Education

Research Description

Dr. Yuan is interested in structural health monitoring, damage tolerance of composite structures, smart materials and structures, and fracture and life prediction of advanced materials and structures. Dr. Yuan is currently developing methods for structural diagnosis and prognosis (involves evaluating remaining life of structures using failure/statistical analysis tools), is developing a wireless sensor that monitors structural integrity, is developing methods for in-situ, mount-ed/embedded sensors for multi-functional composite structures, and is studying bio-inspired morphing technologies for civil, mechanical, and aerospace structures. Within MAE, Dr. Yuan collaborates with Dr. Peters and Dr. Wu.

Publications

A bi-stable horizontal diamagnetic levitation based low frequency vibration energy harvester

Palagummi, S. and Yuan, F. G. (2018), SENSORS AND ACTUATORS A-PHYSICAL, 279(), 743-752.

Air-coupled nondestructive evaluation dissected

Harb, M. S. and Yuan, F. G. (2018), Journal of Nondestructive Evaluation, 37(3), .

Enhanced damage imaging of a metallic plate using matching pursuit algorithm with multiple wavepaths

Kim, Ho-Wuk and Yuan, Fuh-Gwo (2018), ULTRASONICS, 89(), 84-101.

Extraction of guided wave dispersion curve in isotropic and anisotropic materials by Matrix Pencil method

Chang, C. Y. and Yuan, F. G. (2018), ULTRASONICS, 89(), 143-154.

Impact damage visualization in a honeycomb composite panel through laser inspection using zero-lag cross-correlation imaging condition

Girolamo, D. and Chang, H. Y. and Yuan, F. G. (2018), Ultrasonics, 87(), 152-165.

Improvement of progressive damage model to predicting crashworthy composite corrugated plate

Ren, Y. R. and Jiang, H. Y. and Ji, W. Y. and Zhang, H. Y. and Xiang, J. W. and Yuan, F. G. (2018), Applied Composite Materials, 25(1), 45-66.

On vibrations of porous nanotubes

She, G. L. and Ren, Y. R. and Yuan, F. G. and Xiao, W. S. (2018), International Journal of Engineering Science, 125(), 23-35.

On wave propagation of porous nanotubes

She, Gui-Lin and Yuan, Fuh-Gwo and Ren, Yi-Ru (2018), INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE, 130(), 62-74.

A semi-analytical approach for SH guided wave mode conversion from evanescent into propagating

Yan, X. and Yuan, F. G. (2018), Ultrasonics, 84(), 430-437.

Barely visible impact damage imaging using non-contact air-coupled transducer/laser Doppler vibrometer system

Harb, M. and Yuan, F. (2017), Structural Health Monitoring, 16(6), 663-673.

Damage imaging of an isotropic plate using matching pursuit algorithm

Kim, H. W. and Yuan, F. G. (2017), Proceedings of SPIE-the International Society for Optical Engineering, 10168(), .

Design and optimization of an OPFC ultrasonic linear phased array transducer

Wang, Z. P. and Luo, Y. and Zhao, G. Q. and Yuan, F. G. (2017), International Journal of Mechanics and Materials in Design, 13(1), 57-69.

Design of novel plug-type triggers for composite square tubes: Enhancement of energy-absorption capacity and inducing failure mechanisms

Jiang, H. Y. and Ren, Y. R. and Gao, B. H. and Xiang, J. W. and Yuan, F. G. (2017), International Journal of Mechanical Sciences, 131(), 113-136.

Imaging of local porosity/voids using a fully non-contact air-coupled transducer and laser Doppler vibrometer system

Hudson, T. B. and Hou, T. H. and Grimsley, B. W. and Yuan, F. G. (2017), Structural Health Monitoring, 16(2), 164-173.

Lamb wave-based BVID imaging for a curved composite sandwich panel

He, J. Z. and Yuan, F. G. (2017), AIP Conference Proceedings, 1806(), .

Lamb-wave-based two-dimensional areal scan damage imaging using reverse-time migration with a normalized zero-lag cross-correlation imaging condition

He, J. Z. and Yuan, F. G. (2017), Structural Health Monitoring, 16(4), 444-457.

Nonlinear analysis of bending, thermal buckling and post-buckling for functionally graded tubes by using a refined beam theory

She, G. L. and Yuan, F. G. and Ren, Y. R. (2017), Composite Structures, 165(), 74-82.

On buckling and postbuckling behavior of nanotubes

She, G. L. and Yuan, F. G. and Ren, Y. R. and Xiao, W. S. (2017), International Journal of Engineering Science, 121(), 130-142.

Probabilistic fatigue damage prognosis using surrogate models trained via three-dimensional finite element analysis

Leser, P. E. and Hochhalter, J. D. and Warner, J. E. and Newman, J. A. and Leser, W. P. and Wawrzynek, P. A. and Yuan, F. G. (2017), Structural Health Monitoring, 16(3), 291-308.

Research on nonlinear bending behaviors of FGM infinite cylindrical shallow shells resting on elastic foundations in thermal environments

She, G. L. and Yuan, F. G. and Ren, Y. R. (2017), Composite Structures, 170(), 111-121.

Study on random decrement signature under different triggering level and length of time history

Wu, J. Z. and Zheng, X. J. and Hu, J. and Zhang, Y. G. and Yuan, F. G. (2017), Conference Proceedings of the Society for Experimental Mechanics Series, (), 159-166.

Thermal buckling and post-buckling analysis of functionally graded beams based on a general higher-order shear deformation theory

She, G. L. and Yuan, F. G. and Ren, Y. R. (2017), Applied Mathematical Modelling, 47(), 340-357.

An enhanced performance of a horizontal diamagnetic levitation mechanism-based vibration energy harvester for low frequency applications

Palagummi, S. V. and Yuan, F. G. (2017), Journal of Intelligent Material Systems and Structures, 28(5), 578-594.

Damage imaging using non-contact air-coupled transducer/laser Doppler vibrometer system

Harb, M. S. and Yuan, F. G. (2016), Structural Health Monitoring, 15(2), 193-203.

Damage modes recognition and Hilbert-Huang transform analyses of CFRP laminates utilizing acoustic emission technique

Han, W. Q. and Ying, L. and Gu, A. J. and Yuan, F. G. (2016), Applied Composite Materials, 23(2), 155-178.

