- Theoretical study of ultrasonic wave propagation in anisotropic materials (for example transversely isotropic, orthotropic or general anisotropic)
- Plotting dispersion curves depending on frequency and velocity in anisotropic layered strutures using numerical computation.
- Calculating the guided wave amplitudes generated by a distribution of harmonic forces in layered material structures by analytical method based on the reciprocity principle and comparing with numerical results
- Understanding of ultrasonic wave propagation and scattering in layered anisotropic media is applied to develop nondestructive methods for defect detection and material characterization of composite structures (e.g. composites used in airframes and structures). Here, the concept of defects is understood quite broadly, such as cracks, delamination, corrosion, etc. occurring during the operation of the structure or air holes (air trap, vacuum void) generated during production process.

- Theoretical research: the project successfully obtained closed-form solutions of wave motions in anisotropic layered structures under ultrasonic sources. As a result, several peer-reviewed journal papers are published and presentations are presented at international conferences
- Application: this project proposed methods for defect detection and material characterization which served as a foundation for developing ultrasonic methods for nondestructive evaluation (NDE) and bone quantitative ultrasound (Bone QUS).

- Obtaning closed-form solutions of guided wave motions in anisotropic layered structures under time-harmonic sources is main contribution of the current project. We also calculate phase and group velocity dispersion curves superimposed by scattered amplitudes and obtain excellent agreement between analytical predictions and numerical results. These derivations are very important to solving inverse problems and developing practical applications in NDE and bone QUS.

- Scientific papers in referred journals (list):
ISI papers (2):
+ H. T. L. Nguyen, Nguyen, V.-H., Bui, Q. T. L., Nguyen, K.-C. T., H. Phan, Le, L. H. (2021), "Beam-steering ultrasonic guided waves in a bone-mimicking plate by time-delaying the excitation of the elements in a multi-element array: a numerical study", Japanese Journal of Applied Physics, 60(SD), pp. SDDE20.
+ Le, D., Y. Nguyen, H. N. Quy, L. H. Le and H. Phan (2022). "Elastodynamic response of an orthotropic layered elastic half-space to time-harmonic loading." Science Progress 105(4), pp. 00368504221135449.
Scopus papers (3):
+ Q. H. Le, Nguyen, Y., Nguyen, H., Dao, D. K., Tran, H.-N., H. Phan (2022), "Guided Waves in Hollow Cylinders: Theoretical and Numerical Study", CIGOS 2021, Emerging Technologies and Applications for Green Infrastructure, Singapore, Springer Singapore.
+ D. Le, Trinh, N. A., Dang, S.-T., Plan, E., Nguyen M. T., H. Phan (2022), "Model of Guided Waves in Cortical Bones Coated with a Soft-Tissue Layer", CIGOS 2021, Emerging Technologies and Applications for Green Infrastructure, Singapore, Springer Singapore.
+ D. K. Dao, Nguyen, H., Le, D., Pham, D. C., Nguyen, T., H. Phan (2020), "A Theoretical and Numerical Study of Ultrasonic Waves in Laminated Composites for Nondestructive Evaluation of Structures", 2020 5th International Conference on Green Technology and Sustainable Development (GTSD).
Conference papers (1):
+ D. K. Dao, Hoang, N. Q., Nguyen, T. G., Le, D., Nguyen, H., H. Phan (2022), " A study on ultrasonic shear horizontal waves in composite structures ", 2022 6th International Conference on Green Technology and Sustainable Development (GTSD).

The results obtained from this project were used in building experimental setup for measuring surface wave signals and improving the quality of data at Wave and Structural Health Monitoring Lab., Pusan National University.

As a principal investigator, I would like to sincerely thank to Postdoc program of Graduate University of Science and Technology (GUST) who provided us the grant to perform and obtain excellent results for this project. With the support, we successfully developed a new research direction in Vietnam. This Postdoc program is wondeful and significant to young scientists who have a strong desire in research work. For the principal investigator, this funding came in right time when I had new ideas for a breakthrough research direction but had not found a funding yet. The research team also thanks the coordinating unit, Institute of Mechanics, for creating all favorable conditions for the project to have a great success.
Based on the productivity of the current postdoc program, we are expecting another new funding program supported by GUST to continue more advanced research, obtain more high-quality papers and create practical scientific products.