In this study, stability of transverse vibrations of a simply supported rectangular thin plate under periodic passage of equally-spaced moving masses, by considering all components of the mass inertia in the analysis, is examined. The periodical traverse of masses acros More
In this study, stability of transverse vibrations of a simply supported rectangular thin plate under periodic passage of equally-spaced moving masses, by considering all components of the mass inertia in the analysis, is examined. The periodical traverse of masses across the plate results to a linear time-periodic problem. Using Galerkin procedure, the partial differential equation of transverse vibration is transformed to a set of ordinary differential equations. In this study, The Floquet theory is implemented as a numerical method to obtain stable and unstable zones of parameters plane. Applying the strained parameters method as a semi-analytical method, not only certifies the stable and unstable zones resulted by Floquet theory but also clarify the coexistence phenomenon for plate-moving mass system. Numerical simulations of the plate mid-span displacement show the validity of the analytical results obtained by two methods.
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In this article, prediction of lobe stability diagram is presented with the new method of 3th degree of full discretization that is based on direct integral. First, the dynamic model of milling with delay is developed from condition form to integral form. Then e More
In this article, prediction of lobe stability diagram is presented with the new method of 3th degree of full discretization that is based on direct integral. First, the dynamic model of milling with delay is developed from condition form to integral form. Then every period is discretized in limited time sections. Full discretization method is used for manual calculation of system integral. In every small time interval, the Lagrange 3th degree multi term is applied to interpolate the condition part. Furthermore the Lagrange linear multi term is also used for interpolation of delay- and period parts. A discrete dynamic design is achieved. Now it is possible to determine the matrix of condition transition in a time interval. Using this matrix by Floquet theory, lets to predict the stability lobe diagram. A basic example provides verifying of this method by comparison with results from literatures. The MATLAB program to calculate the problem is attached.
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The dynamic instability of single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT) and triple-walled carbon nanotubes (TWCNT) embedded in an elastic medium under combined static and periodic axial loads are investigated using Floquet–Lyapuno More
The dynamic instability of single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT) and triple-walled carbon nanotubes (TWCNT) embedded in an elastic medium under combined static and periodic axial loads are investigated using Floquet–Lyapunov theory. An elastic multiple-beam model is utilized where the nested slender nanotubes are coupled with each other through the van der Waals (vdW) interlayer interaction. Moreover, a radius-dependent vdW interaction coefficient accounting for the contribution of the vdW interactions between adjacent and non-adjacent layers is considered. The Galerkin’s approximate method on the basis of trigonometric mode shape functions is used to reduce the coupled governing partial differential equations to a system of extended Mathieu-Hill equations. Applying Floquet–Lyapunov theory, the effects of elastic medium, length, number of layers and exciting frequencies on the instability conditions of CNTs are investigated. Results show that elastic medium, length of CNTs, number of layer and exciting frequency have significant effect on instability conditions of multi-walled CNTs.
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در این مقاله تحلیل پایداری دینامیکی تیری با تکیه­گاه ساده که تحت عبور متوالی جرم­ها قرار گرفته است بررسی می­شود. چنین شرایط بارگذاری روی تیر در تحلیل مسائلی از قبیل حرکت وسائل نقلیه و قطارها از روی پل­ها، جراثقیل­های حمل بار، لوله­له­های حاوی More
در این مقاله تحلیل پایداری دینامیکی تیری با تکیه­گاه ساده که تحت عبور متوالی جرم­ها قرار گرفته است بررسی می­شود. چنین شرایط بارگذاری روی تیر در تحلیل مسائلی از قبیل حرکت وسائل نقلیه و قطارها از روی پل­ها، جراثقیل­های حمل بار، لوله­له­های حاوی سیال، لوله­ی انواع اسلحه­ها حایز اهمیت است. بر اثر عبور مداوم و پریودیک جرم­ها از روی تیر، یک مسأله­ی خطی پریودیک حاصل می­شود. تئوری فلاکه و روش هارمونیک بالانس نموی برای به دست آوردن مرز پایدار و ناپایدار مسأله بر حسب پارامترهای جرم­های عبوری مورد استفاده قرار می­گیرند. منحنی مشخص کننده­ی نواحی پایدار و ناپایدار حاصل شده با استفاده از بکارگیری این دو روش به خوبی با یکدیگر مطابقت داشته و شبیه­سازیهای عددی برای مقادیر عددی پارامترهای انتخابی جرم متحرک، صحت و دقت روش­های مذکور را تأیید می­کند.
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