Design of an orthotropic piezoelectric composite material phased array transducer for damage detection in a concrete structure

Wang, Z. P. and Luo, Y. and Zhao, G. Q. and Xu, B. Q. and Yuan, F. G. (2016), Research in Nondestructive Evaluation, 27(4), 204-215.

Embedded Ni-Ti particles for the detection of fatigue crack growth in AA7050

Leser, W. P. and Newman, J. A. and Hochhalter, J. D. and Gupta, V. K. and Yuan, F. G. (2016), Fatigue & Fracture of Engineering Materials & Structures, 39(6), 686-695.

Guided torsional wave generation of a linear in-plane shear piezoelectric array in metallic pipes

Zhou, W. S. and Yuan, F. G. and Shi, T. L. (2016), Ultrasonics, 65(), 69-77.

Lamb wave-based subwavelength damage imaging using the DORT-MUSIC technique in metallic plates

He, J. Z. and Yuan, F. G. (2016), Structural Health Monitoring, 15(1), 65-80.

Lamb waves based fast subwavelength imaging using a DORT-MUSIC algorithm

He, J. Z. and Yuan, F. G. (2016), AIP Conference Proceedings, 1706(), .

Non-contact ultrasonic technique for Lamb wave characterization in composite plates

Harb, M. S. and Yuan, F. G. (2016), Ultrasonics, 64(), 162-169.

Study on a flexoelectric microphone using barium strontium titanate

Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2016), Journal of Micromechanics and Microengineering, 26(4), .

System efficiency of miniature horizontal-axis wind turbines with and without gear transmission

Xu, F. J. and Yuan, F. G. and Hu, J. Z. (2016), Journal of Energy Engineering, 142(1), .

A 3D collision avoidance strategy for UAV with physical constraints

Zhu, L. H. and Cheng, X. H. and Yuan, F. G. (2016), Measurement, 77(), 40-49.

A quantitative damage imaging technique based on enhanced CCRTM for composite plates using 2D scan

He, J. Z. and Yuan, F. G. (2016), Smart Materials & Structures, 25(10), .

An anisotropic ultrasonic transducer for Lamb wave applications

Zhou, W. S. and Li, H. and Yuan, F. G. (2016), Smart Structures and Systems, 17(6), 1055-1065.

An efficient low frequency horizontal diamagnetic levitation mechanism based vibration energy harvester

Palagummi, S. and Yuan, F. G. (2016), Proceedings of SPIE-the International Society for Optical Engineering, 9799(), .

An enhanced CCRTM (E-CCRTM) damage imaging technique using a 2-D areal scan for composite plates

He, J. Z. and Yuan, F. G. (2016), Proceedings of SPIE-the International Society for Optical Engineering, 9804(), .

Automated laser-based barely visible impact damage detection in honeycomb sandwich composite structures

Girolamo, D. and Girolamo, L. and Yuan, F. G. (2015), AIP Conference Proceedings, 1650(), 1392-1400.

Conversion of evanescent Lamb waves into propagating waves via a narrow aperture edge

Yan, X. and Yuan, F. G. (2015), Journal of the Acoustical Society of America, 137(6), 3523-3533.

Damage identification for composite structures using a cross-correlation reverse-time migration technique

He, J. Z. and Yuan, F. G. (2015), Structural Health Monitoring, 14(6), 558-570.

Direct measurement of opening mode stress intensity factors using flexoelectric strain gradient sensors

Huang, W. B. and Yang, S. R. and Zhang, N. Y. and Yuan, F. G. and Jiang, X. N. (2015), Experimental Mechanics, 55(2), 313-320.

Fundamental understanding of wave generation and reception using d(36) type piezoelectric transducers

Zhou, W. S. and Li, H. and Yuan, F. G. (2015), Ultrasonics, 57(), 135-143.

Gradient enhanced damage sizing for structural health management

Li, G. and Yuan, F. G. (2015), Smart Materials & Structures, 24(2), .

Lamb wave dispersion and anisotropy profiling of composite plates via non-contact air-coupled and laser ultrasound

Harb, M. S. and Yuan, F. G. (2015), AIP Conference Proceedings, 1650(), 1229-1238.

Microstructural designs of plate-type elastic metamaterial and their potential applications: A review

Zhu, R. and Liu, X. N. and Hu, G. K. and Yuan, F. G. and Huang, G. L. (2015), International Journal of Smart and Nano Materials, 6(1), 14-40.

Numerical modeling of guided ultrasonic waves generated and received by PZT wafer in a beam

Zhang, J. X. and Xu, B. Q. and Xu, G. D. and Xu, C. G. and Luo, Y. and Yuan, F. G. (2015), Proceedings of SPIE-the International Society for Optical Engineering, 9543(), .

Probabilistic fatigue damage prognosis using a surrogate model trained via 3D finite element analysis

Leser, P. E. and Hochhalter, J. D. and Newman, J. A. and Leser, W. P. and Warner, J. E. and Wawrzynek, P. A. and Yuan, F. G. (2015), Structural Health Monitoring, (), 2407-2414.

Response to "Comment on 'A lightweight yet sound-proof honeycomb acoustic metamaterial'" [Appl. Phys. Lett. 107, 216101 (2015)]

Sui, N. and Yan, X. and Huang, T. Y. and Xu, J. and Yuan, F. G. and Jing, Y. (2015), Applied Physics Letters, 107(21), .

Simulation of delamination-migration and core crushing in a CFRP sandwich structure

McElroy, M. and Leone, F. and Ratcliffe, J. and Czabaj, M. and Yuan, F. G. (2015), Composites. Part A, Applied Science and Manufacturing, 79(), 192-202.

Ultrasonic guided wave based horizontal crack imaging in metal plate by local wavenumber analysis

Xu, C. G. and Xu, B. Q. and Luo, Y. and Xu, G. D. and Yuan, F. G. (2015), Proceedings of SPIE-the International Society for Optical Engineering, 9543(), .

A diamagnetically stabilized horizontally levitated electromagnetic vibration energy harvester

Palagummi, S. and Zou, J. and Yuan, F. G. (2015), Proceedings of SPIE-the International Society for Optical Engineering, 9431(), .

