The Finite Element Stress Analysis Of Oblique Pressure Vessel Nozzles

Tegasan di bahagian 'inboard' bekas tekanan muncung yang berserong adalah sangat rumit dan tatacara rekabentuk untuk kes sebegini masih memerlukan penyiasatan. Walaupun demikian, setakat yang penulis tahu, tiada penyelesaian beranalisis yang sempurna wujud untuk meramalkan kesan terhadap tumpuan tegasan di bahagian inboard bekas tekanan muncung yang berserong. Kod-kod piawai ASME dan BS hanya memberi maklumat untuk bekas tekanan muncung yang berjejadan. Oleh yang demikian, penyelidikan ini bertujuan untuk memberi maklumat tentang bekas tekanan muncung yang berserong dengan menyiasat kesan pengubah.a.Q . sudut serong, Alpha= 'I 10°,20°,30° dan parameter yang tldak berdimensi sepertl D!T(D!T= 10,20), d/D(dlD= 0.20, 0.35, 0.50) serta nisbah T(tff= diD atau t!T:;t diD) terhadap puncak tegasan di bahagian 'inboard' penyambungan bekas tekanan muncung. The stressing at the inboard side of the oblique pressure vessel noizle is complex, and the design procedures in such cases are still in need of investigation. However, to JIlt the best of the author's knowledge, no complete analytical solution exists for predicting the effects on stress concentration a the inboard side of the oblique pressure vessel nozzle. Both ASME and BS codes only provide information for radial pressure vessel nozzles. Therefo~e, this research intends to provide information for oblique pressure vessel nozzle by investigating the 'effect of changing the skew angle, Alpha= 10°, 20°, 30°, and the dimensionless parameters such as Dff (Dff= 10,20), dID (dID= 0.20, 0.35, 0.50), and tff (tff=dlD or tff:;t:dID) ratios on the peak stress at the inboard side of the juncture of the cyUndrical pressure vessel nozzles

Comparison of various functionally graded femoral prostheses by finite element analysis

This study is focused on finite element analysis of a model comprising femur into which a femoral component of a total hip replacement was implanted. The considered prosthesis is fabricated from a functionally graded material (FGM) comprising a layer of a titanium alloy bonded to a layer of hydroxyapatite. The elastic modulus of the FGM was adjusted in the radial, longitudinal, and longitudinal-radial directions by altering the volume fraction gradient exponent. Four cases were studied, involving two different methods of anchoring the prosthesis to the spongy bone and two cases of applied loading. The results revealed that the FG prostheses provoked more SED to the bone. The FG prostheses carried less stress, while more stress was induced to the bone and cement. Meanwhile, less shear interface stress was stimulated to the prosthesis-bone interface in the noncemented FG prostheses. The cement-bone interface carried more stress compared to the prosthesis-cement interface. Stair climbing induced more harmful effects to the implanted femur components compared to the normal walking by causing more stress. Therefore, stress shielding, developed stresses, and interface stresses in the THR components could be adjusted through the controlling stiffness of the FG prosthesis by managing volume fraction gradient exponent

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements