Research

Research interests

1: Hard materials and structures
(1) Testing and constitutive modeling of plasticity and fracture for new engineering materials including metals and composites
(2) Studying fundamental mechanisms of plastic deformation and ductile fracture using 3D X-Ray CT imaging, and volumetric digital image correlation (DIC).
(3) Lightweight designs, sheet metal forming, structural impact and vehicle crashworthiness
(4) Multi-scale finite element analysis (FEA), material subroutine development
(5) High velocity impact (including hard body and soft body impacts)
(6) Experimental techniques development, optical measurement with DIC, and their applications
(7) Mechanics of  Additively manufacturing alloys (AMA) and micro lattice structures (MLS)

2: Soft materials
(1) Mechanics of soft tissue materials including hyperelasticity and fracture
(2) Mechanics of virus (SARS-CoV-2, HIV, HEP-B, etc.) and proteins.

Area 1A: Plasticity and fracture of engineering materials

  • Calibration of multi-axial stress material yielding, strain hardening, plastic flow, and fracture.
  • Effects temperature, high strain rate, and nonlinear loading paths.
  • Plasticity model with both stress triaxiality and Lode angle dependencies. Ductile fracture model using Modified Mohr-Coulomb (MMC) criterion and its evolutions (sMMC or eMMC) for different applications.
  • Prediction of both fracture initiation and fracture propagation.
  • Multi-axial low cycle fatigue of materials.
  • Implementation of these models to finite element codes (Abaqus, Ls-Dyna, and VPS).

Area 1B: Anisotropic mechanical testing and modeling of lightweight metal sheets

  • Calibration of anisotropic plastic flow, metal sheet anisotropic strength, and anisotropic fracture.
  • Comprehensive plasticity  and fracture modeling under mutiaxial loading and nonlinear loading paths using a fully modularized framework.
  • Ductile fracture model using Modified Mohr-Coulomb (MMC) criterion and its evolution (sMMC or eMMC).
  • Investigated materials: advanced high strength steels (AHSS), aluminum alloy sheets, magnesium alloy sheets, etc.

Area 1C: Testing, modeling and simulation of various composites

  • Biaxial testing and calibration of fracture properties of carbon fiber reinforced polymer matrix composites (PMCs).
  • Co-existence of brittle and ductile fracture of metallic matrix nano composites (MMNCs).
  • Strength asymmetry and full characterization of mechanical properties for ceramic matrix composites (CMCs).
  • Constitutive modeling and implementation to finite element packages as material subroutines (Abaqus, LsDyna, VPS,…).

Area 1D: Application of fracture mechanics in material advanced manufacturing processes and impact loading

  • Metal cutting for alloys and metallic matrix nano composites (MMNCs).
  • Metal sheet forming with punching device.
  • Nano fragmentation of fiber cables under progressive necking.
  • High velocity impact concrete structures.

Area 2A: Testing, modeling and simulation of soft tissues with medical applications

  • Uniaxial and biaxial testing of soft tissue materials.
  • Constitutive modeling using anisotropic hyperelastic models, fracture of soft tissues.
  • Finite element simulation with a developed material user subroutine.

Area 2B: Mechanics of virus and proteins

  • Mechanical properties of  virus and proteins based on molecular structures.
  • Damage virus using ultrasound technique.