A horizontal diamagnetic levitation based low frequency vibration energy harvester

Palagummi, S. and Zou, J. and Yuan, F. G. (2015), Journal of Vibration and Acoustics-Transactions of the ASME, 137(6), .

A lightweight yet sound-proof honeycomb acoustic metamaterial

Sui, N. and Yan, X. and Huang, T. Y. and Xu, J. and Yuan, F. G. and Jing, Y. (2015), Applied Physics Letters, 106(17), .

A rapid, fully non-contact, hybrid system for generating Lamb wave dispersion curves

Harb, M. S. and Yuan, F. G. (2015), Ultrasonics, 61(), 62-70.

An optimal design of a mono-stable vertical diamagnetic levitation based electromagnetic vibration energy harvester

Palagummi, S. and Yuan, F. G. (2015), Journal of Sound and Vibration, 342(), 330-345.

Cracks monitoring and characterization using Ba0.64Sr0.36TiO3 flexoelectric strain gradient sensors

Huang, W. B. and Yang, S. R. and Zhang, N. Y. and Yuan, F. G. and Jiang, X. N. (2014), Proceedings of SPIE-the International Society for Optical Engineering, 9061(), .

Fabrication and measurement of a flexoelectric micro-pyramid composite

Huang, W. B. and Shu, L. L. and Kwon, S. R. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2014), AIP Advances, 4(12), .

Flexoelectricity in barium strontium titanate thin film

Kwon, S. R. and Huang, W. B. and Shu, L. L. and Yuan, F. G. and Maria, J. P. and Jiang, X. N. (2014), Applied Physics Letters, 105(14), .

Guided wave generation, sensing and damage detection using in-plane shear piezoelectric wafers

Zhou, W. S. and Li, H. and Yuan, F. G. (2014), Smart Materials & Structures, 23(1), .

Miniature horizontal axis wind turbine system for multipurpose application

Xu, F. J. and Yuan, F. G. and Hu, J. Z. and Qiu, Y. P. (2014), Energy (Oxford, England), 75(), 216-224.

Stabilizing carbon nanotube yarns using chemical vapor infiltration

Thiagarajan, V. and Wang, X. and Bradford, P. D. and Zhu, Y. T. and Yuan, F. G. (2014), Composites Science and Technology, 90(), 82-87.

A new type of microphone using flexoelectric barium strontium titnate

Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2014), Proceedings of SPIE-the International Society for Optical Engineering, 9062(), .

A super-compact metamaterial absorber cell in L-band

Cao, Z. X. and Yuan, F. G. and Li, L. H. (2014), Journal of Applied Physics, 115(18), .

A trapezoidal flexoelectric accelerometer

Huang, W. and Kwon, S. R. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2014), Journal of Intelligent Material Systems and Structures, 25(3), 271-277.

An automated phase correction algorithm for retrieving permittivity and permeability of electromagnetic metamaterials

Cao, Z. X. and Yuan, F. G. and Li, L. H. (2014), AIP Advances, 4(6), .

Damage identification for composite structures using a cross-correlation reverse-time migration technique

He, J. and Yuan, F. G. (2013), Structural Health Monitoring 2013, Vols 1 and 2, (), 2185-2193.

Design of a curvature sensor using a flexoelectric material

Yan, X. and Huang, W. B. and Kwon, S. R. and Yang, S. R. and Jiang, X. N. and Yuan, F. G. (2013), Proceedings of SPIE-the International Society for Optical Engineering, 8692(), .

Development of time-reversal method for impact source identification on plate structures

Chen, C. L. and Li, Y. L. and Yuan, F. G. (2013), Shock and Vibration, 20(3), 561-573.

Diamagnetic levitation for nonlinear vibration energy harvesting: Theoretical modeling and analysis

Liu, L. and Yuan, F. G. (2013), Journal of Sound and Vibration, 332(2), 455-464.

Experimental and numerical studies on vertical properties of a new multi-dimensional earthquake isolation and mitigation device

Xu, Z. D. and Lu, L. H. and Shi, B. Q. and Yuan, F. (2013), Shock and Vibration, 20(3), 401-410.

Fast damage imaging using the time-reversal technique in the frequency-wavenumber domain

Zhu, R. and Huang, G. L. and Yuan, F. G. (2013), Smart Materials & Structures, 22(7), .

Flexoelectric sensing using a multilayered barium strontium titanate structure

Kwon, S. R. and Huang, W. B. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2013), Smart Materials & Structures, 22(11), .

Focusing flexural Lamb waves by designing elastic metamaterials bonded on a plate

Yan, X. and Zhu, R. and Huang, G. L. and Yuan, F. G. (2013), Proceedings of SPIE-the International Society for Optical Engineering, 8695(), .

Focusing guided waves using surface bonded elastic metamaterials

Yan, X. and Zhu, R. and Huang, G. L. and Yuan, F. G. (2013), Applied Physics Letters, 103(12), .

Performance prediction and demonstration of a miniature horizontal axis wind turbine

Xu, F. J. and Yuan, F. G. and Liu, L. and Hu, J. Z. and Qiu, Y. P. (2013), Journal of Energy Engineering, 139(3), 143-152.

A magnetically levitated vibration energy harvester

Wang, X. Y. and Palagummi, S. and Liu, L. and Yuan, F. G. (2013), Smart Materials & Structures, 22(5), .

A sensor for the direct measurement of curvature based on flexoelectricity

Yan, X. and Huang, W. B. and Kwon, S. R. and Yang, S. R. and Jiang, X. N. and Yuan, F. G. (2013), Smart Materials & Structures, 22(8), .

A vibration energy harvester using diamagnetic levitation

Palagummi, S. and Yuan, F. G. (2013), Proceedings of SPIE-the International Society for Optical Engineering, 8688(), .

Damage localization using a power-efficient distributed on-board signal processing algorithm in a wireless sensor network

Liu, L. and Liu, S. T. and Yuan, F. G. (2012), Smart Materials & Structures, 21(2), .

Design of a magnetostrictive sensor for structural health monitoring of non-ferromagnetic plates

Zhou, L. and Yang, Y. J. and Yuan, F. G. (2012), Journal of Vibroengineering, 14(1), 280-291.

