High-speed photography together with optical interferometric techniques are being used to investigate dynamic crack initiation and growth. Finite element modeling together with experimental data is being used to develop dynamic failure criteria in compression. In this investigation, experiments are being performed to ascertain the strain hardening, strain rate hardening, and thermal softening of metals and alloys over a wide range of strain, strain rate and temperature. An integral part of this investigation is the measurement fraction of plastic work converted to heat as a function of strain and strain rate. Numerical modeling and material characterization are integral parts of this investigation.
Materials currently being investigated include titanium and aluminum alloys.
Deformation and Failure Behavior of Ceramic Materials Advanced materials such as ceramics and ceramic composites are finding increasing applications in aircraft engine parts such as turbine casings which should be protected against foreign object impact damage. To predict the performance of brittle solids considered for such applications, there is a need to understand the critical conditions for failure and the associated micromechanisms under impact loading conditions. Quasi-static and dynamic experiments are used to assess the role of radial confinement in choice of failure modes. Experiments are performed over a wide range of strain rates to develop constitutive and failure models for brittle solids. Analytical and numerical models are used to predict the role of damage evolution on deformation and strength of ceramic materials.