Perforation Of Structures Research Articles

Numerical analysis for optimizing the determination of dynamic friction coefficient

A proper definition of the real dynamic contact behavior is very important in numerical simulation of different dynamic processes such as machining, high speed cutting, impact and perforation of structures. This paper presents an optimal analysis for accurate estimation of the dynamic friction coefficient using a tribometer device. A three-dimensional finite element (FE) model is developed to better understand the test set-up and its associated method to accurately define the friction coefficient under dynamic loading. The aspect of the experimental methodology currently used to define the dynamic friction law and its main drawbacks are identified and discussed. Based on the FE analysis, a new methodology is proposed to estimate the dynamic friction by introducing the concept of a correction factor that can be used to correct the old experimental data. This correction factor depends on the initial projectile velocity and pressure for any friction coefficient value.

Corrosion of Metals in Tropical Environments

Abstract Eight-year exposure tests of six stainless steels to underwater and atmospheric environments in Panama Canal Zone are described. Test environments included sea water immersion, lake water immersion, seashore inland, inland, sea water mean tide, and seashore. Structural steels, phosphor bronze and naval brass were also evaluated for comparison. Stainless steel plates later were galvanically coupled to carbon steel strips for testing in tropical waters. Stainless steels were not recommended for sea water service where perforation of structure is a consideration. They gave excellent results, however, in tropical fresh water. Tropical atmospheres appeared more corrosive to stainless steels than did temperate climates. 4.2.7, 6.2.5