Experimental study on identifying cracks of increasing size using ultrasonic excitation

An, J. and Haftka, R. T. and Kim, N. H. and Yuan, F. G. and Kwak, B. M. and Sohn, H. and Yeum, C. M. (2012), Structural Health Monitoring, 11(1), 95-108.

Flexoelectric materials and structures for M/NEMS

Huang, W. B. and Kim, K. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2012), Proceedings of the ASME International Mechanical Engineering Congress and Exposition, 2011, vol 11, (), 761-766.

Flexoelectric strain gradient detection using Ba0.64Sr0.36TiO3 for sensing

Huang, W. B. and Yan, X. and Kwon, S. R. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2012), Applied Physics Letters, 101(25), .

Impact source identification in finite isotropic plates using a time-reversal method: experimental study

Chen, C. L. and Li, Y. L. and Yuan, F. G. (2012), Smart Materials & Structures, 21(10), .

Carbon nanotube yarn sensors for structural health monitoring of composites

Zhao, H. B. and Yuan, F. G. (2011), Proceedings of SPIE-the International Society for Optical Engineering, 7983(), .

Mechanical and electrical property improvement in CNT/Nylon composites through drawing and stretching

Wang, X. and Bradford, P. D. and Liu, W. and Zhao, H. B. and Inoue, Y. and Maria, J. P. and Li, Q. W. and Yuan, F. G. and Zhu, Y. T. (2011), Composites Science and Technology, 71(14), 1677-1683.

Producing superior composites by winding carbon nanotubes onto a mandrel under a poly(vinyl alcohol) spray

Liu, W. and Zhang, X. H. and Xu, G. and Bradford, P. D. and Wang, X. and Zhao, H. B. and Zhang, Y. Y. and Jia, Q. X. and Yuan, F. G. and Li, Q. W. and Qiu, Y. P. and Zhu, Y. T. (2011), Carbon, 49(14), 4786-4791.

Scaling effect of flexoelectric (Ba,Sr)TiO(3) microcantilevers

Huang, W. B. and Kim, K. and Zhang, S. J. and Yuan, F. G. and Jiang, X. N. (2011), Physica Status Solidi-Rapid Research Letters, 5(9), 350-352.

Carbon nanotube yarn strain sensors

Zhao, H. B. and Zhang, Y. Y. and Bradford, P. D. and Zhou, Q. A. and Jia, Q. X. and Yuan, F. G. and Zhu, Y. T. (2010), Nanotechnology, 21(30), .

Impact source identification in finite isotropic plates using a time-reversal method: theoretical study

Chen, C. L. and Yuan, F. G. (2010), Smart Materials & Structures, 19(10), .

Uncertainty reduction of damage growth properties using structural health monitoring

Coppe, A. and Haftka, R. T. and Kim, N. H. and Yuan, F. G. (2010), Journal of Aircraft, 47(6), 2030-2038.

A Linear Mapping Technique for Dispersion Removal of Lamb Waves

Liu, L. and Yuan, F. G. (2010), Structural Health Monitoring, 9(1), 75-86.

An intermetallic Fe-Zr catalyst used for growing long carbon nanotube arrays

Zhao, H. and Bradford, P. D. and Wang, X. and Liu, W. and Luo, T. J. M. and Jia, Q. X. and Zhu, Y. T. and Yuan, F. G. (2010), Materials Letters, 64(18), 1947-1950.

Damage identification using electromagnetic waves based on born imaging algorithm

Nojavan, S. and Yuan, F. G. (2009), Journal of Engineering Mechanics, 135(7), 717-728.

Active damage localization for plate-like structures using wireless sensors and a distributed algorithm

Liu, L. and Yuan, F. G. (2008), Smart Materials & Structures, 17(5), .

Vibration energy harvesting by magnetostrictive material

Wang, L. and Yuan, F. G. (2008), Smart Materials & Structures, 17(4), .

Wave reflection and transmission in composite beams containing semi-infinite delamination

Yuan, W. C. and Zhou, L. and Yuan, F. G. (2008), Journal of Sound and Vibration, 313(3-5), 676-695.

Wireless sensors with dual-controller architecture for active diagnosis in structural health monitoring

Liu, L. and Yuan, F. G. (2008), Smart Materials & Structures, 17(2), .

Active damage localization technique based on energy propagation of Lamb waves

Wang, L. and Yuan, F. G. (2007), Smart Structures and Systems, 3(2), 201-217.

Group velocity and characteristic wave curves of Lamb waves in composites: Modeling and experiments

Wang, L. and Yuan, F. G. (2007), Composites Science and Technology, 67(7-8), 1370-1384.

A pre-stack migration method for damage identification in composite structures

Zhou, L. and Yuan, F. G. and Meng, W. J. (2007), Smart Structures and Systems, 3(4), 439-454.

Damage imaging of reinforced concrete structures using electromagnetic migration algorithm

Nojavan, S. and Yuan, F. G. (2006), International Journal of Solids and Structures, 43(18-19), 5886-5908.

Atomistic simulations of J-integral in 2D graphene nanosystems

Jin, Y. and Yuan, F. G. (2005), Journal of Nanoscience and Nanotechnology, 5(12), 2099-2107.

Damage identification in a composite plate using prestack reverse-time migration technique

Wang, L. and Yuan, F. G. (2005), Structural Health Monitoring, 4(3), 195-211.

Experimental study applying a migration technique in structural health monitoring

Lin, X. and Yuan, F. G. (2005), Structural Health Monitoring, 4(4), 341-353.

Nanoscopic modeling of fracture of 2D graphene systems

Jin, Y. and Yuan, F. G. (2005), Journal of Nanoscience and Nanotechnology, 5(4), 601-608.

Transient wave propagation of isotropic plates using a higher-order plate theory

Yang, S. and Yuan, F. G. (2005), International Journal of Solids and Structures, 42(14), 4115-4153.

Micro-stress prediction in composite laminates with high stress gradients

Hutapea, P. and Yuan, F. G. and Pagano, N. J. (2003), International Journal of Solids and Structures, 40(9), 2215-2248.

Simulation of elastic properties of single-walled carbon nanotubes

Jin, Y. and Yuan, F. G. (2003), Composites Science and Technology, 63(11), 1507-1515.

