Elucidating laser-induced metal microjet dynamics and liquid-bridge printing
Ph.D. student Zhao Yishi studied transient elongation and breakup of laser-induced metal microjets via pump-probe imaging. Inertial tip pinch-off (uneven droplets) and capillary breakup (even droplets) are demarcated by a dimensionless stretching rate threshold. A model that correlates critical breakup length, ejection velocity, and time defines the liquid-bridge gap selection window. This work was recently published in ADDIT MANUF
Approximation of ultra-high strain rate stress-strain relationship from spherical projectile impact indentation
Ph.D. student Chen Jiayu proposed a standard methodology to determine materials' ultra-high strain rate stress-strain relationships (>10⁵ /s) via LIPIT-based impact indentation tests. This method avoids real-time measurement, using projectile velocity and crater parameters to extract representative stress and strain, and was applied to pure copper and aluminum. This work was recently published in INT J PLASTICITY
Bifurcation-dominated nonlinear bending behavior of laser peen forming: Analytical modeling and energy competition mechanism
Dr. Jiang identified LPF nonlinear deformation as bifurcation-dominated bending from geometric nonlinearity-governed mismatch strain. An eigenstrain model was developed, with Al alloy experiments validating bifurcation and morphological transitions. Analyses clarified plate dimension/energy effects, derived a criterion and built a shape morphing design theoretical framework. This work was recently published in J MATER PROCESS TECH
Thermal stress wave-driven regime in femtosecond laser-induced nanomaterial transfer revealed by ultrafast electron microscopy and atomic simulation
Dr. Zhou integrated pulsed lasers with TEM to observe nanoisland nanoscale transfer. Combining two-temperature modeling and molecular dynamics simulations, it revealed a novel thermal stress wave-driven transfer regime, with nanoislands detaching in tens of picoseconds and melting in nanoseconds—first confirmed by experiment and simulation. This work was recently published in INT J MACH TOOL MANU
Spatiotemporal visualization of nanoscale rotational dynamics by movie-mode transmission electron microscopy
Dr. Zhou employed movie-mode transmission electron microscopy to investigate the rotational dynamics of laser-excited nanotriangles. It revealed axis-dependent rotation stability consistent with the tennis racket effect, validating classical rigid-body rotational theory at this scale, and quantifying nanotriangle-substrate adhesion to advance understanding of nanoscale rotational dynamics. This work was recently published in ACS NANO
Indentation size effects: A study via finite similitude scaling theory
Dr. Hamed developed a multiscaled approach for indentation experiments using finite-similitude scaling theory. This methodology can capture indentation size effects and enable high-temperature analysis. Simulations and experiments showed that similitude correction can achieve high accuracy in hardness recovery for crystalline materials, with errors mostly under 9%. This work was recently published in MATER DESIGN.
Dynamic dislocation response in aluminum single crystals under multiple laser peening: A physics-based crystal plasticity study
Ph.D. student Siyuan Chen simulated the dislocation response of aluminum single crystals under laser peening based on a crystal plasticity finite element (CPFE) model. The results indicate that dislocation patterns are axisymmetric during laser irradiation due to the ultra-high slip velocity. Phonon drag induced additional strength during the first shock for the low dislocation density. This work was recently published in INT J PLASTICITY
