Behrang Moghaddasie
Ferdowsi University of Mashhad
[ 1 ] - Determination of Stability Domains for Nonlinear Dynamical Systems Using the Weighted Residuals Method
Finding a suitable estimation of stability domain around stable equilibrium points is an important issue in the study of nonlinear dynamical systems. This paper intends to apply a set of analytical-numerical methods to estimate the region of attraction for autonomous nonlinear systems. In mechanical and structural engineering, autonomous systems could be found in large deformation problems or c...
[ 2 ] - آسیب‌یابی بادبندها به یاری روش سادک شبه‌دوگان
راه‌کاری برای شناسایی طبقه‌‌هایی از قابهای ساختمانی ساده که بادبند‌های آن‌ها خراب شده‌اند، در این مقاله پیشنهاد می‌شود. افزون بر این، سختی جانبی هر طبقه به گونه‌ی دقیق حساب میگردد. روش نویسندگان از پاسخ‌های ایستای سازه و یک الگوی بارگذاری بهره می‌گیرد. شایان توجه است، تنها تغییرمکان‌های انتقالی سازه سنجیده میشوند. شناسایی بخش‌های آسیب‌دیده با حل مسأله‌ی برنامه‌ریزی ناخطی انجام می‌پذیرد. ر...
[ 3 ] - تحلیل کمانشی قاب های فولادی دو بعدی با پیوندهای گوناگون
در بیشتر قابهای فولادی، پیوند میان عضوها را ساده یا سخت میپندارند. در حالی که تمامی پیوندها در زیر بار، مقدار مشخصی نرمی از خود نشان میدهند. در این مقاله، اثر نرمی پیوند در تحلیل کمانشی قابهای فولادی دو بعدی بررسی میگردد. در این راستا، با بهره جویی از ضریب گیرداری، اثر پیوندهای ساده، سخت، نیمهسخت و خورجینی در تحلیل وارد میشوند. همچنین، شیوهای برای تحلیل قابهای خورجینی ارائه میگردد. ...
[ 4 ] - On the Geometrically Nonlinear Analysis of Composite Axisymmetric Shells
Composite axisymmetric shells have numerous applications; many researchers have taken advantage of the general shell element or the semi-analytical formulation to analyze these structures. The present study is devoted to the nonlinear analysis of composite axisymmetric shells by using a 1D three nodded axisymmetric shell element. Both low and higher-order shear deformations are included in the ...
[ 5 ] - Free Vibration of a Generalized Plane Frame
This article deals with the free in-plane vibration analysis of a frame with four arbitrary inclined members by differential transform method. Based on four differential equations and sixteen boundary and compatibility conditions, the related structural eigenvalue problem will be analytically formulated. The frequency parameters and mode shapes of the frame will be calculated for various values...
[ 6 ] - Free Vibration Analysis of a Six-degree-of-freedom Mass-spring System Suitable for Dynamic Vibration Absorbing of Space Frames
This study is concentrated on the natural frequencies and mode shapes of a simple three-member space frame coupled with a dynamic vibration absorber. The dynamic vibration absorber is modeled as a six-degree-of-freedom mass-spring system. For the first time, the free vibration of an elastic structure with a six-degree-of-freedom mass-spring system is found. Each member of the space frame has un...
[ 7 ] - Calibration of Hardening Rules for Cyclic Plasticity
In the realm of multi-axial ratcheting, a step by step mathematical approach is developed for the parameter determination of decomposed kinematic hardening rules. For this purpose, key characteristics are mathematically derived for these hardening rules under multi-axial loading. These characteristics are then utilized to develop expressions which relate the loading history to the accumulated p...
[ 8 ] - Static and dynamic nonlinear analysis of steel frame with semi-rigid connections
One of the important issues in the study of steel frames is to find a suitable formulation for semi-rigid connections. In this paper, the explicit stiffness matrix for a two-dimensional beam-column element having end-flexibilities is derived. The effects of the lateral uniformly distributed load on the deflection are considered. Both tensile and compressive axial loads are also taken into accou...
[ 9 ] - Nonlinear Numerical Integration Scheme in Strain Space Plasticity
Strains are applied to the integration procedure in nonlinear increments todecrease the errors arising from the linearization of plastic equations. Two deformationvectors are used to achieve this. The first vector is based on the deformations obtained bythe first iteration of the equilibrium step, and the second is acquired from the sum of thesucceeding iterations. By applying these vectors and...
[ 10 ] - A CLOSED-FORM NON- LINEAR SOLUTION FOR PLASTIC FLANGE WRINKLING OF CIRCULAR PLATES IN DEEP DRAWING PROCESS
This paper deals with two-dimensional plane stress wrinkling model of a plastic annular plate. Based on energy method and the nonlinearity of strain-displacement law, a bifurcation function in polar coordinates is derived analytically. This technique leads to the critical conditions for the onset of the plastic wrinkling of flange during the deep drawing process. To find this solution, the Tres...
[ 11 ] - Some Geometrical Bases for Incremental-Iterative Methods (RESEARCH NOTE)
Finding the equilibrium path by non-linear structural analysis is one of the most important subjects in structural engineering. In this way, Incremental-Iterative methods are extremely used. This paper introduces several factors in incremental steps. In addition, it suggests some control criteria for the iterative part of the non-linear analysis. These techniques are based on the geometric of e...
[ 12 ] - Nonlinear Analysis of Truss Structures Using Dynamic Relaxation (RESEARCH NOTE)
This paper presents a new approach for large-deflection analysis of truss structures employing the Dynamic Relaxation method (DR). The typical formulation for DR has been established utilizing the finite difference technique which is categorized as an explicit method. The special characteristic of the explicit method is its simple algebraic relationships in comparison with complicated matrix op...
[ 13 ] - Explicit Stiffness of Tapered and Monosymmetric i Beam-Columns
A formulation for finite element analysis of tapered and monosymmetric I shaped beam-columns is presented. This is a general way to analyze these types of complex elements. Based upon the formulation, member stiffness matrix is obtained explicitly. The element considered has seven nodal degrees of freedom. In addition, the related stability matrix is found. Numerical studies of the aforementio...
[ 14 ] - به فرمان آوری قاب های دو بعدی با شبکه ی عصبی سازگارشونده
یکی از دغدغه‌های همیشگی مهندسان عمران، کم کردن پاسخ‌های سازه در برابر بارهای پویای ناشی از زمین لرزه، برای جلوگیری از فاجعه‌های انسانی یا زیان های اقتصادی سنگین بوده است. دانشمندان در دو دهه‌ی پیشین، پژوهش‌های فراوانی در این باره انجام داده اند. نگره‌های کنترل پیشرفته به طور گسترده و موفقیت آمیز در سامانه‌های مهندسی برق اجرا گردیده اند. در این سال ها، پژوهش های فراوانی درباره ی کاربرد این روش ه...
[ 15 ] - Three Different Methods for Approximate Analysis of Bar Structures
In this paper, modified solutions were compared through utilizing three different approximate methods for bar structures. The modifications considered various changes in the initial design. To authors' best of knowledge, the studies have carried out on this matter so far are not broad enough and have considerred the simeltaneous variations of size, geometry and topology on the bar structures. I...
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