Size scales for accurate homogenization in the presence of severe stress gradients

Yuan, F. G. and Pagano, N. J. (2003), Mechanics of Advanced Materials and Structures, 10(4), 353-365.

Three-dimensional Green's functions for composite laminates

Yuan, F. G. and Yang, S. and Yang, B. (2003), International Journal of Solids and Structures, 40(2), 331-342.

Three-dimensional stress analyses in composite laminates with an elastically pinned hole

Yang, B. and Pan, E. and Yuan, F. G. (2003), International Journal of Solids and Structures, 40(8), 2017-2035.

Crack-tip fields in anisotropic shells

Yuan, F. G. and Yang, S. (2002), International Journal of Fracture, 113(4), 309-326.

Damage detection of a plate using migration technique

Lin, X. and Yuan, F. G. (2001), Journal of Intelligent Material Systems and Structures, 12(7), 469-482.

Detection of multiple damages by prestack reverse-time migration

Lin, X. and Yuan, F. G. (2001), AIAA Journal, 39(11), 2206-2215.

Diagnostic Lamb waves in an integrated piezoelectric sensor/actuator plate: analytical and experimental studies

Lin, X. and Yuan, F. G. (2001), Smart Materials & Structures, 10(5), 907-913.

Fracture behavior of stitched warp-knit fabric composites

Yuan, F. G. and Yang, S. (2001), International Journal of Fracture, 108(1), 73-94.

Stress analyses around holes in composite laminates using boundary element method

Pan, E. and Yang, B. and Cai, G. and Yuan, F. G. (2001), Engineering Analysis With Boundary Elements, 25(1), 31-40.

Analysis of axisymmetrically-loaded filament wound composite cylindrical shells

Yuan, F. G. and Yang, W. and Kim, H. (2000), Composite Structures, 50(2), 115-130.

Asymptotic crack-tip fields in an anisotropic plate subjected to bending, twisting moments and transverse shear loads

Yuan, F. G. and Yang, S. (2000), Composites Science and Technology, 60(12/13), 2489-2502.

Boundary element analysis of three-dimensional cracks in anisotropic solids

Pan, E. and Yuan, F. G. (2000), International Journal for Numerical Methods in Engineering, 48(2), 211-237.

Crack-tip fields for matrix cracks between dissimilar elastic and creeping materials

Yuan, F. G. and Yang, S. (2000), International Journal of Fracture, 103(4), 327-360.

Determination and representation of the stress coefficient terms by path-independent integrals in anisotropic cracked solids

Yang, S. and Yuan, F. G. (2000), International Journal of Fracture, 101(4), 291-319.

Kinked crack in anisotropic bodies

Yang, S. and Yuan, F. G. (2000), International Journal of Solids and Structures, 37(45), 6635-6682.

Three-dimensional Green's functions in anisotropic piezoelectric bimaterials

Pan, E. and Yuan, F. G. (2000), International Journal of Engineering Science, 38(17), 1939-1960.

A unified loading parameter for creep-crack growth

Wang, W. X. and Yuan, F. G. and Takao, Y. (2000), Proceedings of the Royal Society of London. Series A. Mathematical, Physical and Engineering Sciences, 456(1993), 163-183.

The significance of effective modulus theory (homogenization) in composite laminate mechanics

Pagano, N. J. and Yuan, F. G. (2000), Composites Science and Technology, 60(12/13), 2471-2488.

Electric current-induced stresses at the crack tip in conductors

Cai, G. X. and Yuan, F. G. (1999), International Journal of Fracture, 96(3), 279-301.

The effect of thermal aging on the Mode-I interlaminar fracture behavior of a high-temperature IM7/LaRC-RP46 composite

Hutapea, P. and Yuan, F. G. (1999), Composites Science and Technology, 59(8), 1271-1286.

Stresses around the crack tip due to electric current and self-induced magnetic field

Cai, G. X. and Yuan, F. G. (1998), Advances in Engineering Software, 29(3-6), 297-306.

Three-dimensional wave propagation in composite cylindrical shells

Yuan, F. G. and Hsieh, C. C. (1998), Composite Structures, 42(2), 153-167.

The interlaminar Mode I fracture of IM7/LaRC-RP46 composites at high temperatures

Wang, W. X. and Takao, Y. and Yuan, F. G. and Potter, B. D. and Pater, R. H. (1998), Journal of Composite Materials, 32(16), 1508-1526.

Crack-tip fields in elastic-plastic material under plane stress mode I loading

Yuan, F. G. and Yang, S. (1997), International Journal of Fracture, 85(2), 131-155.

Elastic moduli of brittle matrix composites with interfacial debonding

Yuan, F. G. and Pagano, N. J. and Cai, X. (1997), International Journal of Solids and Structures, 34(2), 177-201.

The curved interfacial crack between dissimilar isotropic solids

Yuan, F. G. and Yang, S. (1997), International Journal of Solids and Structures, 34(6), 641-660.

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Grants

NIA Graduate Research Assistantship for Mr. Dongwon Lee - Investigating the Structural and Mechanical Properties of Boron Nitride Nanotubes and their Polymer Nanocomposites

Korea Institute of Science and Technology (KIST)(8/16/18 - 12/31/18)

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NIA Graduate Research Assistantship for Mr. Dongwon Lee - Investigating the Structural and Mechanical Properties of Boron Nitride Nanotubes and their Polymer Nanocomposites

Sponsor: Korea Institute of Science and Technology (KIST)

Start Date: 8/16/18

End Date: 12/31/18

Abstract

Boron nitride nanotubes (BNNT) have been synthesized using a high temperature-pressure (HTP) method. Without a catalyst, the HTP process produces high-quality BNNTs that have small diameters (~ 5 nm), high aspect ratios (≥ 1:1000), high flexibility, high crystallinity, and piezoelectricity. Their promising material properties include high Young’s modulus (up to 1.3 TPa), excellent thermal stability (up to 900 oC in air), high thermal conductivity (300–3000 W/mK), excellent electrical insulation (with a wide band of ~ 6.0 eV), and high neutron absorption (10B ~3800 barn). With such unique material properties, BNNT materials can open up opportunities for multifunctional applications in extreme environments. The main objective of this research is to study the structure and the material properties of BNNTs and their nanocomposite materials for extreme environment applications and technologies. The BNNT growth will be optimized for high quality and high yield production using in-situ monitoring system. The BNNTs and their nanocomposites are fabricated in multiscale to demonstrate their material properties. Ex-situ material characterization is systematically conducted to confirm the structure and the material properties (thermal, mechanical, electrical, and radiation) of BNNTs and their nanocomposites. In the case of the nanocomposites, various matrices are investigated according to BNNT’s affinity and thermal stability, including high performance polymers and metals. Multifunctional BNNT materials and applications including sensor applications will be demonstrated in multi-scale to target a game-changing system design and innovation for aerospace and future NASA missions.

