Simulation of the processes of drilling polymer composite blanks using digital twins

Polycrystalline composite materials made of carbon fiber reinforced plastics have more and more widespread application in mechanical engineering and become the main material for the production of modern types of high-speed transport. Thus, their share has already reached 35–45 % in the structural design of passenger aircrafts. However, the technology of machining surfaces of parts made of these materials, in particular, holes, is characterized by insufficient knowledge, the absence of regulatory standards for cutting modes and is most often based on the production experience of enterprises. When changing the processing conditions and the material, the pre-production engineering duration causes a significant increase in the cost of manufacturing parts due to the need for experimental selection of the cutting mode rational elements. To exclude the empirical selection of rational elements of the machining equipment cutting mode, the authors considered the possibility of using digital twins for studying the processes of drilling holes in the blanks made of composite materials, including those with the ultrasonic field energy introduction into the new surface shaping zone (to improve the processing quality and productivity). When modeling, the LS-DYNA program was used. The authors prepared the models and processed the results using the LS-PrePost 4.8 program. During the study, an explicit modeling method was used with preliminary validation and calibration of the results of tests of composites. The authors carried out calibration on test operations of tension, three-point bending, and interlaminar shear of the ВКУ-39 polymer composite material based on carbon fibers (carbon fiber reinforced plastic) widely used in domestic engineering. The developed finite element computer models allow simulating drilling procedures without carrying out rather complicated and expensive field tests. As a result of modeling, a simulation file was obtained, which reflects the process of drilling holes in a polymer composite material blank, as close as possible to the real-life situation with chip removal

beta-decay study of Cu-77

A beta-decay study of Cu-77 has been performed at the ISOLDE mass separator with the aim to deduce its beta-decay properties and to obtain spectroscopic information on Zn-77. Neutron-rich copper isotopes were produced by means of proton- or neutron-induced fission reactions on U-238. After the production, Cu-77 was selectively laser ionized, mass separated and sent to different detection systems where beta-gamma and beta-n coincidence data were collected. We report on the deduced half-live, decay scheme, and possible spin assignment of 77Cu

Beta decay of 71,73Co; probing single particle states approaching doubly magic 78Ni

Low-energy excited states in 71,73Ni populated via the {\beta} decay of 71,73Co were investigated in an experiment performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Detailed analysis led to the construction of level schemes of 71,73Ni, which are interpreted using systematics and analyzed using shell model calculations. The 5/2- states attributed to the the f5/2 orbital and positive parity 5/2+ and 7/2+ states from the g9/2 orbital have been identified in both 71,73Ni. In 71Ni the location of a 1/2- {\beta}-decaying isomer is proposed and limits are suggested as to the location of the isomer in 73Ni. The location of positive parity cluster states are also identified in 71,73Ni. Beta-delayed neutron branching ratios obtained from this data are given for both 71,73Co.Comment: Accepted for publication in PR

β-decay studies of the transitional nucleus Cu75 and the structure of Zn75

The β decay of Cu75 [t1/2=1.222(8)s] to levels in Zn75 was studied at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory. The γγ and βγ data were collected at the Low-energy Radioactive Ion Beam Spectroscopy Station using the high-resolution isobar separator to obtain a purified Cu75 beam with a rate of over 2000 ions per second. The excited states in Zn75 have been identified for the first time. A total of 120 γ-ray transitions were placed in a level scheme containing 59 levels including two states above the neutron separation energy and a previously unknown 1/2- isomeric state at 127 keV. Spins and parities of several states were deduced and interpreted based on the observed β feeding and γ-decay pattern. © 2011 American Physical Society

β-Decay study of neutron-rich bromine and krypton isotopes

Short-lived neutron-rich nuclei including 93Br, 93Kr, and 94Kr were produced in proton-induced fission of 238U at the Holifield Radioactive Ion Beam Facility in Oak Ridge. Their β decay was studied by means of a high-resolution online mass separator and β-γ spectroscopy methods. The half-life of T1/2 = 152(8) ms and β-delayed branching ratio of Pn = 53-8+11% measured for 93Br differs from the previously reported values of T1/2 = 102(10) ms and Pn = 68(7)%. At the same time the half-life of 94Kr T1/2 = 227(14) ms and both the half-life of T1/2 = 1.298(54) s and β-delayed branching ratio of Pn = 1.9-0.2+0.6% of 93Kr are in very good agreement with literature values. The decay properties of 93Br include previously unreported γ transitions following β-delayed neutron emission. © 2013 American Physical Society

Long-lived isomeric states and quasiparticle band structures in neutron-rich Gd 162,164 nuclei from β decay

Neutron-rich nuclei Eu162,164 were produced by bombarding a proton beam on a U238 target at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory and mass separating the Eu162,164 products. New level schemes and new γ-ray transitions of the daughters Gd162,164 were identified from β-decay spectroscopy studies. Half-lives of the Eu162,164 were remeasured to clarify the previous ambiguous results. Two quasiparticle band structures were built and compared with neighboring nuclei. The β and γ bands were extended in Gd162 and a γ band was extended in Gd164. Half-lives of the isomeric states at (6-) 1449 keV in Gd162 and (4-) 1096 keV in Gd164 were measured to be 99(3) μs and 0.56(3) μs, respectively. Projected shell model calculations were performed and found to be in good agreement with all of the experimental data

New transitions and levels for Tb 163 obtained from β -decay studies

Transitions in Tb163 following β decay of Gd163 were obtained as part of investigations of γ rays emitted following Eu163β decay to Gd163. Detailed analysis of the low-energy structure of Tb163 has been carried out with these data to expand previous β-decay studies and reactions studies of levels in Tb163. Data were collected at the LeRIBSS station of the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory with an array of four Clover HPGe detectors for γ rays and two plastic scintillators for β detection. The γ rays were identified as belonging to Gd163 and Tb163 via mass selection and γ-γ-β, γ-γ, or γ-x-ray coincidence. In total, 38 new γ-ray transitions were observed in Tb163 from 15 newly identified levels and 12 previously identified levels. Potential energy surface calculations were performed which support a rigid prolate deformation. Previously identified unplaced transitions in Tb163 have been placed within the level scheme of Tb163 and additional states and transitions have been identified