Sharif Digital Repository

In this article a new parameter is introduced that optimizes penetration depth of a long rod penetrating into a semi-infinite target. This parameter helps to optimize penetration depth when the projectile is subjected to transverse loading. This parameter is defined using a simple assumption governing bending moment and deflection of the rod as well as the experimental observation of long rod penetrators having aspect ratios (L/D) of greater than 30. In this article the length of the rod that sustains allowable bending stress but does not fail is calculated. Using the results of the bending analysis and solution of the Alekseevskii & Tate (AT) equation, an analytical method to optimize... 

The present study investigates the lowest possible amount of steel and polypropylene fibers in improving the compressive and flexural strength, stiffness, and energy capacity of high strength 100 MPa concrete with a mix design similar to that of Ultra-High Performance Concrete (UHPC). Twenty-eight 100 × 200 mm cylindrical specimens with 0%, 0.2%, 0.4%, and 0.6% volumetric percentage of short steel fibers and polypropylene fibers were fabricated, which were at the lowest predicted percentages with respect to fiber content recommended in the literature. To assess the flexural performance of fiber-reinforced concrete panels, specimens with dimensions of 200 × 600 × 20 mm were made with the same... 

In addition to enhancement of the results near the point of application of a concentrated load in the vicinity of nano-size defects, capturing surface effects in small structures, in the framework of second strain gradient elasticity is of particular interest. In this framework, sixteen additional material constants are revealed, incorporating the role of atomic structures of the elastic solid. In this work, the analytical formulations of these constants corresponding to fee metals are given in terms of the parameters of Sutton-Chen interatomic potential function. The constants for ten fcc metals are computed and tabulized. Moreover, the exact closed-form solution of the bending of a...