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Augmented Analysis and Data Collection for Materials Design and Evaluation

National Aeronautics & Space Administration (NASA)(10/01/18 - 9/30/19)

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Augmented Analysis and Data Collection for Materials Design and Evaluation

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 10/01/18

End Date: 9/30/19

Abstract

Additive manufacturing (AM), also referred to as 3-D printing has been developing steadily since the 1980s. According to some reports, 3-D printing is expected to be a $5.2 billion industry by 2020. AM allows for the manufacture of highly complex geometries which are difficult to handle using traditional manufacturing techniques. However, AM still has several hurdles that it needs to overcome before its widespread adoption, especially in the manufacture of safety critical components e.g., current aerospace practice requires 100% visual inspection of the manufactured component. Often times, manual inspection of the component is much more time consuming than the lay-up process itself. Most of the conventional additive manufacturing systems fail to notice minor defects during material lay-up that may get compounded layer by layer thereby rendering the final product unsuitable for use. These defects could potentially be automatically corrected if detected before the next layer is deployed. The goal of this work is to process the data collected using high-resolution cameras and then to use computer vision technology to detect defects such as porosity, cracks, warping, delamination etc. during the lay-up process itself thereby reducing or eliminating the need for post manufacture inspection of printed objects. This could also facilitate the AM system to take corrective measures during the lay-up process itself thereby achieving a Real-time control of the manufacturing process.

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Structural Health Monitoring of Persistent Platforms

National Aeronautics & Space Administration (NASA)(8/01/18 - 7/31/20)

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Structural Health Monitoring of Persistent Platforms

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 8/01/18

End Date: 7/31/20

Abstract

The Structural Mechanics and Concepts Branch at NASA Langley Research Center is currently developing a concept for in-space assembly of persistent assets consisting of repeating truss modules. In-space assembly has been recognized as a critically important approach for reducing the cost of major lunar and deep space missions. Multiple smaller payloads can be launched by a variety of vehicles, then assembled in orbit, by robotic/autonomous means. One of the objectives of the research is to develop a method of monitoring structural health through integrated sensors while also minimizing parasitic mass, power consumption, wiring complexity, costs, and volume occupied by the sensor systems. To achieve this goal, Rounak will research methods of determining global health states of the platform and specifying local module detriments such as stress fractures or MMOD impacts. One of the most promising methods is a short pulse based vibration feedback model to determine structural health across the fully assembled structure. By inputting the short pulse with known waveform and magnitude, integrated piezoelectric sensors can sense and analyze the resultant vibrations through their respective portions of the platform to characterize any damage in the struts and/or nodes. Another alternative of using vision-based monitoring techniques will be possibly considered. The usage monitoring using accelerometers for example will be explored. By maximizing the section of the assetthat is being monitored by each sensor system, the number of integrated sensors can be minimized.

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Samuel P. Langley Distinguished Professor Program (LaP) – FY18

National Aeronautics & Space Administration (NASA)(10/01/17 - 9/30/19)

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Samuel P. Langley Distinguished Professor Program (LaP) – FY18

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 10/01/17

End Date: 9/30/19

Abstract

In order to apply this technology to the field applications for inspecting the entire aerospace structures, the laser systems should be portable and noise-insensitive. Additionally, the software will be further developed to image smaller flaws for instance from automated manufacturing. The objective of the proposal is to continue to develop a rapid laser ultrasonic composite inspection system for quantifying the damage. The proposal will develop, demonstrate, and mature two innovation technologies in field applications including new hardware and software tools to be encompassed in the system. The two new innovations will overcome current major obstacles for rapid large area detection and characterization of either manufacturing or in-service damage in composite structures in terms of sensitivity, resolution, and accuracy. The robust system will also identify and classify the flaw types including porosity and delamination. The resolution limit of each flaw type and quality of the flaw characterization will be determined. The system with much rapid signal and imaging processing tool with high component throughput can be an order of magnitude faster than those of current ether contact or non-contact NDI system. The proposal will develop a practical inspection for data acquisition and analysis methods for processing data that enable in the field to increase automation and reduce the subjective nature of many aspects of the current inspection methodology. The system will enable operating in the field instead of being confined to the vibration-free and isolated laboratory testing. The laser generation and reception generated or received from a fiber optical cable will allow greater flexibility in interrogating hard-to-access areas. A computer vision-based SHM system is starting in parallel with the LDV-based system. Several imaging algorithms used in vision-based SHM system are being proposed to image the damage. The image will compare with those by LDV-based system.

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Real-time Cure Monitoring of Composites Using Piezoelectric Wafers and Fiber Bragg Gratings/Phase-Shifted Fiber Bragg Gratings

National Aeronautics & Space Administration (NASA)(8/15/17 - 8/14/18)

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Real-time Cure Monitoring of Composites Using Piezoelectric Wafers and Fiber Bragg Gratings/Phase-Shifted Fiber Bragg Gratings

