longjun Liu, PhD, FE/EIT, US citizen

Structural Dynamic/Vibroacoustic/Vibration/Stress/Fatigue/Optimization Analyst & Researcher

ac3rp1@r.postjobfree.com, 971-***-**** (home), Yorktown, VA 23693

Expert on mechanical structure analysis, testing, and design: loads, dynamics, vibration, vibroacoustic, stress, fatigue/fracture, sloshing; metal, composite, viscoelastic material; design optimization, statistical analysis; launch vehicles, spacecrafts, solid motors, liquid engines, aircraft engines, other vehicles or equipment; tests: fatigue, vibration (sinusoidal, random), modal, engine, acoustic, pyroshock, viscoelastic, wind tunnel

Nominated for technical leadership award at NASA/MSFC/Space Systems Department. Awards for random vibration, fatigue analysis, etc. Award for successful team work.

SKILL SUMMARY

Structural dynamics

Finite element analysis

Dynamic analysis: transient, harmonic, random vibration

Multibody dynamics: vehicle vibration simulation and control

Loads & dynamics

Coupled load analysis (CLA)

Bending modes analysis

Superelements/Craig-Bampton models

Liquid sloshing modeling and analysis

Monte Carlo analysis

Modal testing and analysis

Vibroacoustic, flow induced vibration

Buffet forcing function definitions based on wind tunnel tests

Aerodynamic load definition, in-flight fluctuating pressure

SEA (statistical energy analysis) of launch vehicles

BEM (boundary element modeling and analysis)

Electric equipment/instrument isolation

Vibration control (isolation, dampers, neutralizers, absorbers, detuning, decoupling, etc.)

Vibration data acquisition and analysis

Composite analysis and design

Viscoelastic material testing and analysis

Stress analysis: linear, nonlinear

Buckling analysis

Contact analysis

Fatigue, fracture mechanics

Testing: Aircraft engine, modal, fatigue, random vibration, acoustic, pyroshock, rubber characterization

Optimization: structural optimization, Operations research, genetic algorithm,

Statistics:

DOE (Design of experiments), Response surface methodologies, DACE (Design and analysis of computer experiments, Statistical process control, Statistical Signal Processing, general statistical analysis

Products: Aircraft engines, space vehicles, launch vehicles, solid motor and liquid engine, spacecraft, railcars

Materials: metal, composite, viscoelastic material, wood (total anisotropic, 21 parameters)

Tools: FEA: NASTRAN, ANSYS, ABAQUS, FEMAP, PATRAN,

SEA: VA ONE, WAVE 6,

CAD: NX, SOLID EDGE, AUTOCAD

MATLAB, MATHCAD, CAM,

SAS, SPSS

NeuralWorks, NUCARS, VISUAL C++, DAKOTA

Programming languages: MATLAB, PYTHON, ANSYS(programming), CAM, FORTRAN, LISP

EXPERIENCE

1. Aerospace Engineer, Structural Dynamics and Vibroacoustics, NASA LaRC, Hampton, VA, 1/2017-12/2017

Couple load analysis of Space Launch Systems (SLS) with PYTHON and CAM codes

Buffet forcing function (BFF) definition based on wind tunnel (WT) tests with MATLAB for SpaceX

Provided a formal review for SLS BFF definition based on WT and research plan to significantly improve the methods

2. Senior Structural Dynamics Engineer, Vibroacoustics and dynamic environment, Virgin Galactic, 5/2016-10/2016

Buffet forcing function definition based on wind tunnel test data and correlation length from coherence decay

Created new zoning rules for aeroacoustic vibration analysis, provided effective methods to calibrate and validate

Statistical Energy Analysis (SEA) of a launch vehicle’s response to acoustic excitation with Wave6; FEA: NASTRAN

3. Staff Engineer, Aeroacoustic vibration/structural dynamics /stress/fatigue, Pratt & Whitney, 5/2011-4/2016

Lead aeroacoustic vibration methods, created a real breakthrough for zoning and PSD scaling, matching test results

Structural analysis, static/dynamics, harmonic/random vibration, stress, fatigue, fracture mechanics, with ANSYS

Static/rotating structures, compressor blade/rotor analysis, turbine rotor lifing based on fatigue & fracture mechanics

Post-test analysis with modal superposition: created new methods and matched engine test results; MATLAB for codes

Engine test online monitoring, noise detection and data validation, and digital signal processing

Modal testing and analysis: mode extraction, damping estimate, FEA matching tests (harmonic and random vibration)

Tools: created codes and GUI to combine MATLAB and ANSYS for fracture screening, compiled for Windows Linux

4. Senior Dynamics Engineer, NASA/MSFC (Marshall Space Flight Center), ESTS group, Huntsville, AL, 8/2009-4/2011

Dynamic analysis and testing for launch vehicles and spacecraft, stress, FEA with FEMAP NASTRAN PATRAN

Random vibration loads, aeroacoustic loads, transient loads, satellite structural analysis (LADEE)

Generated vibration test criteria for acceptance and qualification tests; wire rope isolator simulation

Random vibration tests of computers, instrument units, etc., pyroshock tests, acoustic tests; MATLAB for codes

In-flight fluctuating (TBL: turbulent boundary layer and shock) pressure analysis and definition

Wind tunnel and flight test data analysis and comparison with analytical/empirical predictions

Programs: Ares I, Minotaur V and LADEE lunar spacecraft, EELV/Atlas V/XPC, etc. solid modeling with Pro-E

5. Principal Dynamics Engineer, Orbital Science Corporation, Chandler, AZ, 5/2007-7/2009

Launch vehicle loads and dynamic analysis: bending modes, coupled load (CLA), with FEMAP and NASTRAN

Loads: liftoff, transonic, max q-alpha, wind, gust, vortex shedding, thrust, TVC, drag, buffet; material: metal,composite

Craig-Bampton models and superelements; provided support for pogo analysis; solid modeling with Solid Edge

6. Dynamics Engineer, ATK Launch Systems, Promontory, UT, 9/2005-4/2007

Dynamic/vibration analysis and testing, stress analysis, using ABAQUS, NASTRAN, and MATLAB

Viscoelastic material characterization via testing and simulation, close FEA and test match for dynamic stress & strain

Nonlinear FEA of viscoelastic and hyperelastic material with ABAQUS, harmonic and random dynamic ones

7. Senior Design Engineer, Gunderson Inc., Portland, OR, 2/1996-8/2005

Structural design, linear and nonlinear stress analysis, buckling analysis, fatigue analysis, CAD with Solid Edge

Dynamic/vibration analysis, multi-body dynamic modeling and motion control, dramatically reduced vibration

Composite analysis and design; structural optimization (removed 36% weight); FEA with FEMAP NASTRAN

EDUCATION

Ph.D. Systems Science, Optimization of Mechanical Structure Systems, Portland State University

MS in Engineering Management, Portland State University

MS in Structural Engineering, Southwest Transportation University

BS in Mechanical Engineering, Northern Transportation University

License: FE/EIT (76888EIT, OR); Certificates: Vibroacoustic, SEA/BEM analyses, General fluid system simulation

FEA, SEA, BEM; NASTRAN, ANSYS, ABAQUS, FEMAP, PATRAN, VA1, WAVE6; NX, SOLID EDGE; MATLAB

American Institute of Aeronautics and Astronautics (AIAA), American Society of Mechanical Engineers (ASME), Society for the Advancement of Material and Process Engineering (SAMPE), ASM, SME, …

Detailed resume: http://www.indeed.com/r/06df67fe0036fd39, ac3rp1@r.postjobfree.com

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