Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

The cyclic deformation behavior of cryomilled (CM) AA5083 alloys was compared to that of conventional AA5083-H131. The materials studied were a 100 pct CM alloy with a Gaussian grain size average of 315 nm and an alloy created by mixing 85 pct CM powder with 15 pct unmilled powder before consolidation to fabricate a plate with a bimodal grain size distribution with peak averages at 240 nm and 1.8 μm. Although the ultra-fine-grain (UFG) alloys exhibited considerably higher tensile strengths than those of the conventional material, the results from plastic-strain-controlled low-cycle fatigue tests demonstrate that all three materials exhibit identical fatigue lives across a range of plastic strain amplitudes. The CM materials exhibited softening during the first cycle, similar to other alloys produced by conventional powder metallurgy, followed by continual hardening to saturation before failure. The results reported in this study show that fatigue deformation in the CM material is accompanied by slight grain growth, pinning of dislocations at the grain boundaries, and grain rotation to produce macroscopic slip bands that localize strain, creating a single dominant fatigue crack. In contrast, the conventional alloy exhibits a cell structure and more diffuse fatigue damage accumulation

VASILY EROSHENKO AS FOUNDER AND HEADMASTER OF THE FIRST REPUBLICAN ORPHANAGE FOR BLIND CHILDREN OF THE TURKMEN SSR (1935–1945)

The article is dedicated to the 130th anniversary of the symbolist author Vasily Eroshenko and the 85th anniversary of the Turkmen School for Blind Children, founded by him. It is the first attempt to bring together and publish three groups of documents regarding Eroshenko’s work in the first Orphanage for Blind Children in Turkmen SSR created at TSSR People’s Commissariat for Education in April, 1935. Firstly, the article includes copies of TSSR People’s Commissariat for Education’s references and acts. Secondly, the memoirs of a nurse Raisa Kisileva, teacher Zinaida Shamina, and children Musa Amansakhatov, Viktor (Vaclav) Brodo, Petr Maloletenko, Valentina Maloletenko, Nurum Momyev, Bainazar Niyazmengliev, and Zoya Tokaeva. Thirdly, we introduce the articles from Turkmen press and the Moscow magazine “Life of the Blind” (1935–38) that tell about the Turkman Orphanage for Blind Children; as well as later articles of 1973–74 containing teachers and students’ memoirs. Those materials were collected in the 1970–90s by blind and sighted enthusiasts of Eroshkin Studies: Anatoly Masenko, Nikolay Osipenko, Alexander Pankov, Albert Polyakovsky and by the members of the “Poisk (Search)” club at the Ashkhabad School for the blind and partially sighted children. The article also presents new names of the orphanage children, discovered by the researchers for Eroshenko’s 100th anniversary. It is for the first time, that Eroshenko’s role of a blind mentor for blind children has been so fully disclosed. We believe that he designed that orphanage school after elementary missionary indigenous schools for the blind built in the British Burma, where he taught in 1917–18. A big difference, however, was the subordination of the school to People’s Commissariat for Education. The main reason why Eroshenko didn’t work long there was a discrepancy between the educational principles borrowed from Protestant missionary schools and the Soviet system of managing orphanages and special schools

Wavefront coding with adaptive optics

We have implemented an extended depth of field optical system by wavefront coding with a micromachined membrane deformable mirror. This approach provides a versatile extension to standard wavefront coding based on fixed phase mask. First experimental results validate the feasibility of the use of adaptive optics for variable depth wavefront coding in imaging optical systems. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.Delft Center for Systems and ControlMechanical, Maritime and Materials Engineerin