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 8/15/17

End Date: 8/14/18

Abstract

The NASA Advanced Composites Project seeks to develop and transition technology that will reduce the timeline required for development and certification of new aircraft structure that utilizes advanced composite materials. One area of concern is the formation of porosity and fiber waviness defects in composite structural parts during various processing stages, from incoming material handling to the completion of laminate curing in an autoclave/vacuum press. To address this concern, an attempt is being made to develop an in-line, cure monitoring detection technique that can support a physics-based cure model to predict the formation of porosity and fiber waviness. It is not an essential requirement to transition this technology to industry in a mass production environment. Initial results indicate that the group velocity of a guided wave may have the potential to serve as an index for estimating the degree of cure and level of porosity. The work will be to transition to an in-line detection system that will be able to monitor the degree of cure and porosity in real-time within a part based on group velocity. The in-line defect detection system will utilize high temperature piezoelectric actuators and sensors for pitch-catch guided wave emission and response detection as well as investigate other metrics such as attenuation of wave energy which will play a critical role during the early stages of cure. A bulk wave pulse-echo technique will be investigated in addition to a guided wave technique to utilize a higher frequency spectrum (>1 MHz) and gain additional information about the part. Both methods can be operated on a single setup. This method is similar to a C-scan except for the fact that the location of the piezoelectric ultrasonic transducer is fixed and is not able to translate in the X-Y plane. A few studies have been published showing that as the porosity level increases, the ultrasonic velocity of the bulk wave propagating perpendicular to the carbon fibers decreases. Experimental studies have been and will continue to be conducted to measure strains during and after cure in CFRP panels. Fiber Bragg grating sensors (FBGs) were embedded between adjacent plies of prepreg and the wavelength shift was measured throughout the cure cycle. A change in wavelength response from the FBGs is caused by strain and change in temperature at the embedded sensor’s location. In parallel with experimental studies, analytical studies are being conducted on the cure process modeling of CFRP panels using COMPRO®, RAVEN®, and ABAQUS®. The residual strain measurements from laboratory tests will be correlated with the analytical model predictions.

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In-Processing Cure Monitoring of Composites

National Aeronautics & Space Administration (NASA)(8/18/16 - 10/14/17)

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In-Processing Cure Monitoring of Composites

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 8/18/16

End Date: 10/14/17

Abstract

The NASA Advanced Composites Project seeks to develop and transition technology that will reduce the timeline required for development and certification of new aircraft structure that utilizes advanced composite materials. One area of concern is the formation of porosity and fiber waviness defects in composite structural parts during various processing stages, from incoming material handling to the completion of laminate curing in an autoclave/vacuum press. To address this concern, an attempt is being made to develop an in-line, cure monitoring detection technique that can support a physics-based cure model to predict the formation of porosity and fiber waviness. It is not an essential requirement to transition this technology to industry in a mass production environment. Initial results indicate that the group velocity of a guided wave may have the potential to serve as an index for estimating the degree of cure and level of porosity. The work will be to transition to an in-line detection system that will be able to monitor the degree of cure and porosity in real-time within a part based on group velocity. The in-line defect detection system will utilize high temperature piezoelectric actuators and sensors for pitch-catch guided wave emission and response detection as well as investigate other metrics such as attenuation of wave energy which will play a critical role during the early stages of cure. A bulk wave pulse-echo technique will be investigated in addition to a guided wave technique to utilize a higher frequency spectrum (>1 MHz) and gain additional information about the part. Both methods can be operated on a single setup. This method is similar to a C-scan except for the fact that the location of the piezoelectric ultrasonic transducer is fixed and is not able to translate in the X-Y plane. A few studies have been published showing that as the porosity level increases, the ultrasonic velocity of the bulk wave propagating perpendicular to the carbon fibers decreases. Experimental studies have been and will continue to be conducted to measure strains during and after cure in CFRP panels. Fiber Bragg grating sensors (FBGs) were embedded between adjacent plies of prepreg and the wavelength shift was measured throughout the cure cycle. A change in wavelength response from the FBGs is caused by strain and change in temperature at the embedded sensor’s location. In parallel with experimental studies, analytical studies are being conducted on the cure process modeling of CFRP panels using COMPRO®, RAVEN®, and ABAQUS®. The residual strain measurements from laboratory tests will be correlated with the analytical model predictions.

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NIA Graduate Research Assistantship for Mr. Dongwon Lee

US Air Force - Office of Scientific Research (AFOSR)(8/16/16 - 8/15/18)

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NIA Graduate Research Assistantship for Mr. Dongwon Lee

Sponsor: US Air Force - Office of Scientific Research (AFOSR)

Start Date: 8/16/16

End Date: 8/15/18

Abstract

Boron nitride nanotubes (BNNT) have been synthesized using a high temperature-pressure (HTP) method, and studied at the National Institute of Aerospace (NIA) BNNT Lab in collaboration with NASA Langley Research Center. Without a catalyst, the HTP process produces high-quality BNNTs that have small diameters (~ 5 nm), high aspect ratios (≥ 1:1000), high flexibility, high crystallinity, and piezoelectricity. Their promising material properties include high Young’s modulus (up to 1.3 TPa), excellent thermal stability (up to 900 oC in air), high thermal conductivity (300–3000 W/mK), excellent electrical insulation (with a wide band of ~ 6.0 eV), and high neutron absorption (10B ~3800 barn). With such unique material properties, BNNT materials can open up opportunities for multifunctional applications in extreme environments. The main objective of this research is to study the structure and the material properties of BNNTs and their nanocomposite materials for extreme environment applications and technologies. The BNNT growth is optimized for high quality and high yield production using in-situ monitoring system. The BNNTs and their nanocomposites are fabricated in multiscale to demonstrate their material properties. Ex-situ material characterization is systematically conducted to confirm the structure and the material properties (thermal, mechanical, electrical, and radiation) of BNNTs and their nanocomposites. In the case of the nanocomposites, various matrices are investigated according to BNNT’s affinity and thermal stability, including high performance polymers and metals. Multifunctional BNNT materials and applications are demonstrated in multiscale to target a game-changing system design and innovation for aerospace and future NASA missions.

