Assessment of Gas-Surface Interaction Models for Computation of Rarefied Hypersonic Flow

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76727/1/AIAA-36375-113.pd

The effect of the orientation of cubical projectiles on the ballistic limit and failure mode of AA2024-T351 sheets

This paper presents the results of an investigation of the ballistic limits and failure modes of AA2024-T351 sheets impacted by cubical projectiles. The effect of cube orientation on the ballistic limit and failure modes was considered in detail. Three impact configurations were investigated. Configuration one, two and three considered face, edge or corner impacts correspondingly. The experimental results were complemented with finite element analysis results in order to explain the observations. The lowest ballistic limit (202 m/s) was observed when the cube edge impacted on the target. In the cube face impacts, the ballistic limit was higher (223 m/s), and the highest ballistic limit (254 m/s) was observed for the corner impact. Although the face impact did not have the lowest ballistic limit, this impact configuration resulted in the least amount of projectile energy loss for impacts above the ballistic limit. With the aid of finite element modelling, it was possible to develop a better understanding of the test results and explain that the observed differences in impact response were not just due to a difference in projectile frontal area, but also due to the combination of the localised deformation near the projectile impact point and the resulting global (dishing) deformation

Influence of Ground Motion Duration on Responses of Concrete Gravity Dams

This study investigates the duration effect on the responses and damage of a dam–reservoir–foundation system. A group of 95 recorded accelerograms with a wide range of durations are adopted in the analyses. A novel global damage index that takes into consideration the consequences of damage at different locations on the overall dam safety is proposed. Nonlinear analysis results show that the duration is positively correlated with the accumulated damage of the dam system. An amplification coefficient that relates the response of the concrete gravity dam from short-duration and long-duration ground motions is proposed