Materials--Dynamic testing

A survey of MOS RAM failure modes describes those failures
that a complete MOS RAM testing program accelerates and
identifies. Functional testers perform the identification
while burn-in testers accelerate various failure modes. A
dynamic burn-in system that includes temperature, bias, and
operational signal stress has been designed so that a large
number of MOS RAM modules are stressed during a burn-in
cycle. The system requires flexible hardware and software
configurations and an almost universal product interface.
Since these requirements have been met and the characteristics
of the stress signals are similar to those encountered
by the product during a normal lifetime, the dynamic
burn-in system presented in this study can effectively accelerate
the most prominent MOS RAM failure modes.

To better characterize the accumulation of permanent deformation in a granular material, 40 Consolidated Drained (CD) triaxial tests (14 static and 26 cyclic) were performed under various stress conditions. A Digital Image Correlation (DIC) technique was utilized in some Repeated Load Triaxial (RLT) tests to measure global and localized strains visually in a non-contact manner. Additionally, the experimentally determined resilient material properties were used in a finite element based pavement modeling software called MICH-PAVE. Under cyclic loading, the permanent strain accumulation was found to obey the relationship of the form epsilonp =aNb, and the Resilient Modulus was used to develop the nonlinear K-theta model for granular materials. The observed/measured permanent strains using DIC/LVDT techniques compared favorably with the values obtained by the finite element simulation, and the evaluation of granular material by multiple methods seems promising for improved pavement design.