Close

Samuel P. Langley Distinguished Professor Program (LaP)-FY16

National Aeronautics & Space Administration (NASA)(10/01/15 - 12/31/17)

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Samuel P. Langley Distinguished Professor Program (LaP)-FY16

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 10/01/15

End Date: 12/31/17

Abstract

In the last year, an initial promise has been made for imaging the delamination for a honeycomb structure using standing wave concept and a zero-lag cross-correlation imaging condition in the frequency-wavenumber domain. This is very encouraging since the very small barely visible impact damages (BVIDs), one has dimension (11mm×12mm), the other (5 mm×6 mm) can be accurately imaged using this novel concept. However the system developed including pulse laser, galvomirrors, and LDV was demonstrated on an optical table (5 ft×7 ft) shown in the figure. In order to apply this technology to the field applications for inspecting the entire aerospace structures, the laser systems should be portable and noise-insensitive. Additionally, the software will be further developed to image small smaller flaws for instance from automated manufacturing. The objective of the proposal is to develop a rapid laser ultrasonic composite inspection system for quantifying the damage. The proposal will develop, demonstrate, and mature two innovation technologies in field applications including new hardware and software tools to be encompassed in the system. The two new innovations will overcome current major obstacles for rapid large area detection and characterization of either manufacturing or in-service damage in composite structures in terms of sensitivity, resolution, and accuracy. The robust system will also identify and classify the flaw types including porosity and delamination. The resolution limit of each flaw type and quality of the flaw characterization will be determined. The system with much rapid signal and imaging processing tool with high component throughput can be an order of magnitude faster than those of current ether contact or non-contact NDI system. The proposal will develop a practical inspection for data acquisition and analysis methods for processing data that enable in the field to increase automation and reduce the subjective nature of many aspects of the current inspection methodology. The system will enable operating in the field instead of being confined to the vibration-free and isolated laboratory testing. The laser generation and reception generated or received from a fiber optical cable will allow greater flexibility in interrogating hard-to-access areas.

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An Advanced Ultrasonic Imaging System for Rapid Inspection of Ultra Large Complex Composite Structures using Time Reversal-MUSIC Technique

National Aeronautics & Space Administration (NASA)(7/07/15 - 12/07/15)

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An Advanced Ultrasonic Imaging System for Rapid Inspection of Ultra Large Complex Composite Structures using Time Reversal-MUSIC Technique

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 7/07/15

End Date: 12/07/15

Abstract

The proposal is to develop an innovative automated ultrasonic imaging technique system, which is called AUIT system, for rapid inspection of large-area complex composites. The key innovation of the proposed approach lies in the combination of time-reversal multiple signal classification (TR-MUSIC) imaging algorithm and the guided-wave based portable linear-array technology for rapid inspection of ultra large complex composite structures. In the proposed approach, a guided-wave based automated ultrasonic imaging technique system, operating in a pulse-echo mode, is used to activate/receive guided waves. The detected ultrasonic signals from scattered waves are then processed by the TR-MUSIC algorithms to achieve super-resolution images in real-time for ultra large plate-like structures. Not only the group velocity (cg) but also the amplitude and phase information are preserved to evaluate the severity of the damage. The complex composite structures could be characterized experimentally such that no material properties are required for the whole inspection process, which is called non-parametric interrogation. Since the time-domain signals are converted to frequency-domain signals for data processing, the dispersion effect, which is a major challenge in guided wave damage detection, is compensated automatically. In common imaging systems, the resolution is no better than half of the wavelength, λ/2, which is the diffraction limit. Since MUSIC algorithm uses the noise space other the signal space, super resolution could be achieved using the TR-MUSIC imaging algorithms. Due to its super resolution imaging ability, larger wavelengths can be utilized by the AUIT system to achieve equally good damage imaging resolution compared with other imaging algorithms such as phased array (PA) and synthetic aperture focusing technique (SAFT). Thus, relative low frequencies can be used with the AUIT system leading to significant advantages. One advantage is that the hardware is allowed to be with lower sampling rate and smaller data volume storage. Also the application of lower frequency guided waves allows ultra large inspection areas compared with using higher frequency signals, since in plate-like structures, especially for composite materials, the attenuation effect increases significantly with the increase of the input frequency. The lower frequency range of low-order Lamb waves sometimes with higher sensitivity to various kinds of damage. The AUIT system can be easily integrated with robotic arm techniques to create a fully automatic scanning system. Embedded with the TR-MUSIC algorithms, the AUIT system delivers real-time, non-parametric, super resolution damage imaging for ultra large complex composite structures, with the advanced data processing and imaging capabilities. The required complexity of operations and the inspection time will be reduced significantly using the AUIT system.

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In-Processing Cure Monitoring of Composites

National Aeronautics & Space Administration (NASA)(8/15/15 - 8/14/17)

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In-Processing Cure Monitoring of Composites

Sponsor: National Aeronautics & Space Administration (NASA)

Start Date: 8/15/15

End Date: 8/14/17

Abstract

The NASA Advanced Composites Project seeks to develop and transition technology that will reduce the timeline required for development and certification of new aircraft structure that utilizes advanced composite materials. One area of concern is the formation of porosity and fiber waviness defects in composite structural parts during various processing stages, from incoming material handling to the completion of laminate curing in an autoclave/vacuum press. To address this concern, an attempt is being made to develop an in-line, cure monitoring detection technique that can support a physics-based cure model to predict the formation of porosity and fiber waviness. It is not an essential requirement to transition this technology to industry in a mass production environment. Initial results indicate that the group velocity of a guided wave may have the potential to serve as an index for estimating the degree of cure and level of porosity. The work will be to transition to an in-line detection system that will be able to monitor the degree of cure and porosity in real-time within a part based on group velocity. The in-line defect detection system will utilize high temperature piezoelectric actuators and sensors for pitch-catch guided wave emission and response detection as well as investigate other metrics such as attenuation of wave energy which will play a critical role during the early stages of cure. A bulk wave pulse-echo technique will be investigated in addition to a guided wave technique to utilize a higher frequency spectrum (>1 MHz) and gain additional information about the part. Both methods can be operated on a single setup. This method is similar to a C-scan except for the fact that the location of the piezoelectric ultrasonic transducer is fixed and is not able to translate in the X-Y plane. A few studies have been published showing that as the porosity level increases, the ultrasonic velocity of the bulk wave propagating perpendicular to the carbon fibers decreases. Experimental studies have been and will continue to be conducted to measure strains during and after cure in CFRP panels. Fiber Bragg grating sensors (FBGs) were embedded between adjacent plies of prepreg and the wavelength shift was measured throughout the cure cycle. A change in wavelength response from the FBGs is caused by strain and change in temperature at the embedded sensor’s location. In parallel with experimental studies, analytical studies are being conducted on the cure process modeling of CFRP panels using COMPRO®, RAVEN®, and ABAQUS®. The residual strain measurements from laboratory tests will be correlated with the analytical model predictions.

Close