The purpose of this paper is to estimate the optimum improvement of surface treatment on the dynamic buckling behavior of CK35 steel alloy due to shot peening based on the experimental results. Rotating circular column buckling test machine was used to evaluate the buckling life of column under compression and combined loading. The experimental results obtained show a favorable influence of shot peening treatment on mechanical properties and dynamic buckling behavior. A maximum significant life obtained at 25 min SPT (shot peening time) under dynamic buckling. The results showed that shot peening change the type of column from long to intermediate one based on Euler and Johnson formulas.

This paper presents an experimental study on the effect of shot peening on mechanical properties and residual stresses of 2024-T351 Aluminum alloy. Under the effects of shot peening time SPT the results show that the existence of SPT can improve the mechanical properties and fatigue life up to a limit value of SPT. The 15 minutes SPT gave the highest value of (σ u , σ y ) which is about 6.7 % for (σ u ) and 11.7 % for ( σ y ). Empirical equations were proposed to evaluate the SPT with the endurance limit stress and the residual stresses. . = . ( ) . . = . ( ) .

The aim of present work is to improve mechanical and fatigue properties for Aluminum alloy7049 by using Nano composites technique. The ZrO2 with an average grain diameter of 30-40 nm, was selected as Nano particles, to reinforce Aluminum alloy7049 with different percentage as, 2, 4, 6 and 7 %. The Stir casting method was used to fabricate the Nano composites materials due to economical route for improvement and processing of metal matrix composites. The experimental results were shown that the adding of zirconium oxide (ZrO2) as reinforced material leads to improve mechanical properties. The best percentage of improvement of mechanical properties of 7049 AA was with 4% wt. of ZrO2 about (7.76% ) for ultimate tensile stress UTS, (9.62% ) for yield stress YS and (9.92%) for hardness HB than other of adding of 2, 6 and 7% of ZrO2. Also the results shown that the fatigue strength of 7049 AA with 4 % ZrO2 nanoparticles is higher than that of 7049 AA under constant loading 9.86% at 108 cycles as well as the fatigue life factor (IFLF %) at different amplitude stress 400, 350, 300 and 250 MPa  was improvement in range 66, 115, 63 and 107%  respectively.